Release 1.0.223

Change serde_core's html_root_url to docs.rs/serde_core

.github/workflows/ci.yml

@@ -26,6 +26,7 @@ jobs:
         with:
           name: Cargo.lock
           path: Cargo.lock
+        continue-on-error: true
 
   windows:
     name: Test suite (windows)
@@ -51,9 +52,10 @@ jobs:
           toolchain: ${{matrix.rust}}
       - run: cd serde && cargo build --features rc
       - run: cd serde && cargo build --no-default-features
+      - run: cd test_suite/no_std && cargo build
 
   nightly:
-    name: Rust nightly ${{matrix.os == 'windows' && '(windows)' || ''}}
+    name: Rust nightly${{matrix.os == 'windows' && ' (windows)' || ''}}
     runs-on: ${{matrix.os}}-latest
     strategy:
       fail-fast: false
@@ -68,7 +70,7 @@ jobs:
       - run: cd serde && cargo build --no-default-features --features alloc
       - run: cd serde && cargo build --no-default-features --features rc,alloc
       - run: cd serde && cargo build --no-default-features --features unstable
-      - run: cd serde && cargo test --features derive,rc,unstable
+      - run: cd serde_core && cargo test --features rc,unstable
       - run: cd test_suite/no_std && cargo build
         if: matrix.os != 'windows'
       - run: cd serde_derive && cargo check --tests
@@ -82,7 +84,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [1.31.0, 1.34.0]
+        rust: [1.56.0, 1.60.0]
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v4
@@ -92,6 +94,7 @@ jobs:
       - run: sed -i '/"test_suite"/d' Cargo.toml
       - run: cd serde && cargo build --features rc
       - run: cd serde && cargo build --no-default-features
+      - run: cd serde && cargo build --no-default-features --features alloc
       - run: cd serde && cargo build
 
   derive:
@@ -109,16 +112,6 @@ jobs:
       - run: cd serde && cargo check
       - run: cd serde_derive && cargo check
 
-  alloc:
-    name: Rust 1.36.0
-    runs-on: ubuntu-latest
-    timeout-minutes: 45
-    steps:
-      - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.36.0
-      - run: sed -i '/"test_suite"/d' Cargo.toml
-      - run: cd serde && cargo build --no-default-features --features alloc
-
   minimal:
     name: Minimal versions
     runs-on: ubuntu-latest
@@ -152,6 +145,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@clippy
       - run: cd serde && cargo clippy --features rc,unstable -- -Dclippy::all -Dclippy::pedantic
+      - run: cd serde_core && cargo clippy --features rc,unstable -- -Dclippy::all -Dclippy::pedantic
       - run: cd serde_derive && cargo clippy -- -Dclippy::all -Dclippy::pedantic
       - run: cd serde_derive_internals && cargo clippy -- -Dclippy::all -Dclippy::pedantic
       - run: cd test_suite && cargo clippy --tests --features unstable -- -Dclippy::all -Dclippy::pedantic
@@ -164,8 +158,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@miri
+        with:
+          toolchain: nightly-2025-05-16  # https://github.com/rust-lang/miri/issues/4323
       - run: cargo miri setup
-      - run: cd serde && cargo miri test --features derive,rc,unstable
+      - run: cd serde_core && cargo miri test --features rc,unstable
         env:
           MIRIFLAGS: -Zmiri-strict-provenance
       - run: cd test_suite && cargo miri test --features unstable

.gitignore

@@ -1,4 +1,2 @@
-target/
-**/*.rs.bk
-*.sw[po]
-Cargo.lock
+/target/
+/Cargo.lock

Cargo.toml

@@ -1,13 +1,17 @@
 [workspace]
 members = [
     "serde",
+    "serde_core",
     "serde_derive",
     "serde_derive_internals",
     "test_suite",
 ]
+resolver = "2"
 
 [patch.crates-io]
 serde = { path = "serde" }
+serde_core = { path = "serde_core" }
+serde_derive = { path = "serde_derive" }
 
 [workspace.dependencies]
 proc-macro2 = { version = "1.0.74", default-features = false }

README.md

@@ -1,4 +1,4 @@
-# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde msrv]][Rust 1.31] [![serde_derive msrv]][Rust 1.61]
+# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde msrv]][Rust 1.56] [![serde_derive msrv]][Rust 1.61]
 
 [Build Status]: https://img.shields.io/github/actions/workflow/status/serde-rs/serde/ci.yml?branch=master
 [actions]: https://github.com/serde-rs/serde/actions?query=branch%3Amaster
@@ -6,7 +6,7 @@
 [crates.io]: https://crates.io/crates/serde
 [serde msrv]: https://img.shields.io/crates/msrv/serde.svg?label=serde%20msrv&color=lightgray
 [serde_derive msrv]: https://img.shields.io/crates/msrv/serde_derive.svg?label=serde_derive%20msrv&color=lightgray
-[Rust 1.31]: https://blog.rust-lang.org/2018/12/06/Rust-1.31-and-rust-2018.html
+[Rust 1.56]: https://blog.rust-lang.org/2021/10/21/Rust-1.56.0.html
 [Rust 1.61]: https://blog.rust-lang.org/2022/05/19/Rust-1.61.0.html
 
 **Serde is a framework for *ser*ializing and *de*serializing Rust data structures efficiently and generically.**
@@ -15,7 +15,7 @@
 
 You may be looking for:
 
-- [An overview of Serde](https://serde.rs/)
+- [An overview of Serde](https://serde.rs)
 - [Data formats supported by Serde](https://serde.rs/#data-formats)
 - [Setting up `#[derive(Serialize, Deserialize)]`](https://serde.rs/derive.html)
 - [Examples](https://serde.rs/examples.html)
@@ -27,7 +27,7 @@ You may be looking for:
 <details>
 <summary>
 Click to show Cargo.toml.
-<a href="https://play.rust-lang.org/?edition=2018&gist=72755f28f99afc95e01d63174b28c1f5" target="_blank">Run this code in the playground.</a>
+<a href="https://play.rust-lang.org/?edition=2021&gist=72755f28f99afc95e01d63174b28c1f5" target="_blank">Run this code in the playground.</a>
 </summary>
 
 ```toml

crates-io.md

@@ -6,7 +6,7 @@
 
 You may be looking for:
 
-- [An overview of Serde](https://serde.rs/)
+- [An overview of Serde](https://serde.rs)
 - [Data formats supported by Serde](https://serde.rs/#data-formats)
 - [Setting up `#[derive(Serialize, Deserialize)]`](https://serde.rs/derive.html)
 - [Examples](https://serde.rs/examples.html)

serde/Cargo.toml

@@ -1,43 +1,35 @@
 [package]
 name = "serde"
-version = "1.0.211"
+version = "1.0.223"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 build = "build.rs"
 categories = ["encoding", "no-std", "no-std::no-alloc"]
 description = "A generic serialization/deserialization framework"
 documentation = "https://docs.rs/serde"
-edition = "2018"
+edition = "2021"
 homepage = "https://serde.rs"
 keywords = ["serde", "serialization", "no_std"]
 license = "MIT OR Apache-2.0"
 readme = "crates-io.md"
 repository = "https://github.com/serde-rs/serde"
-rust-version = "1.31"
+rust-version = "1.56"
 
 [dependencies]
+serde_core = { version = "=1.0.223", path = "../serde_core", default-features = false, features = ["result"] }
 serde_derive = { version = "1", optional = true, path = "../serde_derive" }
 
-[dev-dependencies]
-serde_derive = { version = "1", path = "../serde_derive" }
-
-[lib]
-doc-scrape-examples = false
-
 [package.metadata.playground]
 features = ["derive", "rc"]
 
 [package.metadata.docs.rs]
 features = ["derive", "rc", "unstable"]
 targets = ["x86_64-unknown-linux-gnu"]
-rustdoc-args = ["--generate-link-to-definition"]
-
-# This cfg cannot be enabled, but it still forces Cargo to keep serde_derive's
-# version in lockstep with serde's, even if someone depends on the two crates
-# separately with serde's "derive" feature disabled. Every serde_derive release
-# is compatible with exactly one serde release because the generated code
-# involves nonpublic APIs which are not bound by semver.
-[target.'cfg(any())'.dependencies]
-serde_derive = { version = "=1.0.211", path = "../serde_derive" }
+rustdoc-args = [
+    "--generate-link-to-definition",
+    "--extern-html-root-url=core=https://doc.rust-lang.org",
+    "--extern-html-root-url=alloc=https://doc.rust-lang.org",
+    "--extern-html-root-url=std=https://doc.rust-lang.org",
+]
 
 
 ### FEATURES #################################################################
@@ -50,20 +42,20 @@ derive = ["serde_derive"]
 
 # Provide impls for common standard library types like Vec<T> and HashMap<K, V>.
 # Requires a dependency on the Rust standard library.
-std = []
+std = ["serde_core/std"]
 
 # Provide impls for types that require unstable functionality. For tracking and
 # discussion of unstable functionality please refer to this issue:
 #
 #    https://github.com/serde-rs/serde/issues/812
-unstable = []
+unstable = ["serde_core/unstable"]
 
 # Provide impls for types in the Rust core allocation and collections library
 # including String, Box<T>, Vec<T>, and Cow<T>. This is a subset of std but may
 # be enabled without depending on all of std.
-alloc = []
+alloc = ["serde_core/alloc"]
 
 # Opt into impls for Rc<T> and Arc<T>. Serializing and deserializing these types
 # does not preserve identity and may result in multiple copies of the same data.
 # Be sure that this is what you want before enabling this feature.
-rc = []
+rc = ["serde_core/rc"]

serde/build.rs

@@ -1,6 +1,6 @@
 use std::env;
 use std::process::Command;
-use std::str::{self, FromStr};
+use std::str;
 
 // The rustc-cfg strings below are *not* public API. Please let us know by
 // opening a GitHub issue if your build environment requires some way to enable
@@ -14,124 +14,22 @@ fn main() {
     };
 
     if minor >= 77 {
-        println!("cargo:rustc-check-cfg=cfg(no_core_cstr)");
-        println!("cargo:rustc-check-cfg=cfg(no_core_error)");
-        println!("cargo:rustc-check-cfg=cfg(no_core_net)");
-        println!("cargo:rustc-check-cfg=cfg(no_core_num_saturating)");
-        println!("cargo:rustc-check-cfg=cfg(no_core_try_from)");
-        println!("cargo:rustc-check-cfg=cfg(no_diagnostic_namespace)");
-        println!("cargo:rustc-check-cfg=cfg(no_float_copysign)");
-        println!("cargo:rustc-check-cfg=cfg(no_num_nonzero_signed)");
-        println!("cargo:rustc-check-cfg=cfg(no_relaxed_trait_bounds)");
         println!("cargo:rustc-check-cfg=cfg(no_serde_derive)");
-        println!("cargo:rustc-check-cfg=cfg(no_std_atomic)");
-        println!("cargo:rustc-check-cfg=cfg(no_std_atomic64)");
-        println!("cargo:rustc-check-cfg=cfg(no_systemtime_checked_add)");
-        println!("cargo:rustc-check-cfg=cfg(no_target_has_atomic)");
-    }
-
-    let target = env::var("TARGET").unwrap();
-    let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
-
-    // TryFrom, Atomic types, non-zero signed integers, and SystemTime::checked_add
-    // stabilized in Rust 1.34:
-    // https://blog.rust-lang.org/2019/04/11/Rust-1.34.0.html#tryfrom-and-tryinto
-    // https://blog.rust-lang.org/2019/04/11/Rust-1.34.0.html#library-stabilizations
-    if minor < 34 {
-        println!("cargo:rustc-cfg=no_core_try_from");
-        println!("cargo:rustc-cfg=no_num_nonzero_signed");
-        println!("cargo:rustc-cfg=no_systemtime_checked_add");
-        println!("cargo:rustc-cfg=no_relaxed_trait_bounds");
-    }
-
-    // f32::copysign and f64::copysign stabilized in Rust 1.35.
-    // https://blog.rust-lang.org/2019/05/23/Rust-1.35.0.html#copy-the-sign-of-a-floating-point-number-onto-another
-    if minor < 35 {
-        println!("cargo:rustc-cfg=no_float_copysign");
-    }
-
-    // Support for #[cfg(target_has_atomic = "...")] stabilized in Rust 1.60.
-    if minor < 60 {
-        println!("cargo:rustc-cfg=no_target_has_atomic");
-        // Allowlist of archs that support std::sync::atomic module. This is
-        // based on rustc's compiler/rustc_target/src/spec/*.rs.
-        let has_atomic64 = target.starts_with("x86_64")
-            || target.starts_with("i686")
-            || target.starts_with("aarch64")
-            || target.starts_with("powerpc64")
-            || target.starts_with("sparc64")
-            || target.starts_with("mips64el")
-            || target.starts_with("riscv64");
-        let has_atomic32 = has_atomic64 || emscripten;
-        if minor < 34 || !has_atomic64 {
-            println!("cargo:rustc-cfg=no_std_atomic64");
-        }
-        if minor < 34 || !has_atomic32 {
-            println!("cargo:rustc-cfg=no_std_atomic");
-        }
     }
 
     // Current minimum supported version of serde_derive crate is Rust 1.61.
     if minor < 61 {
         println!("cargo:rustc-cfg=no_serde_derive");
     }
-
-    // Support for core::ffi::CStr and alloc::ffi::CString stabilized in Rust 1.64.
-    // https://blog.rust-lang.org/2022/09/22/Rust-1.64.0.html#c-compatible-ffi-types-in-core-and-alloc
-    if minor < 64 {
-        println!("cargo:rustc-cfg=no_core_cstr");
-    }
-
-    // Support for core::num::Saturating and std::num::Saturating stabilized in Rust 1.74
-    // https://blog.rust-lang.org/2023/11/16/Rust-1.74.0.html#stabilized-apis
-    if minor < 74 {
-        println!("cargo:rustc-cfg=no_core_num_saturating");
-    }
-
-    // Support for core::net stabilized in Rust 1.77.
-    // https://blog.rust-lang.org/2024/03/21/Rust-1.77.0.html
-    if minor < 77 {
-        println!("cargo:rustc-cfg=no_core_net");
-    }
-
-    // Support for the `#[diagnostic]` tool attribute namespace
-    // https://blog.rust-lang.org/2024/05/02/Rust-1.78.0.html#diagnostic-attributes
-    if minor < 78 {
-        println!("cargo:rustc-cfg=no_diagnostic_namespace");
-    }
-
-    // The Error trait became available in core in 1.81.
-    // https://blog.rust-lang.org/2024/09/05/Rust-1.81.0.html#coreerrorerror
-    if minor < 81 {
-        println!("cargo:rustc-cfg=no_core_error");
-    }
 }
 
 fn rustc_minor_version() -> Option<u32> {
-    let rustc = match env::var_os("RUSTC") {
-        Some(rustc) => rustc,
-        None => return None,
-    };
-
-    let output = match Command::new(rustc).arg("--version").output() {
-        Ok(output) => output,
-        Err(_) => return None,
-    };
-
-    let version = match str::from_utf8(&output.stdout) {
-        Ok(version) => version,
-        Err(_) => return None,
-    };
-
+    let rustc = env::var_os("RUSTC")?;
+    let output = Command::new(rustc).arg("--version").output().ok()?;
+    let version = str::from_utf8(&output.stdout).ok()?;
     let mut pieces = version.split('.');
     if pieces.next() != Some("rustc 1") {
         return None;
     }
-
-    let next = match pieces.next() {
-        Some(next) => next,
-        None => return None,
-    };
-
-    u32::from_str(next).ok()
+    pieces.next()?.parse().ok()
 }

serde/src/integer128.rs

@@ -1,6 +1,11 @@
-// No longer used. Old versions of serde used this macro for supporting targets
-// that did not yet have 128-bit integer support.
 #[macro_export]
+#[deprecated = "
+This macro has no effect on any version of Serde released in the past 2 years.
+It was used long ago in crates that needed to support Rustc older than 1.26.0,
+or Emscripten targets older than 1.40.0, which did not yet have 128-bit integer
+support. These days Serde requires a Rust compiler newer than that so 128-bit
+integers are always supported.
+"]
 #[doc(hidden)]
 macro_rules! serde_if_integer128 {
     ($($tt:tt)*) => {

serde/src/lib.rs

@@ -9,7 +9,7 @@
 //! these two groups interact with each other, allowing any supported data
 //! structure to be serialized and deserialized using any supported data format.
 //!
-//! See the Serde website <https://serde.rs/> for additional documentation and
+//! See the Serde website <https://serde.rs> for additional documentation and
 //! usage examples.
 //!
 //! ## Design
@@ -95,7 +95,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.211")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.223")]
 // Support using Serde without the standard library!
 #![cfg_attr(not(feature = "std"), no_std)]
 // Show which crate feature enables conditionally compiled APIs in documentation.
@@ -106,7 +106,12 @@
 //
 //    https://github.com/serde-rs/serde/issues/812
 #![cfg_attr(feature = "unstable", feature(never_type))]
-#![allow(unknown_lints, bare_trait_objects, deprecated)]
+#![allow(
+    unknown_lints,
+    bare_trait_objects,
+    deprecated,
+    mismatched_lifetime_syntaxes
+)]
 // Ignored clippy and clippy_pedantic lints
 #![allow(
     // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704
@@ -144,6 +149,7 @@
     clippy::too_many_lines,
     // preference
     clippy::doc_markdown,
+    clippy::elidable_lifetime_names,
     clippy::needless_lifetimes,
     clippy::unseparated_literal_suffix,
     // false positive
@@ -174,25 +180,18 @@ mod lib {
     }
 
     pub use self::core::{f32, f64};
-    pub use self::core::{i16, i32, i64, i8, isize};
-    pub use self::core::{iter, num, ptr, str};
-    pub use self::core::{u16, u32, u64, u8, usize};
+    pub use self::core::{ptr, str};
 
     #[cfg(any(feature = "std", feature = "alloc"))]
-    pub use self::core::{cmp, mem, slice};
+    pub use self::core::slice;
 
-    pub use self::core::cell::{Cell, RefCell};
     pub use self::core::clone;
-    pub use self::core::cmp::Reverse;
     pub use self::core::convert;
     pub use self::core::default;
     pub use self::core::fmt::{self, Debug, Display, Write as FmtWrite};
     pub use self::core::marker::{self, PhantomData};
-    pub use self::core::num::Wrapping;
-    pub use self::core::ops::{Bound, Range, RangeFrom, RangeInclusive, RangeTo};
     pub use self::core::option;
     pub use self::core::result;
-    pub use self::core::time::Duration;
 
     #[cfg(all(feature = "alloc", not(feature = "std")))]
     pub use alloc::borrow::{Cow, ToOwned};
@@ -213,84 +212,13 @@ mod lib {
     pub use alloc::boxed::Box;
     #[cfg(feature = "std")]
     pub use std::boxed::Box;
-
-    #[cfg(all(feature = "rc", feature = "alloc", not(feature = "std")))]
-    pub use alloc::rc::{Rc, Weak as RcWeak};
-    #[cfg(all(feature = "rc", feature = "std"))]
-    pub use std::rc::{Rc, Weak as RcWeak};
-
-    #[cfg(all(feature = "rc", feature = "alloc", not(feature = "std")))]
-    pub use alloc::sync::{Arc, Weak as ArcWeak};
-    #[cfg(all(feature = "rc", feature = "std"))]
-    pub use std::sync::{Arc, Weak as ArcWeak};
-
-    #[cfg(all(feature = "alloc", not(feature = "std")))]
-    pub use alloc::collections::{BTreeMap, BTreeSet, BinaryHeap, LinkedList, VecDeque};
-    #[cfg(feature = "std")]
-    pub use std::collections::{BTreeMap, BTreeSet, BinaryHeap, LinkedList, VecDeque};
-
-    #[cfg(all(not(no_core_cstr), not(feature = "std")))]
-    pub use self::core::ffi::CStr;
-    #[cfg(feature = "std")]
-    pub use std::ffi::CStr;
-
-    #[cfg(all(not(no_core_cstr), feature = "alloc", not(feature = "std")))]
-    pub use alloc::ffi::CString;
-    #[cfg(feature = "std")]
-    pub use std::ffi::CString;
-
-    #[cfg(all(not(no_core_net), not(feature = "std")))]
-    pub use self::core::net;
-    #[cfg(feature = "std")]
-    pub use std::net;
-
-    #[cfg(feature = "std")]
-    pub use std::error;
-
-    #[cfg(feature = "std")]
-    pub use std::collections::{HashMap, HashSet};
-    #[cfg(feature = "std")]
-    pub use std::ffi::{OsStr, OsString};
-    #[cfg(feature = "std")]
-    pub use std::hash::{BuildHasher, Hash};
-    #[cfg(feature = "std")]
-    pub use std::io::Write;
-    #[cfg(feature = "std")]
-    pub use std::path::{Path, PathBuf};
-    #[cfg(feature = "std")]
-    pub use std::sync::{Mutex, RwLock};
-    #[cfg(feature = "std")]
-    pub use std::time::{SystemTime, UNIX_EPOCH};
-
-    #[cfg(all(feature = "std", no_target_has_atomic, not(no_std_atomic)))]
-    pub use std::sync::atomic::{
-        AtomicBool, AtomicI16, AtomicI32, AtomicI8, AtomicIsize, AtomicU16, AtomicU32, AtomicU8,
-        AtomicUsize, Ordering,
-    };
-    #[cfg(all(feature = "std", no_target_has_atomic, not(no_std_atomic64)))]
-    pub use std::sync::atomic::{AtomicI64, AtomicU64};
-
-    #[cfg(all(feature = "std", not(no_target_has_atomic)))]
-    pub use std::sync::atomic::Ordering;
-    #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "8"))]
-    pub use std::sync::atomic::{AtomicBool, AtomicI8, AtomicU8};
-    #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "16"))]
-    pub use std::sync::atomic::{AtomicI16, AtomicU16};
-    #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "32"))]
-    pub use std::sync::atomic::{AtomicI32, AtomicU32};
-    #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "64"))]
-    pub use std::sync::atomic::{AtomicI64, AtomicU64};
-    #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "ptr"))]
-    pub use std::sync::atomic::{AtomicIsize, AtomicUsize};
-
-    #[cfg(not(no_core_num_saturating))]
-    pub use self::core::num::Saturating;
 }
 
 // None of this crate's error handling needs the `From::from` error conversion
 // performed implicitly by the `?` operator or the standard library's `try!`
 // macro. This simplified macro gives a 5.5% improvement in compile time
 // compared to standard `try!`, and 9% improvement compared to `?`.
+#[cfg(not(no_serde_derive))]
 macro_rules! tri {
     ($expr:expr) => {
         match $expr {
@@ -302,33 +230,18 @@ macro_rules! tri {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[macro_use]
-mod macros;
+pub use serde_core::{
+    de, forward_to_deserialize_any, ser, Deserialize, Deserializer, Serialize, Serializer,
+};
 
 #[macro_use]
 mod integer128;
 
-pub mod de;
-pub mod ser;
-
-mod format;
-
-#[doc(inline)]
-pub use crate::de::{Deserialize, Deserializer};
-#[doc(inline)]
-pub use crate::ser::{Serialize, Serializer};
-
 // Used by generated code and doc tests. Not public API.
 #[doc(hidden)]
 #[path = "private/mod.rs"]
 pub mod __private;
 
-#[path = "de/seed.rs"]
-mod seed;
-
-#[cfg(all(not(feature = "std"), no_core_error))]
-mod std_error;
-
 // Re-export #[derive(Serialize, Deserialize)].
 //
 // The reason re-exporting is not enabled by default is that disabling it would
@@ -342,7 +255,8 @@ extern crate serde_derive;
 #[cfg_attr(docsrs, doc(cfg(feature = "derive")))]
 pub use serde_derive::{Deserialize, Serialize};
 
-#[cfg(all(not(no_serde_derive), any(feature = "std", feature = "alloc")))]
-mod actually_private {
-    pub struct T;
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __require_serde_not_serde_core {
+    () => {};
 }

serde/src/private/mod.rs

@@ -3,11 +3,8 @@ pub mod de;
 #[cfg(not(no_serde_derive))]
 pub mod ser;
 
-// FIXME: #[cfg(doctest)] once https://github.com/rust-lang/rust/issues/67295 is fixed.
-pub mod doc;
-
 pub use crate::lib::clone::Clone;
-pub use crate::lib::convert::{From, Into};
+pub use crate::lib::convert::{From, Into, TryFrom};
 pub use crate::lib::default::Default;
 pub use crate::lib::fmt::{self, Formatter};
 pub use crate::lib::marker::PhantomData;
@@ -15,34 +12,7 @@ pub use crate::lib::option::Option::{self, None, Some};
 pub use crate::lib::ptr;
 pub use crate::lib::result::Result::{self, Err, Ok};
 
-pub use self::string::from_utf8_lossy;
+pub use serde_core::__private::string::from_utf8_lossy;
 
 #[cfg(any(feature = "alloc", feature = "std"))]
 pub use crate::lib::{ToString, Vec};
-
-#[cfg(not(no_core_try_from))]
-pub use crate::lib::convert::TryFrom;
-
-mod string {
-    use crate::lib::*;
-
-    #[cfg(any(feature = "std", feature = "alloc"))]
-    pub fn from_utf8_lossy(bytes: &[u8]) -> Cow<str> {
-        String::from_utf8_lossy(bytes)
-    }
-
-    // The generated code calls this like:
-    //
-    //     let value = &_serde::__private::from_utf8_lossy(bytes);
-    //     Err(_serde::de::Error::unknown_variant(value, VARIANTS))
-    //
-    // so it is okay for the return type to be different from the std case as long
-    // as the above works.
-    #[cfg(not(any(feature = "std", feature = "alloc")))]
-    pub fn from_utf8_lossy(bytes: &[u8]) -> &str {
-        // Three unicode replacement characters if it fails. They look like a
-        // white-on-black question mark. The user will recognize it as invalid
-        // UTF-8.
-        str::from_utf8(bytes).unwrap_or("\u{fffd}\u{fffd}\u{fffd}")
-    }
-}

serde/src/private/ser.rs

@@ -54,6 +54,7 @@ enum Unsupported {
     Sequence,
     Tuple,
     TupleStruct,
+    #[cfg(not(any(feature = "std", feature = "alloc")))]
     Enum,
 }
 
@@ -70,6 +71,7 @@ impl Display for Unsupported {
             Unsupported::Sequence => formatter.write_str("a sequence"),
             Unsupported::Tuple => formatter.write_str("a tuple"),
             Unsupported::TupleStruct => formatter.write_str("a tuple struct"),
+            #[cfg(not(any(feature = "std", feature = "alloc")))]
             Unsupported::Enum => formatter.write_str("an enum"),
         }
     }
@@ -1095,9 +1097,9 @@ where
         self,
         _: &'static str,
         _: u32,
-        _: &'static str,
+        variant: &'static str,
     ) -> Result<Self::Ok, Self::Error> {
-        Err(Self::bad_type(Unsupported::Enum))
+        self.0.serialize_entry(variant, &())
     }
 
     fn serialize_newtype_struct<T>(

serde_core/Cargo.toml

@@ -0,0 +1,69 @@
+[package]
+name = "serde_core"
+version = "1.0.223"
+authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
+build = "build.rs"
+categories = ["encoding", "no-std", "no-std::no-alloc"]
+description = "Serde traits only, with no support for derive -- use the `serde` crate instead"
+documentation = "https://docs.rs/serde_core"
+edition = "2021"
+homepage = "https://serde.rs"
+keywords = ["serde", "serialization", "no_std"]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/serde-rs/serde"
+rust-version = "1.56"
+
+[dev-dependencies]
+serde = { version = "1", path = "../serde" }
+serde_derive = { version = "1", path = "../serde_derive" }
+
+[package.metadata.playground]
+features = ["rc", "result"]
+
+[package.metadata.docs.rs]
+features = ["rc", "result", "unstable"]
+targets = ["x86_64-unknown-linux-gnu"]
+rustdoc-args = [
+    "--generate-link-to-definition",
+    "--extern-html-root-url=core=https://doc.rust-lang.org",
+    "--extern-html-root-url=alloc=https://doc.rust-lang.org",
+    "--extern-html-root-url=std=https://doc.rust-lang.org",
+]
+
+# This cfg cannot be enabled, but it still forces Cargo to keep serde_derive's
+# version in lockstep with serde's, even if someone depends on the two crates
+# separately with serde's "derive" feature disabled. Every serde_derive release
+# is compatible with exactly one serde release because the generated code
+# involves nonpublic APIs which are not bound by semver.
+[target.'cfg(any())'.dependencies]
+serde_derive = { version = "=1.0.223", path = "../serde_derive" }
+
+
+### FEATURES #################################################################
+
+[features]
+default = ["std", "result"]
+
+# Provide impls for common standard library types like Vec<T> and HashMap<K, V>.
+# Requires a dependency on the Rust standard library.
+std = []
+
+# Provide impls for types that require unstable functionality. For tracking and
+# discussion of unstable functionality please refer to this issue:
+#
+#    https://github.com/serde-rs/serde/issues/812
+unstable = []
+
+# Provide impls for types in the Rust core allocation and collections library
+# including String, Box<T>, Vec<T>, and Cow<T>. This is a subset of std but may
+# be enabled without depending on all of std.
+alloc = []
+
+# Opt into impls for Rc<T> and Arc<T>. Serializing and deserializing these types
+# does not preserve identity and may result in multiple copies of the same data.
+# Be sure that this is what you want before enabling this feature.
+rc = []
+
+# Provide impls for Result<T, E>. Convenient in some contexts but can lead to
+# confusion if ? or unwrap are used incautiously.
+result = []

serde_core/LICENSE-APACHE

@@ -0,0 +1 @@
+../LICENSE-APACHE

serde_core/LICENSE-MIT

@@ -0,0 +1 @@
+../LICENSE-MIT

serde_core/README.md

@@ -0,0 +1,28 @@
+The `serde_core` crate contains Serde's trait definitions with **no support for
+#\[derive()\]**.
+
+In crates that derive an implementation of `Serialize` or `Deserialize`, you
+must depend on the [`serde`] crate, not `serde_core`.
+
+[`serde`]: https://crates.io/crates/serde
+
+In crates that handwrite implementations of Serde traits, or only use them as
+trait bounds, depending on `serde_core` is permitted. But `serde` re-exports all
+of these traits and can be used for this use case too. If in doubt, disregard
+`serde_core` and always use `serde`.
+
+Crates that depend on `serde_core` instead of `serde` are able to compile in
+parallel with `serde_derive` even when `serde`'s "derive" feature is turned on,
+as shown in the following build timings.
+
+<br>
+
+| When `serde_json` depends on `serde` |
+|---|
+| <img src="https://github.com/user-attachments/assets/78dc179c-6ab1-4059-928c-1474b0d9d0bb"> |
+
+<br>
+
+| When `serde_json` depends on `serde_core` |
+|---|
+| <img src="https://github.com/user-attachments/assets/6b6cff5e-3e45-4ac7-9db1-d99ee8b9f5f7"> |

serde_core/build.rs

@@ -0,0 +1,97 @@
+use std::env;
+use std::process::Command;
+use std::str;
+
+// The rustc-cfg strings below are *not* public API. Please let us know by
+// opening a GitHub issue if your build environment requires some way to enable
+// these cfgs other than by executing our build script.
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+
+    let minor = match rustc_minor_version() {
+        Some(minor) => minor,
+        None => return,
+    };
+
+    if minor >= 77 {
+        println!("cargo:rustc-check-cfg=cfg(no_core_cstr)");
+        println!("cargo:rustc-check-cfg=cfg(no_core_error)");
+        println!("cargo:rustc-check-cfg=cfg(no_core_net)");
+        println!("cargo:rustc-check-cfg=cfg(no_core_num_saturating)");
+        println!("cargo:rustc-check-cfg=cfg(no_diagnostic_namespace)");
+        println!("cargo:rustc-check-cfg=cfg(no_serde_derive)");
+        println!("cargo:rustc-check-cfg=cfg(no_std_atomic)");
+        println!("cargo:rustc-check-cfg=cfg(no_std_atomic64)");
+        println!("cargo:rustc-check-cfg=cfg(no_target_has_atomic)");
+    }
+
+    let target = env::var("TARGET").unwrap();
+    let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
+
+    // Support for #[cfg(target_has_atomic = "...")] stabilized in Rust 1.60.
+    if minor < 60 {
+        println!("cargo:rustc-cfg=no_target_has_atomic");
+        // Allowlist of archs that support std::sync::atomic module. This is
+        // based on rustc's compiler/rustc_target/src/spec/*.rs.
+        let has_atomic64 = target.starts_with("x86_64")
+            || target.starts_with("i686")
+            || target.starts_with("aarch64")
+            || target.starts_with("powerpc64")
+            || target.starts_with("sparc64")
+            || target.starts_with("mips64el")
+            || target.starts_with("riscv64");
+        let has_atomic32 = has_atomic64 || emscripten;
+        if minor < 34 || !has_atomic64 {
+            println!("cargo:rustc-cfg=no_std_atomic64");
+        }
+        if minor < 34 || !has_atomic32 {
+            println!("cargo:rustc-cfg=no_std_atomic");
+        }
+    }
+
+    // Current minimum supported version of serde_derive crate is Rust 1.61.
+    if minor < 61 {
+        println!("cargo:rustc-cfg=no_serde_derive");
+    }
+
+    // Support for core::ffi::CStr and alloc::ffi::CString stabilized in Rust 1.64.
+    // https://blog.rust-lang.org/2022/09/22/Rust-1.64.0.html#c-compatible-ffi-types-in-core-and-alloc
+    if minor < 64 {
+        println!("cargo:rustc-cfg=no_core_cstr");
+    }
+
+    // Support for core::num::Saturating and std::num::Saturating stabilized in Rust 1.74
+    // https://blog.rust-lang.org/2023/11/16/Rust-1.74.0.html#stabilized-apis
+    if minor < 74 {
+        println!("cargo:rustc-cfg=no_core_num_saturating");
+    }
+
+    // Support for core::net stabilized in Rust 1.77.
+    // https://blog.rust-lang.org/2024/03/21/Rust-1.77.0.html
+    if minor < 77 {
+        println!("cargo:rustc-cfg=no_core_net");
+    }
+
+    // Support for the `#[diagnostic]` tool attribute namespace
+    // https://blog.rust-lang.org/2024/05/02/Rust-1.78.0.html#diagnostic-attributes
+    if minor < 78 {
+        println!("cargo:rustc-cfg=no_diagnostic_namespace");
+    }
+
+    // The Error trait became available in core in 1.81.
+    // https://blog.rust-lang.org/2024/09/05/Rust-1.81.0.html#coreerrorerror
+    if minor < 81 {
+        println!("cargo:rustc-cfg=no_core_error");
+    }
+}
+
+fn rustc_minor_version() -> Option<u32> {
+    let rustc = env::var_os("RUSTC")?;
+    let output = Command::new(rustc).arg("--version").output().ok()?;
+    let version = str::from_utf8(&output.stdout).ok()?;
+    let mut pieces = version.split('.');
+    if pieces.next() != Some("rustc 1") {
+        return None;
+    }
+    pieces.next()?.parse().ok()
+}

serde_core/src/de/impls.rs

@@ -4,11 +4,10 @@ use crate::de::{
     Deserialize, Deserializer, EnumAccess, Error, MapAccess, SeqAccess, Unexpected, VariantAccess,
     Visitor,
 };
-
-use crate::seed::InPlaceSeed;
+use crate::private::{self, InPlaceSeed};
 
 #[cfg(any(feature = "std", feature = "alloc"))]
-use crate::de::size_hint;
+use crate::private::size_hint;
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -80,10 +79,9 @@ impl<'de> Deserialize<'de> for bool {
 ////////////////////////////////////////////////////////////////////////////////
 
 macro_rules! impl_deserialize_num {
-    ($primitive:ident, $nonzero:ident $(cfg($($cfg:tt)*))*, $deserialize:ident $($method:ident!($($val:ident : $visit:ident)*);)*) => {
+    ($primitive:ident, $nonzero:ident, $deserialize:ident $($method:ident!($($val:ident : $visit:ident)*);)*) => {
         impl_deserialize_num!($primitive, $deserialize $($method!($($val : $visit)*);)*);
 
-        $(#[cfg($($cfg)*)])*
         impl<'de> Deserialize<'de> for num::$nonzero {
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
@@ -228,12 +226,12 @@ macro_rules! num_as_copysign_self {
         where
             E: Error,
         {
-            #[cfg(any(no_float_copysign, not(feature = "std")))]
+            #[cfg(not(feature = "std"))]
             {
                 Ok(v as Self::Value)
             }
 
-            #[cfg(all(not(no_float_copysign), feature = "std"))]
+            #[cfg(feature = "std")]
             {
                 // Preserve sign of NaN. The `as` produces a nondeterministic sign.
                 let sign = if v.is_sign_positive() { 1.0 } else { -1.0 };
@@ -250,13 +248,8 @@ macro_rules! int_to_int {
         where
             E: Error,
         {
-            if Self::Value::min_value() as i64 <= v as i64
-                && v as i64 <= Self::Value::max_value() as i64
-            {
-                Ok(v as Self::Value)
-            } else {
-                Err(Error::invalid_value(Unexpected::Signed(v as i64), &self))
-            }
+            Self::Value::try_from(v as i64)
+                .map_err(|_| Error::invalid_value(Unexpected::Signed(v as i64), &self))
         }
     };
 
@@ -265,10 +258,8 @@ macro_rules! int_to_int {
         where
             E: Error,
         {
-            if $primitive::min_value() as i64 <= v as i64
-                && v as i64 <= $primitive::max_value() as i64
-            {
-                if let Some(nonzero) = Self::Value::new(v as $primitive) {
+            if let Ok(v) = $primitive::try_from(v as i64) {
+                if let Some(nonzero) = Self::Value::new(v) {
                     return Ok(nonzero);
                 }
             }
@@ -299,11 +290,13 @@ macro_rules! int_to_uint {
         where
             E: Error,
         {
-            if 0 <= v && v as u64 <= Self::Value::max_value() as u64 {
-                Ok(v as Self::Value)
-            } else {
-                Err(Error::invalid_value(Unexpected::Signed(v as i64), &self))
+            if 0 <= v {
+                #[allow(irrefutable_let_patterns)]
+                if let Ok(v) = Self::Value::try_from(v as u64) {
+                    return Ok(v as Self::Value);
+                }
             }
+            Err(Error::invalid_value(Unexpected::Signed(v as i64), &self))
         }
     };
 
@@ -312,9 +305,12 @@ macro_rules! int_to_uint {
         where
             E: Error,
         {
-            if 0 < v && v as u64 <= $primitive::max_value() as u64 {
-                if let Some(nonzero) = Self::Value::new(v as $primitive) {
-                    return Ok(nonzero);
+            if 0 < v {
+                #[allow(irrefutable_let_patterns)]
+                if let Ok(v) = $primitive::try_from(v as u64) {
+                    if let Some(nonzero) = Self::Value::new(v) {
+                        return Ok(nonzero);
+                    }
                 }
             }
             Err(Error::invalid_value(Unexpected::Signed(v as i64), &self))
@@ -344,11 +340,8 @@ macro_rules! uint_to_self {
         where
             E: Error,
         {
-            if v as u64 <= Self::Value::max_value() as u64 {
-                Ok(v as Self::Value)
-            } else {
-                Err(Error::invalid_value(Unexpected::Unsigned(v as u64), &self))
-            }
+            Self::Value::try_from(v as u64)
+                .map_err(|_| Error::invalid_value(Unexpected::Unsigned(v as u64), &self))
         }
     };
 
@@ -357,8 +350,8 @@ macro_rules! uint_to_self {
         where
             E: Error,
         {
-            if v as u64 <= $primitive::max_value() as u64 {
-                if let Some(nonzero) = Self::Value::new(v as $primitive) {
+            if let Ok(v) = $primitive::try_from(v as u64) {
+                if let Some(nonzero) = Self::Value::new(v) {
                     return Ok(nonzero);
                 }
             }
@@ -371,7 +364,7 @@ macro_rules! uint_to_self {
         where
             E: Error,
         {
-            if v as u64 <= $primitive::MAX as u64 {
+            if let Ok(v) = $primitive::try_from(v as u64) {
                 Ok(Saturating(v as $primitive))
             } else {
                 Ok(Saturating($primitive::MAX))
@@ -381,14 +374,14 @@ macro_rules! uint_to_self {
 }
 
 impl_deserialize_num! {
-    i8, NonZeroI8 cfg(not(no_num_nonzero_signed)), deserialize_i8
+    i8, NonZeroI8, deserialize_i8
     num_self!(i8:visit_i8);
     int_to_int!(i16:visit_i16 i32:visit_i32 i64:visit_i64);
     uint_to_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
 }
 
 impl_deserialize_num! {
-    i16, NonZeroI16 cfg(not(no_num_nonzero_signed)), deserialize_i16
+    i16, NonZeroI16, deserialize_i16
     num_self!(i16:visit_i16);
     num_as_self!(i8:visit_i8);
     int_to_int!(i32:visit_i32 i64:visit_i64);
@@ -396,7 +389,7 @@ impl_deserialize_num! {
 }
 
 impl_deserialize_num! {
-    i32, NonZeroI32 cfg(not(no_num_nonzero_signed)), deserialize_i32
+    i32, NonZeroI32, deserialize_i32
     num_self!(i32:visit_i32);
     num_as_self!(i8:visit_i8 i16:visit_i16);
     int_to_int!(i64:visit_i64);
@@ -404,14 +397,14 @@ impl_deserialize_num! {
 }
 
 impl_deserialize_num! {
-    i64, NonZeroI64 cfg(not(no_num_nonzero_signed)), deserialize_i64
+    i64, NonZeroI64, deserialize_i64
     num_self!(i64:visit_i64);
     num_as_self!(i8:visit_i8 i16:visit_i16 i32:visit_i32);
     uint_to_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
 }
 
 impl_deserialize_num! {
-    isize, NonZeroIsize cfg(not(no_num_nonzero_signed)), deserialize_i64
+    isize, NonZeroIsize, deserialize_i64
     num_as_self!(i8:visit_i8 i16:visit_i16);
     int_to_int!(i32:visit_i32 i64:visit_i64);
     uint_to_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
@@ -476,9 +469,7 @@ macro_rules! num_128 {
         where
             E: Error,
         {
-            if v as i128 >= Self::Value::min_value() as i128
-                && v as u128 <= Self::Value::max_value() as u128
-            {
+            if v as i128 >= Self::Value::MIN as i128 && v as u128 <= Self::Value::MAX as u128 {
                 Ok(v as Self::Value)
             } else {
                 Err(Error::invalid_value(
@@ -494,9 +485,7 @@ macro_rules! num_128 {
         where
             E: Error,
         {
-            if v as i128 >= $primitive::min_value() as i128
-                && v as u128 <= $primitive::max_value() as u128
-            {
+            if v as i128 >= $primitive::MIN as i128 && v as u128 <= $primitive::MAX as u128 {
                 if let Some(nonzero) = Self::Value::new(v as $primitive) {
                     Ok(nonzero)
                 } else {
@@ -528,7 +517,7 @@ macro_rules! num_128 {
 }
 
 impl_deserialize_num! {
-    i128, NonZeroI128 cfg(not(no_num_nonzero_signed)), deserialize_i128
+    i128, NonZeroI128, deserialize_i128
     num_self!(i128:visit_i128);
     num_as_self!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
     num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
@@ -2184,7 +2173,7 @@ impl<'de> Deserialize<'de> for Duration {
                             b"secs" => Ok(Field::Secs),
                             b"nanos" => Ok(Field::Nanos),
                             _ => {
-                                let value = crate::__private::from_utf8_lossy(value);
+                                let value = private::string::from_utf8_lossy(value);
                                 Err(Error::unknown_field(&*value, FIELDS))
                             }
                         }
@@ -2415,13 +2404,9 @@ impl<'de> Deserialize<'de> for SystemTime {
 
         const FIELDS: &[&str] = &["secs_since_epoch", "nanos_since_epoch"];
         let duration = tri!(deserializer.deserialize_struct("SystemTime", FIELDS, DurationVisitor));
-        #[cfg(not(no_systemtime_checked_add))]
-        let ret = UNIX_EPOCH
+        UNIX_EPOCH
             .checked_add(duration)
-            .ok_or_else(|| D::Error::custom("overflow deserializing SystemTime"));
-        #[cfg(no_systemtime_checked_add)]
-        let ret = Ok(UNIX_EPOCH + duration);
-        ret
+            .ok_or_else(|| D::Error::custom("overflow deserializing SystemTime"))
     }
 }
 
@@ -2479,6 +2464,7 @@ mod range {
     use crate::lib::*;
 
     use crate::de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
+    use crate::private;
 
     pub const FIELDS: &[&str] = &["start", "end"];
 
@@ -2524,7 +2510,7 @@ mod range {
                         b"start" => Ok(Field::Start),
                         b"end" => Ok(Field::End),
                         _ => {
-                            let value = crate::__private::from_utf8_lossy(value);
+                            let value = private::string::from_utf8_lossy(value);
                             Err(Error::unknown_field(&*value, FIELDS))
                         }
                     }
@@ -2637,6 +2623,7 @@ mod range_from {
     use crate::lib::*;
 
     use crate::de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
+    use crate::private;
 
     pub const FIELDS: &[&str] = &["start"];
 
@@ -2679,7 +2666,7 @@ mod range_from {
                     match value {
                         b"start" => Ok(Field::Start),
                         _ => {
-                            let value = crate::__private::from_utf8_lossy(value);
+                            let value = private::string::from_utf8_lossy(value);
                             Err(Error::unknown_field(&*value, FIELDS))
                         }
                     }
@@ -2775,6 +2762,7 @@ mod range_to {
     use crate::lib::*;
 
     use crate::de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
+    use crate::private;
 
     pub const FIELDS: &[&str] = &["end"];
 
@@ -2817,7 +2805,7 @@ mod range_to {
                     match value {
                         b"end" => Ok(Field::End),
                         _ => {
-                            let value = crate::__private::from_utf8_lossy(value);
+                            let value = private::string::from_utf8_lossy(value);
                             Err(Error::unknown_field(&*value, FIELDS))
                         }
                     }
@@ -2989,6 +2977,8 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
+#[cfg(feature = "result")]
+#[cfg_attr(docsrs, doc(cfg(feature = "result")))]
 impl<'de, T, E> Deserialize<'de> for Result<T, E>
 where
     T: Deserialize<'de>,

serde_core/src/de/mod.rs

@@ -101,8 +101,8 @@
 //!    - SocketAddrV6
 //!
 //! [Implementing `Deserialize`]: https://serde.rs/impl-deserialize.html
-//! [`Deserialize`]: ../trait.Deserialize.html
-//! [`Deserializer`]: ../trait.Deserializer.html
+//! [`Deserialize`]: crate::Deserialize
+//! [`Deserializer`]: crate::Deserializer
 //! [`LinkedHashMap<K, V>`]: https://docs.rs/linked-hash-map/*/linked_hash_map/struct.LinkedHashMap.html
 //! [`postcard`]: https://github.com/jamesmunns/postcard
 //! [`linked-hash-map`]: https://crates.io/crates/linked-hash-map
@@ -120,10 +120,9 @@ pub mod value;
 
 mod ignored_any;
 mod impls;
-pub(crate) mod size_hint;
 
 pub use self::ignored_any::IgnoredAny;
-
+pub use crate::private::InPlaceSeed;
 #[cfg(all(not(feature = "std"), no_core_error))]
 #[doc(no_inline)]
 pub use crate::std_error::Error as StdError;
@@ -158,6 +157,12 @@ macro_rules! declare_error_trait {
         /// type appropriate for a basic JSON data format.
         ///
         /// [example data format]: https://serde.rs/data-format.html
+        #[cfg_attr(
+            not(no_diagnostic_namespace),
+            diagnostic::on_unimplemented(
+                message = "the trait bound `{Self}: serde::de::Error` is not satisfied",
+            )
+        )]
         pub trait Error: Sized $(+ $($supertrait)::+)* {
             /// Raised when there is general error when deserializing a type.
             ///
@@ -206,7 +211,7 @@ macro_rules! declare_error_trait {
             /// containing an integer, the unexpected type is the integer and the
             /// expected type is the string.
             #[cold]
-            fn invalid_type(unexp: Unexpected, exp: &Expected) -> Self {
+            fn invalid_type(unexp: Unexpected, exp: &dyn Expected) -> Self {
                 Error::custom(format_args!("invalid type: {}, expected {}", unexp, exp))
             }
 
@@ -224,7 +229,7 @@ macro_rules! declare_error_trait {
             /// that is not valid UTF-8, the unexpected value is the bytes and the
             /// expected value is a string.
             #[cold]
-            fn invalid_value(unexp: Unexpected, exp: &Expected) -> Self {
+            fn invalid_value(unexp: Unexpected, exp: &dyn Expected) -> Self {
                 Error::custom(format_args!("invalid value: {}, expected {}", unexp, exp))
             }
 
@@ -238,7 +243,7 @@ macro_rules! declare_error_trait {
             /// expected. For example `exp` might say that a tuple of size 6 was
             /// expected.
             #[cold]
-            fn invalid_length(len: usize, exp: &Expected) -> Self {
+            fn invalid_length(len: usize, exp: &dyn Expected) -> Self {
                 Error::custom(format_args!("invalid length {}, expected {}", len, exp))
             }
 
@@ -471,6 +476,12 @@ impl<'a> fmt::Display for Unexpected<'a> {
 /// ));
 /// # }
 /// ```
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::Expected` is not satisfied",
+    )
+)]
 pub trait Expected {
     /// Format an explanation of what data was being expected. Same signature as
     /// the `Display` and `Debug` traits.
@@ -492,7 +503,7 @@ impl Expected for &str {
     }
 }
 
-impl Display for Expected + '_ {
+impl Display for dyn Expected + '_ {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         Expected::fmt(self, formatter)
     }
@@ -534,6 +545,9 @@ impl Display for Expected + '_ {
 #[cfg_attr(
     not(no_diagnostic_namespace),
     diagnostic::on_unimplemented(
+        // Prevents `serde_core::de::Deserialize` appearing in the error message
+        // in projects with no direct dependency on serde_core.
+        message = "the trait bound `{Self}: serde::Deserialize<'de>` is not satisfied",
         note = "for local types consider adding `#[derive(serde::Deserialize)]` to your `{Self}` type",
         note = "for types from other crates check whether the crate offers a `serde` feature flag",
     )
@@ -610,6 +624,12 @@ pub trait Deserialize<'de>: Sized {
 /// lifetimes].
 ///
 /// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::DeserializeOwned` is not satisfied",
+    )
+)]
 pub trait DeserializeOwned: for<'de> Deserialize<'de> {}
 impl<T> DeserializeOwned for T where T: for<'de> Deserialize<'de> {}
 
@@ -775,6 +795,12 @@ impl<T> DeserializeOwned for T where T: for<'de> Deserialize<'de> {}
 /// #     Ok(())
 /// # }
 /// ```
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::DeserializeSeed<'de>` is not satisfied",
+    )
+)]
 pub trait DeserializeSeed<'de>: Sized {
     /// The type produced by using this seed.
     type Value;
@@ -911,6 +937,12 @@ where
 /// a basic JSON `Deserializer`.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::Deserializer<'de>` is not satisfied",
+    )
+)]
 pub trait Deserializer<'de>: Sized {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -1226,13 +1258,9 @@ pub trait Deserializer<'de>: Sized {
     // Not public API.
     #[cfg(all(not(no_serde_derive), any(feature = "std", feature = "alloc")))]
     #[doc(hidden)]
-    fn __deserialize_content<V>(
-        self,
-        _: crate::actually_private::T,
-        visitor: V,
-    ) -> Result<crate::__private::de::Content<'de>, Self::Error>
+    fn __deserialize_content_v1<V>(self, visitor: V) -> Result<V::Value, Self::Error>
     where
-        V: Visitor<'de, Value = crate::__private::de::Content<'de>>,
+        V: Visitor<'de, Value = crate::private::Content<'de>>,
     {
         self.deserialize_any(visitor)
     }
@@ -1281,6 +1309,12 @@ pub trait Deserializer<'de>: Sized {
 ///     }
 /// }
 /// ```
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::Visitor<'de>` is not satisfied",
+    )
+)]
 pub trait Visitor<'de>: Sized {
     /// The value produced by this visitor.
     type Value;
@@ -1707,6 +1741,12 @@ pub trait Visitor<'de>: Sized {
 /// implementation of `SeqAccess` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::SeqAccess<'de>` is not satisfied",
+    )
+)]
 pub trait SeqAccess<'de> {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -1789,6 +1829,12 @@ where
 /// implementation of `MapAccess` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::MapAccess<'de>` is not satisfied",
+    )
+)]
 pub trait MapAccess<'de> {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -1981,6 +2027,12 @@ where
 /// implementation of `EnumAccess` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::EnumAccess<'de>` is not satisfied",
+    )
+)]
 pub trait EnumAccess<'de>: Sized {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -2028,6 +2080,12 @@ pub trait EnumAccess<'de>: Sized {
 /// implementation of `VariantAccess` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::VariantAccess<'de>` is not satisfied",
+    )
+)]
 pub trait VariantAccess<'de>: Sized {
     /// The error type that can be returned if some error occurs during
     /// deserialization. Must match the error type of our `EnumAccess`.

serde_core/src/de/value.rs

@@ -24,7 +24,8 @@
 use crate::lib::*;
 
 use self::private::{First, Second};
-use crate::de::{self, size_hint, Deserializer, Expected, IntoDeserializer, SeqAccess, Visitor};
+use crate::de::{self, Deserializer, Expected, IntoDeserializer, SeqAccess, Visitor};
+use crate::private::size_hint;
 use crate::ser;
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -175,6 +176,17 @@ where
     }
 }
 
+impl<'de, E> IntoDeserializer<'de, E> for UnitDeserializer<E>
+where
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 impl<E> Debug for UnitDeserializer<E> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         formatter.debug_struct("UnitDeserializer").finish()
@@ -225,6 +237,18 @@ where
     }
 }
 
+#[cfg(feature = "unstable")]
+impl<'de, E> IntoDeserializer<'de, E> for NeverDeserializer<E>
+where
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 macro_rules! primitive_deserializer {
@@ -279,6 +303,17 @@ macro_rules! primitive_deserializer {
             }
         }
 
+        impl<'de, E> IntoDeserializer<'de, E> for $name<E>
+        where
+            E: de::Error,
+        {
+            type Deserializer = Self;
+
+            fn into_deserializer(self) -> Self {
+                self
+            }
+        }
+
         impl<E> Debug for $name<E> {
             fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
                 formatter
@@ -369,6 +404,17 @@ where
     }
 }
 
+impl<'de, E> IntoDeserializer<'de, E> for U32Deserializer<E>
+where
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 impl<'de, E> de::EnumAccess<'de> for U32Deserializer<E>
 where
     E: de::Error,
@@ -458,6 +504,17 @@ where
     }
 }
 
+impl<'de, 'a, E> IntoDeserializer<'de, E> for StrDeserializer<'a, E>
+where
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 impl<'de, 'a, E> de::EnumAccess<'de> for StrDeserializer<'a, E>
 where
     E: de::Error,
@@ -537,6 +594,17 @@ where
     }
 }
 
+impl<'de, E> IntoDeserializer<'de, E> for BorrowedStrDeserializer<'de, E>
+where
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 impl<'de, E> de::EnumAccess<'de> for BorrowedStrDeserializer<'de, E>
 where
     E: de::Error,
@@ -640,6 +708,18 @@ where
     }
 }
 
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'de, E> IntoDeserializer<'de, E> for StringDeserializer<E>
+where
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 #[cfg(any(feature = "std", feature = "alloc"))]
 impl<'de, E> de::EnumAccess<'de> for StringDeserializer<E>
 where
@@ -748,6 +828,18 @@ where
     }
 }
 
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'de, 'a, E> IntoDeserializer<'de, E> for CowStrDeserializer<'a, E>
+where
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 #[cfg(any(feature = "std", feature = "alloc"))]
 impl<'de, 'a, E> de::EnumAccess<'de> for CowStrDeserializer<'a, E>
 where
@@ -825,6 +917,17 @@ where
     }
 }
 
+impl<'de, 'a, E> IntoDeserializer<'de, E> for BytesDeserializer<'a, E>
+where
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 impl<'a, E> Debug for BytesDeserializer<'a, E> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         formatter
@@ -873,6 +976,17 @@ where
     }
 }
 
+impl<'de, E> IntoDeserializer<'de, E> for BorrowedBytesDeserializer<'de, E>
+where
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 impl<'de, E> Debug for BorrowedBytesDeserializer<'de, E> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         formatter
@@ -952,6 +1066,19 @@ where
     }
 }
 
+impl<'de, I, T, E> IntoDeserializer<'de, E> for SeqDeserializer<I, E>
+where
+    I: Iterator<Item = T>,
+    T: IntoDeserializer<'de, E>,
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 impl<'de, I, T, E> de::SeqAccess<'de> for SeqDeserializer<I, E>
 where
     I: Iterator<Item = T>,
@@ -1083,6 +1210,17 @@ where
     }
 }
 
+impl<'de, A> IntoDeserializer<'de, A::Error> for SeqAccessDeserializer<A>
+where
+    A: de::SeqAccess<'de>,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer that iterates over a map.
@@ -1197,6 +1335,21 @@ where
     }
 }
 
+impl<'de, I, E> IntoDeserializer<'de, E> for MapDeserializer<'de, I, E>
+where
+    I: Iterator,
+    I::Item: private::Pair,
+    First<I::Item>: IntoDeserializer<'de, E>,
+    Second<I::Item>: IntoDeserializer<'de, E>,
+    E: de::Error,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 impl<'de, I, E> de::MapAccess<'de> for MapDeserializer<'de, I, E>
 where
     I: Iterator,
@@ -1498,6 +1651,17 @@ where
     }
 }
 
+impl<'de, A> IntoDeserializer<'de, A::Error> for MapAccessDeserializer<A>
+where
+    A: de::MapAccess<'de>,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 impl<'de, A> de::EnumAccess<'de> for MapAccessDeserializer<A>
 where
     A: de::MapAccess<'de>,
@@ -1551,6 +1715,17 @@ where
     }
 }
 
+impl<'de, A> IntoDeserializer<'de, A::Error> for EnumAccessDeserializer<A>
+where
+    A: de::EnumAccess<'de>,
+{
+    type Deserializer = Self;
+
+    fn into_deserializer(self) -> Self {
+        self
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 mod private {

serde_core/src/lib.rs

@@ -0,0 +1,270 @@
+//! Serde is a framework for ***ser***ializing and ***de***serializing Rust data
+//! structures efficiently and generically.
+//!
+//! The `serde_core` crate contains Serde's trait definitions with **no support
+//! for #\[derive()\]**.
+//!
+//! In crates that derive an implementation of `Serialize` or `Deserialize`, you
+//! must depend on the [`serde`] crate, not `serde_core`.
+//!
+//! [`serde`]: https://crates.io/crates/serde
+//!
+//! In crates that handwrite implementations of Serde traits, or only use them
+//! as trait bounds, depending on `serde_core` is permitted. But `serde`
+//! re-exports all of these traits and can be used for this use case too. If in
+//! doubt, disregard `serde_core` and always use `serde`.
+//!
+//! Crates that depend on `serde_core` instead of `serde` are able to compile in
+//! parallel with `serde_derive` even when `serde`'s "derive" feature is turned on,
+//! as shown in the following build timings.
+//!
+//! <br>
+//!
+//! <table>
+//! <tr><td align="center">When <code>serde_json</code> depends on <code>serde</code></td></tr>
+//! <tr><td><img src="https://github.com/user-attachments/assets/78dc179c-6ab1-4059-928c-1474b0d9d0bb"></td></tr>
+//! </table>
+//!
+//! <br>
+//!
+//! <table>
+//! <tr><td align="center">When <code>serde_json</code> depends on <code>serde_core</code></td></tr>
+//! <tr><td><img src="https://github.com/user-attachments/assets/6b6cff5e-3e45-4ac7-9db1-d99ee8b9f5f7"></td></tr>
+//! </table>
+
+////////////////////////////////////////////////////////////////////////////////
+
+// Serde types in rustdoc of other crates get linked to here.
+#![doc(html_root_url = "https://docs.rs/serde_core/1.0.223")]
+// Support using Serde without the standard library!
+#![cfg_attr(not(feature = "std"), no_std)]
+// Show which crate feature enables conditionally compiled APIs in documentation.
+#![cfg_attr(docsrs, feature(doc_cfg, rustdoc_internals))]
+#![cfg_attr(docsrs, allow(internal_features))]
+// Unstable functionality only if the user asks for it. For tracking and
+// discussion of these features please refer to this issue:
+//
+//    https://github.com/serde-rs/serde/issues/812
+#![cfg_attr(feature = "unstable", feature(never_type))]
+#![allow(unknown_lints, bare_trait_objects, deprecated)]
+// Ignored clippy and clippy_pedantic lints
+#![allow(
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704
+    clippy::unnested_or_patterns,
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/7768
+    clippy::semicolon_if_nothing_returned,
+    // not available in our oldest supported compiler
+    clippy::empty_enum,
+    clippy::type_repetition_in_bounds, // https://github.com/rust-lang/rust-clippy/issues/8772
+    // integer and float ser/de requires these sorts of casts
+    clippy::cast_possible_truncation,
+    clippy::cast_possible_wrap,
+    clippy::cast_precision_loss,
+    clippy::cast_sign_loss,
+    // things are often more readable this way
+    clippy::cast_lossless,
+    clippy::module_name_repetitions,
+    clippy::single_match_else,
+    clippy::type_complexity,
+    clippy::use_self,
+    clippy::zero_prefixed_literal,
+    // correctly used
+    clippy::derive_partial_eq_without_eq,
+    clippy::enum_glob_use,
+    clippy::explicit_auto_deref,
+    clippy::incompatible_msrv,
+    clippy::let_underscore_untyped,
+    clippy::map_err_ignore,
+    clippy::new_without_default,
+    clippy::result_unit_err,
+    clippy::wildcard_imports,
+    // not practical
+    clippy::needless_pass_by_value,
+    clippy::similar_names,
+    clippy::too_many_lines,
+    // preference
+    clippy::doc_markdown,
+    clippy::elidable_lifetime_names,
+    clippy::needless_lifetimes,
+    clippy::unseparated_literal_suffix,
+    // false positive
+    clippy::needless_doctest_main,
+    // noisy
+    clippy::missing_errors_doc,
+    clippy::must_use_candidate,
+)]
+// Restrictions
+#![deny(clippy::question_mark_used)]
+// Rustc lints.
+#![deny(missing_docs, unused_imports)]
+
+////////////////////////////////////////////////////////////////////////////////
+
+#[cfg(feature = "alloc")]
+extern crate alloc;
+
+/// A facade around all the types we need from the `std`, `core`, and `alloc`
+/// crates. This avoids elaborate import wrangling having to happen in every
+/// module.
+mod lib {
+    mod core {
+        #[cfg(not(feature = "std"))]
+        pub use core::*;
+        #[cfg(feature = "std")]
+        pub use std::*;
+    }
+
+    pub use self::core::{f32, f64};
+    pub use self::core::{iter, num, str};
+
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    pub use self::core::{cmp, mem};
+
+    pub use self::core::cell::{Cell, RefCell};
+    pub use self::core::cmp::Reverse;
+    pub use self::core::fmt::{self, Debug, Display, Write as FmtWrite};
+    pub use self::core::marker::PhantomData;
+    pub use self::core::num::Wrapping;
+    pub use self::core::ops::{Bound, Range, RangeFrom, RangeInclusive, RangeTo};
+    pub use self::core::result;
+    pub use self::core::time::Duration;
+
+    #[cfg(all(feature = "alloc", not(feature = "std")))]
+    pub use alloc::borrow::{Cow, ToOwned};
+    #[cfg(feature = "std")]
+    pub use std::borrow::{Cow, ToOwned};
+
+    #[cfg(all(feature = "alloc", not(feature = "std")))]
+    pub use alloc::string::{String, ToString};
+    #[cfg(feature = "std")]
+    pub use std::string::{String, ToString};
+
+    #[cfg(all(feature = "alloc", not(feature = "std")))]
+    pub use alloc::vec::Vec;
+    #[cfg(feature = "std")]
+    pub use std::vec::Vec;
+
+    #[cfg(all(feature = "alloc", not(feature = "std")))]
+    pub use alloc::boxed::Box;
+    #[cfg(feature = "std")]
+    pub use std::boxed::Box;
+
+    #[cfg(all(feature = "rc", feature = "alloc", not(feature = "std")))]
+    pub use alloc::rc::{Rc, Weak as RcWeak};
+    #[cfg(all(feature = "rc", feature = "std"))]
+    pub use std::rc::{Rc, Weak as RcWeak};
+
+    #[cfg(all(feature = "rc", feature = "alloc", not(feature = "std")))]
+    pub use alloc::sync::{Arc, Weak as ArcWeak};
+    #[cfg(all(feature = "rc", feature = "std"))]
+    pub use std::sync::{Arc, Weak as ArcWeak};
+
+    #[cfg(all(feature = "alloc", not(feature = "std")))]
+    pub use alloc::collections::{BTreeMap, BTreeSet, BinaryHeap, LinkedList, VecDeque};
+    #[cfg(feature = "std")]
+    pub use std::collections::{BTreeMap, BTreeSet, BinaryHeap, LinkedList, VecDeque};
+
+    #[cfg(all(not(no_core_cstr), not(feature = "std")))]
+    pub use self::core::ffi::CStr;
+    #[cfg(feature = "std")]
+    pub use std::ffi::CStr;
+
+    #[cfg(all(not(no_core_cstr), feature = "alloc", not(feature = "std")))]
+    pub use alloc::ffi::CString;
+    #[cfg(feature = "std")]
+    pub use std::ffi::CString;
+
+    #[cfg(all(not(no_core_net), not(feature = "std")))]
+    pub use self::core::net;
+    #[cfg(feature = "std")]
+    pub use std::net;
+
+    #[cfg(feature = "std")]
+    pub use std::error;
+
+    #[cfg(feature = "std")]
+    pub use std::collections::{HashMap, HashSet};
+    #[cfg(feature = "std")]
+    pub use std::ffi::{OsStr, OsString};
+    #[cfg(feature = "std")]
+    pub use std::hash::{BuildHasher, Hash};
+    #[cfg(feature = "std")]
+    pub use std::io::Write;
+    #[cfg(feature = "std")]
+    pub use std::path::{Path, PathBuf};
+    #[cfg(feature = "std")]
+    pub use std::sync::{Mutex, RwLock};
+    #[cfg(feature = "std")]
+    pub use std::time::{SystemTime, UNIX_EPOCH};
+
+    #[cfg(all(feature = "std", no_target_has_atomic, not(no_std_atomic)))]
+    pub use std::sync::atomic::{
+        AtomicBool, AtomicI16, AtomicI32, AtomicI8, AtomicIsize, AtomicU16, AtomicU32, AtomicU8,
+        AtomicUsize, Ordering,
+    };
+    #[cfg(all(feature = "std", no_target_has_atomic, not(no_std_atomic64)))]
+    pub use std::sync::atomic::{AtomicI64, AtomicU64};
+
+    #[cfg(all(feature = "std", not(no_target_has_atomic)))]
+    pub use std::sync::atomic::Ordering;
+    #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "8"))]
+    pub use std::sync::atomic::{AtomicBool, AtomicI8, AtomicU8};
+    #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "16"))]
+    pub use std::sync::atomic::{AtomicI16, AtomicU16};
+    #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "32"))]
+    pub use std::sync::atomic::{AtomicI32, AtomicU32};
+    #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "64"))]
+    pub use std::sync::atomic::{AtomicI64, AtomicU64};
+    #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "ptr"))]
+    pub use std::sync::atomic::{AtomicIsize, AtomicUsize};
+
+    #[cfg(not(no_core_num_saturating))]
+    pub use self::core::num::Saturating;
+}
+
+// None of this crate's error handling needs the `From::from` error conversion
+// performed implicitly by the `?` operator or the standard library's `try!`
+// macro. This simplified macro gives a 5.5% improvement in compile time
+// compared to standard `try!`, and 9% improvement compared to `?`.
+macro_rules! tri {
+    ($expr:expr) => {
+        match $expr {
+            Ok(val) => val,
+            Err(err) => return Err(err),
+        }
+    };
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+#[macro_use]
+mod macros;
+
+pub mod de;
+pub mod ser;
+
+mod format;
+
+#[doc(inline)]
+pub use crate::de::{Deserialize, Deserializer};
+#[doc(inline)]
+pub use crate::ser::{Serialize, Serializer};
+
+// Used by generated code. Not public API.
+#[doc(hidden)]
+#[path = "private/mod.rs"]
+pub mod __private;
+use self::__private as private;
+
+#[cfg(all(not(feature = "std"), no_core_error))]
+mod std_error;
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __require_serde_not_serde_core {
+    () => {
+        ::core::compile_error!(
+            "Serde derive requires a dependency on the serde crate, not serde_core"
+        );
+    };
+}

serde_core/src/macros.rs

@@ -1,7 +1,6 @@
 // Super explicit first paragraph because this shows up at the top level and
 // trips up people who are just looking for basic Serialize / Deserialize
 // documentation.
-//
 /// Helper macro when implementing the `Deserializer` part of a new data format
 /// for Serde.
 ///
@@ -104,9 +103,9 @@
 /// # }
 /// ```
 ///
-/// [`Deserializer`]: trait.Deserializer.html
-/// [`Visitor`]: de/trait.Visitor.html
-/// [`Deserializer::deserialize_any`]: trait.Deserializer.html#tymethod.deserialize_any
+/// [`Deserializer`]: crate::Deserializer
+/// [`Visitor`]: crate::de::Visitor
+/// [`Deserializer::deserialize_any`]: crate::Deserializer::deserialize_any
 #[macro_export(local_inner_macros)]
 macro_rules! forward_to_deserialize_any {
     (<$visitor:ident: Visitor<$lifetime:tt>> $($func:ident)*) => {

serde_core/src/private/content.rs

@@ -0,0 +1,39 @@
+use crate::lib::*;
+
+// Used from generated code to buffer the contents of the Deserializer when
+// deserializing untagged enums and internally tagged enums.
+//
+// Not public API. Use serde-value instead.
+//
+// Obsoleted by format-specific buffer types (https://github.com/serde-rs/serde/pull/2912).
+#[doc(hidden)]
+pub enum Content<'de> {
+    Bool(bool),
+
+    U8(u8),
+    U16(u16),
+    U32(u32),
+    U64(u64),
+
+    I8(i8),
+    I16(i16),
+    I32(i32),
+    I64(i64),
+
+    F32(f32),
+    F64(f64),
+
+    Char(char),
+    String(String),
+    Str(&'de str),
+    ByteBuf(Vec<u8>),
+    Bytes(&'de [u8]),
+
+    None,
+    Some(Box<Content<'de>>),
+
+    Unit,
+    Newtype(Box<Content<'de>>),
+    Seq(Vec<Content<'de>>),
+    Map(Vec<(Content<'de>, Content<'de>)>),
+}

serde_core/src/private/mod.rs

@@ -0,0 +1,21 @@
+#[cfg(all(not(no_serde_derive), any(feature = "std", feature = "alloc")))]
+mod content;
+mod seed;
+
+// FIXME: #[cfg(doctest)] once https://github.com/rust-lang/rust/issues/67295 is fixed.
+#[doc(hidden)]
+pub mod doc;
+
+#[doc(hidden)]
+pub mod size_hint;
+
+#[doc(hidden)]
+pub mod string;
+
+#[cfg(all(not(no_serde_derive), any(feature = "std", feature = "alloc")))]
+#[doc(hidden)]
+pub use self::content::Content;
+#[doc(hidden)]
+pub use self::seed::InPlaceSeed;
+#[doc(hidden)]
+pub use crate::lib::result::Result;

serde_core/src/private/size_hint.rs

@@ -1,3 +1,4 @@
+#[cfg(any(feature = "std", feature = "alloc"))]
 use crate::lib::*;
 
 pub fn from_bounds<I>(iter: &I) -> Option<usize>

serde_core/src/private/string.rs

@@ -0,0 +1,23 @@
+use crate::lib::*;
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+#[doc(hidden)]
+pub fn from_utf8_lossy(bytes: &[u8]) -> Cow<'_, str> {
+    String::from_utf8_lossy(bytes)
+}
+
+// The generated code calls this like:
+//
+//     let value = &_serde::__private::from_utf8_lossy(bytes);
+//     Err(_serde::de::Error::unknown_variant(value, VARIANTS))
+//
+// so it is okay for the return type to be different from the std case as long
+// as the above works.
+#[cfg(not(any(feature = "std", feature = "alloc")))]
+#[doc(hidden)]
+pub fn from_utf8_lossy(bytes: &[u8]) -> &str {
+    // Three unicode replacement characters if it fails. They look like a
+    // white-on-black question mark. The user will recognize it as invalid
+    // UTF-8.
+    str::from_utf8(bytes).unwrap_or("\u{fffd}\u{fffd}\u{fffd}")
+}

serde_core/src/ser/impls.rs

@@ -185,11 +185,10 @@ where
     }
 }
 
-#[cfg(not(no_relaxed_trait_bounds))]
 macro_rules! seq_impl {
     (
         $(#[$attr:meta])*
-        $ty:ident <T $(: $tbound1:ident $(+ $tbound2:ident)*)* $(, $typaram:ident : $bound:ident)*>
+        $ty:ident <T $(, $typaram:ident : $bound:ident)*>
     ) => {
         $(#[$attr])*
         impl<T $(, $typaram)*> Serialize for $ty<T $(, $typaram)*>
@@ -207,45 +206,22 @@ macro_rules! seq_impl {
     }
 }
 
-#[cfg(no_relaxed_trait_bounds)]
-macro_rules! seq_impl {
-    (
-        $(#[$attr:meta])*
-        $ty:ident <T $(: $tbound1:ident $(+ $tbound2:ident)*)* $(, $typaram:ident : $bound:ident)*>
-    ) => {
-        $(#[$attr])*
-        impl<T $(, $typaram)*> Serialize for $ty<T $(, $typaram)*>
-        where
-            T: Serialize $(+ $tbound1 $(+ $tbound2)*)*,
-            $($typaram: $bound,)*
-        {
-            #[inline]
-            fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-            where
-                S: Serializer,
-            {
-                serializer.collect_seq(self)
-            }
-        }
-    }
+seq_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    BinaryHeap<T>
 }
 
 seq_impl! {
     #[cfg(any(feature = "std", feature = "alloc"))]
     #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
-    BinaryHeap<T: Ord>
-}
-
-seq_impl! {
-    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
-    BTreeSet<T: Ord>
+    BTreeSet<T>
 }
 
 seq_impl! {
     #[cfg(feature = "std")]
     #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
-    HashSet<T: Eq + Hash, H: BuildHasher>
+    HashSet<T, H: BuildHasher>
 }
 
 seq_impl! {
@@ -445,7 +421,6 @@ tuple_impls! {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(not(no_relaxed_trait_bounds))]
 macro_rules! map_impl {
     (
         $(#[$attr:meta])*
@@ -468,30 +443,6 @@ macro_rules! map_impl {
     }
 }
 
-#[cfg(no_relaxed_trait_bounds)]
-macro_rules! map_impl {
-    (
-        $(#[$attr:meta])*
-        $ty:ident <K $(: $kbound1:ident $(+ $kbound2:ident)*)*, V $(, $typaram:ident : $bound:ident)*>
-    ) => {
-        $(#[$attr])*
-        impl<K, V $(, $typaram)*> Serialize for $ty<K, V $(, $typaram)*>
-        where
-            K: Serialize $(+ $kbound1 $(+ $kbound2)*)*,
-            V: Serialize,
-            $($typaram: $bound,)*
-        {
-            #[inline]
-            fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-            where
-                S: Serializer,
-            {
-                serializer.collect_map(self)
-            }
-        }
-    }
-}
-
 map_impl! {
     #[cfg(any(feature = "std", feature = "alloc"))]
     #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
@@ -631,16 +582,6 @@ macro_rules! nonzero_integers {
     }
 }
 
-nonzero_integers! {
-    NonZeroU8,
-    NonZeroU16,
-    NonZeroU32,
-    NonZeroU64,
-    NonZeroU128,
-    NonZeroUsize,
-}
-
-#[cfg(not(no_num_nonzero_signed))]
 nonzero_integers! {
     NonZeroI8,
     NonZeroI16,
@@ -648,6 +589,12 @@ nonzero_integers! {
     NonZeroI64,
     NonZeroI128,
     NonZeroIsize,
+    NonZeroU8,
+    NonZeroU16,
+    NonZeroU32,
+    NonZeroU64,
+    NonZeroU128,
+    NonZeroUsize,
 }
 
 impl<T> Serialize for Cell<T>
@@ -713,6 +660,8 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
+#[cfg(feature = "result")]
+#[cfg_attr(docsrs, doc(cfg(feature = "result")))]
 impl<T, E> Serialize for Result<T, E>
 where
     T: Serialize,

serde_core/src/ser/impossible.rs

@@ -17,7 +17,7 @@ use crate::ser::{
 ///
 /// ```edition2021
 /// # use serde::ser::{Serializer, Impossible};
-/// # use serde::__private::doc::Error;
+/// # use serde_core::__private::doc::Error;
 /// #
 /// # struct MySerializer;
 /// #
@@ -41,7 +41,7 @@ use crate::ser::{
 ///     }
 ///
 ///     /* other Serializer methods */
-/// #     serde::__serialize_unimplemented! {
+/// #     serde_core::__serialize_unimplemented! {
 /// #         bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str bytes none some
 /// #         unit unit_struct unit_variant newtype_struct newtype_variant
 /// #         tuple tuple_struct tuple_variant map struct struct_variant
@@ -49,14 +49,14 @@ use crate::ser::{
 /// }
 /// ```
 ///
-/// [`Serializer`]: trait.Serializer.html
-/// [`SerializeSeq`]: trait.SerializeSeq.html
-/// [`SerializeTuple`]: trait.SerializeTuple.html
-/// [`SerializeTupleStruct`]: trait.SerializeTupleStruct.html
-/// [`SerializeTupleVariant`]: trait.SerializeTupleVariant.html
-/// [`SerializeMap`]: trait.SerializeMap.html
-/// [`SerializeStruct`]: trait.SerializeStruct.html
-/// [`SerializeStructVariant`]: trait.SerializeStructVariant.html
+/// [`Serializer`]: crate::Serializer
+/// [`SerializeSeq`]: crate::ser::SerializeSeq
+/// [`SerializeTuple`]: crate::ser::SerializeTuple
+/// [`SerializeTupleStruct`]: crate::ser::SerializeTupleStruct
+/// [`SerializeTupleVariant`]: crate::ser::SerializeTupleVariant
+/// [`SerializeMap`]: crate::ser::SerializeMap
+/// [`SerializeStruct`]: crate::ser::SerializeStruct
+/// [`SerializeStructVariant`]: crate::ser::SerializeStructVariant
 pub struct Impossible<Ok, Error> {
     void: Void,
     ok: PhantomData<Ok>,

serde_core/src/ser/mod.rs

@@ -97,8 +97,8 @@
 //!
 //! [Implementing `Serialize`]: https://serde.rs/impl-serialize.html
 //! [`LinkedHashMap<K, V>`]: https://docs.rs/linked-hash-map/*/linked_hash_map/struct.LinkedHashMap.html
-//! [`Serialize`]: ../trait.Serialize.html
-//! [`Serializer`]: ../trait.Serializer.html
+//! [`Serialize`]: crate::Serialize
+//! [`Serializer`]: crate::Serializer
 //! [`postcard`]: https://github.com/jamesmunns/postcard
 //! [`linked-hash-map`]: https://crates.io/crates/linked-hash-map
 //! [`serde_derive`]: https://crates.io/crates/serde_derive
@@ -139,6 +139,12 @@ macro_rules! declare_error_trait {
         /// type appropriate for a basic JSON data format.
         ///
         /// [example data format]: https://serde.rs/data-format.html
+        #[cfg_attr(
+            not(no_diagnostic_namespace),
+            diagnostic::on_unimplemented(
+                message = "the trait bound `{Self}: serde::ser::Error` is not satisfied",
+            )
+        )]
         pub trait Error: Sized $(+ $($supertrait)::+)* {
             /// Used when a [`Serialize`] implementation encounters any error
             /// while serializing a type.
@@ -173,8 +179,8 @@ macro_rules! declare_error_trait {
             /// }
             /// ```
             ///
-            /// [`Path`]: https://doc.rust-lang.org/std/path/struct.Path.html
-            /// [`Serialize`]: ../trait.Serialize.html
+            /// [`Path`]: std::path::Path
+            /// [`Serialize`]: crate::Serialize
             fn custom<T>(msg: T) -> Self
             where
                 T: Display;
@@ -218,6 +224,9 @@ declare_error_trait!(Error: Sized + Debug + Display);
 #[cfg_attr(
     not(no_diagnostic_namespace),
     diagnostic::on_unimplemented(
+        // Prevents `serde_core::ser::Serialize` appearing in the error message
+        // in projects with no direct dependency on serde_core.
+        message = "the trait bound `{Self}: serde::Serialize` is not satisfied",
         note = "for local types consider adding `#[derive(serde::Serialize)]` to your `{Self}` type",
         note = "for types from other crates check whether the crate offers a `serde` feature flag",
     )
@@ -337,6 +346,12 @@ pub trait Serialize {
 /// a basic JSON `Serializer`.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::Serializer` is not satisfied",
+    )
+)]
 pub trait Serializer: Sized {
     /// The output type produced by this `Serializer` during successful
     /// serialization. Most serializers that produce text or binary output
@@ -345,7 +360,7 @@ pub trait Serializer: Sized {
     /// in-memory data structures may be simplified by using `Ok` to propagate
     /// the data structure around.
     ///
-    /// [`io::Write`]: https://doc.rust-lang.org/std/io/trait.Write.html
+    /// [`io::Write`]: std::io::Write
     type Ok;
 
     /// The error type when some error occurs during serialization.
@@ -398,7 +413,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for bool {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -420,7 +435,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for i8 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -442,7 +457,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for i16 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -464,7 +479,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for i32 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -482,7 +497,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for i64 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -500,7 +515,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for i128 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -527,7 +542,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for u8 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -549,7 +564,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for u16 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -571,7 +586,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for u32 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -589,7 +604,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for u64 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -607,7 +622,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for u128 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -634,7 +649,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for f32 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -652,7 +667,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for f64 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -673,7 +688,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for char {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -691,7 +706,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for str {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -714,7 +729,7 @@ pub trait Serializer: Sized {
     ///
     /// ```edition2021
     /// # use serde::ser::{Serializer, SerializeSeq};
-    /// # use serde::__private::doc::Error;
+    /// # use serde_core::__private::doc::Error;
     /// #
     /// # struct MySerializer;
     /// #
@@ -730,7 +745,7 @@ pub trait Serializer: Sized {
     ///     seq.end()
     /// }
     /// #
-    /// #     serde::__serialize_unimplemented! {
+    /// #     serde_core::__serialize_unimplemented! {
     /// #         bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str none some
     /// #         unit unit_struct unit_variant newtype_struct newtype_variant
     /// #         seq tuple tuple_struct tuple_variant map struct struct_variant
@@ -769,7 +784,7 @@ pub trait Serializer: Sized {
     /// # fn main() {}
     /// ```
     ///
-    /// [`None`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.None
+    /// [`None`]: core::option::Option::None
     fn serialize_none(self) -> Result<Self::Ok, Self::Error>;
 
     /// Serialize a [`Some(T)`] value.
@@ -802,7 +817,7 @@ pub trait Serializer: Sized {
     /// # fn main() {}
     /// ```
     ///
-    /// [`Some(T)`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.Some
+    /// [`Some(T)`]: core::option::Option::Some
     fn serialize_some<T>(self, value: &T) -> Result<Self::Ok, Self::Error>
     where
         T: ?Sized + Serialize;
@@ -812,7 +827,7 @@ pub trait Serializer: Sized {
     /// ```edition2021
     /// # use serde::Serializer;
     /// #
-    /// # serde::__private_serialize!();
+    /// # serde_core::__private_serialize!();
     /// #
     /// impl Serialize for () {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -1353,8 +1368,7 @@ pub trait Serializer: Sized {
     /// }
     /// ```
     ///
-    /// [`String`]: https://doc.rust-lang.org/std/string/struct.String.html
-    /// [`serialize_str`]: #tymethod.serialize_str
+    /// [`serialize_str`]: Self::serialize_str
     #[cfg(any(feature = "std", feature = "alloc"))]
     fn collect_str<T>(self, value: &T) -> Result<Self::Ok, Self::Error>
     where
@@ -1495,6 +1509,12 @@ pub trait Serializer: Sized {
 /// implementation of `SerializeSeq` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeSeq` is not satisfied",
+    )
+)]
 pub trait SerializeSeq {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1595,6 +1615,12 @@ pub trait SerializeSeq {
 /// implementation of `SerializeTuple` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeTuple` is not satisfied",
+    )
+)]
 pub trait SerializeTuple {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1640,6 +1666,12 @@ pub trait SerializeTuple {
 /// implementation of `SerializeTupleStruct` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeTupleStruct` is not satisfied",
+    )
+)]
 pub trait SerializeTupleStruct {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1698,6 +1730,12 @@ pub trait SerializeTupleStruct {
 /// implementation of `SerializeTupleVariant` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeTupleVariant` is not satisfied",
+    )
+)]
 pub trait SerializeTupleVariant {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1764,6 +1802,12 @@ pub trait SerializeTupleVariant {
 /// implementation of `SerializeMap` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeMap` is not satisfied",
+    )
+)]
 pub trait SerializeMap {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1805,9 +1849,9 @@ pub trait SerializeMap {
     /// care about performance or are not able to optimize `serialize_entry` any
     /// better than this.
     ///
-    /// [`Serialize`]: ../trait.Serialize.html
-    /// [`serialize_key`]: #tymethod.serialize_key
-    /// [`serialize_value`]: #tymethod.serialize_value
+    /// [`Serialize`]: crate::Serialize
+    /// [`serialize_key`]: Self::serialize_key
+    /// [`serialize_value`]: Self::serialize_value
     fn serialize_entry<K, V>(&mut self, key: &K, value: &V) -> Result<(), Self::Error>
     where
         K: ?Sized + Serialize,
@@ -1854,6 +1898,12 @@ pub trait SerializeMap {
 /// implementation of `SerializeStruct` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeStruct` is not satisfied",
+    )
+)]
 pub trait SerializeStruct {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1918,6 +1968,12 @@ pub trait SerializeStruct {
 /// implementation of `SerializeStructVariant` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeStructVariant` is not satisfied",
+    )
+)]
 pub trait SerializeStructVariant {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;

serde_core/src/std_error.rs

@@ -42,7 +42,7 @@ use crate::lib::{Debug, Display};
 /// ```
 pub trait Error: Debug + Display {
     /// The underlying cause of this error, if any.
-    fn source(&self) -> Option<&(Error + 'static)> {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
         None
     }
 }

serde_derive/Cargo.toml

@@ -1,11 +1,11 @@
 [package]
 name = "serde_derive"
-version = "1.0.211"
+version = "1.0.223"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 categories = ["no-std", "no-std::no-alloc"]
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
 documentation = "https://serde.rs/derive.html"
-edition = "2015"
+edition = "2021"
 exclude = ["build.rs"]
 homepage = "https://serde.rs"
 keywords = ["serde", "serialization", "no_std", "derive"]
@@ -32,4 +32,10 @@ serde = { version = "1", path = "../serde" }
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
-rustdoc-args = ["--generate-link-to-definition"]
+rustdoc-args = [
+    "--generate-link-to-definition",
+    "--extern-html-root-url=core=https://doc.rust-lang.org",
+    "--extern-html-root-url=alloc=https://doc.rust-lang.org",
+    "--extern-html-root-url=std=https://doc.rust-lang.org",
+    "--extern-html-root-url=proc_macro=https://doc.rust-lang.org",
+]

serde_derive/src/de.rs

@@ -1,5 +1,6 @@
 use crate::fragment::{Expr, Fragment, Match, Stmts};
 use crate::internals::ast::{Container, Data, Field, Style, Variant};
+use crate::internals::name::Name;
 use crate::internals::{attr, replace_receiver, ungroup, Ctxt, Derive};
 use crate::{bound, dummy, pretend, this};
 use proc_macro2::{Literal, Span, TokenStream};
@@ -32,6 +33,7 @@ pub fn expand_derive_deserialize(input: &mut syn::DeriveInput) -> syn::Result<To
         let vis = &input.vis;
         let used = pretend::pretend_used(&cont, params.is_packed);
         quote! {
+            #[automatically_derived]
             impl #de_impl_generics #ident #ty_generics #where_clause {
                 #vis fn deserialize<__D>(__deserializer: __D) -> #serde::__private::Result<#remote #ty_generics, __D::Error>
                 where
@@ -423,6 +425,7 @@ fn deserialize_unit_struct(params: &Parameters, cattrs: &attr::Container) -> Fra
             lifetime: _serde::__private::PhantomData<&#delife ()>,
         }
 
+        #[automatically_derived]
         impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
             type Value = #this_type #ty_generics;
 
@@ -558,6 +561,7 @@ fn deserialize_tuple(
             lifetime: _serde::__private::PhantomData<&#delife ()>,
         }
 
+        #[automatically_derived]
         impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
             type Value = #this_type #ty_generics;
 
@@ -657,6 +661,7 @@ fn deserialize_tuple_in_place(
             lifetime: _serde::__private::PhantomData<&#delife ()>,
         }
 
+        #[automatically_derived]
         impl #in_place_impl_generics _serde::de::Visitor<#delife> for __Visitor #in_place_ty_generics #where_clause {
             type Value = ();
 
@@ -875,13 +880,14 @@ fn deserialize_newtype_struct(
 ) -> TokenStream {
     let delife = params.borrowed.de_lifetime();
     let field_ty = field.ty;
+    let deserializer_var = quote!(__e);
 
     let value = match field.attrs.deserialize_with() {
         None => {
             let span = field.original.span();
             let func = quote_spanned!(span=> <#field_ty as _serde::Deserialize>::deserialize);
             quote! {
-                #func(__e)?
+                #func(#deserializer_var)?
             }
         }
         Some(path) => {
@@ -890,7 +896,7 @@ fn deserialize_newtype_struct(
             // on the #[serde(with = "...")]
             //                       ^^^^^
             quote_spanned! {path.span()=>
-                #path(__e)?
+                #path(#deserializer_var)?
             }
         }
     };
@@ -906,7 +912,7 @@ fn deserialize_newtype_struct(
 
     quote! {
         #[inline]
-        fn visit_newtype_struct<__E>(self, __e: __E) -> _serde::__private::Result<Self::Value, __E::Error>
+        fn visit_newtype_struct<__E>(self, #deserializer_var: __E) -> _serde::__private::Result<Self::Value, __E::Error>
         where
             __E: _serde::Deserializer<#delife>,
         {
@@ -1018,6 +1024,7 @@ fn deserialize_struct(
 
     let visitor_seed = match form {
         StructForm::ExternallyTagged(..) if has_flatten => Some(quote! {
+            #[automatically_derived]
             impl #de_impl_generics _serde::de::DeserializeSeed<#delife> for __Visitor #de_ty_generics #where_clause {
                 type Value = #this_type #ty_generics;
 
@@ -1082,6 +1089,7 @@ fn deserialize_struct(
             lifetime: _serde::__private::PhantomData<&#delife ()>,
         }
 
+        #[automatically_derived]
         impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
             type Value = #this_type #ty_generics;
 
@@ -1163,6 +1171,7 @@ fn deserialize_struct_in_place(
             lifetime: _serde::__private::PhantomData<&#delife ()>,
         }
 
+        #[automatically_derived]
         impl #in_place_impl_generics _serde::de::Visitor<#delife> for __Visitor #in_place_ty_generics #where_clause {
             type Value = ();
 
@@ -1336,6 +1345,7 @@ fn deserialize_externally_tagged_enum(
             lifetime: _serde::__private::PhantomData<&#delife ()>,
         }
 
+        #[automatically_derived]
         impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
             type Value = #this_type #ty_generics;
 
@@ -1597,6 +1607,7 @@ fn deserialize_adjacently_tagged_enum(
             lifetime: _serde::__private::PhantomData<&#delife ()>,
         }
 
+        #[automatically_derived]
         impl #de_impl_generics _serde::de::DeserializeSeed<#delife> for __Seed #de_ty_generics #where_clause {
             type Value = #this_type #ty_generics;
 
@@ -1616,6 +1627,7 @@ fn deserialize_adjacently_tagged_enum(
             lifetime: _serde::__private::PhantomData<&#delife ()>,
         }
 
+        #[automatically_derived]
         impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
             type Value = #this_type #ty_generics;
 
@@ -1657,7 +1669,7 @@ fn deserialize_adjacently_tagged_enum(
                     // First key is the content.
                     _serde::__private::Some(_serde::__private::de::TagOrContentField::Content) => {
                         // Buffer up the content.
-                        let __content = _serde::de::MapAccess::next_value::<_serde::__private::de::Content>(&mut __map)?;
+                        let __content = _serde::de::MapAccess::next_value_seed(&mut __map, _serde::__private::de::ContentVisitor::new())?;
                         // Visit the second key.
                         match #next_relevant_key {
                             // Second key is the tag.
@@ -1777,7 +1789,7 @@ fn deserialize_untagged_enum_after(
     });
 
     quote_block! {
-        let __content = <_serde::__private::de::Content as _serde::Deserialize>::deserialize(__deserializer)?;
+        let __content = _serde::de::DeserializeSeed::deserialize(_serde::__private::de::ContentVisitor::new(), __deserializer)?;
         let __deserializer = _serde::__private::de::ContentRefDeserializer::<__D::Error>::new(&__content);
 
         #first_attempt
@@ -2001,7 +2013,7 @@ fn deserialize_untagged_newtype_variant(
 
 struct FieldWithAliases<'a> {
     ident: Ident,
-    aliases: &'a BTreeSet<String>,
+    aliases: &'a BTreeSet<Name>,
 }
 
 fn deserialize_generated_identifier(
@@ -2044,12 +2056,14 @@ fn deserialize_generated_identifier(
         #[doc(hidden)]
         struct __FieldVisitor;
 
+        #[automatically_derived]
         impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
             type Value = __Field #lifetime;
 
             #visitor_impl
         }
 
+        #[automatically_derived]
         impl<'de> _serde::Deserialize<'de> for __Field #lifetime {
             #[inline]
             fn deserialize<__D>(__deserializer: __D) -> _serde::__private::Result<Self, __D::Error>
@@ -2188,6 +2202,7 @@ fn deserialize_custom_identifier(
             lifetime: _serde::__private::PhantomData<&#delife ()>,
         }
 
+        #[automatically_derived]
         impl #de_impl_generics _serde::de::Visitor<#delife> for __FieldVisitor #de_ty_generics #where_clause {
             type Value = #this_type #ty_generics;
 
@@ -2215,7 +2230,11 @@ fn deserialize_identifier(
         let ident = &field.ident;
         let aliases = field.aliases;
         // `aliases` also contains a main name
-        quote!(#(#aliases)|* => _serde::__private::Ok(#this_value::#ident))
+        quote! {
+            #(
+                #aliases => _serde::__private::Ok(#this_value::#ident),
+            )*
+        }
     });
     let bytes_mapping = deserialized_fields.iter().map(|field| {
         let ident = &field.ident;
@@ -2223,8 +2242,12 @@ fn deserialize_identifier(
         let aliases = field
             .aliases
             .iter()
-            .map(|alias| Literal::byte_string(alias.as_bytes()));
-        quote!(#(#aliases)|* => _serde::__private::Ok(#this_value::#ident))
+            .map(|alias| Literal::byte_string(alias.value.as_bytes()));
+        quote! {
+            #(
+                #aliases => _serde::__private::Ok(#this_value::#ident),
+            )*
+        }
     });
 
     let expecting = expecting.unwrap_or(if is_variant {
@@ -2422,7 +2445,7 @@ fn deserialize_identifier(
                 __E: _serde::de::Error,
             {
                 match __value {
-                    #(#str_mapping,)*
+                    #(#str_mapping)*
                     _ => {
                         #value_as_borrowed_str_content
                         #fallthrough_borrowed_arm
@@ -2435,7 +2458,7 @@ fn deserialize_identifier(
                 __E: _serde::de::Error,
             {
                 match __value {
-                    #(#bytes_mapping,)*
+                    #(#bytes_mapping)*
                     _ => {
                         #bytes_to_str
                         #value_as_borrowed_bytes_content
@@ -2460,7 +2483,7 @@ fn deserialize_identifier(
             __E: _serde::de::Error,
         {
             match __value {
-                #(#str_mapping,)*
+                #(#str_mapping)*
                 _ => {
                     #value_as_str_content
                     #fallthrough_arm
@@ -2473,7 +2496,7 @@ fn deserialize_identifier(
             __E: _serde::de::Error,
         {
             match __value {
-                #(#bytes_mapping,)*
+                #(#bytes_mapping)*
                 _ => {
                     #bytes_to_str
                     #value_as_bytes_content
@@ -2569,7 +2592,7 @@ fn deserialize_map(
             __Field::__other(__name) => {
                 __collect.push(_serde::__private::Some((
                     __name,
-                    _serde::de::MapAccess::next_value(&mut __map)?)));
+                    _serde::de::MapAccess::next_value_seed(&mut __map, _serde::__private::de::ContentVisitor::new())?)));
             }
         })
     } else if cattrs.deny_unknown_fields() {
@@ -2639,7 +2662,7 @@ fn deserialize_map(
             if let _serde::__private::Some(_serde::__private::Some((__key, _))) =
                 __collect.into_iter().filter(_serde::__private::Option::is_some).next()
             {
-                if let _serde::__private::Some(__key) = __key.as_str() {
+                if let _serde::__private::Some(__key) = _serde::__private::de::content_as_str(&__key) {
                     return _serde::__private::Err(
                         _serde::de::Error::custom(format_args!("unknown field `{}`", &__key)));
                 } else {
@@ -2882,13 +2905,14 @@ fn wrap_deserialize_with(
     let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
         split_with_de_lifetime(params);
     let delife = params.borrowed.de_lifetime();
+    let deserializer_var = quote!(__deserializer);
 
     // If #deserialize_with returns wrong type, error will be reported here (^^^^^).
     // We attach span of the path to the function so it will be reported
     // on the #[serde(with = "...")]
     //                       ^^^^^
     let value = quote_spanned! {deserialize_with.span()=>
-        #deserialize_with(__deserializer)?
+        #deserialize_with(#deserializer_var)?
     };
     let wrapper = quote! {
         #[doc(hidden)]
@@ -2898,8 +2922,9 @@ fn wrap_deserialize_with(
             lifetime: _serde::__private::PhantomData<&#delife ()>,
         }
 
+        #[automatically_derived]
         impl #de_impl_generics _serde::Deserialize<#delife> for __DeserializeWith #de_ty_generics #where_clause {
-            fn deserialize<__D>(__deserializer: __D) -> _serde::__private::Result<Self, __D::Error>
+            fn deserialize<__D>(#deserializer_var: __D) -> _serde::__private::Result<Self, __D::Error>
             where
                 __D: _serde::Deserializer<#delife>,
             {

serde_derive/src/dummy.rs

@@ -14,9 +14,17 @@ pub fn wrap_in_const(serde_path: Option<&syn::Path>, code: TokenStream) -> Token
 
     quote! {
         #[doc(hidden)]
-        #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+        #[allow(
+            non_upper_case_globals,
+            unused_attributes,
+            unused_qualifications,
+            clippy::absolute_paths,
+        )]
         const _: () = {
             #use_serde
+
+            _serde::__require_serde_not_serde_core!();
+
             #code
         };
     }

serde_derive/src/internals/attr.rs

@@ -1,3 +1,4 @@
+use crate::internals::name::{MultiName, Name};
 use crate::internals::symbol::*;
 use crate::internals::{ungroup, Ctxt};
 use proc_macro2::{Spacing, Span, TokenStream, TokenTree};
@@ -21,7 +22,7 @@ use syn::{parse_quote, token, Ident, Lifetime, Token};
 
 pub use crate::internals::case::RenameRule;
 
-struct Attr<'c, T> {
+pub(crate) struct Attr<'c, T> {
     cx: &'c Ctxt,
     name: Symbol,
     tokens: TokenStream,
@@ -62,7 +63,7 @@ impl<'c, T> Attr<'c, T> {
         }
     }
 
-    fn get(self) -> Option<T> {
+    pub(crate) fn get(self) -> Option<T> {
         self.value
     }
 
@@ -90,7 +91,7 @@ impl<'c> BoolAttr<'c> {
     }
 }
 
-struct VecAttr<'c, T> {
+pub(crate) struct VecAttr<'c, T> {
     cx: &'c Ctxt,
     name: Symbol,
     first_dup_tokens: TokenStream,
@@ -125,63 +126,13 @@ impl<'c, T> VecAttr<'c, T> {
         }
     }
 
-    fn get(self) -> Vec<T> {
+    pub(crate) fn get(self) -> Vec<T> {
         self.values
     }
 }
 
-pub struct Name {
-    serialize: String,
-    serialize_renamed: bool,
-    deserialize: String,
-    deserialize_renamed: bool,
-    deserialize_aliases: BTreeSet<String>,
-}
-
-fn unraw(ident: &Ident) -> String {
-    ident.to_string().trim_start_matches("r#").to_owned()
-}
-
-impl Name {
-    fn from_attrs(
-        source_name: String,
-        ser_name: Attr<String>,
-        de_name: Attr<String>,
-        de_aliases: Option<VecAttr<String>>,
-    ) -> Name {
-        let mut alias_set = BTreeSet::new();
-        if let Some(de_aliases) = de_aliases {
-            for alias_name in de_aliases.get() {
-                alias_set.insert(alias_name);
-            }
-        }
-
-        let ser_name = ser_name.get();
-        let ser_renamed = ser_name.is_some();
-        let de_name = de_name.get();
-        let de_renamed = de_name.is_some();
-        Name {
-            serialize: ser_name.unwrap_or_else(|| source_name.clone()),
-            serialize_renamed: ser_renamed,
-            deserialize: de_name.unwrap_or(source_name),
-            deserialize_renamed: de_renamed,
-            deserialize_aliases: alias_set,
-        }
-    }
-
-    /// Return the container name for the container when serializing.
-    pub fn serialize_name(&self) -> &str {
-        &self.serialize
-    }
-
-    /// Return the container name for the container when deserializing.
-    pub fn deserialize_name(&self) -> &str {
-        &self.deserialize
-    }
-
-    fn deserialize_aliases(&self) -> &BTreeSet<String> {
-        &self.deserialize_aliases
-    }
+fn unraw(ident: &Ident) -> Ident {
+    Ident::new(ident.to_string().trim_start_matches("r#"), ident.span())
 }
 
 #[derive(Copy, Clone)]
@@ -203,7 +154,7 @@ impl RenameAllRules {
 
 /// Represents struct or enum attribute information.
 pub struct Container {
-    name: Name,
+    name: MultiName,
     transparent: bool,
     deny_unknown_fields: bool,
     default: Default,
@@ -327,8 +278,8 @@ impl Container {
                     // #[serde(rename = "foo")]
                     // #[serde(rename(serialize = "foo", deserialize = "bar"))]
                     let (ser, de) = get_renames(cx, RENAME, &meta)?;
-                    ser_name.set_opt(&meta.path, ser.as_ref().map(syn::LitStr::value));
-                    de_name.set_opt(&meta.path, de.as_ref().map(syn::LitStr::value));
+                    ser_name.set_opt(&meta.path, ser.as_ref().map(Name::from));
+                    de_name.set_opt(&meta.path, de.as_ref().map(Name::from));
                 } else if meta.path == RENAME_ALL {
                     // #[serde(rename_all = "foo")]
                     // #[serde(rename_all(serialize = "foo", deserialize = "bar"))]
@@ -567,7 +518,7 @@ impl Container {
         }
 
         Container {
-            name: Name::from_attrs(unraw(&item.ident), ser_name, de_name, None),
+            name: MultiName::from_attrs(Name::from(&unraw(&item.ident)), ser_name, de_name, None),
             transparent: transparent.get(),
             deny_unknown_fields: deny_unknown_fields.get(),
             default: default.get().unwrap_or(Default::None),
@@ -594,7 +545,7 @@ impl Container {
         }
     }
 
-    pub fn name(&self) -> &Name {
+    pub fn name(&self) -> &MultiName {
         &self.name
     }
 
@@ -781,7 +732,7 @@ fn decide_identifier(
 
 /// Represents variant attribute information
 pub struct Variant {
-    name: Name,
+    name: MultiName,
     rename_all_rules: RenameAllRules,
     ser_bound: Option<Vec<syn::WherePredicate>>,
     de_bound: Option<Vec<syn::WherePredicate>>,
@@ -832,15 +783,15 @@ impl Variant {
                     // #[serde(rename = "foo")]
                     // #[serde(rename(serialize = "foo", deserialize = "bar"))]
                     let (ser, de) = get_multiple_renames(cx, &meta)?;
-                    ser_name.set_opt(&meta.path, ser.as_ref().map(syn::LitStr::value));
+                    ser_name.set_opt(&meta.path, ser.as_ref().map(Name::from));
                     for de_value in de {
-                        de_name.set_if_none(de_value.value());
-                        de_aliases.insert(&meta.path, de_value.value());
+                        de_name.set_if_none(Name::from(&de_value));
+                        de_aliases.insert(&meta.path, Name::from(&de_value));
                     }
                 } else if meta.path == ALIAS {
                     // #[serde(alias = "foo")]
                     if let Some(s) = get_lit_str(cx, ALIAS, &meta)? {
-                        de_aliases.insert(&meta.path, s.value());
+                        de_aliases.insert(&meta.path, Name::from(&s));
                     }
                 } else if meta.path == RENAME_ALL {
                     // #[serde(rename_all = "foo")]
@@ -947,7 +898,12 @@ impl Variant {
         }
 
         Variant {
-            name: Name::from_attrs(unraw(&variant.ident), ser_name, de_name, Some(de_aliases)),
+            name: MultiName::from_attrs(
+                Name::from(&unraw(&variant.ident)),
+                ser_name,
+                de_name,
+                Some(de_aliases),
+            ),
             rename_all_rules: RenameAllRules {
                 serialize: rename_all_ser_rule.get().unwrap_or(RenameRule::None),
                 deserialize: rename_all_de_rule.get().unwrap_or(RenameRule::None),
@@ -964,20 +920,23 @@ impl Variant {
         }
     }
 
-    pub fn name(&self) -> &Name {
+    pub fn name(&self) -> &MultiName {
         &self.name
     }
 
-    pub fn aliases(&self) -> &BTreeSet<String> {
+    pub fn aliases(&self) -> &BTreeSet<Name> {
         self.name.deserialize_aliases()
     }
 
     pub fn rename_by_rules(&mut self, rules: RenameAllRules) {
         if !self.name.serialize_renamed {
-            self.name.serialize = rules.serialize.apply_to_variant(&self.name.serialize);
+            self.name.serialize.value =
+                rules.serialize.apply_to_variant(&self.name.serialize.value);
         }
         if !self.name.deserialize_renamed {
-            self.name.deserialize = rules.deserialize.apply_to_variant(&self.name.deserialize);
+            self.name.deserialize.value = rules
+                .deserialize
+                .apply_to_variant(&self.name.deserialize.value);
         }
         self.name
             .deserialize_aliases
@@ -1023,7 +982,7 @@ impl Variant {
 
 /// Represents field attribute information
 pub struct Field {
-    name: Name,
+    name: MultiName,
     skip_serializing: bool,
     skip_deserializing: bool,
     skip_serializing_if: Option<syn::ExprPath>,
@@ -1082,8 +1041,11 @@ impl Field {
         let mut flatten = BoolAttr::none(cx, FLATTEN);
 
         let ident = match &field.ident {
-            Some(ident) => unraw(ident),
-            None => index.to_string(),
+            Some(ident) => Name::from(&unraw(ident)),
+            None => Name {
+                value: index.to_string(),
+                span: Span::call_site(),
+            },
         };
 
         if let Some(borrow_attribute) = attrs.and_then(|variant| variant.borrow.as_ref()) {
@@ -1119,15 +1081,15 @@ impl Field {
                     // #[serde(rename = "foo")]
                     // #[serde(rename(serialize = "foo", deserialize = "bar"))]
                     let (ser, de) = get_multiple_renames(cx, &meta)?;
-                    ser_name.set_opt(&meta.path, ser.as_ref().map(syn::LitStr::value));
+                    ser_name.set_opt(&meta.path, ser.as_ref().map(Name::from));
                     for de_value in de {
-                        de_name.set_if_none(de_value.value());
-                        de_aliases.insert(&meta.path, de_value.value());
+                        de_name.set_if_none(Name::from(&de_value));
+                        de_aliases.insert(&meta.path, Name::from(&de_value));
                     }
                 } else if meta.path == ALIAS {
                     // #[serde(alias = "foo")]
                     if let Some(s) = get_lit_str(cx, ALIAS, &meta)? {
-                        de_aliases.insert(&meta.path, s.value());
+                        de_aliases.insert(&meta.path, Name::from(&s));
                     }
                 } else if meta.path == DEFAULT {
                     if meta.input.peek(Token![=]) {
@@ -1290,7 +1252,7 @@ impl Field {
         }
 
         Field {
-            name: Name::from_attrs(ident, ser_name, de_name, Some(de_aliases)),
+            name: MultiName::from_attrs(ident, ser_name, de_name, Some(de_aliases)),
             skip_serializing: skip_serializing.get(),
             skip_deserializing: skip_deserializing.get(),
             skip_serializing_if: skip_serializing_if.get(),
@@ -1306,20 +1268,22 @@ impl Field {
         }
     }
 
-    pub fn name(&self) -> &Name {
+    pub fn name(&self) -> &MultiName {
         &self.name
     }
 
-    pub fn aliases(&self) -> &BTreeSet<String> {
+    pub fn aliases(&self) -> &BTreeSet<Name> {
         self.name.deserialize_aliases()
     }
 
     pub fn rename_by_rules(&mut self, rules: RenameAllRules) {
         if !self.name.serialize_renamed {
-            self.name.serialize = rules.serialize.apply_to_field(&self.name.serialize);
+            self.name.serialize.value = rules.serialize.apply_to_field(&self.name.serialize.value);
         }
         if !self.name.deserialize_renamed {
-            self.name.deserialize = rules.deserialize.apply_to_field(&self.name.deserialize);
+            self.name.deserialize.value = rules
+                .deserialize
+                .apply_to_field(&self.name.deserialize.value);
         }
         self.name
             .deserialize_aliases
@@ -1769,7 +1733,7 @@ fn is_primitive_path(path: &syn::Path, primitive: &str) -> bool {
 // attribute on the field so there must be at least one borrowable lifetime.
 fn borrowable_lifetimes(
     cx: &Ctxt,
-    name: &str,
+    name: &Name,
     field: &syn::Field,
 ) -> Result<BTreeSet<syn::Lifetime>, ()> {
     let mut lifetimes = BTreeSet::new();

serde_derive/src/internals/check.rs

@@ -329,13 +329,13 @@ fn check_internal_tag_field_name_conflict(cx: &Ctxt, cont: &Container) {
                     let name = field.attrs.name();
                     let ser_name = name.serialize_name();
 
-                    if check_ser && ser_name == tag {
+                    if check_ser && ser_name.value == tag {
                         diagnose_conflict();
                         return;
                     }
 
                     for de_name in field.attrs.aliases() {
-                        if check_de && de_name == tag {
+                        if check_de && de_name.value == tag {
                             diagnose_conflict();
                             return;
                         }

serde_derive/src/internals/mod.rs

@@ -1,5 +1,6 @@
 pub mod ast;
 pub mod attr;
+pub mod name;
 
 mod case;
 mod check;

serde_derive/src/internals/name.rs

@@ -0,0 +1,113 @@
+use crate::internals::attr::{Attr, VecAttr};
+use proc_macro2::{Ident, Span, TokenStream};
+use quote::ToTokens;
+use std::cmp::Ordering;
+use std::collections::BTreeSet;
+use std::fmt::{self, Display};
+use syn::LitStr;
+
+pub struct MultiName {
+    pub(crate) serialize: Name,
+    pub(crate) serialize_renamed: bool,
+    pub(crate) deserialize: Name,
+    pub(crate) deserialize_renamed: bool,
+    pub(crate) deserialize_aliases: BTreeSet<Name>,
+}
+
+impl MultiName {
+    pub(crate) fn from_attrs(
+        source_name: Name,
+        ser_name: Attr<Name>,
+        de_name: Attr<Name>,
+        de_aliases: Option<VecAttr<Name>>,
+    ) -> Self {
+        let mut alias_set = BTreeSet::new();
+        if let Some(de_aliases) = de_aliases {
+            for alias_name in de_aliases.get() {
+                alias_set.insert(alias_name);
+            }
+        }
+
+        let ser_name = ser_name.get();
+        let ser_renamed = ser_name.is_some();
+        let de_name = de_name.get();
+        let de_renamed = de_name.is_some();
+        MultiName {
+            serialize: ser_name.unwrap_or_else(|| source_name.clone()),
+            serialize_renamed: ser_renamed,
+            deserialize: de_name.unwrap_or(source_name),
+            deserialize_renamed: de_renamed,
+            deserialize_aliases: alias_set,
+        }
+    }
+
+    /// Return the container name for the container when serializing.
+    pub fn serialize_name(&self) -> &Name {
+        &self.serialize
+    }
+
+    /// Return the container name for the container when deserializing.
+    pub fn deserialize_name(&self) -> &Name {
+        &self.deserialize
+    }
+
+    pub(crate) fn deserialize_aliases(&self) -> &BTreeSet<Name> {
+        &self.deserialize_aliases
+    }
+}
+
+#[derive(Clone)]
+pub struct Name {
+    pub value: String,
+    pub span: Span,
+}
+
+impl ToTokens for Name {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        LitStr::new(&self.value, self.span).to_tokens(tokens);
+    }
+}
+
+impl Ord for Name {
+    fn cmp(&self, other: &Self) -> Ordering {
+        Ord::cmp(&self.value, &other.value)
+    }
+}
+
+impl PartialOrd for Name {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(Ord::cmp(self, other))
+    }
+}
+
+impl Eq for Name {}
+
+impl PartialEq for Name {
+    fn eq(&self, other: &Self) -> bool {
+        self.value == other.value
+    }
+}
+
+impl From<&Ident> for Name {
+    fn from(ident: &Ident) -> Self {
+        Name {
+            value: ident.to_string(),
+            span: ident.span(),
+        }
+    }
+}
+
+impl From<&LitStr> for Name {
+    fn from(lit: &LitStr) -> Self {
+        Name {
+            value: lit.value(),
+            span: lit.span(),
+        }
+    }
+}
+
+impl Display for Name {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.value, formatter)
+    }
+}

serde_derive/src/internals/receiver.rs

@@ -2,7 +2,6 @@ use crate::internals::respan::respan;
 use proc_macro2::Span;
 use quote::ToTokens;
 use std::mem;
-use syn::punctuated::Punctuated;
 use syn::{
     parse_quote, Data, DeriveInput, Expr, ExprPath, GenericArgument, GenericParam, Generics, Macro,
     Path, PathArguments, QSelf, ReturnType, Token, Type, TypeParamBound, TypePath, WherePredicate,
@@ -49,7 +48,7 @@ impl ReplaceReceiver<'_> {
 
         path.leading_colon = Some(**path.segments.pairs().next().unwrap().punct().unwrap());
 
-        let segments = mem::replace(&mut path.segments, Punctuated::new());
+        let segments = mem::take(&mut path.segments);
         path.segments = segments.into_pairs().skip(1).collect();
     }
 

serde_derive/src/lib.rs

@@ -13,7 +13,7 @@
 //!
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html
 
-#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.211")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.223")]
 #![cfg_attr(not(check_cfg), allow(unexpected_cfgs))]
 // Ignored clippy lints
 #![allow(
@@ -41,6 +41,7 @@
     clippy::cast_possible_truncation,
     clippy::checked_conversions,
     clippy::doc_markdown,
+    clippy::elidable_lifetime_names,
     clippy::enum_glob_use,
     clippy::indexing_slicing,
     clippy::items_after_statements,
@@ -63,6 +64,7 @@
     clippy::wildcard_imports
 )]
 #![cfg_attr(all(test, exhaustive), feature(non_exhaustive_omitted_patterns_lint))]
+#![allow(unknown_lints, mismatched_lifetime_syntaxes)]
 
 extern crate proc_macro2;
 extern crate quote;

serde_derive/src/ser.rs

@@ -1,5 +1,6 @@
 use crate::fragment::{Fragment, Match, Stmts};
 use crate::internals::ast::{Container, Data, Field, Style, Variant};
+use crate::internals::name::Name;
 use crate::internals::{attr, replace_receiver, Ctxt, Derive};
 use crate::{bound, dummy, pretend, this};
 use proc_macro2::{Span, TokenStream};
@@ -28,6 +29,7 @@ pub fn expand_derive_serialize(input: &mut syn::DeriveInput) -> syn::Result<Toke
         let vis = &input.vis;
         let used = pretend::pretend_used(&cont, params.is_packed);
         quote! {
+            #[automatically_derived]
             impl #impl_generics #ident #ty_generics #where_clause {
                 #vis fn serialize<__S>(__self: &#remote #ty_generics, __serializer: __S) -> #serde::__private::Result<__S::Ok, __S::Error>
                 where
@@ -148,7 +150,7 @@ fn build_generics(cont: &Container) -> syn::Generics {
 }
 
 // Fields with a `skip_serializing` or `serialize_with` attribute, or which
-// belong to a variant with a 'skip_serializing` or `serialize_with` attribute,
+// belong to a variant with a `skip_serializing` or `serialize_with` attribute,
 // are not serialized by us so we do not generate a bound. Fields with a `bound`
 // attribute specify their own bound so we do not generate one. All other fields
 // may need a `T: Serialize` bound where T is the type of the field.
@@ -732,6 +734,7 @@ fn serialize_adjacently_tagged_variant(
             phantom: _serde::__private::PhantomData<#this_type #ty_generics>,
         }
 
+        #[automatically_derived]
         impl #wrapper_impl_generics _serde::Serialize for __AdjacentlyTagged #wrapper_ty_generics #where_clause {
             fn serialize<__S>(&self, __serializer: __S) -> _serde::__private::Result<__S::Ok, __S::Error>
             where
@@ -798,9 +801,9 @@ fn serialize_untagged_variant(
 
 enum TupleVariant<'a> {
     ExternallyTagged {
-        type_name: &'a str,
+        type_name: &'a Name,
         variant_index: u32,
-        variant_name: &'a str,
+        variant_name: &'a Name,
     },
     Untagged,
 }
@@ -867,11 +870,11 @@ fn serialize_tuple_variant(
 enum StructVariant<'a> {
     ExternallyTagged {
         variant_index: u32,
-        variant_name: &'a str,
+        variant_name: &'a Name,
     },
     InternallyTagged {
         tag: &'a str,
-        variant_name: &'a str,
+        variant_name: &'a Name,
     },
     Untagged,
 }
@@ -880,7 +883,7 @@ fn serialize_struct_variant(
     context: StructVariant,
     params: &Parameters,
     fields: &[Field],
-    name: &str,
+    name: &Name,
 ) -> Fragment {
     if fields.iter().any(|field| field.attrs.flatten()) {
         return serialize_struct_variant_with_flatten(context, params, fields, name);
@@ -964,7 +967,7 @@ fn serialize_struct_variant_with_flatten(
     context: StructVariant,
     params: &Parameters,
     fields: &[Field],
-    name: &str,
+    name: &Name,
 ) -> Fragment {
     let struct_trait = StructTrait::SerializeMap;
     let serialize_fields = serialize_struct_visitor(fields, params, true, &struct_trait);
@@ -996,6 +999,7 @@ fn serialize_struct_variant_with_flatten(
                     phantom: _serde::__private::PhantomData<#this_type #ty_generics>,
                 }
 
+                #[automatically_derived]
                 impl #wrapper_impl_generics _serde::Serialize for __EnumFlatten #wrapper_ty_generics #where_clause {
                     fn serialize<__S>(&self, __serializer: __S) -> _serde::__private::Result<__S::Ok, __S::Error>
                     where
@@ -1220,23 +1224,27 @@ fn wrap_serialize_with(
         })
     });
 
+    let self_var = quote!(self);
+    let serializer_var = quote!(__s);
+
     // If #serialize_with returns wrong type, error will be reported on here.
     // We attach span of the path to this piece so error will be reported
     // on the #[serde(with = "...")]
     //                       ^^^^^
     let wrapper_serialize = quote_spanned! {serialize_with.span()=>
-        #serialize_with(#(self.values.#field_access, )* __s)
+        #serialize_with(#(#self_var.values.#field_access, )* #serializer_var)
     };
 
-    quote!({
+    quote!(&{
         #[doc(hidden)]
         struct __SerializeWith #wrapper_impl_generics #where_clause {
             values: (#(&'__a #field_tys, )*),
             phantom: _serde::__private::PhantomData<#this_type #ty_generics>,
         }
 
+        #[automatically_derived]
         impl #wrapper_impl_generics _serde::Serialize for __SerializeWith #wrapper_ty_generics #where_clause {
-            fn serialize<__S>(&self, __s: __S) -> _serde::__private::Result<__S::Ok, __S::Error>
+            fn serialize<__S>(&#self_var, #serializer_var: __S) -> _serde::__private::Result<__S::Ok, __S::Error>
             where
                 __S: _serde::Serializer,
             {
@@ -1244,7 +1252,7 @@ fn wrap_serialize_with(
             }
         }
 
-        &__SerializeWith {
+        __SerializeWith {
             values: (#(#field_exprs, )*),
             phantom: _serde::__private::PhantomData::<#this_type #ty_generics>,
         }

serde_derive_internals/Cargo.toml

@@ -4,7 +4,7 @@ version = "0.29.1"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 description = "AST representation used by Serde derive macros. Unstable."
 documentation = "https://docs.rs/serde_derive_internals"
-edition = "2015"
+edition = "2021"
 exclude = ["build.rs"]
 homepage = "https://serde.rs"
 keywords = ["serde", "serialization"]
@@ -22,4 +22,10 @@ syn = { workspace = true, features = ["clone-impls", "derive", "parsing", "print
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
-rustdoc-args = ["--generate-link-to-definition"]
+rustdoc-args = [
+    "--generate-link-to-definition",
+    "--extern-html-root-url=core=https://doc.rust-lang.org",
+    "--extern-html-root-url=alloc=https://doc.rust-lang.org",
+    "--extern-html-root-url=std=https://doc.rust-lang.org",
+    "--extern-html-root-url=proc_macro=https://doc.rust-lang.org",
+]

serde_derive_internals/lib.rs

@@ -21,6 +21,7 @@
 // Ignored clippy_pedantic lints
 #![allow(
     clippy::doc_markdown,
+    clippy::elidable_lifetime_names,
     clippy::enum_glob_use,
     clippy::items_after_statements,
     clippy::let_underscore_untyped,
@@ -40,6 +41,7 @@
     clippy::unused_self,
     clippy::wildcard_imports
 )]
+#![allow(unknown_lints, mismatched_lifetime_syntaxes)]
 
 extern crate proc_macro2;
 extern crate quote;

test_suite/Cargo.toml

@@ -2,7 +2,7 @@
 name = "serde_test_suite"
 version = "0.0.0"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [features]
@@ -13,9 +13,9 @@ serde = { path = "../serde" }
 
 [dev-dependencies]
 automod = "1.0.1"
-fnv = "1.0"
+foldhash = "0.2"
 rustversion = "1.0"
 serde = { path = "../serde", features = ["rc"] }
 serde_derive = { path = "../serde_derive", features = ["deserialize_in_place"] }
 serde_test = "1.0.176"
-trybuild = { version = "1.0.97", features = ["diff"] }
+trybuild = { version = "1.0.108", features = ["diff"] }

test_suite/no_std/.gitignore

@@ -0,0 +1,2 @@
+/target/
+/Cargo.lock

test_suite/no_std/Cargo.toml

@@ -2,7 +2,7 @@
 name = "serde_derive_tests_no_std"
 version = "0.0.0"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [dependencies]
@@ -10,4 +10,10 @@ libc = { version = "0.2", default-features = false }
 serde = { path = "../../serde", default-features = false }
 serde_derive = { path = "../../serde_derive" }
 
+[profile.dev]
+panic = "abort"
+
+[profile.release]
+panic = "abort"
+
 [workspace]

test_suite/no_std/src/main.rs

@@ -1,16 +1,13 @@
-#![allow(internal_features)]
-#![feature(lang_items, start)]
 #![no_std]
+#![no_main]
 
-#[start]
-fn start(_argc: isize, _argv: *const *const u8) -> isize {
+use core::ffi::c_int;
+
+#[no_mangle]
+extern "C" fn main(_argc: c_int, _argv: *const *const u8) -> c_int {
     0
 }
 
-#[lang = "eh_personality"]
-#[no_mangle]
-pub extern "C" fn rust_eh_personality() {}
-
 #[panic_handler]
 fn panic(_info: &core::panic::PanicInfo) -> ! {
     unsafe {

test_suite/tests/macros/mod.rs

@@ -34,9 +34,8 @@ macro_rules! hashset {
         $(set.insert($value);)+
         set
     }};
-    ($hasher:ident @ $($value:expr),+) => {{
-        use std::hash::BuildHasherDefault;
-        let mut set = HashSet::with_hasher(BuildHasherDefault::<$hasher>::default());
+    ($hasher:ty; $($value:expr),+) => {{
+        let mut set = HashSet::<_, $hasher>::default();
         $(set.insert($value);)+
         set
     }};
@@ -51,9 +50,8 @@ macro_rules! hashmap {
         $(map.insert($key, $value);)+
         map
     }};
-    ($hasher:ident @ $($key:expr => $value:expr),+) => {{
-        use std::hash::BuildHasherDefault;
-        let mut map = HashMap::with_hasher(BuildHasherDefault::<$hasher>::default());
+    ($hasher:ty; $($key:expr => $value:expr),+) => {{
+        let mut map = HashMap::<_, _, $hasher>::default();
         $(map.insert($key, $value);)+
         map
     }};

test_suite/tests/regression/issue2371.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)]
+
 use serde_derive::Deserialize;
 
 #[derive(Deserialize)]

test_suite/tests/regression/issue2409.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)]
+
 use serde_derive::Deserialize;
 
 macro_rules! bug {

test_suite/tests/regression/issue2415.rs

@@ -2,4 +2,5 @@ use serde_derive::Serialize;
 
 #[derive(Serialize)]
 #[serde()]
+#[allow(dead_code)]
 pub struct S;

test_suite/tests/regression/issue2565.rs

@@ -1,4 +1,4 @@
-use serde_derive::{Serialize, Deserialize};
+use serde_derive::{Deserialize, Serialize};
 use serde_test::{assert_tokens, Token};
 
 #[derive(Serialize, Deserialize, Debug, PartialEq)]
@@ -18,11 +18,15 @@ fn simple_variant() {
     assert_tokens(
         &Enum::Simple { a: 42 },
         &[
-            Token::StructVariant { name: "Enum", variant: "Simple", len: 1 },
+            Token::StructVariant {
+                name: "Enum",
+                variant: "Simple",
+                len: 1,
+            },
             Token::Str("a"),
             Token::I32(42),
             Token::StructVariantEnd,
-        ]
+        ],
     );
 }
 
@@ -31,11 +35,14 @@ fn flatten_variant() {
     assert_tokens(
         &Enum::Flatten { flatten: (), a: 42 },
         &[
-            Token::NewtypeVariant { name: "Enum", variant: "Flatten" },
+            Token::NewtypeVariant {
+                name: "Enum",
+                variant: "Flatten",
+            },
             Token::Map { len: None },
             Token::Str("a"),
             Token::I32(42),
             Token::MapEnd,
-        ]
+        ],
     );
 }

test_suite/tests/regression/issue2844.rs

@@ -0,0 +1,33 @@
+#![allow(clippy::trivially_copy_pass_by_ref, dead_code)]
+
+use serde_derive::{Deserialize, Serialize};
+
+macro_rules! declare_in_macro {
+    ($with:literal) => {
+        #[derive(Serialize, Deserialize)]
+        pub struct S {
+            #[serde(with = $with)]
+            f: i32,
+        }
+    };
+}
+
+declare_in_macro!("with");
+
+mod with {
+    use serde::{Deserializer, Serializer};
+
+    pub fn serialize<S>(_: &i32, _: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        unimplemented!()
+    }
+
+    pub fn deserialize<'de, D>(_: D) -> Result<i32, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        unimplemented!()
+    }
+}

test_suite/tests/regression/issue2846.rs

@@ -0,0 +1,27 @@
+#![allow(clippy::trivially_copy_pass_by_ref, dead_code)]
+
+use serde_derive::Deserialize;
+
+macro_rules! declare_in_macro {
+    ($with:literal) => {
+        #[derive(Deserialize)]
+        pub struct S(
+            #[serde(with = $with)]
+            #[allow(dead_code)]
+            i32,
+        );
+    };
+}
+
+declare_in_macro!("with");
+
+mod with {
+    use serde::Deserializer;
+
+    pub fn deserialize<'de, D>(_: D) -> Result<i32, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        unimplemented!()
+    }
+}

test_suite/tests/test_annotations.rs

@@ -2655,11 +2655,46 @@ mod flatten {
 
             #[derive(Debug, PartialEq, Serialize, Deserialize)]
             enum Enum {
+                Unit,
                 Newtype(HashMap<String, String>),
                 Tuple(u32, u32),
                 Struct { index: u32, value: u32 },
             }
 
+            #[test]
+            fn unit() {
+                let value = Flatten {
+                    data: Enum::Unit,
+                    extra: HashMap::from_iter([("extra_key".into(), "extra value".into())]),
+                };
+                assert_tokens(
+                    &value,
+                    &[
+                        Token::Map { len: None },
+                        // data
+                        Token::Str("Unit"), // variant
+                        Token::Unit,
+                        // extra
+                        Token::Str("extra_key"),
+                        Token::Str("extra value"),
+                        Token::MapEnd,
+                    ],
+                );
+                assert_de_tokens(
+                    &value,
+                    &[
+                        Token::Map { len: None },
+                        // extra
+                        Token::Str("extra_key"),
+                        Token::Str("extra value"),
+                        // data
+                        Token::Str("Unit"), // variant
+                        Token::Unit,
+                        Token::MapEnd,
+                    ],
+                );
+            }
+
             #[test]
             fn newtype() {
                 assert_tokens(

test_suite/tests/test_borrow.rs

@@ -1,7 +1,10 @@
 #![allow(
     clippy::derive_partial_eq_without_eq,
     clippy::items_after_statements,
-    clippy::used_underscore_binding
+    clippy::used_underscore_binding,
+    // We use lots of declarations inside function bodies to avoid conflicts,
+    // but they aren't used. We just want to make sure they compile.
+    dead_code,
 )]
 
 use serde::de::value::{BorrowedStrDeserializer, MapDeserializer};

test_suite/tests/test_de.rs

@@ -10,7 +10,6 @@
 )]
 #![cfg_attr(feature = "unstable", feature(never_type))]
 
-use fnv::FnvHasher;
 use serde::de::value::{F32Deserializer, F64Deserializer};
 use serde::de::{Deserialize, DeserializeOwned, Deserializer, IntoDeserializer};
 use serde_derive::Deserialize;
@@ -1040,7 +1039,7 @@ fn test_hashset() {
         ],
     );
     test(
-        hashset![FnvHasher @ 1, 2, 3],
+        hashset![foldhash::fast::FixedState; 1, 2, 3],
         &[
             Token::Seq { len: Some(3) },
             Token::I32(1),
@@ -1275,7 +1274,7 @@ fn test_hashmap() {
         ],
     );
     test(
-        hashmap![FnvHasher @ 1 => 2, 3 => 4],
+        hashmap![foldhash::fast::FixedState; 1 => 2, 3 => 4],
         &[
             Token::Map { len: Some(2) },
             Token::I32(1),

test_suite/tests/test_gen.rs

@@ -18,7 +18,10 @@
     clippy::ptr_arg,
     clippy::too_many_lines,
     clippy::trivially_copy_pass_by_ref,
-    clippy::type_repetition_in_bounds
+    clippy::type_repetition_in_bounds,
+    // We use lots of declarations inside function bodies to avoid conflicts,
+    // but they aren't used. We just want to make sure they compile.
+    dead_code,
 )]
 #![deny(clippy::collection_is_never_read)]
 
@@ -689,6 +692,7 @@ fn test_gen() {
 
     #[derive(Serialize, Deserialize)]
     #[serde(untagged)]
+    #[allow(dead_code)]
     pub enum UntaggedNewtypeVariantWith {
         Newtype(
             #[serde(serialize_with = "ser_x")]
@@ -699,6 +703,7 @@ fn test_gen() {
 
     #[derive(Serialize, Deserialize)]
     #[serde(transparent)]
+    #[allow(dead_code)]
     pub struct TransparentWith {
         #[serde(serialize_with = "ser_x")]
         #[serde(deserialize_with = "de_x")]
@@ -707,6 +712,7 @@ fn test_gen() {
 
     #[derive(Deserialize)]
     #[serde(untagged)]
+    #[allow(dead_code)]
     pub enum UntaggedWithBorrow<'a> {
         Single(
             #[serde(borrow)]
@@ -769,7 +775,7 @@ fn test_gen() {
     }
 
     #[derive(Serialize)]
-    #[repr(packed)]
+    #[repr(C, packed)]
     #[allow(dead_code)]
     struct Packed {
         x: u8,
@@ -805,6 +811,8 @@ fn test_gen() {
         pub vec: Vec<Self>,
     }
 
+    assert_ser::<Struct>();
+
     #[derive(Deserialize)]
     #[serde(bound(deserialize = "[&'de str; N]: Copy"))]
     pub struct GenericUnitStruct<const N: usize>;
@@ -915,14 +923,14 @@ where
 
 //////////////////////////////////////////////////////////////////////////
 
-#[repr(packed)]
+#[repr(C, packed)]
 pub struct RemotePacked {
     pub a: u16,
     pub b: u32,
 }
 
 #[derive(Serialize)]
-#[repr(packed)]
+#[repr(C, packed)]
 #[serde(remote = "RemotePacked")]
 pub struct RemotePackedDef {
     a: u16,
@@ -933,14 +941,14 @@ impl Drop for RemotePackedDef {
     fn drop(&mut self) {}
 }
 
-#[repr(packed)]
+#[repr(C, packed)]
 pub struct RemotePackedNonCopy {
     pub a: u16,
     pub b: String,
 }
 
 #[derive(Deserialize)]
-#[repr(packed)]
+#[repr(C, packed)]
 #[serde(remote = "RemotePackedNonCopy")]
 pub struct RemotePackedNonCopyDef {
     a: u16,

test_suite/tests/test_remote.rs

@@ -1,4 +1,4 @@
-#![allow(clippy::redundant_field_names)]
+#![allow(clippy::redundant_field_names, dead_code)]
 
 use serde_derive::{Deserialize, Serialize};
 

test_suite/tests/test_self.rs

@@ -1,4 +1,4 @@
-#![allow(clippy::used_underscore_binding)]
+#![allow(clippy::used_underscore_binding, dead_code)]
 
 use serde_derive::{Deserialize, Serialize};
 

test_suite/tests/test_ser.rs

@@ -1,7 +1,6 @@
 #![allow(clippy::derive_partial_eq_without_eq, clippy::unreadable_literal)]
 #![cfg_attr(feature = "unstable", feature(never_type))]
 
-use fnv::FnvHasher;
 use serde_derive::Serialize;
 use serde_test::{assert_ser_tokens, assert_ser_tokens_error, Configure, Token};
 use std::cell::RefCell;
@@ -220,7 +219,7 @@ fn test_hashset() {
         &[Token::Seq { len: Some(1) }, Token::I32(1), Token::SeqEnd],
     );
     assert_ser_tokens(
-        &hashset![FnvHasher @ 1],
+        &hashset![foldhash::fast::FixedState; 1],
         &[Token::Seq { len: Some(1) }, Token::I32(1), Token::SeqEnd],
     );
 }
@@ -300,7 +299,7 @@ fn test_hashmap() {
         ],
     );
     assert_ser_tokens(
-        &hashmap![FnvHasher @ 1 => 2],
+        &hashmap![foldhash::fast::FixedState; 1 => 2],
         &[
             Token::Map { len: Some(1) },
             Token::I32(1),

test_suite/tests/test_serde_path.rs

@@ -1,4 +1,5 @@
 #![allow(
+    clippy::elidable_lifetime_names,
     clippy::extra_unused_type_parameters,
     clippy::needless_lifetimes,
     clippy::type_repetition_in_bounds

test_suite/tests/ui/conflict/alias-enum.rs

@@ -0,0 +1,75 @@
+#![allow(non_camel_case_types)]
+
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+enum E {
+    S1 {
+        #[serde(alias = "a", alias = "b", alias = "c")]
+        a: (),
+
+        // Warning on "c" and "b"
+        #[serde(alias = "c")]
+        b: (),
+
+        #[serde(skip_deserializing)]
+        c: (),
+    },
+
+    S2 {
+        #[serde(alias = "b", alias = "c")]
+        a: (),
+
+        // Warning on "c"
+        #[serde(rename = "c")]
+        b: (),
+    },
+
+    #[serde(rename_all = "UPPERCASE")]
+    S3 {
+        #[serde(alias = "B", alias = "c")]
+        a: (),
+
+        // Warning on "b" because this collides with the "B" above after
+        // applying rename rules
+        b: (),
+    },
+}
+
+#[derive(Deserialize)]
+enum E1 {
+    #[serde(alias = "a", alias = "b", alias = "c")]
+    a,
+
+    // Warning on "c" and "b"
+    #[serde(alias = "c")]
+    b,
+
+    #[serde(skip_deserializing)]
+    c,
+}
+
+#[derive(Deserialize)]
+enum E2 {
+    #[serde(alias = "b", alias = "c")]
+    a,
+
+    // Warning on "c"
+    #[serde(rename = "c")]
+    b,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "UPPERCASE")]
+enum E3 {
+    #[serde(alias = "B", alias = "c")]
+    a,
+
+    // Warning on "b" because this collides with the "B" above after applying
+    // rename rules
+    b,
+}
+
+fn main() {
+    __FAIL__;
+}

test_suite/tests/ui/conflict/alias-enum.stderr

@@ -0,0 +1,79 @@
+error[E0425]: cannot find value `__FAIL__` in this scope
+  --> tests/ui/conflict/alias-enum.rs:74:5
+   |
+74 |     __FAIL__;
+   |     ^^^^^^^^ not found in this scope
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:13:9
+   |
+ 8 |         #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                      --- matches all the relevant values
+...
+13 |         b: (),
+   |         ^ no value can reach this
+   |
+   = note: `#[warn(unreachable_patterns)]` (part of `#[warn(unused)]`) on by default
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:12:25
+   |
+ 8 |         #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                                   --- matches all the relevant values
+...
+12 |         #[serde(alias = "c")]
+   |                         ^^^ no value can reach this
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:24:26
+   |
+20 |         #[serde(alias = "b", alias = "c")]
+   |                                      --- matches all the relevant values
+...
+24 |         #[serde(rename = "c")]
+   |                          ^^^ no value can reach this
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:35:9
+   |
+30 |         #[serde(alias = "B", alias = "c")]
+   |                         --- matches all the relevant values
+...
+35 |         b: (),
+   |         ^ no value can reach this
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:46:5
+   |
+41 |     #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                  --- matches all the relevant values
+...
+46 |     b,
+   |     ^ no value can reach this
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:45:21
+   |
+41 |     #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                               --- matches all the relevant values
+...
+45 |     #[serde(alias = "c")]
+   |                     ^^^ no value can reach this
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:58:22
+   |
+54 |     #[serde(alias = "b", alias = "c")]
+   |                                  --- matches all the relevant values
+...
+58 |     #[serde(rename = "c")]
+   |                      ^^^ no value can reach this
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:70:5
+   |
+65 |     #[serde(alias = "B", alias = "c")]
+   |                     --- matches all the relevant values
+...
+70 |     b,
+   |     ^ no value can reach this

test_suite/tests/ui/conflict/alias.rs

@@ -0,0 +1,39 @@
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+struct S1 {
+    #[serde(alias = "a", alias = "b", alias = "c")]
+    a: (),
+
+    // Warning on "c" and "b"
+    #[serde(alias = "c")]
+    b: (),
+
+    #[serde(skip_deserializing)]
+    c: (),
+}
+
+#[derive(Deserialize)]
+struct S2 {
+    #[serde(alias = "b", alias = "c")]
+    a: (),
+
+    // Warning on "c"
+    #[serde(rename = "c")]
+    b: (),
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "UPPERCASE")]
+struct S3 {
+    #[serde(alias = "B", alias = "c")]
+    a: (),
+
+    // Warning on "b" because this collides with the "B" above after applying
+    // rename rules
+    b: (),
+}
+
+fn main() {
+    __FAIL__;
+}

test_suite/tests/ui/conflict/alias.stderr

@@ -0,0 +1,43 @@
+error[E0425]: cannot find value `__FAIL__` in this scope
+  --> tests/ui/conflict/alias.rs:38:5
+   |
+38 |     __FAIL__;
+   |     ^^^^^^^^ not found in this scope
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias.rs:10:5
+   |
+ 5 |     #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                  --- matches all the relevant values
+...
+10 |     b: (),
+   |     ^ no value can reach this
+   |
+   = note: `#[warn(unreachable_patterns)]` (part of `#[warn(unused)]`) on by default
+
+warning: unreachable pattern
+ --> tests/ui/conflict/alias.rs:9:21
+  |
+5 |     #[serde(alias = "a", alias = "b", alias = "c")]
+  |                                               --- matches all the relevant values
+...
+9 |     #[serde(alias = "c")]
+  |                     ^^^ no value can reach this
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias.rs:22:22
+   |
+18 |     #[serde(alias = "b", alias = "c")]
+   |                                  --- matches all the relevant values
+...
+22 |     #[serde(rename = "c")]
+   |                      ^^^ no value can reach this
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias.rs:34:5
+   |
+29 |     #[serde(alias = "B", alias = "c")]
+   |                     --- matches all the relevant values
+...
+34 |     b: (),
+   |     ^ no value can reach this

test_suite/tests/ui/conflict/internal-tag-alias.stderr

@@ -1,11 +1,11 @@
 error: variant field name `conflict` conflicts with internal tag
   --> tests/ui/conflict/internal-tag-alias.rs:4:1
    |
-4  | / #[serde(tag = "conflict")]
-5  | | enum E {
-6  | |     A {
-7  | |         #[serde(alias = "conflict")]
-8  | |         x: (),
-9  | |     },
+ 4 | / #[serde(tag = "conflict")]
+ 5 | | enum E {
+ 6 | |     A {
+ 7 | |         #[serde(alias = "conflict")]
+ 8 | |         x: (),
+ 9 | |     },
 10 | | }
    | |_^

test_suite/tests/ui/conflict/internal-tag.stderr

@@ -1,11 +1,11 @@
 error: variant field name `conflict` conflicts with internal tag
   --> tests/ui/conflict/internal-tag.rs:4:1
    |
-4  | / #[serde(tag = "conflict")]
-5  | | enum E {
-6  | |     A {
-7  | |         #[serde(rename = "conflict")]
-8  | |         x: (),
-9  | |     },
+ 4 | / #[serde(tag = "conflict")]
+ 5 | | enum E {
+ 6 | |     A {
+ 7 | |         #[serde(rename = "conflict")]
+ 8 | |         x: (),
+ 9 | |     },
 10 | | }
    | |_^

test_suite/tests/ui/default-attribute/incorrect_type_enum_adjacently_tagged.stderr

@@ -1,7 +1,7 @@
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_enum_adjacently_tagged.rs:10:33
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `i8`
@@ -13,7 +13,7 @@ error[E0308]: `match` arms have incompatible types
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_enum_adjacently_tagged.rs:12:27
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `u8`
@@ -25,7 +25,7 @@ error[E0308]: `match` arms have incompatible types
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_enum_adjacently_tagged.rs:15:27
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `i8`

test_suite/tests/ui/default-attribute/incorrect_type_enum_externally_tagged.stderr

@@ -13,7 +13,7 @@ error[E0308]: `match` arms have incompatible types
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_enum_externally_tagged.rs:11:27
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `u8`
@@ -25,7 +25,7 @@ error[E0308]: `match` arms have incompatible types
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_enum_externally_tagged.rs:14:27
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `i8`

test_suite/tests/ui/default-attribute/incorrect_type_enum_internally_tagged.stderr

@@ -1,7 +1,7 @@
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_enum_internally_tagged.rs:12:27
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `u8`
@@ -13,7 +13,7 @@ error[E0308]: `match` arms have incompatible types
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_enum_internally_tagged.rs:15:27
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `i8`

test_suite/tests/ui/default-attribute/incorrect_type_enum_untagged.stderr

@@ -1,7 +1,7 @@
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_enum_untagged.rs:10:33
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `i8`
@@ -13,7 +13,7 @@ error[E0308]: `match` arms have incompatible types
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_enum_untagged.rs:12:27
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `u8`
@@ -25,7 +25,7 @@ error[E0308]: `match` arms have incompatible types
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_enum_untagged.rs:15:27
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `i8`

test_suite/tests/ui/default-attribute/incorrect_type_newtype.stderr

@@ -2,10 +2,7 @@ error[E0308]: mismatched types
  --> tests/ui/default-attribute/incorrect_type_newtype.rs:6:19
   |
 6 | #[serde(default = "main")]
-  |                   ^^^^^^
-  |                   |
-  |                   expected `Newtype`, found `()`
-  |                   expected due to this
+  |                   ^^^^^^ expected `Newtype`, found `()`
 
 error[E0308]: `match` arms have incompatible types
  --> tests/ui/default-attribute/incorrect_type_newtype.rs:7:34

test_suite/tests/ui/default-attribute/incorrect_type_struct.stderr

@@ -2,10 +2,7 @@ error[E0308]: mismatched types
  --> tests/ui/default-attribute/incorrect_type_struct.rs:6:19
   |
 6 | #[serde(default = "main")]
-  |                   ^^^^^^
-  |                   |
-  |                   expected `Struct`, found `()`
-  |                   expected due to this
+  |                   ^^^^^^ expected `Struct`, found `()`
 
 error[E0308]: `match` arms have incompatible types
  --> tests/ui/default-attribute/incorrect_type_struct.rs:8:23
@@ -22,7 +19,7 @@ error[E0308]: `match` arms have incompatible types
 error[E0308]: `match` arms have incompatible types
   --> tests/ui/default-attribute/incorrect_type_struct.rs:11:23
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          -----------
    |          |
    |          this is found to be of type `i8`
@@ -51,7 +48,7 @@ error[E0308]: mismatched types
 error[E0308]: mismatched types
   --> tests/ui/default-attribute/incorrect_type_struct.rs:11:23
    |
-5  | #[derive(Deserialize)]
+ 5 | #[derive(Deserialize)]
    |          ----------- expected due to the type of this binding
 ...
 11 |     #[serde(default = "main")]

test_suite/tests/ui/default-attribute/incorrect_type_tuple.stderr

@@ -2,10 +2,7 @@ error[E0308]: mismatched types
  --> tests/ui/default-attribute/incorrect_type_tuple.rs:6:19
   |
 6 | #[serde(default = "main")]
-  |                   ^^^^^^
-  |                   |
-  |                   expected `Tuple`, found `()`
-  |                   expected due to this
+  |                   ^^^^^^ expected `Tuple`, found `()`
 
 error[E0308]: `match` arms have incompatible types
  --> tests/ui/default-attribute/incorrect_type_tuple.rs:7:36

test_suite/tests/ui/remote/unknown_field.stderr

@@ -6,8 +6,9 @@ error[E0609]: no field `b` on type `&remote::S`
    |
 help: a field with a similar name exists
    |
-12 |     a: u8,
-   |     ~
+12 -     b: u8,
+12 +     a: u8,
+   |
 
 error[E0560]: struct `remote::S` has no field named `b`
   --> tests/ui/remote/unknown_field.rs:12:5

test_suite/tests/ui/transparent/de_at_least_one.stderr

@@ -1,11 +1,11 @@
 error: #[serde(transparent)] requires at least one field that is neither skipped nor has a default
   --> tests/ui/transparent/de_at_least_one.rs:4:1
    |
-4  | / #[serde(transparent)]
-5  | | struct S {
-6  | |     #[serde(skip)]
-7  | |     a: u8,
-8  | |     #[serde(default)]
-9  | |     b: u8,
+ 4 | / #[serde(transparent)]
+ 5 | | struct S {
+ 6 | |     #[serde(skip)]
+ 7 | |     a: u8,
+ 8 | |     #[serde(default)]
+ 9 | |     b: u8,
 10 | | }
    | |_^

test_suite/tests/ui/unimplemented/required_by_dependency.rs

@@ -0,0 +1,6 @@
+struct MyStruct;
+
+fn main() {
+    serde_test::assert_ser_tokens(&MyStruct, &[]);
+    serde_test::assert_de_tokens(&MyStruct, &[]);
+}

test_suite/tests/ui/unimplemented/required_by_dependency.stderr

@@ -0,0 +1,113 @@
+error[E0277]: the trait bound `MyStruct: serde::Serialize` is not satisfied
+ --> tests/ui/unimplemented/required_by_dependency.rs:4:35
+  |
+4 |     serde_test::assert_ser_tokens(&MyStruct, &[]);
+  |     ----------------------------- ^^^^^^^^^ unsatisfied trait bound
+  |     |
+  |     required by a bound introduced by this call
+  |
+help: the trait `serde_core::ser::Serialize` is not implemented for `MyStruct`
+ --> tests/ui/unimplemented/required_by_dependency.rs:1:1
+  |
+1 | struct MyStruct;
+  | ^^^^^^^^^^^^^^^
+  = note: for local types consider adding `#[derive(serde::Serialize)]` to your `MyStruct` type
+  = note: for types from other crates check whether the crate offers a `serde` feature flag
+  = help: the following other types implement trait `serde_core::ser::Serialize`:
+            &'a T
+            &'a mut T
+            ()
+            (T,)
+            (T0, T1)
+            (T0, T1, T2)
+            (T0, T1, T2, T3)
+            (T0, T1, T2, T3, T4)
+          and $N others
+note: required by a bound in `assert_ser_tokens`
+ --> $CARGO/serde_test-$VERSION/src/assert.rs
+  |
+  | pub fn assert_ser_tokens<T>(value: &T, tokens: &[Token])
+  |        ----------------- required by a bound in this function
+  | where
+  |     T: ?Sized + Serialize,
+  |                 ^^^^^^^^^ required by this bound in `assert_ser_tokens`
+
+error[E0277]: the trait bound `MyStruct: serde::Deserialize<'de>` is not satisfied
+ --> tests/ui/unimplemented/required_by_dependency.rs:5:34
+  |
+5 |     serde_test::assert_de_tokens(&MyStruct, &[]);
+  |     ---------------------------- ^^^^^^^^^ unsatisfied trait bound
+  |     |
+  |     required by a bound introduced by this call
+  |
+help: the trait `serde_core::de::Deserialize<'_>` is not implemented for `MyStruct`
+ --> tests/ui/unimplemented/required_by_dependency.rs:1:1
+  |
+1 | struct MyStruct;
+  | ^^^^^^^^^^^^^^^
+  = note: for local types consider adding `#[derive(serde::Deserialize)]` to your `MyStruct` type
+  = note: for types from other crates check whether the crate offers a `serde` feature flag
+  = help: the following other types implement trait `serde_core::de::Deserialize<'de>`:
+            &'a Path
+            &'a [u8]
+            &'a str
+            ()
+            (T,)
+            (T0, T1)
+            (T0, T1, T2)
+            (T0, T1, T2, T3)
+          and $N others
+note: required by a bound in `assert_de_tokens`
+ --> $CARGO/serde_test-$VERSION/src/assert.rs
+  |
+  | pub fn assert_de_tokens<'de, T>(value: &T, tokens: &'de [Token])
+  |        ---------------- required by a bound in this function
+  | where
+  |     T: Deserialize<'de> + PartialEq + Debug,
+  |        ^^^^^^^^^^^^^^^^ required by this bound in `assert_de_tokens`
+
+error[E0277]: can't compare `MyStruct` with `MyStruct`
+ --> tests/ui/unimplemented/required_by_dependency.rs:5:34
+  |
+5 |     serde_test::assert_de_tokens(&MyStruct, &[]);
+  |     ---------------------------- ^^^^^^^^^ no implementation for `MyStruct == MyStruct`
+  |     |
+  |     required by a bound introduced by this call
+  |
+  = help: the trait `PartialEq` is not implemented for `MyStruct`
+note: required by a bound in `assert_de_tokens`
+ --> $CARGO/serde_test-$VERSION/src/assert.rs
+  |
+  | pub fn assert_de_tokens<'de, T>(value: &T, tokens: &'de [Token])
+  |        ---------------- required by a bound in this function
+  | where
+  |     T: Deserialize<'de> + PartialEq + Debug,
+  |                           ^^^^^^^^^ required by this bound in `assert_de_tokens`
+help: consider annotating `MyStruct` with `#[derive(PartialEq)]`
+  |
+  1 + #[derive(PartialEq)]
+  2 | struct MyStruct;
+    |
+
+error[E0277]: `MyStruct` doesn't implement `Debug`
+ --> tests/ui/unimplemented/required_by_dependency.rs:5:34
+  |
+5 |     serde_test::assert_de_tokens(&MyStruct, &[]);
+  |     ---------------------------- ^^^^^^^^^ the trait `Debug` is not implemented for `MyStruct`
+  |     |
+  |     required by a bound introduced by this call
+  |
+  = note: add `#[derive(Debug)]` to `MyStruct` or manually `impl Debug for MyStruct`
+note: required by a bound in `assert_de_tokens`
+ --> $CARGO/serde_test-$VERSION/src/assert.rs
+  |
+  | pub fn assert_de_tokens<'de, T>(value: &T, tokens: &'de [Token])
+  |        ---------------- required by a bound in this function
+  | where
+  |     T: Deserialize<'de> + PartialEq + Debug,
+  |                                       ^^^^^ required by this bound in `assert_de_tokens`
+help: consider annotating `MyStruct` with `#[derive(Debug)]`
+  |
+  1 + #[derive(Debug)]
+  2 | struct MyStruct;
+    |

test_suite/tests/ui/unimplemented/required_locally.stderr

@@ -1,11 +1,16 @@
-error[E0277]: the trait bound `MyStruct: Serialize` is not satisfied
-  --> tests/ui/on_unimplemented.rs:21:15
+error[E0277]: the trait bound `MyStruct: serde::Serialize` is not satisfied
+  --> tests/ui/unimplemented/required_locally.rs:21:15
    |
 21 |     to_string(&MyStruct);
-   |     --------- ^^^^^^^^^ the trait `Serialize` is not implemented for `MyStruct`
+   |     --------- ^^^^^^^^^ unsatisfied trait bound
    |     |
    |     required by a bound introduced by this call
    |
+help: the trait `Serialize` is not implemented for `MyStruct`
+  --> tests/ui/unimplemented/required_locally.rs:18:1
+   |
+18 | struct MyStruct;
+   | ^^^^^^^^^^^^^^^
    = note: for local types consider adding `#[derive(serde::Serialize)]` to your `MyStruct` type
    = note: for types from other crates check whether the crate offers a `serde` feature flag
    = help: the following other types implement trait `Serialize`:
@@ -19,20 +24,25 @@ error[E0277]: the trait bound `MyStruct: Serialize` is not satisfied
              (T0, T1, T2, T3, T4)
            and $N others
 note: required by a bound in `to_string`
-  --> tests/ui/on_unimplemented.rs:6:8
+  --> tests/ui/unimplemented/required_locally.rs:6:8
    |
-4  | fn to_string<T>(_: &T) -> String
+ 4 | fn to_string<T>(_: &T) -> String
    |    --------- required by a bound in this function
-5  | where
-6  |     T: Serialize,
+ 5 | where
+ 6 |     T: Serialize,
    |        ^^^^^^^^^ required by this bound in `to_string`
 
-error[E0277]: the trait bound `MyStruct: Deserialize<'_>` is not satisfied
-  --> tests/ui/on_unimplemented.rs:22:23
+error[E0277]: the trait bound `MyStruct: serde::Deserialize<'de>` is not satisfied
+  --> tests/ui/unimplemented/required_locally.rs:22:23
    |
 22 |     let _: MyStruct = from_str("");
-   |                       ^^^^^^^^^^^^ the trait `Deserialize<'_>` is not implemented for `MyStruct`
+   |                       ^^^^^^^^^^^^ unsatisfied trait bound
    |
+help: the trait `Deserialize<'_>` is not implemented for `MyStruct`
+  --> tests/ui/unimplemented/required_locally.rs:18:1
+   |
+18 | struct MyStruct;
+   | ^^^^^^^^^^^^^^^
    = note: for local types consider adding `#[derive(serde::Deserialize)]` to your `MyStruct` type
    = note: for types from other crates check whether the crate offers a `serde` feature flag
    = help: the following other types implement trait `Deserialize<'de>`:
@@ -46,7 +56,7 @@ error[E0277]: the trait bound `MyStruct: Deserialize<'_>` is not satisfied
              (T0, T1, T2, T3)
            and $N others
 note: required by a bound in `from_str`
-  --> tests/ui/on_unimplemented.rs:13:8
+  --> tests/ui/unimplemented/required_locally.rs:13:8
    |
 11 | fn from_str<'de, T>(_: &'de str) -> T
    |    -------- required by a bound in this function

test_suite/tests/ui/with-variant/skip_de_struct_field.stderr

@@ -1,10 +1,10 @@
 error: variant `Struct` cannot have both #[serde(deserialize_with)] and a field `f1` marked with #[serde(skip_deserializing)]
   --> tests/ui/with-variant/skip_de_struct_field.rs:5:5
    |
-5  | /     #[serde(deserialize_with = "deserialize_some_other_variant")]
-6  | |     Struct {
-7  | |         #[serde(skip_deserializing)]
-8  | |         f1: String,
-9  | |         f2: u8,
+ 5 | /     #[serde(deserialize_with = "deserialize_some_other_variant")]
+ 6 | |     Struct {
+ 7 | |         #[serde(skip_deserializing)]
+ 8 | |         f1: String,
+ 9 | |         f2: u8,
 10 | |     },
    | |_____^

test_suite/tests/ui/with-variant/skip_ser_struct_field.stderr

@@ -1,10 +1,10 @@
 error: variant `Struct` cannot have both #[serde(serialize_with)] and a field `f1` marked with #[serde(skip_serializing)]
   --> tests/ui/with-variant/skip_ser_struct_field.rs:5:5
    |
-5  | /     #[serde(serialize_with = "serialize_some_other_variant")]
-6  | |     Struct {
-7  | |         #[serde(skip_serializing)]
-8  | |         f1: String,
-9  | |         f2: u8,
+ 5 | /     #[serde(serialize_with = "serialize_some_other_variant")]
+ 6 | |     Struct {
+ 7 | |         #[serde(skip_serializing)]
+ 8 | |         f1: String,
+ 9 | |         f2: u8,
 10 | |     },
    | |_____^

test_suite/tests/ui/with-variant/skip_ser_struct_field_if.stderr

@@ -1,10 +1,10 @@
 error: variant `Struct` cannot have both #[serde(serialize_with)] and a field `f1` marked with #[serde(skip_serializing_if)]
   --> tests/ui/with-variant/skip_ser_struct_field_if.rs:5:5
    |
-5  | /     #[serde(serialize_with = "serialize_some_newtype_variant")]
-6  | |     Struct {
-7  | |         #[serde(skip_serializing_if = "always")]
-8  | |         f1: String,
-9  | |         f2: u8,
+ 5 | /     #[serde(serialize_with = "serialize_some_newtype_variant")]
+ 6 | |     Struct {
+ 7 | |         #[serde(skip_serializing_if = "always")]
+ 8 | |         f1: String,
+ 9 | |         f2: u8,
 10 | |     },
    | |_____^

test_suite/tests/ui/with/incorrect_type.stderr

@@ -1,4 +1,4 @@
-error[E0277]: the trait bound `&u8: Serializer` is not satisfied
+error[E0277]: the trait bound `&u8: serde::Serializer` is not satisfied
   --> tests/ui/with/incorrect_type.rs:14:10
    |
 14 | #[derive(Serialize, Deserialize)]
@@ -13,22 +13,24 @@ error[E0277]: the trait bound `&u8: Serializer` is not satisfied
 note: required by a bound in `w::serialize`
   --> tests/ui/with/incorrect_type.rs:9:28
    |
-9  |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
+ 9 |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
    |                            ^^^^^^^^^^ required by this bound in `serialize`
 
 error[E0061]: this function takes 1 argument but 2 arguments were supplied
   --> tests/ui/with/incorrect_type.rs:15:25
    |
+14 | #[derive(Serialize, Deserialize)]
+   |          --------- unexpected argument #2 of type `__S`
 15 | struct W(#[serde(with = "w")] u8, u8);
-   |                         ^^^ unexpected argument #2 of type `__S`
+   |                         ^^^
    |
 note: function defined here
   --> tests/ui/with/incorrect_type.rs:9:12
    |
-9  |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
-   |            ^^^^^^^^^                   ----
+ 9 |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
+   |            ^^^^^^^^^
 
-error[E0277]: the trait bound `&u8: Serializer` is not satisfied
+error[E0277]: the trait bound `&u8: serde::Serializer` is not satisfied
   --> tests/ui/with/incorrect_type.rs:15:25
    |
 15 | struct W(#[serde(with = "w")] u8, u8);
@@ -47,7 +49,7 @@ error[E0308]: `?` operator has incompatible types
    |
    = note: `?` operator cannot convert from `()` to `u8`
 
-error[E0277]: the trait bound `&u8: Serializer` is not satisfied
+error[E0277]: the trait bound `&u8: serde::Serializer` is not satisfied
   --> tests/ui/with/incorrect_type.rs:17:10
    |
 17 | #[derive(Serialize, Deserialize)]
@@ -62,22 +64,24 @@ error[E0277]: the trait bound `&u8: Serializer` is not satisfied
 note: required by a bound in `w::serialize`
   --> tests/ui/with/incorrect_type.rs:9:28
    |
-9  |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
+ 9 |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
    |                            ^^^^^^^^^^ required by this bound in `serialize`
 
 error[E0061]: this function takes 1 argument but 2 arguments were supplied
   --> tests/ui/with/incorrect_type.rs:18:35
    |
+17 | #[derive(Serialize, Deserialize)]
+   |          --------- unexpected argument #2 of type `__S`
 18 | struct S(#[serde(serialize_with = "w::serialize")] u8, u8);
-   |                                   ^^^^^^^^^^^^^^ unexpected argument #2 of type `__S`
+   |                                   ^^^^^^^^^^^^^^
    |
 note: function defined here
   --> tests/ui/with/incorrect_type.rs:9:12
    |
-9  |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
-   |            ^^^^^^^^^                   ----
+ 9 |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
+   |            ^^^^^^^^^
 
-error[E0277]: the trait bound `&u8: Serializer` is not satisfied
+error[E0277]: the trait bound `&u8: serde::Serializer` is not satisfied
   --> tests/ui/with/incorrect_type.rs:18:35
    |
 18 | struct S(#[serde(serialize_with = "w::serialize")] u8, u8);