Release 1.0.204

Add ui test of unsatisfied serde trait bound

.github/workflows/ci.yml

@@ -84,6 +84,7 @@ jobs:
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{matrix.rust}}
+      - 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
@@ -95,6 +96,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@1.56.0
+      - run: sed -i '/"test_suite"/d' Cargo.toml
       - run: cd serde && cargo check --no-default-features
       - run: cd serde && cargo check
       - run: cd serde_derive && cargo check
@@ -106,6 +108,7 @@ jobs:
     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:

crates-io.md

@@ -46,8 +46,8 @@ fn main() {
 Serde is one of the most widely used Rust libraries so any place that Rustaceans
 congregate will be able to help you out. For chat, consider trying the
 [#rust-questions] or [#rust-beginners] channels of the unofficial community
-Discord (invite: <https://discord.gg/rust-lang-community>, the [#rust-usage] or
-[#beginners] channels of the official Rust Project Discord (invite:
+Discord (invite: <https://discord.gg/rust-lang-community>), the [#rust-usage]
+or [#beginners] channels of the official Rust Project Discord (invite:
 <https://discord.gg/rust-lang>), or the [#general][zulip] stream in Zulip. For
 asynchronous, consider the [\[rust\] tag on StackOverflow][stackoverflow], the
 [/r/rust] subreddit which has a pinned weekly easy questions post, or the Rust

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.203"
+version = "1.0.204"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 build = "build.rs"
 categories = ["encoding", "no-std", "no-std::no-alloc"]
@@ -37,7 +37,7 @@ rustdoc-args = ["--generate-link-to-definition"]
 # 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 = "=1.0.203", path = "../serde_derive" }
+serde_derive = { version = "=1.0.204", path = "../serde_derive" }
 
 
 ### FEATURES #################################################################

serde/build.rs

@@ -17,6 +17,7 @@ fn main() {
         println!("cargo:rustc-check-cfg=cfg(no_core_cstr)");
         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)");
@@ -84,6 +85,12 @@ fn main() {
     if minor < 74 {
         println!("cargo:rustc-cfg=no_core_num_saturating");
     }
+
+    // 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");
+    }
 }
 
 fn rustc_minor_version() -> Option<u32> {

serde/src/de/mod.rs

@@ -532,6 +532,13 @@ impl<'a> Display for Expected + 'a {
 /// deserializer lifetimes] for a more detailed explanation of these lifetimes.
 ///
 /// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        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",
+    )
+)]
 pub trait Deserialize<'de>: Sized {
     /// Deserialize this value from the given Serde deserializer.
     ///

serde/src/lib.rs

@@ -95,7 +95,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.203")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.204")]
 // Support using Serde without the standard library!
 #![cfg_attr(not(feature = "std"), no_std)]
 // Show which crate feature enables conditionally compiled APIs in documentation.
@@ -105,7 +105,7 @@
 // discussion of these features please refer to this issue:
 //
 //    https://github.com/serde-rs/serde/issues/812
-#![cfg_attr(feature = "unstable", feature(error_in_core, never_type))]
+#![cfg_attr(feature = "unstable", feature(never_type))]
 #![allow(unknown_lints, bare_trait_objects, deprecated)]
 // Ignored clippy and clippy_pedantic lints
 #![allow(

serde/src/ser/mod.rs

@@ -215,6 +215,13 @@ declare_error_trait!(Error: Sized + Debug + Display);
 /// [`linked-hash-map`]: https://crates.io/crates/linked-hash-map
 /// [`serde_derive`]: https://crates.io/crates/serde_derive
 /// [derive section of the manual]: https://serde.rs/derive.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        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",
+    )
+)]
 pub trait Serialize {
     /// Serialize this value into the given Serde serializer.
     ///

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.203"
+version = "1.0.204"
 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)]"

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/1.0.203")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.204")]
 #![cfg_attr(not(check_cfg), allow(unexpected_cfgs))]
 // Ignored clippy lints
 #![allow(

test_suite/Cargo.toml

@@ -18,4 +18,4 @@ rustversion = "1.0"
 serde = { path = "../serde", features = ["rc"] }
 serde_derive = { path = "../serde_derive", features = ["deserialize_in_place"] }
 serde_test = "1.0.176"
-trybuild = { version = "1.0.66", features = ["diff"] }
+trybuild = { version = "1.0.97", features = ["diff"] }

test_suite/tests/compiletest.rs

@@ -1,6 +1,6 @@
-#[cfg_attr(target_os = "emscripten", ignore)]
-#[rustversion::attr(not(nightly), ignore)]
-#[cfg_attr(miri, ignore)]
+#[cfg_attr(target_os = "emscripten", ignore = "disabled on Emscripten")]
+#[rustversion::attr(not(nightly), ignore = "requires nightly")]
+#[cfg_attr(miri, ignore = "incompatible with miri")]
 #[allow(unused_attributes)]
 #[test]
 fn ui() {

test_suite/tests/test_gen.rs

@@ -422,6 +422,7 @@ fn test_gen() {
 
     #[derive(Serialize, Deserialize)]
     #[serde(remote = "Self")]
+    #[allow(dead_code)]
     struct RemoteSelf;
 
     #[derive(Serialize, Deserialize)]

test_suite/tests/ui/on_unimplemented.rs

@@ -0,0 +1,23 @@
+use serde::de::Deserialize;
+use serde::ser::Serialize;
+
+fn to_string<T>(_: &T) -> String
+where
+    T: Serialize,
+{
+    unimplemented!()
+}
+
+fn from_str<'de, T>(_: &'de str) -> T
+where
+    T: Deserialize<'de>,
+{
+    unimplemented!()
+}
+
+struct MyStruct;
+
+fn main() {
+    to_string(&MyStruct);
+    let _: MyStruct = from_str("");
+}

test_suite/tests/ui/on_unimplemented.stderr

@@ -0,0 +1,55 @@
+error[E0277]: the trait bound `MyStruct: Serialize` is not satisfied
+  --> tests/ui/on_unimplemented.rs:21:15
+   |
+21 |     to_string(&MyStruct);
+   |     --------- ^^^^^^^^^ the trait `Serialize` is not implemented for `MyStruct`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = 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`:
+             &'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 `to_string`
+  --> tests/ui/on_unimplemented.rs:6:8
+   |
+4  | fn to_string<T>(_: &T) -> String
+   |    --------- required by a bound in this function
+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
+   |
+22 |     let _: MyStruct = from_str("");
+   |                       ^^^^^^^^^^^^ the trait `Deserialize<'_>` is not implemented for `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>`:
+             &'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 `from_str`
+  --> tests/ui/on_unimplemented.rs:13:8
+   |
+11 | fn from_str<'de, T>(_: &'de str) -> T
+   |    -------- required by a bound in this function
+12 | where
+13 |     T: Deserialize<'de>,
+   |        ^^^^^^^^^^^^^^^^ required by this bound in `from_str`