Merge pull request #3019 from xibeiyoumian/master

chore: improve code comments clarity

.github/workflows/ci.yml

@@ -18,10 +18,10 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@nightly
       - run: cd test_suite && cargo test --features unstable
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v6
         if: always()
         with:
           name: Cargo.lock
@@ -33,7 +33,7 @@ jobs:
     runs-on: windows-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@nightly
       - run: cd test_suite && cargo test --features unstable -- --skip ui --exact
 
@@ -46,7 +46,7 @@ jobs:
         rust: [stable, beta]
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{matrix.rust}}
@@ -63,7 +63,7 @@ jobs:
         os: [ubuntu, windows]
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@nightly
       - run: cd serde && cargo build
       - run: cd serde && cargo build --no-default-features
@@ -87,7 +87,7 @@ jobs:
         rust: [1.56.0, 1.60.0]
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{matrix.rust}}
@@ -98,12 +98,12 @@ jobs:
       - run: cd serde && cargo build
 
   derive:
-    name: Rust 1.61.0
+    name: Rust 1.68.0
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
-      - uses: dtolnay/rust-toolchain@1.61.0
+      - uses: dtolnay/rust-toolchain@1.68.0
       - run: |
           sed -i 's/proc-macro2 = { workspace = true/proc-macro2 = { version = "1"/' serde_derive*/Cargo.toml
           sed -i 's/quote = { workspace = true/quote = { version = "1"/' serde_derive*/Cargo.toml
@@ -117,7 +117,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@nightly
       - run: cargo generate-lockfile -Z minimal-versions
       - run: cargo check --locked --workspace
@@ -129,7 +129,7 @@ jobs:
     env:
       RUSTDOCFLAGS: -Dwarnings
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@nightly
       - uses: dtolnay/install@cargo-docs-rs
       - run: cargo docs-rs -p serde
@@ -143,7 +143,7 @@ jobs:
     if: github.event_name != 'pull_request'
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - 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
@@ -157,7 +157,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@miri
         with:
           toolchain: nightly-2025-05-16  # https://github.com/rust-lang/miri/issues/4323
@@ -175,7 +175,7 @@ jobs:
     if: github.event_name != 'pull_request'
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - uses: dtolnay/install@cargo-outdated
       - run: cargo outdated --workspace --exit-code 1

README.md

@@ -1,4 +1,4 @@
-# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde msrv]][Rust 1.56] [![serde_derive msrv]][Rust 1.61]
+# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde msrv]][Rust 1.56] [![serde_derive msrv]][Rust 1.68]
 
 [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
@@ -6,8 +6,8 @@
 [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 1.56]: https://blog.rust-lang.org/2021/10/21/Rust-1.56.0.html
+[Rust 1.56]: https://blog.rust-lang.org/2021/10/21/Rust-1.56.0/
-[Rust 1.61]: https://blog.rust-lang.org/2022/05/19/Rust-1.61.0.html
+[Rust 1.68]: https://blog.rust-lang.org/2023/03/09/Rust-1.68.0/
 
 **Serde is a framework for *ser*ializing and *de*serializing Rust data structures efficiently and generically.**
 

serde/build.rs

@@ -45,8 +45,8 @@ fn main() {
         println!("cargo:rustc-check-cfg=cfg(no_target_has_atomic)");
     }
 
-    // Current minimum supported version of serde_derive crate is Rust 1.61.
+    // Current minimum supported version of serde_derive crate is Rust 1.68.
-    if minor < 61 {
+    if minor < 68 {
         println!("cargo:rustc-cfg=no_serde_derive");
     }
 

serde/src/lib.rs

@@ -119,7 +119,7 @@
     // 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::empty_enums,
     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,

serde_core/build.rs

@@ -65,17 +65,17 @@ fn main() {
         }
     }
 
-    // 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");
     }
 
+    // Current minimum supported version of serde_derive crate is Rust 1.68.
+    if minor < 68 {
+        println!("cargo:rustc-cfg=no_serde_derive");
+    }
+
     // 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 {

serde_core/src/lib.rs

@@ -54,7 +54,7 @@
     // 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::empty_enums,
     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,

serde_derive/Cargo.toml

@@ -12,7 +12,7 @@ keywords = ["serde", "serialization", "no_std", "derive"]
 license = "MIT OR Apache-2.0"
 readme = "crates-io.md"
 repository = "https://github.com/serde-rs/serde"
-rust-version = "1.61"
+rust-version = "1.68"
 
 [features]
 default = []

serde_derive/src/de.rs

@@ -26,9 +26,9 @@ pub fn expand_derive_deserialize(input: &mut syn::DeriveInput) -> syn::Result<To
     replace_receiver(input);
 
     let ctxt = Ctxt::new();
-    let cont = match Container::from_ast(&ctxt, input, Derive::Deserialize, &private.ident()) {
+    let Some(cont) = Container::from_ast(&ctxt, input, Derive::Deserialize, &private.ident())
-        Some(cont) => cont,
+    else {
-        None => return Err(ctxt.check().unwrap_err()),
+        return Err(ctxt.check().unwrap_err());
     };
     precondition(&ctxt, &cont);
     ctxt.check()?;
@@ -594,13 +594,16 @@ fn deserialize_seq_in_place(
                     let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
                     quote!({
                         #wrapper
-                        match _serde::de::SeqAccess::next_element::<#wrapper_ty>(&mut __seq)? {
+                        match _serde::de::SeqAccess::next_element::<#wrapper_ty>(&mut __seq) {
-                            _serde::#private::Some(__wrap) => {
+                            _serde::#private::Ok(_serde::#private::Some(__wrap)) => {
                                 self.place.#member = __wrap.value;
                             }
-                            _serde::#private::None => {
+                            _serde::#private::Ok(_serde::#private::None) => {
                                 #value_if_none;
                             }
+                            _serde::#private::Err(__err) => {
+                                return _serde::#private::Err(__err);
+                            }
                         }
                     })
                 }

serde_derive/src/de/enum_adjacently.rs

@@ -282,8 +282,8 @@ pub(super) fn deserialize(
                 __A: _serde::de::SeqAccess<#delife>,
             {
                 // Visit the first element - the tag.
-                match _serde::de::SeqAccess::next_element(&mut __seq)? {
+                match _serde::de::SeqAccess::next_element(&mut __seq) {
-                    _serde::#private::Some(__variant) => {
+                    _serde::#private::Ok(_serde::#private::Some(__variant)) => {
                         // Visit the second element - the content.
                         match _serde::de::SeqAccess::next_element_seed(
                             &mut __seq,
@@ -292,18 +292,20 @@ pub(super) fn deserialize(
                                 marker: _serde::#private::PhantomData,
                                 lifetime: _serde::#private::PhantomData,
                             },
-                        )? {
+                        ) {
-                            _serde::#private::Some(__ret) => _serde::#private::Ok(__ret),
+                            _serde::#private::Ok(_serde::#private::Some(__ret)) => _serde::#private::Ok(__ret),
                             // There is no second element.
-                            _serde::#private::None => {
+                            _serde::#private::Ok(_serde::#private::None) => {
                                 _serde::#private::Err(_serde::de::Error::invalid_length(1, &self))
                             }
+                            _serde::#private::Err(__err) => _serde::#private::Err(__err),
                         }
                     }
                     // There is no first element.
-                    _serde::#private::None => {
+                    _serde::#private::Ok(_serde::#private::None) => {
                         _serde::#private::Err(_serde::de::Error::invalid_length(0, &self))
                     }
+                    _serde::#private::Err(__err) => _serde::#private::Err(__err),
                 }
             }
         }

serde_derive/src/de/enum_externally.rs

@@ -49,7 +49,7 @@ pub(super) fn deserialize(
             ));
 
             quote! {
-                (__Field::#variant_name, __variant) => #block
+                _serde::#private::Ok((__Field::#variant_name, __variant)) => #block
             }
         });
 
@@ -69,8 +69,9 @@ pub(super) fn deserialize(
         }
     } else {
         quote! {
-            match _serde::de::EnumAccess::variant(__data)? {
+            match _serde::de::EnumAccess::variant(__data) {
                 #(#variant_arms)*
+                _serde::#private::Err(__err) => _serde::#private::Err(__err),
             }
         }
     };

serde_derive/src/internals/attr.rs

@@ -1185,13 +1185,11 @@ impl Field {
             }
         }
 
-        // Is skip_deserializing, initialize the field to Default::default() unless a
+        // If skip_deserializing, initialize the field to Default::default() unless a
         // different default is specified by `#[serde(default = "...")]` on
         // ourselves or our container (e.g. the struct we are in).
-        if let Default::None = *container_default {
+        if container_default.is_none() && skip_deserializing.0.value.is_some() {
-            if skip_deserializing.0.value.is_some() {
+            default.set_if_none(Default::Default);
-                default.set_if_none(Default::Default);
-            }
         }
 
         let mut borrowed_lifetimes = borrowed_lifetimes.get().unwrap_or_default();
@@ -1459,9 +1457,8 @@ fn parse_lit_into_path(
     attr_name: Symbol,
     meta: &ParseNestedMeta,
 ) -> syn::Result<Option<syn::Path>> {
-    let string = match get_lit_str(cx, attr_name, meta)? {
+    let Some(string) = get_lit_str(cx, attr_name, meta)? else {
-        Some(string) => string,
+        return Ok(None);
-        None => return Ok(None),
     };
 
     Ok(match string.parse() {
@@ -1481,9 +1478,8 @@ fn parse_lit_into_expr_path(
     attr_name: Symbol,
     meta: &ParseNestedMeta,
 ) -> syn::Result<Option<syn::ExprPath>> {
-    let string = match get_lit_str(cx, attr_name, meta)? {
+    let Some(string) = get_lit_str(cx, attr_name, meta)? else {
-        Some(string) => string,
+        return Ok(None);
-        None => return Ok(None),
     };
 
     Ok(match string.parse() {
@@ -1504,9 +1500,8 @@ fn parse_lit_into_where(
     meta_item_name: Symbol,
     meta: &ParseNestedMeta,
 ) -> syn::Result<Vec<syn::WherePredicate>> {
-    let string = match get_lit_str2(cx, attr_name, meta_item_name, meta)? {
+    let Some(string) = get_lit_str2(cx, attr_name, meta_item_name, meta)? else {
-        Some(string) => string,
+        return Ok(Vec::new());
-        None => return Ok(Vec::new()),
     };
 
     Ok(
@@ -1525,9 +1520,8 @@ fn parse_lit_into_ty(
     attr_name: Symbol,
     meta: &ParseNestedMeta,
 ) -> syn::Result<Option<syn::Type>> {
-    let string = match get_lit_str(cx, attr_name, meta)? {
+    let Some(string) = get_lit_str(cx, attr_name, meta)? else {
-        Some(string) => string,
+        return Ok(None);
-        None => return Ok(None),
     };
 
     Ok(match string.parse() {
@@ -1548,9 +1542,8 @@ fn parse_lit_into_lifetimes(
     cx: &Ctxt,
     meta: &ParseNestedMeta,
 ) -> syn::Result<BTreeSet<syn::Lifetime>> {
-    let string = match get_lit_str(cx, BORROW, meta)? {
+    let Some(string) = get_lit_str(cx, BORROW, meta)? else {
-        Some(string) => string,
+        return Ok(BTreeSet::new());
-        None => return Ok(BTreeSet::new()),
     };
 
     if let Ok(lifetimes) = string.parse_with(|input: ParseStream| {
@@ -1620,11 +1613,8 @@ fn is_cow(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
             return false;
         }
     };
-    let seg = match path.segments.last() {
+    let Some(seg) = path.segments.last() else {
-        Some(seg) => seg,
+        return false;
-        None => {
-            return false;
-        }
     };
     let args = match &seg.arguments {
         syn::PathArguments::AngleBracketed(bracketed) => &bracketed.args,
@@ -1647,11 +1637,8 @@ fn is_option(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
             return false;
         }
     };
-    let seg = match path.segments.last() {
+    let Some(seg) = path.segments.last() else {
-        Some(seg) => seg,
+        return false;
-        None => {
-            return false;
-        }
     };
     let args = match &seg.arguments {
         syn::PathArguments::AngleBracketed(bracketed) => &bracketed.args,

serde_derive/src/internals/ctxt.rs

@@ -46,9 +46,8 @@ impl Ctxt {
     pub fn check(self) -> syn::Result<()> {
         let mut errors = self.errors.borrow_mut().take().unwrap().into_iter();
 
-        let mut combined = match errors.next() {
+        let Some(mut combined) = errors.next() else {
-            Some(first) => first,
+            return Ok(());
-            None => return Ok(()),
         };
 
         for rest in errors {

serde_derive/src/ser.rs

@@ -13,9 +13,8 @@ pub fn expand_derive_serialize(input: &mut syn::DeriveInput) -> syn::Result<Toke
     replace_receiver(input);
 
     let ctxt = Ctxt::new();
-    let cont = match Container::from_ast(&ctxt, input, Derive::Serialize, &private.ident()) {
+    let Some(cont) = Container::from_ast(&ctxt, input, Derive::Serialize, &private.ident()) else {
-        Some(cont) => cont,
+        return Err(ctxt.check().unwrap_err());
-        None => return Err(ctxt.check().unwrap_err()),
     };
     precondition(&ctxt, &cont);
     ctxt.check()?;

serde_derive_internals/Cargo.toml

@@ -10,7 +10,7 @@ homepage = "https://serde.rs"
 keywords = ["serde", "serialization"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/serde-rs/serde"
-rust-version = "1.61"
+rust-version = "1.68"
 
 [lib]
 path = "lib.rs"

test_suite/tests/test_de.rs

@@ -2,7 +2,7 @@
     clippy::cast_lossless,
     clippy::decimal_literal_representation,
     clippy::derive_partial_eq_without_eq,
-    clippy::empty_enum,
+    clippy::empty_enums,
     clippy::manual_assert,
     clippy::needless_pass_by_value,
     clippy::uninlined_format_args,

test_suite/tests/test_de_error.rs

@@ -1,6 +1,6 @@
 #![allow(
     clippy::derive_partial_eq_without_eq,
-    clippy::empty_enum,
+    clippy::empty_enums,
     clippy::unreadable_literal
 )]
 #![cfg_attr(feature = "unstable", feature(never_type))]

test_suite/tests/ui/default-attribute/tuple_struct.rs

@@ -11,7 +11,7 @@ struct T0(u8, u8);
 struct T1(u8, #[serde(default)] u8);
 
 // ERROR: The first field can get default value only if sequence is empty, but
-// that mean that all other fields cannot be deserialized without errors.
+// that means that all other fields cannot be deserialized without errors.
 #[derive(Deserialize)]
 struct T2(#[serde(default)] u8, u8, u8);
 

test_suite/tests/ui/default-attribute/tuple_struct_path.rs

@@ -11,7 +11,7 @@ fn d<T>() -> T {
 struct T1(u8, #[serde(default = "d")] u8);
 
 // ERROR: The first field can get default value only if sequence is empty, but
-// that mean that all other fields cannot be deserialized without errors.
+// that means that all other fields cannot be deserialized without errors.
 #[derive(Deserialize)]
 struct T2(#[serde(default = "d")] u8, u8, u8);
 

test_suite/tests/ui/with/incorrect_type.stderr

@@ -6,7 +6,11 @@ error[E0277]: the trait bound `&u8: serde::Serializer` is not satisfied
 15 | struct W(#[serde(with = "w")] u8, u8);
    |                         --- required by a bound introduced by this call
    |
-   = help: the trait `Serializer` is implemented for `&mut Formatter<'a>`
+help: the trait `Serializer` is implemented for `&mut Formatter<'a>`
+  --> $WORKSPACE/serde_core/src/ser/fmt.rs
+   |
+   | impl<'a> Serializer for &mut fmt::Formatter<'a> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 note: required by a bound in `w::serialize`
   --> tests/ui/with/incorrect_type.rs:9:28
    |
@@ -33,7 +37,11 @@ error[E0277]: the trait bound `&u8: serde::Serializer` is not satisfied
 15 | struct W(#[serde(with = "w")] u8, u8);
    |                         ^^^ the trait `Serializer` is not implemented for `&u8`
    |
-   = help: the trait `Serializer` is implemented for `&mut Formatter<'a>`
+help: the trait `Serializer` is implemented for `&mut Formatter<'a>`
+  --> $WORKSPACE/serde_core/src/ser/fmt.rs
+   |
+   | impl<'a> Serializer for &mut fmt::Formatter<'a> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0308]: `?` operator has incompatible types
   --> tests/ui/with/incorrect_type.rs:15:25
@@ -51,7 +59,11 @@ error[E0277]: the trait bound `&u8: serde::Serializer` is not satisfied
 18 | struct S(#[serde(serialize_with = "w::serialize")] u8, u8);
    |                                   -------------- required by a bound introduced by this call
    |
-   = help: the trait `Serializer` is implemented for `&mut Formatter<'a>`
+help: the trait `Serializer` is implemented for `&mut Formatter<'a>`
+  --> $WORKSPACE/serde_core/src/ser/fmt.rs
+   |
+   | impl<'a> Serializer for &mut fmt::Formatter<'a> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 note: required by a bound in `w::serialize`
   --> tests/ui/with/incorrect_type.rs:9:28
    |
@@ -78,7 +90,11 @@ error[E0277]: the trait bound `&u8: serde::Serializer` is not satisfied
 18 | struct S(#[serde(serialize_with = "w::serialize")] u8, u8);
    |                                   ^^^^^^^^^^^^^^ the trait `Serializer` is not implemented for `&u8`
    |
-   = help: the trait `Serializer` is implemented for `&mut Formatter<'a>`
+help: the trait `Serializer` is implemented for `&mut Formatter<'a>`
+  --> $WORKSPACE/serde_core/src/ser/fmt.rs
+   |
+   | impl<'a> Serializer for &mut fmt::Formatter<'a> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0308]: `?` operator has incompatible types
   --> tests/ui/with/incorrect_type.rs:21:37