Resolve unexpected_cfgs warning

    warning: unexpected `cfg` condition name: `serde_build_from_git`
      --> serde_derive_internals/lib.rs:45:12
       |
    45 | #[cfg_attr(serde_build_from_git, path = "../serde_derive/src/internals/mod.rs")]
       |            ^^^^^^^^^^^^^^^^^^^^
       |
       = help: expected names are: `clippy`, `debug_assertions`, `doc`, `docsrs`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `rustfmt`, `sanitize`, `sanitizer_cfi_generalize_pointers`, `sanitizer_cfi_normalize_integers`, `target_abi`, `target_arch`, `target_endian`, `target_env`, `target_family`, `target_feature`, `target_has_atomic`, `target_has_atomic_equal_alignment`, `target_has_atomic_load_store`, `target_os`, `target_pointer_width`, `target_thread_local`, `target_vendor`, `test`, `ub_checks`, `unix`, `windows`
       = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(serde_build_from_git)");` to the top of the `build.rs`
       = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration
       = note: `#[warn(unexpected_cfgs)]` on by default

    warning: unexpected `cfg` condition name: `serde_build_from_git`
      --> serde_derive_internals/lib.rs:46:16
       |
    46 | #[cfg_attr(not(serde_build_from_git), path = "src/mod.rs")]
       |                ^^^^^^^^^^^^^^^^^^^^
       |
       = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(serde_build_from_git)");` to the top of the `build.rs`
       = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition value: `deserialize_in_place`
       --> serde_derive_internals/src/attr.rs:276:11
        |
    276 |     #[cfg(feature = "deserialize_in_place")]
        |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove the condition
        |
        = note: no expected values for `feature`
        = help: consider adding `deserialize_in_place` as a feature in `Cargo.toml`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
        --> serde_derive_internals/src/attr.rs:1797:31
         |
    1797 |         #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
         |                               ^^^^^^^^^^
         |
         = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
         = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive_internals/src/receiver.rs:110:35
        |
    110 |             #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                   ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive_internals/src/receiver.rs:181:47
        |
    181 |                         #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                               ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive_internals/src/receiver.rs:210:35
        |
    210 |             #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                   ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive_internals/src/receiver.rs:231:43
        |
    231 |                     #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                           ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
      --> serde_derive/src/lib.rs:62:23
       |
    62 | #![cfg_attr(all(test, exhaustive), feature(non_exhaustive_omitted_patterns_lint))]
       |                       ^^^^^^^^^^
       |
       = help: expected names are: `clippy`, `debug_assertions`, `doc`, `docsrs`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `rustfmt`, `sanitize`, `sanitizer_cfi_generalize_pointers`, `sanitizer_cfi_normalize_integers`, `target_abi`, `target_arch`, `target_endian`, `target_env`, `target_family`, `target_feature`, `target_has_atomic`, `target_has_atomic_equal_alignment`, `target_has_atomic_load_store`, `target_os`, `target_pointer_width`, `target_thread_local`, `target_vendor`, `test`, `ub_checks`, `unix`, `windows`
       = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
       = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration
       = note: `#[warn(unexpected_cfgs)]` on by default

    warning: unexpected `cfg` condition name: `exhaustive`
        --> serde_derive/src/internals/attr.rs:1797:31
         |
    1797 |         #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
         |                               ^^^^^^^^^^
         |
         = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
         = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive/src/internals/receiver.rs:110:35
        |
    110 |             #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                   ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive/src/internals/receiver.rs:181:47
        |
    181 |                         #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                               ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive/src/internals/receiver.rs:210:35
        |
    210 |             #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                   ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive/src/internals/receiver.rs:231:43
        |
    231 |                     #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                           ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive/src/bound.rs:147:39
        |
    147 |                 #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                       ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive/src/bound.rs:199:51
        |
    199 | ...                   #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                             ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `exhaustive`
       --> serde_derive/src/bound.rs:228:39
        |
    228 |                 #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
        |                                       ^^^^^^^^^^
        |
        = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(exhaustive)");` to the top of the `build.rs`
        = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

    warning: unexpected `cfg` condition name: `systemtime_checked_add`
        --> test_suite/tests/test_de_error.rs:1527:7
         |
    1527 | #[cfg(systemtime_checked_add)]
         |       ^^^^^^^^^^^^^^^^^^^^^^
         |
         = help: expected names are: `clippy`, `debug_assertions`, `doc`, `docsrs`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `rustfmt`, `sanitize`, `sanitizer_cfi_generalize_pointers`, `sanitizer_cfi_normalize_integers`, `target_abi`, `target_arch`, `target_endian`, `target_env`, `target_family`, `target_feature`, `target_has_atomic`, `target_has_atomic_equal_alignment`, `target_has_atomic_load_store`, `target_os`, `target_pointer_width`, `target_thread_local`, `target_vendor`, `test`, `ub_checks`, `unix`, `windows`
         = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(systemtime_checked_add)");` to the top of the `build.rs`
         = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration
         = note: `#[warn(unexpected_cfgs)]` on by default

serde/build.rs

@@ -13,6 +13,21 @@ fn main() {
         None => return,
     };
 
+    if minor >= 77 {
+        println!("cargo:rustc-check-cfg=cfg(doc_cfg)");
+        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_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";
 

serde_derive/Cargo.toml

@@ -6,6 +6,7 @@ categories = ["no-std", "no-std::no-alloc"]
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
 documentation = "https://serde.rs/derive.html"
 edition = "2015"
+exclude = ["build.rs"]
 homepage = "https://serde.rs"
 keywords = ["serde", "serialization", "no_std", "derive"]
 license = "MIT OR Apache-2.0"

serde_derive/build.rs

@@ -0,0 +1,7 @@
+fn main() {
+    // Warning: build.rs is not published to crates.io.
+
+    println!("cargo:rustc-cfg=check_cfg");
+    println!("cargo:rustc-check-cfg=cfg(check_cfg)");
+    println!("cargo:rustc-check-cfg=cfg(exhaustive)");
+}

serde_derive/src/lib.rs

@@ -14,6 +14,7 @@
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html
 
 #![doc(html_root_url = "https://docs.rs/serde_derive/1.0.200")]
+#![cfg_attr(not(check_cfg), allow(unexpected_cfgs))]
 // Ignored clippy lints
 #![allow(
     // clippy false positive: https://github.com/rust-lang/rust-clippy/issues/7054

serde_derive_internals/build.rs

@@ -1,9 +1,17 @@
 use std::path::Path;
 
 fn main() {
+    // Warning: build.rs is not published to crates.io.
+
     println!("cargo:rerun-if-changed=build.rs");
     println!("cargo:rerun-if-changed=src/mod.rs");
 
+    println!("cargo:rustc-cfg=check_cfg");
+    println!("cargo:rustc-check-cfg=cfg(check_cfg)");
+    println!("cargo:rustc-check-cfg=cfg(exhaustive)");
+    println!("cargo:rustc-check-cfg=cfg(serde_build_from_git)");
+    println!("cargo:rustc-check-cfg=cfg(feature, values(\"deserialize_in_place\"))");
+
     // Sometimes on Windows the git checkout does not correctly wire up the
     // symlink from serde_derive_internals/src to serde_derive/src/internals.
     // When this happens we'll just build based on relative paths within the git

serde_derive_internals/lib.rs

@@ -1,4 +1,5 @@
 #![doc(html_root_url = "https://docs.rs/serde_derive_internals/0.29.0")]
+#![cfg_attr(not(check_cfg), allow(unexpected_cfgs))]
 // Ignored clippy lints
 #![allow(
     clippy::cognitive_complexity,

test_suite/tests/test_de_error.rs

@@ -1524,7 +1524,6 @@ fn test_systemtime_overflow_struct() {
     );
 }
 
-#[cfg(not(no_systemtime_checked_add))]
 #[test]
 fn test_systemtime_overflow() {
     assert_de_tokens_error::<SystemTime>(