[build.rs] Support unexpected_cfgs lint

build.rs

@@ -65,6 +65,20 @@ fn main() {
     let version_cfgs = parse_version_cfgs_from_cargo_toml();
     let rustc_version = rustc_version();
 
+    if rustc_version >= (Version { major: 1, minor: 77, patch: 0 }) {
+        // This tells the `unexpected_cfgs` lint to expect to see all of these
+        // `cfg`s. The `cargo::` syntax was only added in 1.77, so we don't emit
+        // these on earlier toolchain versions.
+        for version_cfg in &version_cfgs {
+            println!("cargo:rustc-check-cfg=cfg({})", version_cfg.cfg_name);
+        }
+        // TODO(https://github.com/rust-lang/rust/issues/124816): Remove these
+        // once they're no longer needed.
+        println!("cargo:rustc-check-cfg=cfg(doc_cfg)");
+        println!("cargo:rustc-check-cfg=cfg(kani)");
+        println!("cargo:rustc-check-cfg=cfg(__INTERNAL_USE_ONLY_NIGHTLY_FEATURES_IN_TESTS)");
+    }
+
     for version_cfg in version_cfgs {
         if rustc_version >= version_cfg.version {
             println!("cargo:rustc-cfg={}", version_cfg.cfg_name);

src/lib.rs

@@ -173,9 +173,7 @@
 // `unknown_lints` is `warn` by default and we deny warnings in CI, so without
 // this attribute, any unknown lint would cause a CI failure when testing with
 // our MSRV.
-//
-// TODO(#1201): Remove `unexpected_cfgs`
-#![allow(unknown_lints, unexpected_cfgs)]
+#![allow(unknown_lints)]
 #![deny(renamed_and_removed_lints)]
 #![deny(
     anonymous_parameters,
@@ -8926,7 +8924,7 @@ mod tests {
                 vector_signed_long,
                 vector_unsigned_long
             );
-            #[cfg(all(target_arch = "aarch64", zerocopy_aarch_simd))]
+            #[cfg(all(target_arch = "aarch64", zerocopy_aarch64_simd))]
             #[rustfmt::skip]
             test_simd_arch_mod!(
                 aarch64, float32x2_t, float32x4_t, float64x1_t, float64x2_t, int8x8_t, int8x8x2_t,