Merge pull request #87 from dtolnay/checkcfg

Resolve unexpected_cfgs warning

Author: dtolnay

impl/Cargo.toml

@@ -5,6 +5,7 @@ authors = ["David Tolnay <[email protected]>"]
 description = "Implementation detail of the linkme crate"
 documentation = "https://docs.rs/linkme"
 edition = "2021"
+exclude = ["build.rs"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/dtolnay/linkme"
 rust-version = "1.62"

impl/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)");
+}

impl/src/lib.rs

@@ -1,4 +1,5 @@
 #![cfg_attr(all(test, exhaustive), feature(non_exhaustive_omitted_patterns_lint))]
+#![cfg_attr(not(check_cfg), allow(unexpected_cfgs))]
 #![allow(
     clippy::cast_possible_truncation, // https://github.com/rust-lang/rust-clippy/issues/7486
     clippy::needless_pass_by_value,