build-update

build.rs

@@ -146,7 +146,9 @@ fn generate_aarch64_outlined_atomics() {
     std::fs::write(dst, buf).unwrap();
 }
 
-/// Emit directives for features we expect to support that aren't in `Cargo.toml`
+/// Emit directives for features we expect to support that aren't in `Cargo.toml`.
+///
+/// These are mostly cfg elements emitted by this `build.rs`.
 fn configure_check_cfg() {
     // Functions where we can set the "optimized-c" flag
     const HAS_OPTIMIZED_C: &[&str] = &[
@@ -185,6 +187,8 @@ fn configure_check_cfg() {
     println!("cargo::rustc-check-cfg=cfg(feature, values(\"unstable\"))");
     println!("cargo::rustc-check-cfg=cfg(assert_no_panic)");
     println!("cargo::rustc-check-cfg=cfg(kernel_user_helpers)");
+    println!("cargo::rustc-check-cfg=cfg(rustbuild)");
+    println!("cargo::rustc-check-cfg=cfg(thumb)");
 
     // FIXME: this feature definitely exists in
     // `rustc --print target-features --target sparc64-unknown-linux-gnu`. Why do check-cfg