rewrite used-cdylib-macos to rmake

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -212,7 +212,6 @@ run-make/translation/Makefile
 run-make/type-mismatch-same-crate-name/Makefile
 run-make/unstable-flag-required/Makefile
 run-make/use-suggestions-rust-2018/Makefile
-run-make/used-cdylib-macos/Makefile
 run-make/volatile-intrinsics/Makefile
 run-make/wasm-exceptions-nostd/Makefile
 run-make/wasm-override-linker/Makefile

tests/run-make/textrel-on-minimal-lib/rmake.rs

@@ -6,7 +6,8 @@
 // See https://github.com/rust-lang/rust/issues/68794
 
 //@ ignore-cross-compile
-//FIXME(Oneirical): check that it works on more than just only-linux
+//@ ignore-windows
+// Reason: There is no `bar.dll` produced by CC to run readobj on
 
 use run_make_support::{
     cc, dynamic_lib_name, extra_c_flags, extra_cxx_flags, llvm_readobj, rustc, static_lib_name,

tests/run-make/used-cdylib-macos/rmake.rs

@@ -0,0 +1,16 @@
+// This checks that `#[used]` passes through to the linker on
+// Apple targets. This is subject to change in the future.
+// See https://github.com/rust-lang/rust/pull/93718
+
+//@ only-apple
+
+use run_make_support::{dynamic_lib_name, llvm_readobj, rustc};
+
+fn main() {
+    rustc().opt_level("3").input("dylib_used.rs").run();
+    llvm_readobj()
+        .input(dynamic_lib_name("dylib_used"))
+        .arg("--dt")
+        .run()
+        .assert_stdout_contains("VERY_IMPORTANT_SYMBOL");
+}