rewrite cross-lang-lto-clang to rmake

src/tools/run-make-support/src/command.rs

@@ -258,6 +258,13 @@ impl CompletedProcess {
         self
     }
 
+    /// Checks that `stderr` does not contain the regex pattern `unexpected`.
+    #[track_caller]
+    pub fn assert_stderr_not_contains_regex<S: AsRef<str>>(&self, unexpected: S) -> &Self {
+        assert_not_contains_regex(&self.stdout_utf8(), unexpected);
+        self
+    }
+
     #[track_caller]
     pub fn assert_exit_code(&self, code: i32) -> &Self {
         assert!(self.output.status.code() == Some(code));

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -1,7 +1,6 @@
 run-make/branch-protection-check-IBT/Makefile
 run-make/cat-and-grep-sanity-check/Makefile
 run-make/cdylib-dylib-linkage/Makefile
-run-make/cross-lang-lto-clang/Makefile
 run-make/cross-lang-lto-pgo-smoketest/Makefile
 run-make/cross-lang-lto-upstream-rlibs/Makefile
 run-make/dep-info-doesnt-run-much/Makefile

tests/run-make/cross-lang-lto-clang/rmake.rs

@@ -0,0 +1,61 @@
+// This test checks that cross-language inlining actually works by checking
+// the generated machine code.
+// See https://github.com/rust-lang/rust/pull/57514
+
+//@ needs-force-clang-based-tests
+// FIXME(#126180): This test doesn't actually run anywhere, because the only
+// CI job that sets RUSTBUILD_FORCE_CLANG_BASED_TESTS runs very few tests.
+
+use run_make_support::{clang, env_var, llvm_ar, llvm_objdump, rustc, static_lib_name};
+
+fn main() {
+    rustc()
+        .linker_plugin_lto("on")
+        .output(static_lib_name("rustlib-xlto"))
+        .opt_level("2")
+        .codegen_units(1)
+        .input("rustlib.rs")
+        .run();
+    clang()
+        .lto("thin")
+        .use_ld("lld")
+        .arg("-lrustlib-xlto")
+        .out_exe("cmain")
+        .input("cmain.c")
+        .arg("-O3")
+        .run();
+    // Make sure we don't find a call instruction to the function we expect to
+    // always be inlined.
+    llvm_objdump()
+        .arg("-d")
+        .input("cmain")
+        .run()
+        .assert_stdout_not_contains_regex("call.*rust_always_inlined");
+    // As a sanity check, make sure we do find a call instruction to a
+    // non-inlined function
+    llvm_objdump()
+        .arg("-d")
+        .input("cmain")
+        .run()
+        .assert_stdout_contains_regex("call.*rust_never_inlined");
+    clang().input("clib.c").lto("thin").arg("-c").out_exe("clib.o").arg("-O2").run();
+    llvm_ar().obj_to_ar().output_input(static_lib_name("xyz"), "clib.o").run();
+    rustc()
+        .linker_plugin_lto("on")
+        .opt_level("2")
+        .linker(&env_var("CLANG"))
+        .link_arg("-fuse-ld=lld")
+        .input("main.rs")
+        .output("rsmain")
+        .run();
+    llvm_objdump()
+        .arg("-d")
+        .input("rsmain")
+        .run()
+        .assert_stdout_not_contains_regex("call.*c_always_inlined");
+    llvm_objdump()
+        .arg("-d")
+        .input("rsmain")
+        .run()
+        .assert_stdout_contains_regex("call.*c_never_inlined");
+}