Rollup merge of rust-lang#125227 - Oneirical:seventh, r=jieyouxu

Migrate `run-make/issue-30063` to `rmake`

Part of rust-lang#121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).

(Sorry about the [inconvenience](rust-lang#125224 (comment)) of all these PRs, this is the last one batched for today. I will discuss how we can cut these down a bit.)

The last check was previously commented out in the Makefile, and I have readded it. If it fails the CI, this can be reconsidered.

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -101,7 +101,6 @@ run-make/issue-25581/Makefile
 run-make/issue-26006/Makefile
 run-make/issue-26092/Makefile
 run-make/issue-28595/Makefile
-run-make/issue-30063/Makefile
 run-make/issue-33329/Makefile
 run-make/issue-35164/Makefile
 run-make/issue-36710/Makefile

tests/run-make/reset-codegen-1/rmake.rs

@@ -0,0 +1,38 @@
+// When rustc received 4 codegen-units, an output path and an emit flag all simultaneously,
+// this could cause an annoying recompilation issue, uselessly lengthening the build process.
+// A fix was delivered, which resets codegen-units to 1 when necessary,
+// but as it directly affected the way codegen-units are manipulated,
+// this test was created to check that this fix did not cause compilation failures.
+// See https://github.com/rust-lang/rust/issues/30063
+
+//@ ignore-cross-compile
+
+use run_make_support::{rustc, tmp_dir};
+use std::fs;
+
+fn compile(output_file: &str, emit: Option<&str>) {
+    let mut rustc = rustc();
+    let rustc = rustc.codegen_units(4).output(tmp_dir().join(output_file)).input("foo.rs");
+    if let Some(emit) = emit {
+        rustc.emit(emit);
+    }
+    rustc.run();
+}
+
+fn main() {
+    let flags = [
+        ("foo-output", None),
+        ("asm-output", Some("asm")),
+        ("bc-output", Some("llvm-bc")),
+        ("ir-output", Some("llvm-ir")),
+        ("link-output", Some("link")),
+        ("obj-output", Some("obj")),
+        ("dep-output", Some("dep-info")),
+        ("multi-output", Some("asm,obj")),
+    ];
+    for (output_file, emit) in flags {
+        fs::remove_file(output_file).unwrap_or_default();
+        compile(output_file, emit);
+        fs::remove_file(output_file);
+    }
+}