rewrite and rename issue-10971-temps-dir to rmake format

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -79,7 +79,6 @@ run-make/invalid-library/Makefile
 run-make/invalid-so/Makefile
 run-make/invalid-staticlib/Makefile
 run-make/issue-107094/Makefile
-run-make/issue-10971-temps-dir/Makefile
 run-make/issue-109934-lto-debuginfo/Makefile
 run-make/issue-14698/Makefile
 run-make/issue-15460/Makefile

tests/run-make/issue-10971-temps-dir/Makefile

@@ -1,10 +0,0 @@
-include ../tools.mk
-
-# Regression test for issue #10971
-# Running two invocations in parallel would overwrite each other's temp files.
-
-all:
-	touch $(TMPDIR)/lib.rs
-
-	$(RUSTC) --crate-type=lib -Z temps-dir=$(TMPDIR)/temp1 $(TMPDIR)/lib.rs & \
-	$(RUSTC) --crate-type=staticlib -Z temps-dir=$(TMPDIR)/temp2 $(TMPDIR)/lib.rs

tests/run-make/parallel-rustc-no-overwrite/rmake.rs

@@ -0,0 +1,22 @@
+// When two instances of rustc are invoked in parallel, they
+// can conflict on their temporary files and overwrite each others',
+// leading to unsuccessful compilation. The -Z temps-dir flag adds
+// separate designated directories for each rustc invocation, preventing
+// conflicts. This test uses this flag and checks for successful compilation.
+// See https://github.com/rust-lang/rust/pull/83846
+
+use run_make_support::{fs_wrapper, rustc};
+use std::thread;
+
+fn main() {
+    fs_wrapper::create_file("lib.rs");
+    let handle1 = thread::spawn(move || {
+        rustc().crate_type("lib").arg("-Ztemps-dir=temp1").input("lib.rs");
+    });
+
+    let handle2 = thread::spawn(move || {
+        rustc().crate_type("staticlib").arg("-Ztemps-dir=temp2").input("lib.rs");
+    });
+    handle1.join().expect("lib thread panicked");
+    handle2.join().expect("staticlib thread panicked");
+}