rewrite incr-add-rust-src-component to rmake

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -7,7 +7,6 @@ run-make/dep-info-spaces/Makefile
 run-make/dep-info/Makefile
 run-make/emit-to-stdout/Makefile
 run-make/extern-fn-reachable/Makefile
-run-make/incr-add-rust-src-component/Makefile
 run-make/issue-84395-lto-embed-bitcode/Makefile
 run-make/jobserver-error/Makefile
 run-make/libs-through-symlinks/Makefile

tests/run-make/incr-add-rust-src-component/rmake.rs

@@ -0,0 +1,22 @@
+// rust-lang/rust#70924: Test that if we add rust-src component in between two
+// incremental compiles, the compiler does not ICE on the second.
+// Remove the rust-src part of the sysroot for the *first* build.
+// Then put in a facsimile of the rust-src
+// component for the second build, in order to expose the ICE from issue #70924.
+// See https://github.com/rust-lang/rust/pull/72952
+
+//FIXME(Oneirical): try on test-various and windows
+//FIXME(Oneirical): check that the direct edit of the sysroot is not messing things up
+
+use run_make_support::{path, rfs, rustc};
+
+fn main() {
+    let sysroot = rustc().print("sysroot").run().stdout_utf8();
+    let sysroot = sysroot.trim();
+    let sysroot = format!("{sysroot}-sysroot");
+    rfs::remove_dir_all(path(&sysroot).join("lib/rustlib/src/rust"));
+    rustc().arg("--sysroot").arg(&sysroot).incremental("incr").input("main.rs").run();
+    rfs::create_dir_all(path(&sysroot).join("lib/rustlib/src/rust/src/libstd"));
+    rfs::create_file(path(&sysroot).join("lib/rustlib/src/rust/src/libstd/lib.rs"));
+    rustc().arg("--sysroot").arg(&sysroot).incremental("incr").input("main.rs").run();
+}