Unrolled build for rust-lang#128099

Rollup merge of rust-lang#128099 - lolbinarycat:extern-flag-disambiguates-rmake, r=Kobzol

migrate tests/run-make/extern-flag-disambiguates to rmake

Author: rust-timer

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -13,7 +13,6 @@ run-make/dep-info/Makefile
 run-make/dump-ice-to-disk/Makefile
 run-make/emit-to-stdout/Makefile
 run-make/export-executable-symbols/Makefile
-run-make/extern-flag-disambiguates/Makefile
 run-make/extern-fn-reachable/Makefile
 run-make/fmt-write-bloat/Makefile
 run-make/foreign-double-unwind/Makefile

tests/run-make/README.md

@@ -41,3 +41,8 @@ The setup for the `rmake.rs` version is a 3-stage process:
 
 [`run_make_support`]: ../../src/tools/run-make-support
 [extern_prelude]: https://doc.rust-lang.org/reference/names/preludes.html#extern-prelude
+
+### Formatting
+
+Note that files under `tests/` are not formatted by `./x fmt`,
+use `rustfmt tests/path/to/file.rs` to format a specific file if desired.

tests/run-make/extern-flag-disambiguates/Makefile

@@ -0,0 +1,30 @@
+//@ ignore-cross-compile
+
+use run_make_support::{cwd, run, rustc};
+
+// Attempt to build this dependency tree:
+//
+//    A.1   A.2
+//     |\    |
+//     | \   |
+//     B  \  C
+//      \ | /
+//       \|/
+//        D
+//
+// Note that A.1 and A.2 are crates with the same name.
+
+// original Makefile at https://github.com/rust-lang/rust/issues/14469
+
+fn main() {
+    rustc().metadata("1").extra_filename("-1").input("a.rs").run();
+    rustc().metadata("2").extra_filename("-2").input("a.rs").run();
+    rustc().input("b.rs").extern_("a", "liba-1.rlib").run();
+    rustc().input("c.rs").extern_("a", "liba-2.rlib").run();
+    println!("before");
+    rustc().cfg("before").input("d.rs").extern_("a", "liba-1.rlib").run();
+    run("d");
+    println!("after");
+    rustc().cfg("after").input("d.rs").extern_("a", "liba-1.rlib").run();
+    run("d");
+}