rewrite extern-flag-pathless to rmake

Author: Oneirical

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -33,7 +33,6 @@ run-make/env-dep-info/Makefile
 run-make/export-executable-symbols/Makefile
 run-make/extern-diff-internal-name/Makefile
 run-make/extern-flag-disambiguates/Makefile
-run-make/extern-flag-pathless/Makefile
 run-make/extern-fn-explicit-align/Makefile
 run-make/extern-fn-generic/Makefile
 run-make/extern-fn-mangle/Makefile

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

@@ -0,0 +1,40 @@
+// It is possible, since #64882, to use the --extern flag without an explicit
+// path. In the event of two --extern flags, the explicit one with a path will take
+// priority, but otherwise, it is a more concise way of fetching specific libraries.
+// This test checks that the default priority of explicit extern flags and rlibs is
+// respected.
+// See https://github.com/rust-lang/rust/pull/64882
+
+use run_make_support::{dynamic_lib_name, fs_wrapper, run, run_fail, rust_lib_name, rustc};
+
+fn main() {
+    rustc().input("bar.rs").crate_type("rlib").crate_type("dylib").arg("-Cprefer-dynamic").run();
+
+    // By default, the rlib has priority over the dylib.
+    rustc().input("foo.rs").arg("--extern").arg("bar").run();
+    fs_wrapper::rename(dynamic_lib_name("bar"), "bar.tmp");
+    run("foo");
+    fs_wrapper::rename("bar.tmp", dynamic_lib_name("bar"));
+
+    rustc().input("foo.rs").extern_("bar", rust_lib_name("bar")).arg("--extern").arg("bar").run();
+    fs_wrapper::rename(dynamic_lib_name("bar"), "bar.tmp");
+    run("foo");
+    fs_wrapper::rename("bar.tmp", dynamic_lib_name("bar"));
+
+    // The first explicit usage of extern overrides the second pathless --extern bar.
+    rustc()
+        .input("foo.rs")
+        .extern_("bar", dynamic_lib_name("bar"))
+        .arg("--extern")
+        .arg("bar")
+        .run();
+    fs_wrapper::rename(dynamic_lib_name("bar"), "bar.tmp");
+    run_fail("foo");
+    fs_wrapper::rename("bar.tmp", dynamic_lib_name("bar"));
+
+    // With prefer-dynamic, execution fails as it refuses to use the rlib.
+    rustc().input("foo.rs").arg("--extern").arg("bar").arg("-Cprefer-dynamic").run();
+    fs_wrapper::rename(dynamic_lib_name("bar"), "bar.tmp");
+    run_fail("foo");
+    fs_wrapper::rename("bar.tmp", dynamic_lib_name("bar"));
+}