rewrite type-mismatch-same-crate-name to rmake

Author: Oneirical

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -142,6 +142,5 @@ run-make/test-benches/Makefile
 run-make/thumb-none-cortex-m/Makefile
 run-make/thumb-none-qemu/Makefile
 run-make/translation/Makefile
-run-make/type-mismatch-same-crate-name/Makefile
 run-make/unstable-flag-required/Makefile
 run-make/x86_64-fortanix-unknown-sgx-lvi/Makefile

tests/run-make/type-mismatch-same-crate-name/Makefile

@@ -0,0 +1,29 @@
+// When a compilation failure deals with seemingly identical types, some helpful
+// errors should be printed.
+// The main use case of this error is when there are two crates
+// (generally different versions of the same crate) with the same name
+// causing a type mismatch. In this test, one of the crates
+// is only introduced as an indirect dependency and the type is accessed via a reexport.
+// See https://github.com/rust-lang/rust/pull/42826
+
+use run_make_support::{rust_lib_name, rustc};
+
+fn main() {
+    rustc().crate_type("rlib").input("crateA.rs").metadata("-1").extra_filename("-1").run();
+    rustc().crate_type("rlib").input("crateA.rs").metadata("-2").extra_filename("-2").run();
+    rustc()
+        .crate_type("rlib")
+        .input("crateB.rs")
+        .extern_("crateA", rust_lib_name("crateA-1"))
+        .run();
+    rustc()
+        .input("crateC.rs")
+        .extern_("crateA", rust_lib_name("crateA-2"))
+        .run_fail()
+        .assert_stderr_contains("mismatched types")
+        .assert_stderr_contains("crateB::try_foo(foo2);")
+        .assert_stderr_contains("different versions of crate `crateA`")
+        .assert_stderr_contains("crateB::try_bar(bar2);")
+        .assert_stderr_contains("expected trait `crateA::bar::Bar`, found trait `Bar`")
+        .assert_stderr_contains("different versions of crate `crateA`");
+}