rewrite and rename issue-18943 to rmake

Author: Oneirical

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -81,7 +81,6 @@ run-make/issue-10971-temps-dir/Makefile
 run-make/issue-109934-lto-debuginfo/Makefile
 run-make/issue-14698/Makefile
 run-make/issue-15460/Makefile
-run-make/issue-18943/Makefile
 run-make/issue-20626/Makefile
 run-make/issue-22131/Makefile
 run-make/issue-25581/Makefile

tests/run-make/issue-18943/Makefile

@@ -0,0 +1,13 @@
+// Inside a library, implementing a trait for another trait
+// with a lifetime used to cause an internal compiler error (ICE).
+// This test checks that this bug does not make a resurgence -
+// first by ensuring successful compilation, then verifying that
+// the lib crate-type flag was actually followed.
+// See https://github.com/rust-lang/rust/issues/18943
+
+use run_make_support::{count_rlibs, rustc};
+
+fn main() {
+    rustc().input("foo.rs").crate_type("lib").run();
+    assert_eq!(count_rlibs("foo"), 1);
+}