rewrite staticlib-blank-lib to rmake

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -102,7 +102,6 @@ run-make/simd-ffi/Makefile
 run-make/split-debuginfo/Makefile
 run-make/stable-symbol-names/Makefile
 run-make/static-dylib-by-default/Makefile
-run-make/staticlib-blank-lib/Makefile
 run-make/staticlib-dylib-linkage/Makefile
 run-make/symbol-mangling-hashed/Makefile
 run-make/symbol-visibility/Makefile

tests/run-make/staticlib-blank-lib/Makefile

@@ -1,6 +0,0 @@
-include ../tools.mk
-
-all:
-	$(AR) crus $(TMPDIR)/libfoo.a foo.rs
-	$(AR) d $(TMPDIR)/libfoo.a foo.rs
-	$(RUSTC) foo.rs

tests/run-make/staticlib-blank-lib/rmake.rs

@@ -0,0 +1,13 @@
+// In this test, the static library foo is made blank, which used to cause
+// a compilation error. As the compiler now returns Ok upon encountering a blank
+// staticlib as of #12379, this test checks that compilation is successful despite
+// the blank staticlib.
+// See https://github.com/rust-lang/rust/pull/12379
+
+use run_make_support::{llvm_ar, rustc, static_lib_name};
+
+fn main() {
+    llvm_ar().obj_to_ar().output_input(static_lib_name("foo"), "foo.rs").run();
+    llvm_ar().arg("d").output_input(static_lib_name("foo"), "foo.rs").run();
+    rustc().input("foo.rs").run();
+}