tg.runFail("build", "x")
	tg.grepStderr("invalid input file name \"-y.go\"", "did not reject -y.go")
	tg.must(os.Remove(tg.path("src/x/-y.go")))

	if runtime.Compiler == "gccgo" {
		tg.runFail("build", "-gccgoflags=all=@x", "x")
	} else {
		tg.runFail("build", "-gcflags=all=@x", "x")
	}
	tg.grepStderr("invalid command-line argument @x in command", "did not reject @x during exec")