--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp0x/udlit-macros.C	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,31 @@
+// PR c++/80955
+// { dg-do run { target c++11 } }
+
+extern "C" int sprintf (char *s, const char *format, ...);
+extern "C" int strcmp (const char *s1, const char *s2);
+
+#define __PRI64_PREFIX        "l"
+#define PRId64         __PRI64_PREFIX "d"
+
+using size_t = decltype(sizeof(0));
+#define _zero
+#define _ID _xx
+int operator""_zero(const char*, size_t) { return 0; }
+int operator""_ID(const char*, size_t) { return 0; }
+
+int main()
+{
+  long i64 = 123;
+  char buf[] = "xxxxxx"__FILE__;      // { dg-warning "invalid suffix on literal" }
+  sprintf(buf, "%"PRId64"abc", i64);  // { dg-warning "invalid suffix on literal" }
+  return strcmp(buf, "123abc")
+	 + ""_zero
+	 + "bob"_zero
+	 + R"#(raw
+	       string)#"_zero
+	 + "xx"_ID
+	 + ""_ID
+	 + R"AA(another
+		raw
+		string)AA"_ID;
+}