diff --git a/gcc/testsuite/gcc.dg/cpp-mi.c b/gcc/testsuite/gcc.dg/cpp-mi.c
index f667d0c4b9d..1fb62788925 100644
--- a/gcc/testsuite/gcc.dg/cpp-mi.c
+++ b/gcc/testsuite/gcc.dg/cpp-mi.c
@@ -6,10 +6,8 @@
 /* We have to test two cases: C comments at the top and C++ comments
    at the top.  */
 
-/*
-{ dg-do preprocess }
-{ dg-options "-Wp,-lang-c-c++-comments" }
-*/
+/* { dg-do preprocess }
+   { dg-options "" } */
 
 #include "cpp-mic.h"
 #include "cpp-mic.h"
diff --git a/gcc/testsuite/gcc.dg/cpp-redef-2.c b/gcc/testsuite/gcc.dg/cpp-redef-2.c
new file mode 100644
index 00000000000..8d34ddfa05d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp-redef-2.c
@@ -0,0 +1,27 @@
+/* Test for redefining macros with significant differences.  */
+
+/* { dg-do preprocess }
+   { dg-options "-pedantic -Wall" } */
+
+#define mac(a, b) (a) + (b)
+#define mac(a, b) (a) * (b)
+#define mac(a, b) (a) * (x)
+
+#define ro(x) foo x bar
+#define ro(x, b) foo x bar
+
+#define va(a...) a
+#define va(...) __VA_ARGS__
+
+/* { dg-warning "redefined" "redef mac"     { target *-*-* } 7  }
+   { dg-warning "redefined" "redef mac"     { target *-*-* } 8  }
+   { dg-warning "redefined" "redef ro"      { target *-*-* } 11 }
+   { dg-warning "redefined" "redef va"      { target *-*-* } 14 }
+
+   { dg-warning "previous"  "prev def mac"  { target *-*-* } 6  }
+   { dg-warning "previous"  "prev def mac"  { target *-*-* } 7  }
+   { dg-warning "previous"  "prev def ro"   { target *-*-* } 10 }
+   { dg-warning "previous"  "prev def va"   { target *-*-* } 13 }
+
+   { dg-warning "varargs"   "named varargs" { target *-*-* } 13 }
+   { dg-warning "varargs"   "anon varargs"  { target *-*-* } 14 } */