Guard notes for -Waddress-of-packed-member on warning emission (PR c/89985)

gcc/c-family/ChangeLog:
	PR c/89985
	* c-warn.c (check_address_or_pointer_of_packed_member): Add
	auto_diagnostic_group.  Guard inform calls by result of
	warning_at call.

gcc/testsuite/ChangeLog:
	PR c/89985
	* c-c++-common/pr89985.c: New test.

From-SVN: r270169

gcc/c-family/ChangeLog

+2019-04-05  David Malcolm  <dmalcolm@redhat.com>
+
+	PR c/89985
+	* c-warn.c (check_address_or_pointer_of_packed_member): Add
+	auto_diagnostic_group.  Guard inform calls by result of
+	warning_at call.
+
 2019-04-05  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/89973 - -Waddress-of-packed-member ICE with invalid conversion. 

gcc/c-family/c-warn.c

@@ -2783,18 +2783,21 @@ check_address_or_pointer_of_packed_member (tree type, tree rhs)
 	  unsigned int rhs_align = min_align_of_type (rhstype);
 	  if (rhs_align < type_align)
 	    {
+	      auto_diagnostic_group d;
 	      location_t location = EXPR_LOC_OR_LOC (rhs, input_location);
-	      warning_at (location, OPT_Waddress_of_packed_member,
-			  "converting a packed %qT pointer (alignment %d) "
-			  "to a %qT pointer (alignment %d) may result in an "
-			  "unaligned pointer value",
-			  rhstype, rhs_align, type, type_align);
-	      tree decl = TYPE_STUB_DECL (rhstype);
-	      if (decl)
-		inform (DECL_SOURCE_LOCATION (decl), "defined here");
-	      decl = TYPE_STUB_DECL (type);
-	      if (decl)
-		inform (DECL_SOURCE_LOCATION (decl), "defined here");
+	      if (warning_at (location, OPT_Waddress_of_packed_member,
+			      "converting a packed %qT pointer (alignment %d) "
+			      "to a %qT pointer (alignment %d) may result in "
+			      "an unaligned pointer value",
+			      rhstype, rhs_align, type, type_align))
+		{
+		  tree decl = TYPE_STUB_DECL (rhstype);
+		  if (decl)
+		    inform (DECL_SOURCE_LOCATION (decl), "defined here");
+		  decl = TYPE_STUB_DECL (type);
+		  if (decl)
+		    inform (DECL_SOURCE_LOCATION (decl), "defined here");
+		}
 	    }
 	}
       return NULL_TREE;

gcc/testsuite/ChangeLog

+2019-04-05  David Malcolm  <dmalcolm@redhat.com>
+
+	PR c/89985
+	* c-c++-common/pr89985.c: New test.
+
 2019-04-05  Christophe Lyon  <christophe.lyon@linaro.org>
 
 	PR c/71598

gcc/testsuite/c-c++-common/pr89985.c

+/* Ensure that -Waddress-of-packed-member doesn't emit notes when
+   suppressed via -w, rather than -Wno-address-of-packed-member.  */
+
+/* { dg-do compile } */
+/* { dg-options "-w" } */
+
+struct a { /* { dg-bogus "defined here" } */
+  void *ptr;
+} __attribute__((packed));
+
+struct b { /* { dg-bogus "defined here" } */
+  void *ptr;
+};
+
+void
+test (struct a *p)
+{
+  struct b *q = (struct b *)p;
+}