c: Stray inform note with -Waddress [PR106947]

A trivial fix for maybe_warn_for_null_address where we print an
inform note without first checking the return value of a warning
call.

	PR c/106947

gcc/c/ChangeLog:

	* c-typeck.cc (maybe_warn_for_null_address): Don't emit stray
	notes.

gcc/testsuite/ChangeLog:

	* c-c++-common/Waddress-7.c: New test.

2 files changed, 32 insertions, 9 deletions

diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 43a910d..33d1e84 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -11738,18 +11738,19 @@ maybe_warn_for_null_address (location_t loc, tree op, tree_code code)
       || from_macro_expansion_at (loc))
     return;
 
+  bool w;
   if (code == EQ_EXPR)
-    warning_at (loc, OPT_Waddress,
-		"the comparison will always evaluate as %<false%> "
-		"for the address of %qE will never be NULL",
-		op);
+    w = warning_at (loc, OPT_Waddress,
+		    "the comparison will always evaluate as %<false%> "
+		    "for the address of %qE will never be NULL",
+		    op);
   else
-    warning_at (loc, OPT_Waddress,
-		"the comparison will always evaluate as %<true%> "
-		"for the address of %qE will never be NULL",
-		op);
+    w = warning_at (loc, OPT_Waddress,
+		    "the comparison will always evaluate as %<true%> "
+		    "for the address of %qE will never be NULL",
+		    op);
 
-  if (DECL_P (op))
+  if (w && DECL_P (op))
     inform (DECL_SOURCE_LOCATION (op), "%qD declared here", op);
 }
 
diff --git a/gcc/testsuite/c-c++-common/Waddress-7.c b/gcc/testsuite/c-c++-common/Waddress-7.c
new file mode 100644
index 0000000..1799485
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Waddress-7.c
@@ -0,0 +1,22 @@
+/* PR c/106947 */
+/* { dg-do compile } */
+/* { dg-options "-Waddress" } */
+
+#ifndef __cplusplus
+# define bool _Bool
+#endif
+
+#pragma GCC diagnostic ignored "-Waddress"
+int s; /* { dg-bogus "declared" } */
+bool e = &s;
+int
+main ()
+{
+  int error = 0;
+  {
+    bool e1 = &s;
+    if (!e1)
+      error = 1;
+  }
+  return error;
+}