PR c/7776

	* common.opt (Wstring-literal-comparison): New command line option.
	* c-opts.c (c_common_handle_option): Set it with -Wall.
	* c-typeck.c (parser_build_binary_op): Issue warning if either
	operand of a comparison operator is a string literal, except for
	testing equality or inequality against NULL.

	* doc/invoke.texi: Document new -Wstring-literal-comparison option.

	* gcc.dg/Wstring-literal-comparison-1.c: New test case.
	* gcc.dg/Wstring-literal-comparison-2.c: Likewise.
	* gcc.dg/Wstring-literal-comparison-3.c: Likewise.
	* gcc.dg/Wstring-literal-comparison-4.c: Likewise.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@108018 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 29 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/Wstring-literal-comparison-1.c b/gcc/testsuite/gcc.dg/Wstring-literal-comparison-1.c
new file mode 100644
index 00000000000..c5dea463b51
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wstring-literal-comparison-1.c
@@ -0,0 +1,29 @@
+/* PR c/7776 */
+/* { dg-do compile } */
+/* { dg-options "-Wstring-literal-comparison" } */
+
+int test1(char *ptr)
+{
+  return ptr == "foo";  /* { dg-warning "comparison with string" } */
+}
+
+int test2()
+{
+  return "foo" != (const char*)0;
+}
+
+int test3()
+{
+  return "foo" == (const char*)0;
+}
+
+int test4()
+{
+  return (const char*)0 != "foo";
+}
+
+int test5()
+{
+  return (const char*)0 == "foo";
+}
+