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-rw-r--r--gcc/ChangeLog11
-rw-r--r--gcc/c-opts.c1
-rw-r--r--gcc/c-typeck.c14
-rw-r--r--gcc/common.opt4
-rw-r--r--gcc/testsuite/ChangeLog8
-rw-r--r--gcc/testsuite/gcc.dg/Wstring-literal-comparison-1.c29
-rw-r--r--gcc/testsuite/gcc.dg/Wstring-literal-comparison-2.c29
-rw-r--r--gcc/testsuite/gcc.dg/Wstring-literal-comparison-3.c29
-rw-r--r--gcc/testsuite/gcc.dg/Wstring-literal-comparison-4.c29
9 files changed, 154 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index afe22a09faa..d8fc5310c8c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2005-12-04 Roger Sayle <roger@eyesopen.com>
+
+ 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.
+
2005-12-03 Joseph S. Myers <joseph@codesourcery.com>
* c-common.c (c_sizeof_or_alignof_type): Use fold_convert instead
diff --git a/gcc/c-opts.c b/gcc/c-opts.c
index 62db668b4e1..86f224407be 100644
--- a/gcc/c-opts.c
+++ b/gcc/c-opts.c
@@ -386,6 +386,7 @@ c_common_handle_option (size_t scode, const char *arg, int value)
warn_sign_compare = value;
warn_switch = value;
warn_strict_aliasing = value;
+ warn_string_literal_comparison = value;
/* Only warn about unknown pragmas that are not in system
headers. */
diff --git a/gcc/c-typeck.c b/gcc/c-typeck.c
index 8b8eb56ea44..062de7cded0 100644
--- a/gcc/c-typeck.c
+++ b/gcc/c-typeck.c
@@ -2552,6 +2552,20 @@ parser_build_binary_op (enum tree_code code, struct c_expr arg1,
}
+ /* Warn about comparisons against string literals, with the exception
+ of testing for equality or inequality of a string literal with NULL. */
+ if (code == EQ_EXPR || code == NE_EXPR)
+ {
+ if ((code1 == STRING_CST && !integer_zerop (arg2.value))
+ || (code2 == STRING_CST && !integer_zerop (arg1.value)))
+ warning (OPT_Wstring_literal_comparison,
+ "comparison with string literal");
+ }
+ else if (TREE_CODE_CLASS (code) == tcc_comparison
+ && (code1 == STRING_CST || code2 == STRING_CST))
+ warning (OPT_Wstring_literal_comparison,
+ "comparison with string literal");
+
unsigned_conversion_warning (result.value, arg1.value);
unsigned_conversion_warning (result.value, arg2.value);
overflow_warning (result.value);
diff --git a/gcc/common.opt b/gcc/common.opt
index 6ac77fdddee..e49838ae5f0 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -125,6 +125,10 @@ Wstrict-aliasing=
Common Joined UInteger
Warn about code which might break strict aliasing rules
+Wstring-literal-comparison
+Common Var(warn_string_literal_comparison)
+Warn about comparisons to constant string literals
+
Wswitch
Common Var(warn_switch)
Warn about enumerated switches, with no default, missing a case
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 257c74a5d1a..f08c25259dd 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2005-12-04 Roger Sayle <roger@eyesopen.com>
+
+ PR c/7776
+ * 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.
+
2005-12-03 Joseph S. Myers <joseph@codesourcery.com>
* gcc.dg/cast-pretty-print-1.c: New test.
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";
+}
+
diff --git a/gcc/testsuite/gcc.dg/Wstring-literal-comparison-2.c b/gcc/testsuite/gcc.dg/Wstring-literal-comparison-2.c
new file mode 100644
index 00000000000..3eb91eeca49
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wstring-literal-comparison-2.c
@@ -0,0 +1,29 @@
+/* PR c/7776 */
+/* { dg-do compile } */
+/* { dg-options "-Wall" } */
+
+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";
+}
+
diff --git a/gcc/testsuite/gcc.dg/Wstring-literal-comparison-3.c b/gcc/testsuite/gcc.dg/Wstring-literal-comparison-3.c
new file mode 100644
index 00000000000..f700a51a87b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wstring-literal-comparison-3.c
@@ -0,0 +1,29 @@
+/* PR c/7776 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+int test1(char *ptr)
+{
+ return ptr == "foo";
+}
+
+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";
+}
+
diff --git a/gcc/testsuite/gcc.dg/Wstring-literal-comparison-4.c b/gcc/testsuite/gcc.dg/Wstring-literal-comparison-4.c
new file mode 100644
index 00000000000..27f25f3ca98
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wstring-literal-comparison-4.c
@@ -0,0 +1,29 @@
+/* PR c/7776 */
+/* { dg-do compile } */
+/* { dg-options "-Wall -Wno-string-literal-comparison" } */
+
+int test1(char *ptr)
+{
+ return ptr == "foo";
+}
+
+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";
+}
+
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