This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
[C++ PATCH] Warn about if ("abc" < "xyz")...
- From: Roger Sayle <roger at eyesopen dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Mon, 5 Dec 2005 07:24:32 -0700 (MST)
- Subject: [C++ PATCH] Warn about if ("abc" < "xyz")...
This is the promised C++ version of my fix for enhancement request
PR c/7776. The documentation and command line option bits were
already applied to mainline as part of the C patch.
The following patch has been tested on i686-pc-linux-gnu with a
full "make bootstrap", and regression tested with a top-level
"make -k check" with no new failures.
Ok for mainline?
2005-12-05 Roger Sayle <roger@eyesopen.com>
* typeck.c (build_binary_op): Issue warning if either operand of a
comparison operator is a string literal, except for testing equality
or inequality against NULL.
* g++.dg/warn/Wstring-literal-comparison-1.C: New test case.
* g++.dg/warn/Wstring-literal-comparison-2.C: Likewise.
* g++.dg/warn/Wstring-literal-comparison-3.C: Likewise.
* g++.dg/warn/Wstring-literal-comparison-4.C: Likewise.
Index: typeck.c
===================================================================
*** typeck.c (revision 108018)
--- typeck.c (working copy)
*************** build_binary_op (enum tree_code code, tr
*** 3089,3094 ****
--- 3089,3098 ----
case NE_EXPR:
if (warn_float_equal && (code0 == REAL_TYPE || code1 == REAL_TYPE))
warning (0, "comparing floating point with == or != is unsafe");
+ if ((TREE_CODE (orig_op0) == STRING_CST && !integer_zerop (op1))
+ || (TREE_CODE (orig_op1) == STRING_CST && !integer_zerop (op0)))
+ warning (OPT_Wstring_literal_comparison,
+ "comparison with string literal");
build_type = boolean_type_node;
if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
*************** build_binary_op (enum tree_code code, tr
*** 3194,3199 ****
--- 3198,3208 ----
case GE_EXPR:
case LT_EXPR:
case GT_EXPR:
+ if (TREE_CODE (orig_op0) == STRING_CST
+ || TREE_CODE (orig_op1) == STRING_CST)
+ warning (OPT_Wstring_literal_comparison,
+ "comparison with string literal");
+
build_type = boolean_type_node;
if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
&& (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
/* 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";
}
/* 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";
}
/* 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";
}
/* 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";
}
Roger
--
Roger Sayle, E-mail: roger@eyesopen.com
OpenEye Scientific Software, WWW: http://www.eyesopen.com/
Suite 1107, 3600 Cerrillos Road, Tel: (+1) 505-473-7385
Santa Fe, New Mexico, 87507. Fax: (+1) 505-473-0833