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re PR c/7776 (const char* p = "foo"; if (p == "foo") ... is compiled without warning!)

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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.

From-SVN: r108018
This commit is contained in:
Roger Sayle 2005-12-04 19:56:47 +00:00 committed by Roger Sayle
parent 93af36c5c1
commit e994a705a9
9 changed files with 154 additions and 0 deletions
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11
gcc/ChangeLog
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@ -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

1
gcc/c-opts.c
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@ -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. */

14
gcc/c-typeck.c
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@ -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);

4
gcc/common.opt
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@ -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

8
gcc/testsuite/ChangeLog
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@ -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.

29
gcc/testsuite/gcc.dg/Wstring-literal-comparison-1.c Normal file
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@ -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";
}

29
gcc/testsuite/gcc.dg/Wstring-literal-comparison-2.c Normal file
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@ -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";
}

29
gcc/testsuite/gcc.dg/Wstring-literal-comparison-3.c Normal file
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@ -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";
}

29
gcc/testsuite/gcc.dg/Wstring-literal-comparison-4.c Normal file
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@ -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";
}