From 19f0596c4a5e1a38ec4e960f475f89dab547665d Mon Sep 17 00:00:00 2001 From: sayle Date: Sun, 4 Dec 2005 19:56:47 +0000 Subject: [PATCH] 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 --- gcc/ChangeLog | 11 ++++++++ gcc/c-opts.c | 1 + gcc/c-typeck.c | 14 +++++++++++ gcc/common.opt | 4 +++ gcc/testsuite/ChangeLog | 8 ++++++ .../gcc.dg/Wstring-literal-comparison-1.c | 29 ++++++++++++++++++++++ .../gcc.dg/Wstring-literal-comparison-2.c | 29 ++++++++++++++++++++++ .../gcc.dg/Wstring-literal-comparison-3.c | 29 ++++++++++++++++++++++ .../gcc.dg/Wstring-literal-comparison-4.c | 29 ++++++++++++++++++++++ 9 files changed, 154 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/Wstring-literal-comparison-1.c create mode 100644 gcc/testsuite/gcc.dg/Wstring-literal-comparison-2.c create mode 100644 gcc/testsuite/gcc.dg/Wstring-literal-comparison-3.c create mode 100644 gcc/testsuite/gcc.dg/Wstring-literal-comparison-4.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index afe22a0..d8fc531 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,14 @@ +2005-12-04 Roger Sayle + + 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 * 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 62db668..86f2244 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 8b8eb56..062de7c 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 6ac77fd..e49838a 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 257c74a..f08c252 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,11 @@ +2005-12-04 Roger Sayle + + 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 * 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 0000000..c5dea46 --- /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 0000000..3eb91ee --- /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 0000000..f700a51 --- /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 0000000..27f25f3 --- /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"; +} + -- 2.7.4