diff options
| author | Dirk Mueller <dmueller@suse.de> | 2007-03-09 16:16:35 +0000 |
|---|---|---|
| committer | Dirk Mueller <mueller@gcc.gnu.org> | 2007-03-09 16:16:35 +0000 |
| commit | 63a0874077b3325c2b3cc47401d8bfe916d8f128 (patch) | |
| tree | 0678efcbaa9704baaeb7ec0f167caf43462406c8 /gcc/c-common.c | |
| parent | 0de2ae02735c71f5318af4486444d33c26fc211a (diff) | |
| download | gcc-63a0874077b3325c2b3cc47401d8bfe916d8f128.zip gcc-63a0874077b3325c2b3cc47401d8bfe916d8f128.tar.gz gcc-63a0874077b3325c2b3cc47401d8bfe916d8f128.tar.bz2 | |
re PR c/17946 (wanted: warning for "a && MASK" when "a & MASK" was probably intended)
2007-03-09 Dirk Mueller <dmueller@suse.de>
PR c++/17946
* doc/invoke.texi (-Wlogical-op): Document.
* common.opt (-Wlogical-op): New.
* c-common.h (warn_logical_operator): Declare.
* c-common.c (warn_logical_operator): Define.
* c-typeck.c (parser_build_binary_op): Call
warn_logical_operator.
* cp/call.c (build_new_op): Call warn_logical_operator.
* testsuite/gcc.dg/Wlogical-op-1.c: New.
* testsuite/g++.dg/warn/Wlogical-op-1.C: New.
From-SVN: r122751
Diffstat (limited to 'gcc/c-common.c')
| -rw-r--r-- | gcc/c-common.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/gcc/c-common.c b/gcc/c-common.c index 0bcd462..6216d5e 100644 --- a/gcc/c-common.c +++ b/gcc/c-common.c @@ -978,6 +978,44 @@ overflow_warning (tree value) } } + +/* Warn about use of a logical || / && operator being used in a + context where it is likely that the bitwise equivalent was intended + by the programmer. CODE is the TREE_CODE of the operator, ARG1 + and ARG2 the arguments. */ + +void +warn_logical_operator (enum tree_code code, tree arg1, tree + arg2) +{ + switch (code) + { + case TRUTH_ANDIF_EXPR: + case TRUTH_ORIF_EXPR: + case TRUTH_OR_EXPR: + case TRUTH_AND_EXPR: + if (!TREE_NO_WARNING (arg1) + && INTEGRAL_TYPE_P (TREE_TYPE (arg1)) + && !CONSTANT_CLASS_P (arg1) + && TREE_CODE (arg2) == INTEGER_CST + && !integer_zerop (arg2) + && !integer_onep (arg2)) + { + warning (OPT_Wlogical_op, + "logical %<%s%> with non-zero constant " + "will always evaluate as true", + ((code == TRUTH_ANDIF_EXPR) + || (code == TRUTH_AND_EXPR)) ? "&&" : "||"); + TREE_NO_WARNING (arg1) = true; + } + + break; + default: + break; + } +} + + /* Print a warning about casts that might indicate violation of strict aliasing rules if -Wstrict-aliasing is used and strict aliasing mode is in effect. OTYPE is the original |