diff options
Diffstat (limited to 'gcc/c-family/c-common.c')
| -rw-r--r-- | gcc/c-family/c-common.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c index acc9a20..901a5ed 100644 --- a/gcc/c-family/c-common.c +++ b/gcc/c-family/c-common.c @@ -11612,6 +11612,39 @@ maybe_warn_unused_local_typedefs (void) vec_free (l->local_typedefs); } +/* Warn about boolean expression compared with an integer value different + from true/false. Warns also e.g. about "(i1 == i2) == 2". + LOC is the location of the comparison, CODE is its code, OP0 and OP1 + are the operands of the comparison. The caller must ensure that + either operand is a boolean expression. */ + +void +maybe_warn_bool_compare (location_t loc, enum tree_code code, tree op0, + tree op1) +{ + if (TREE_CODE_CLASS (code) != tcc_comparison) + return; + + tree cst = (TREE_CODE (op0) == INTEGER_CST) + ? op0 : (TREE_CODE (op1) == INTEGER_CST) ? op1 : NULL_TREE; + if (!cst) + return; + + if (!integer_zerop (cst) && !integer_onep (cst)) + { + int sign = (TREE_CODE (op0) == INTEGER_CST) + ? tree_int_cst_sgn (cst) : -tree_int_cst_sgn (cst); + if (code == EQ_EXPR + || ((code == GT_EXPR || code == GE_EXPR) && sign < 0) + || ((code == LT_EXPR || code == LE_EXPR) && sign > 0)) + warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE " + "with boolean expression is always false", cst); + else + warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE " + "with boolean expression is always true", cst); + } +} + /* The C and C++ parsers both use vectors to hold function arguments. For efficiency, we keep a cache of unused vectors. This is the cache. */ |