Adds a warning when identical expressions are found on both sides of the '&&' operator. This is a common error resulting from copy & paste.
Excludes identical expressions found while preprocessing, so we don't get upset about #if defined(FOO) && defined(BAR), which happens all the time, and is perfectly valid.
Signed-off-by: Chris Forbes <chrisf@xxxxxxxxx>
---
evaluate.c | 133 +++++++++++++++++++++++++++++
validation/check_identical_exprs_on_and.c | 30 +++++++
2 files changed, 163 insertions(+), 0 deletions(-)
create mode 100644 validation/check_identical_exprs_on_and.c
diff --git a/evaluate.c b/evaluate.c
index f7a5678..08f6ae6 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -853,8 +853,141 @@ static struct symbol *evaluate_conditional(struct expression *expr, int iterator
return ctype;
}
+static int str_equal(struct string *a, struct string *b)
+{
+ return a->length == b->length &&
+ !memcmp(a->data, b->data, a->length);
+}
+
+static int ident_equal(struct ident *a, struct ident *b)
+{
+ /* only correct when used in the context of expr_equiv.
+ should compare symbols? for general case? */
+ return a->len == b->len &&
+ !memcmp(a->name, b->name, a->len);
+}
+
+/* expr_equiv and expr_list_equiv are mutually recursive */
+static int expr_equiv(struct expression *lhs, struct expression *rhs);
+
+static int expr_list_equiv(struct expression_list *lhs,
+ struct expression_list *rhs)
+{
+ int l_length = expression_list_size(lhs);
+ int r_length = expression_list_size(rhs);
+ struct expression **l_items, **r_items;
+ int i;
+
+ if (l_length != r_length)
+ return 0;
+
+ l_items = alloca(sizeof( *l_items ) * l_length);
+ r_items = alloca(sizeof( *r_items ) * r_length);
+
+ linearize_ptr_list((struct ptr_list *)lhs, (void **)l_items, l_length);
+ linearize_ptr_list((struct ptr_list *)rhs, (void **)r_items, r_length);
+
+ for (i = 0; i < l_length; i++) {
+ if (!expr_equiv(l_items[i], r_items[i]))
+ return 0;
+ }
+
+ return 1;
+}
+
+int expr_equiv(struct expression *lhs, struct expression *rhs)
+{
+ /* recursively determine if lhs ~ rhs. */
+ if (!lhs ^ !rhs) return 0;
+
+ if (lhs->type != rhs->type) return 0;
+ if (lhs->flags != rhs->flags) return 0;
+ if (lhs->op != rhs->op) return 0;
+ if (lhs->ctype != rhs->ctype) return 0;
+
+ switch (lhs->type) {
+ case EXPR_VALUE:
+ return lhs->value == rhs->value &&
+ lhs->taint == rhs->taint;
+ case EXPR_FVALUE:
+ return lhs->fvalue == rhs->fvalue;
+ case EXPR_STRING:
+ return lhs->wide == rhs->wide &&
+ str_equal(lhs->string, rhs->string);
+/* case EXPR_UNOP: */ /* this is mentioned in the union, but doesn't
+ actually exist */
+ case EXPR_PREOP:
+ case EXPR_POSTOP:
+ return lhs->op_value == rhs->op_value &&
+ expr_equiv(lhs->unop, rhs->unop);
+ case EXPR_SYMBOL:
+ case EXPR_TYPE:
+ return lhs->symbol == rhs->symbol;
+ case EXPR_BINOP:
+ case EXPR_COMMA:
+ case EXPR_COMPARE:
+ case EXPR_LOGICAL:
+ case EXPR_ASSIGNMENT:
+ return expr_equiv(lhs->left, rhs->left) &&
+ expr_equiv(lhs->right, rhs->right);
+ case EXPR_DEREF:
+ return expr_equiv(lhs->deref, rhs->deref) &&
+ ident_equal(lhs->member, rhs->member);
+ case EXPR_SLICE:
+ return expr_equiv(lhs->base, rhs->base) &&
+ lhs->r_bitpos == rhs->r_bitpos &&
+ lhs->r_nrbits == rhs->r_nrbits;
+ case EXPR_CAST:
+ case EXPR_SIZEOF:
+ return lhs->cast_type == rhs->cast_type &&
+ expr_equiv(lhs->cast_expression,
+ rhs->cast_expression);
+ case EXPR_CONDITIONAL:
+ case EXPR_SELECT:
+ return expr_equiv(lhs->conditional, rhs->conditional) &&
+ expr_equiv(lhs->cond_true, rhs->cond_true) &&
+ expr_equiv(lhs->cond_false, rhs->cond_false);
+ case EXPR_CALL:
+ return expr_equiv(lhs->fn, rhs->fn) &&
+ expr_list_equiv(lhs->args, rhs->args);
+ case EXPR_LABEL:
+ return lhs->label_symbol == rhs->label_symbol;
+ case EXPR_INITIALIZER:
+ return expr_list_equiv(lhs->expr_list, rhs->expr_list);
+ case EXPR_IDENTIFIER:
+ return ident_equal(lhs->expr_ident, rhs->expr_ident) &&
+ lhs->field == rhs->field &&
+ expr_equiv(lhs->ident_expression,
+ rhs->ident_expression);
+ case EXPR_INDEX:
+ return lhs->idx_from == rhs->idx_from &&
+ lhs->idx_to == rhs->idx_to &&
+ expr_equiv(lhs->idx_expression, rhs->idx_expression);
+ case EXPR_POS:
+ return lhs->init_offset == rhs->init_offset &&
+ lhs->init_nr == rhs->init_nr &&
+ expr_equiv(lhs->init_expr, rhs->init_expr);
+ case EXPR_OFFSETOF:
+ return lhs->in == rhs->in &&
+ expr_equiv(lhs->down, rhs->down);
+
+ default:
+ return 0;
+ }
+
+ return 1;
+}
+
static struct symbol *evaluate_logical(struct expression *expr)
{
+ if (!preprocessing) {
+ if (expr->op == SPECIAL_LOGICAL_AND &&
+ expr_equiv(expr->left, expr->right)) {
+ warning(expr->pos, "identical expressions on both "
+ "sides of '&&'");
+ }
+ }
+
if (!evaluate_conditional(expr->left, 0))
return NULL;
if (!evaluate_conditional(expr->right, 0))
diff --git a/validation/check_identical_exprs_on_and.c b/validation/check_identical_exprs_on_and.c
new file mode 100644
index 0000000..6560429
--- /dev/null
+++ b/validation/check_identical_exprs_on_and.c
@@ -0,0 +1,30 @@
+extern void bar(void);
+
+static void foo(void *a, void *b, void *c)
+{
+ if (a && a) /* should warn */
+ bar();
+
+ if (a && b) /* should not warn */
+ bar();
+
+ if ((a == b) && (a == b)) /* should warn */
+ bar();
+
+ if ((a == b) && (b == c)) /* should not warn */
+ bar();
+}
+
+/* should not warn */
+#if defined(BLETCHEROUS_PLATFORM) && defined(BROKEN_VERSION_OF_SAME)
+ /* do something suitably bizarre */
+#endif
+
+/*
+ * check-name: A warning should be issued for identical expressions on both sides of the '&&' operator.
+ *
+ * check-error-start
+check_identical_exprs_on_and.c:5:15: warning: identical expressions on both sides of '&&'
+check_identical_exprs_on_and.c:11:22: warning: identical expressions on both sides of '&&'
+ * check-error-end
+ */
--
1.7.4.1
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