Move the whole calculation of cast expressions' constness flags to the
evaluation phase such that expressions like
(int)__builtin_choose_expr(0, 0, 0)
can now be recognized as qualifying as integer constant expressions.
Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
---
evaluate.c | 27 ++++++++++++++++++---------
expression.c | 21 ---------------------
expression.h | 10 ++++++++++
validation/constexpr-cast.c | 25 +++++++++++++++++++++++++
4 files changed, 53 insertions(+), 30 deletions(-)
create mode 100644 validation/constexpr-cast.c
diff --git a/evaluate.c b/evaluate.c
index 7bce4fb..24a7f2f 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -323,7 +323,6 @@ static struct expression * cast_to(struct expression *old, struct symbol *type)
}
expr = alloc_expression(old->pos, EXPR_IMPLIED_CAST);
- expr->constexpr_flags = old->constexpr_flags;
expr->ctype = type;
expr->cast_type = type;
expr->cast_expression = old;
@@ -2745,14 +2744,24 @@ static struct symbol *evaluate_cast(struct expression *expr)
class1 = classify_type(ctype, &t1);
- /* cast to non-integer type -> not an integer constant expression */
- if (!is_int(class1))
- expr->constexpr_flags = CONSTEXPR_FLAG_NONE;
- /* if argument turns out to be not an integer constant expression *and*
- it was not a floating literal to start with -> too bad */
- else if (expr->constexpr_flags & CONSTEXPR_FLAG_INT_CONST_EXPR &&
- !(target->constexpr_flags & CONSTEXPR_FLAG_INT_CONST_EXPR))
- expr->constexpr_flags = CONSTEXPR_FLAG_NONE;
+ if (class1 & TYPE_NUM) {
+ expr->constexpr_flags = target->constexpr_flags &
+ ~CONSTEXPR_FLAG_DECAY_CONSTS_MASK;
+ /*
+ * Cast to float type -> not an integer constant
+ * expression [6.6(6)].
+ */
+ if (class1 & TYPE_FLOAT)
+ expr->constexpr_flags &=
+ ~CONSTEXPR_FLAG_INT_CONST_EXPR_CLEAR_MASK;
+ /*
+ * Casts of float literals to integer type results in
+ * a constant integer expression [6.6(6)].
+ */
+ else if (target->constexpr_flags & CONSTEXPR_FLAG_FP_CONST)
+ expr->constexpr_flags =
+ CONSTEXPR_FLAG_INT_CONST_EXPR_SET_MASK;
+ }
/*
* You can always throw a value away by casting to
diff --git a/expression.c b/expression.c
index f9adab6..759bee8 100644
--- a/expression.c
+++ b/expression.c
@@ -730,27 +730,6 @@ static struct token *cast_expression(struct token *token, struct expression **tr
if (!v)
return token;
cast->cast_expression = v;
-
- cast->constexpr_flags = v->constexpr_flags &
- ~CONSTEXPR_FLAG_DECAY_CONSTS_MASK;
- /*
- * Up to now, we missed the (int).0 case here
- * which should really get a
- * CONSTEXPR_FLAG_INT_CONST_EXPR marker. Also,
- * conversion to non-numeric types is not
- * properly reflected up to this point.
- * However, we do not know until evaluation.
- * For the moment, in order to preserve
- * semantics, speculatively set
- * CONSTEXPR_FLAG_INT_CONST_EXPR if
- * CONSTEXPR_FLAG_FP_CONST is
- * set. evaluate_cast() will unset
- * inappropriate flags again after examining
- * type information.
- */
- if (v->constexpr_flags & CONSTEXPR_FLAG_FP_CONST)
- cast->constexpr_flags |=
- CONSTEXPR_FLAG_INT_CONST_EXPR_SET_MASK;
return token;
}
}
diff --git a/expression.h b/expression.h
index 8a943a4..408382e 100644
--- a/expression.h
+++ b/expression.h
@@ -119,6 +119,16 @@ enum constexpr_flag {
(CONSTEXPR_FLAG_CHAR_CONST | CONSTEXPR_FLAG_INT_CONST_EXPR_SET_MASK)
/*
+ * not an integer constant expression => neither of integer,
+ * enumeration and character constant
+*/
+#define CONSTEXPR_FLAG_INT_CONST_EXPR_CLEAR_MASK \
+ (CONSTEXPR_FLAG_INT_CONST_EXPR | \
+ CONSTEXPR_FLAG_INT_CONST | \
+ CONSTEXPR_FLAG_ENUM_CONST | \
+ CONSTEXPR_FLAG_CHAR_CONST)
+
+/*
* Remove any "Constant" [6.4.4] flag, but retain the "constant
* expression" [6.6] flags.
*/
diff --git a/validation/constexpr-cast.c b/validation/constexpr-cast.c
new file mode 100644
index 0000000..2706961
--- /dev/null
+++ b/validation/constexpr-cast.c
@@ -0,0 +1,25 @@
+static int a[] = {
+ [(int)0] = 0, // OK
+ [(int)(int)0] = 0, // OK
+ [(int)0.] = 0, // OK
+ [(int)(int)0.] = 0, // OK
+ [(int)__builtin_choose_expr(0, 0, 0)] = 0, // OK
+ [(int)__builtin_choose_expr(0, 0, 0.)] = 0, // OK
+
+ [(int)(float)0] = 0, // KO
+ [(int)(float)0.] = 0, // KO
+
+ [(int)(void*)0] = 0, // KO
+ [(int)(void*)0.] = 0, // KO
+
+};
+/*
+ * check-name: Expression constness propagation in casts
+ *
+ * check-error-start
+constexpr-cast.c:9:11: error: bad integer constant expression
+constexpr-cast.c:10:11: error: bad integer constant expression
+constexpr-cast.c:12:11: error: bad integer constant expression
+constexpr-cast.c:13:11: error: bad integer constant expression
+ * check-error-end
+ */
--
2.7.0
--
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