[PATCH v3 11/21] evaluate: recognize address constants created through casts

[Nicolai Stange <nicstange@gmail.com>]

According to 6.6(9), an address constant may get created by casting
an integer constant to pointer type.

Make evaluate_cast() handle this case, that is tag a cast expression
as being an address constant if the target is a integer constant and
the destination is of pointer type.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
---
 evaluate.c                          | 10 +++++++++-
 validation/constexpr-pointer-cast.c | 13 +++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 validation/constexpr-pointer-cast.c

diff --git a/evaluate.c b/evaluate.c
index 91f89f4..a740474 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -2767,7 +2767,15 @@ static struct symbol *evaluate_cast(struct expression *expr)
 
 	class1 = classify_type(ctype, &t1);
 
-	if (class1 & TYPE_NUM) {
+	if (!(class1 & TYPE_NUM)) {
+		/*
+		 * Casts of integer literals to pointer type yield
+		 * address constants [6.6(9)].
+		 */
+		if (class1 & TYPE_PTR &&
+			(target->constexpr_flags & CONSTEXPR_FLAG_INT_CONST))
+			expr->constexpr_flags = CONSTEXPR_FLAG_ADDR_CONST;
+	} else {
 		/*
 		 * Casts to numeric types never result in address
 		 * constants [6.6(9)].
diff --git a/validation/constexpr-pointer-cast.c b/validation/constexpr-pointer-cast.c
new file mode 100644
index 0000000..d19c108
--- /dev/null
+++ b/validation/constexpr-pointer-cast.c
@@ -0,0 +1,13 @@
+static int *a = (int*)0;	// OK
+static int b = 0;
+static int *c = (int*)b;	// KO
+
+
+/*
+ * check-name: integer literal cast to pointer type constness verification.
+ * check-command: sparse -Wconstexpr-not-const $file
+ *
+ * check-error-start
+constexpr-pointer-cast.c:3:18: warning: non-constant initializer for static object
+ * check-error-end
+ */
-- 
2.7.0