Here's a patch that tidies up diagnostics given when there's
an arithmetic on pointer to an incomplete type. Firstly, we ought not
to say "unknown structure" when the type is not a structure; secondly,
we shouldn't report identical error twice.
(It might make sense to instead "increment/decrement of" just say
"arithmetic on", but I'm not changing that now.)
Regtested on x86_64-unknown-linux-gnu, bootstrapped on
powerpc64-unknown-linux-gnu, ok for trunk?
2014-04-18 Marek Polacek <pola...@redhat.com>
PR c/25801
* c-typeck.c (c_size_in_bytes): Don't call error.
(pointer_diff): Remove comment.
(build_unary_op): Improve error messages.
* gcc.dg/pr25801.c: New test.
diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
index 65aad45..bc977a7 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -1760,15 +1760,10 @@ c_size_in_bytes (const_tree type)
{
enum tree_code code = TREE_CODE (type);
- if (code == FUNCTION_TYPE || code == VOID_TYPE || code == ERROR_MARK)
+ if (code == FUNCTION_TYPE || code == VOID_TYPE || code == ERROR_MARK
+ || !COMPLETE_OR_VOID_TYPE_P (type))
return size_one_node;
- if (!COMPLETE_OR_VOID_TYPE_P (type))
- {
- error ("arithmetic on pointer to an incomplete type");
- return size_one_node;
- }
-
/* Convert in case a char is more than one unit. */
return size_binop_loc (input_location, CEIL_DIV_EXPR, TYPE_SIZE_UNIT (type),
size_int (TYPE_PRECISION (char_type_node)
@@ -3528,7 +3523,6 @@ pointer_diff (location_t loc, tree op0, tree op1)
if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (TREE_TYPE (orig_op1))))
error_at (loc, "arithmetic on pointer to an incomplete type");
- /* This generates an error if op0 is pointer to incomplete type. */
op1 = c_size_in_bytes (target_type);
if (pointer_to_zero_sized_aggr_p (TREE_TYPE (orig_op1)))
@@ -4002,16 +3996,18 @@ build_unary_op (location_t location,
if (typecode == POINTER_TYPE)
{
- /* If pointer target is an undefined struct,
+ /* If pointer target is an incomplete type,
we just cannot know how to do the arithmetic. */
if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (argtype)))
{
if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
error_at (location,
- "increment of pointer to unknown structure");
+ "increment of pointer to an incomplete type %qT",
+ TREE_TYPE (argtype));
else
error_at (location,
- "decrement of pointer to unknown structure");
+ "decrement of pointer to an incomplete type %qT",
+ TREE_TYPE (argtype));
}
else if (TREE_CODE (TREE_TYPE (argtype)) == FUNCTION_TYPE
|| TREE_CODE (TREE_TYPE (argtype)) == VOID_TYPE)
diff --git gcc/testsuite/gcc.dg/pr25801.c gcc/testsuite/gcc.dg/pr25801.c
index e69de29..70b4ef8 100644
--- gcc/testsuite/gcc.dg/pr25801.c
+++ gcc/testsuite/gcc.dg/pr25801.c
@@ -0,0 +1,19 @@
+/* PR c/25801 */
+/* { dg-do compile } */
+
+int (*a)[];
+struct S *s;
+
+void
+f (void)
+{
+ a++; /* { dg-error "increment of pointer to an incomplete type" } */
+ ++a; /* { dg-error "increment of pointer to an incomplete type" } */
+ a--; /* { dg-error "decrement of pointer to an incomplete type" } */
+ --a; /* { dg-error "decrement of pointer to an incomplete type" } */
+
+ s++; /* { dg-error "increment of pointer to an incomplete type" } */
+ ++s; /* { dg-error "increment of pointer to an incomplete type" } */
+ s--; /* { dg-error "decrement of pointer to an incomplete type" } */
+ --s; /* { dg-error "decrement of pointer to an incomplete type" } */
+}
Marek
