On Thu, May 01, 2014 at 10:54:18PM +0000, Joseph S. Myers wrote:
> I think the comment on this function should be updated to explain the
> interface contract when an incomplete (or function) type is passed (i.e.
> return size_one_node, caller is responsible for any diagnostics).
Done.
> The test should I think also cover incomplete union types, and pointer
> subtraction for all the different cases of incomplete types, and the +=
> and -= operators (i.e. cover invalid arithmetic on pointers to incomplete
> types more thoroughly, even if not actually affected by this patch).
Done.
Another change is that I used COMPLETE_TYPE_P instead of
COMPLETE_OR_VOID_TYPE_P, that would be a bug and before it didn't make
much sense: we checked VOID_TYPE before.
Tested x86_64-linux, ok now?
2014-05-02 Marek Polacek <pola...@redhat.com>
PR c/25801
* c-typeck.c (c_size_in_bytes): Update comment. Don't call error.
Return size_one_node when the type is not complete.
(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 98567b4..41770bc 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -1754,22 +1754,20 @@ type_lists_compatible_p (const_tree args1, const_tree
args2,
}
}
-/* Compute the size to increment a pointer by. */
+/* Compute the size to increment a pointer by. When a function type or void
+ type or incomplete type is passed, size_one_node is returned.
+ This function does not emit any diagnostics; the caller is responsible
+ for that. */
static tree
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_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)
@@ -3530,7 +3528,6 @@ 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)))
@@ -4004,16 +4001,18 @@ 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..10b53d3 100644
--- gcc/testsuite/gcc.dg/pr25801.c
+++ gcc/testsuite/gcc.dg/pr25801.c
@@ -0,0 +1,44 @@
+/* PR c/25801 */
+/* { dg-do compile } */
+/* { dg-options "-std=c99" } */
+
+int (*a)[];
+struct S *s;
+union U *u;
+enum E *e;
+
+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" } */
+ a += 1; /* { dg-error "invalid use of array with unspecified bounds" } */
+ a -= 1; /* { dg-error "invalid use of array with unspecified bounds" } */
+ a - a; /* { dg-error "arithmetic on 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" } */
+ s += 1; /* { dg-error "invalid use of undefined type" } */
+ s -= 1; /* { dg-error "invalid use of undefined type" } */
+ s - s; /* { dg-error "arithmetic on pointer to an incomplete type" } */
+
+ u++; /* { dg-error "increment of pointer to an incomplete type" } */
+ ++u; /* { dg-error "increment of pointer to an incomplete type" } */
+ u--; /* { dg-error "decrement of pointer to an incomplete type" } */
+ --u; /* { dg-error "decrement of pointer to an incomplete type" } */
+ u += 1; /* { dg-error "invalid use of undefined type" } */
+ u -= 1; /* { dg-error "invalid use of undefined type" } */
+ u - u; /* { dg-error "arithmetic on pointer to an incomplete type" } */
+
+ e++; /* { dg-error "increment of pointer to an incomplete type" } */
+ ++e; /* { dg-error "increment of pointer to an incomplete type" } */
+ e--; /* { dg-error "decrement of pointer to an incomplete type" } */
+ --e; /* { dg-error "decrement of pointer to an incomplete type" } */
+ e += 1; /* { dg-error "invalid use of undefined type" } */
+ e -= 1; /* { dg-error "invalid use of undefined type" } */
+ e - e; /* { dg-error "arithmetic on pointer to an incomplete type" } */
+}
Marek
