================
@@ -222,3 +222,49 @@ struct on_void_ty {
// expected-error@+1{{field has incomplete type 'void'}}
void wrong_ty __counted_by_or_null(count);
};
+
+//==============================================================================
+// __counted_by_or_null on pointer members in unions
+//==============================================================================
+
+// Pointer in anonymous union with count in parent struct - OK
+struct ptr_in_anon_union_count_in_parent {
+ int count;
+ union {
+ int a;
+ struct size_known *buf __counted_by_or_null(count);
+ };
+};
+
+// Pointer in named union - ERROR
+union ptr_in_named_union {
+ int count;
+ struct size_known *buf __counted_by_or_null(count); // expected-error
{{'counted_by_or_null' cannot be applied to a union member}}
+};
+
+// Both pointer and count in same anonymous union - ERROR (they share storage)
+struct ptr_and_count_in_same_anon_union {
+ union {
+ int count;
+ struct size_known *buf __counted_by_or_null(count); // expected-error
{{'counted_by_or_null' cannot be applied to a union member}}
+ };
+};
+
+// Count in anonymous union, pointer in parent struct - ERROR (count in union)
+struct count_in_anon_union_ptr_in_parent {
+ union {
+ int count;
+ int x;
+ };
+ struct size_known *buf __counted_by_or_null(count); // expected-error
{{'counted_by_or_null' argument cannot refer to a union member}}
+};
+
+// Count in anonymous union, but hidden by struct - ERROR (count in union)
+struct count_in_deep_anon_union {
+ union {
+ struct {
+ int count;
+ };
+ };
+ struct size_known *buf __counted_by_or_null(count); // expected-error
{{'counted_by_or_null' argument cannot refer to a union member}}
+};
----------------
bwendling wrote:
They could be valid if and only if the count doesn't overlap with the object
being counted. So @ojhunt's example would be valid for both, I think.
```c
struct foo {
union {
int count1;
struct {
struct bar *buf1 __counted_by(count1); // invalid because count and this
struct overlap.
};
};
union {
struct {
int count2;
struct bar *buf2 __counted_by(count2); // valid because no overlap
};
};
struct bar *buf3 __counted_by(count1); // valid because there's no overlap
with 'count'.
struct bar *buf4 __counted_by(count2); // valid because there's no overlap
with 'count'.
};
```
https://github.com/llvm/llvm-project/pull/171996
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