[clang] [BoundsSafety] Allow 'counted_by' attribute on pointers in structs in C (PR #90786)

[Bill Wendling via cfe-commits]

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@@ -6534,6 +6536,15 @@ def err_counted_by_attr_refer_to_union : Error<
   "'counted_by' argument cannot refer to a union member">;
 def note_flexible_array_counted_by_attr_field : Note<
   "field %0 declared here">;
+def err_counted_by_attr_pointee_unknown_size : Error<
+  "'counted_by' cannot be applied a pointer with pointee with unknown size "
+  "because %0 is %select{"
+    "an incomplete type|"  // CountedByInvalidPointeeTypeKind::INCOMPLETE
+    "a sizeless type|"     // CountedByInvalidPointeeTypeKind::SIZELESS
+    "a function type|"     // CountedByInvalidPointeeTypeKind::FUNCTION
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bwendling wrote:

I think that as long as it's a pointer we're okay, at least w.r.t. the `counted_by` attribute. We know the size of pointers at least. :-)

https://github.com/llvm/llvm-project/pull/90786