[clang] [attributes][-Wunsafe-buffer-usage] Support adding unsafe_buffer_usage attribute to struct fields (PR #101585)

[via cfe-commits]

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@@ -6763,15 +6763,18 @@ attribute requires a string literal argument to identify the handle being releas
 def UnsafeBufferUsageDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{
-The attribute ``[[clang::unsafe_buffer_usage]]`` should be placed on functions
-that need to be avoided as they are prone to buffer overflows. It is designed to
-work together with the off-by-default compiler warning ``-Wunsafe-buffer-usage``
-to help codebases transition away from raw pointer based buffer management,
-in favor of safer abstractions such as C++20 ``std::span``. The attribute causes
-``-Wunsafe-buffer-usage`` to warn on every use of the function, and it may
-enable ``-Wunsafe-buffer-usage`` to emit automatic fix-it hints
-which would help the user replace such unsafe functions with safe
-alternatives, though the attribute can be used even when the fix can't be automated.
+The attribute ``[[clang::unsafe_buffer_usage]]`` should be placed on functions or
+struct fields that are buffers, that must to be avoided as they are prone to 
+buffer overflows. It is designed to work together with the off-by-default compiler 
+warning ``-Wunsafe-buffer-usage``to help codebases transition away from raw pointer 
+based buffer management, in favor of safer abstractions such as C++20 ``std::span``. 
+The attribute causes ``-Wunsafe-buffer-usage`` to warn on every use of the function or 
+the field it is attached to, and it may enable ``-Wunsafe-buffer-usage`` to emit 
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jkorous-apple wrote:

I'm afraid it is not clear (from a user perspective) what is meant by "enable ``-Wunsafe-buffer-usage`` to emit ...".
Maybe that's an implementation detail and we don't need to inform the user?
Or maybe we can somehow simplify the message?

https://github.com/llvm/llvm-project/pull/101585