[clang] [Parser][BoundsSafety] Print attribute as macro if it's system defined (PR #107619)

[Yeoul Na via cfe-commits]

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@@ -1105,16 +1120,16 @@ enum AttributeDeclKind {
 
 inline const StreamingDiagnostic &operator<<(const StreamingDiagnostic &DB,
                                              const ParsedAttr &At) {
-  DB.AddTaggedVal(reinterpret_cast<uint64_t>(At.getAttrName()),
+  const IdentifierInfo *AttrName =
+      At.printAsMacro() ? At.getMacroIdentifier() : At.getAttrName();
+  DB.AddTaggedVal(reinterpret_cast<uint64_t>(AttrName),
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rapidsna wrote:

@AaronBallman @erichkeane Thanks for the valuable feedback!

Our motivation was that with `-fbounds-safety`, we would have a toolchain header defines this:
`#define __counted_by(c) __attribute__((__counted_by(c)__))` 

then the user code uses it as `__counted_by` spelling, 

we'd like it to be just printed as `__counted_by` and we don't want it to be printed as `__counted_by__` nor having a redundant aka (`__counted_by__` ) next to `__counted_by`.

Also, that was why we were limiting this change specifically to "system-defined" macros.

Does it make sense? I guess there might be a better way to implement this behavior in Clang?

https://github.com/llvm/llvm-project/pull/107619