[clang] [lldb] [BoundsSafety] Introduce LateParsedAttrType AST placeholder type (PR #204125)

[Yeoul Na via cfe-commits]

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@@ -1358,6 +1358,37 @@ class CountAttributedTypeLoc final
   SourceRange getLocalSourceRange() const;
 };
 
+struct LateParsedAttrLocInfo {
+  SourceLocation AttrNameLoc;
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rapidsna wrote:

Argument locations are preserved inside `LateParsedTypeAttribute::CachedTokens` (via `the LateParsedTypeAttribute *` payload of the type) with their original SourceLocations, and re-emerge as proper SourceRanges on the parsed `Expr*` once late parsing runs. All argument-shape diagnostics (integer type, undeclared identifier, invalid decl kind, count-argument-must-be-integer, etc.) fire during / after late parsing when we have the parsed Expr — they don't run in the pre-resolution window.

If a case arises where we need to diagnose an argument before replaying the tokens (e.g. in case we add very early type-shape validation in the future), we can either extend LateParsedAttrLocInfo or peek into the cached-token range at that point. Do you have a specific case in mind that motivated the question?

https://github.com/llvm/llvm-project/pull/204125