[clang] [clang][ExtractAPI] combine typedef records if the underlying type's name is underscored (PR #125964)

[Pete Lawrence via cfe-commits]

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@@ -1146,11 +1146,29 @@ bool ExtractAPIVisitorBase<Derived>::VisitTypedefNameDecl(
 
   StringRef Name = Decl->getName();
 
+  auto nameMatches = [&Name](TagDecl *TagDecl) {
+    StringRef TagName = TagDecl->getName();
+
+    if (TagName == Name)
+      return true;
+
+    // Also check whether the tag decl's name is the same as the typedef name
+    // with prefixed underscores
+    if (TagName.starts_with('_')) {
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PortalPete wrote:

Is it worth catching a `typedef` of a `typedef` that also begins with an underscore?
This could go into a loop, perhaps with some sort of upper iteration limit, say `5` to catch daisy-chain types.

https://github.com/llvm/llvm-project/pull/125964