[clang] [llvm] Reland "[DebugMetadata][DwarfDebug] Support function-local types in lexical block scopes (4/7)" (PR #165032)

[Jeremy Morse via llvm-commits]

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@@ -448,6 +452,10 @@ class MetadataLoader::MetadataLoaderImpl {
   /// metadata.
   SmallDenseMap<Function *, DISubprogram *, 16> FunctionsWithSPs;
 
+  /// retainedNodes of these subprograms should be cleaned up from incorrectly
+  /// scoped local types.
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jmorse wrote:

IMO to avoid confusing future readers, we need to signal something about the fact that it's LLVM/ORDUniquing that's causing things to be invalid, not the input. Possibly "See the comment on \ref DISubprogram::cleanupRetainedNodes"?

https://github.com/llvm/llvm-project/pull/165032