[clang] WIP: [clang] MicrosoftCXXABI: Fix exception copy constructor LUT after loading AST (PR #114075)

[Reid Kleckner via cfe-commits]

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@@ -2316,6 +2316,20 @@ void ASTDeclReader::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
   }
 
   VisitCXXMethodDecl(D);
+
+  // Microsoft CXX ABI specific:
+  // Restore the RecordToCopyCtor sidecar LUT entry so that `throw` expressions
+  // find the correct copy constructor for exceptions during codegen.
+  // There is no need to check the target info because the
+  // HasCopyConstructorForExceptionObject bit only gets set for the MS ABI.
+  if (D->isCopyConstructor()) {
+    // TODO What if this is not the same copy constructor which was chosen by
+    //      LookupCopyingConstructor() in SemaExprCXX? Is there a better way?
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rnk wrote:

Sorry, I think that's dangling leftover text from previous edits. I think I re-edited that fragment into the earlier "I  propose" paragraph, so I don't have anything more to add.

https://github.com/llvm/llvm-project/pull/114075