[clang] [C++20] [Modules] [Itanium ABI] Generate the vtable in the module unit of dynamic classes (PR #75912)

[Eli Friedman via cfe-commits]

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@@ -318,6 +318,9 @@ namespace {
       if (Diags.hasUnrecoverableErrorOccurred())
         return;
 
+      if (RD->shouldEmitInExternalSource())
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efriedma-quic wrote:

Most of the CodeGen code surrounding vtable emission is optimizations.  Specifically, to avoid emitting vtables which are odr-used but not actually necessary to emit, and to allow emitting available_externally vtables.  If we didn't care about those optimizations, the code would be pretty simple.

https://github.com/llvm/llvm-project/pull/75912