[clang] Reland [C++20] [Modules] [Itanium ABI] Generate the vtable in the mod… (PR #102287)

[Chuanqi Xu via cfe-commits]

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@@ -18484,11 +18484,15 @@ bool Sema::DefineUsedVTables() {
 
     bool DefineVTable = true;
 
-    // If this class has a key function, but that key function is
-    // defined in another translation unit, we don't need to emit the
-    // vtable even though we're using it.
     const CXXMethodDecl *KeyFunction = Context.getCurrentKeyFunction(Class);
-    if (KeyFunction && !KeyFunction->hasBody()) {
+    // V-tables for non-template classes with an owning module are always
+    // uniquely emitted in that module.
+    if (Class->isInCurrentModuleUnit())
+      DefineVTable = true;
+    else if (KeyFunction && !KeyFunction->hasBody()) {
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ChuanqiXu9 wrote:

Done

https://github.com/llvm/llvm-project/pull/102287