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

This reverts commit 18f3bcbb13ca83d33223b00761d8cddf463e9ffb, 15bb02650e26875c48889053d6a9697444583721 and
99873b35da7ecb905143c8a6b8deca4d4416f1a9.

See the post commit message in
https://github.com/llvm/llvm-project/pull/75912 to see the reasons.

1 files changed, 11 insertions, 19 deletions

diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 98c55d6..eef946e 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -1122,31 +1122,23 @@ bool Decl::isInExportDeclContext() const {
 bool Decl::isInAnotherModuleUnit() const {
   auto *M = getOwningModule();
 
-  if (!M || !M->isNamedModule())
+  if (!M)
     return false;
 
-  return M != getASTContext().getCurrentNamedModule();
-}
-
-bool Decl::isInCurrentModuleUnit() const {
-  auto *M = getOwningModule();
-
-  if (!M || !M->isNamedModule())
+  M = M->getTopLevelModule();
+  // FIXME: It is problematic if the header module lives in another module
+  // unit. Consider to fix this by techniques like
+  // ExternalASTSource::hasExternalDefinitions.
+  if (M->isHeaderLikeModule())
     return false;
 
-  return M == getASTContext().getCurrentNamedModule();
-}
-
-bool Decl::shouldEmitInExternalSource() const {
-  ExternalASTSource *Source = getASTContext().getExternalSource();
-  if (!Source)
+  // A global module without parent implies that we're parsing the global
+  // module. So it can't be in another module unit.
+  if (M->isGlobalModule())
     return false;
 
-  return Source->hasExternalDefinitions(this) == ExternalASTSource::EK_Always;
-}
-
-bool Decl::isInNamedModule() const {
-  return getOwningModule() && getOwningModule()->isNamedModule();
+  assert(M->isNamedModule() && "New module kind?");
+  return M != getASTContext().getCurrentNamedModule();
 }
 
 bool Decl::isFromExplicitGlobalModule() const {