Track definition merging on the canonical declaration even when local

submodule visibility is disabled.

Attempting to pick a specific declaration to make visible when the
module containing the merged declaration becomes visible is error-prone,
as we don't yet know which declaration we'll choose to be the definition
when we are informed of the merging.

This reinstates r342019, reverted in r342020. The regression previously
observed after this commit was fixed in r342096.

llvm-svn: 342097

2 files changed, 3 insertions, 23 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index b60e5f14a67..ac3b7374018 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3780,22 +3780,15 @@ void ASTReader::makeModuleVisible(Module *Mod,
 /// visible.
 void ASTReader::mergeDefinitionVisibility(NamedDecl *Def,
                                           NamedDecl *MergedDef) {
-  // FIXME: This doesn't correctly handle the case where MergedDef is visible
-  // in modules other than its owning module. We should instead give the
-  // ASTContext a list of merged definitions for Def.
   if (Def->isHidden()) {
     // If MergedDef is visible or becomes visible, make the definition visible.
     if (!MergedDef->isHidden())
       Def->setVisibleDespiteOwningModule();
-    else if (getContext().getLangOpts().ModulesLocalVisibility) {
+    else {
       getContext().mergeDefinitionIntoModule(
           Def, MergedDef->getImportedOwningModule(),
           /*NotifyListeners*/ false);
       PendingMergedDefinitionsToDeduplicate.insert(Def);
-    } else {
-      auto SubmoduleID = MergedDef->getOwningModuleID();
-      assert(SubmoduleID && "hidden definition in no module");
-      HiddenNamesMap[getSubmodule(SubmoduleID)].push_back(Def);
     }
   }
 }
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 00fad25eeac..82951074764 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -4419,22 +4419,9 @@ void ASTDeclReader::UpdateDecl(Decl *D,
     case UPD_DECL_EXPORTED: {
       unsigned SubmoduleID = readSubmoduleID();
       auto *Exported = cast<NamedDecl>(D);
-      if (auto *TD = dyn_cast<TagDecl>(Exported))
-        Exported = TD->getDefinition();
       Module *Owner = SubmoduleID ? Reader.getSubmodule(SubmoduleID) : nullptr;
-      if (Reader.getContext().getLangOpts().ModulesLocalVisibility) {
-        Reader.getContext().mergeDefinitionIntoModule(cast<NamedDecl>(Exported),
-                                                      Owner);
-        Reader.PendingMergedDefinitionsToDeduplicate.insert(
-            cast<NamedDecl>(Exported));
-      } else if (Owner && Owner->NameVisibility != Module::AllVisible) {
-        // If Owner is made visible at some later point, make this declaration
-        // visible too.
-        Reader.HiddenNamesMap[Owner].push_back(Exported);
-      } else {
-        // The declaration is now visible.
-        Exported->setVisibleDespiteOwningModule();
-      }
+      Reader.getContext().mergeDefinitionIntoModule(Exported, Owner);
+      Reader.PendingMergedDefinitionsToDeduplicate.insert(Exported);
       break;
     }