Revert "[NFC] [C++20] [Modules] Refactor Sema::isModuleUnitOfCurrentT…

…U into"

This reverts commit f109b10 as required
in
f109b10#commitcomment-113477829.

clang/include/clang/AST/ASTContext.h

@@ -447,8 +447,9 @@ class ASTContext : public RefCountedBase<ASTContext> {
   };
   llvm::DenseMap<Module*, PerModuleInitializers*> ModuleInitializers;
 
-  /// This is the top-level (C++20) Named module we are building.
-  Module *CurrentCXXNamedModule = nullptr;
+  /// For module code-gen cases, this is the top-level (C++20) Named module
+  /// we are building.
+  Module *TopLevelCXXNamedModule = nullptr;
 
   static constexpr unsigned ConstantArrayTypesLog2InitSize = 8;
   static constexpr unsigned GeneralTypesLog2InitSize = 9;
@@ -1051,10 +1052,10 @@ class ASTContext : public RefCountedBase<ASTContext> {
   ArrayRef<Decl*> getModuleInitializers(Module *M);
 
   /// Set the (C++20) module we are building.
-  void setCurrentNamedModule(Module *M);
+  void setNamedModuleForCodeGen(Module *M) { TopLevelCXXNamedModule = M; }
 
   /// Get module under construction, nullptr if this is not a C++20 module.
-  Module *getCurrentNamedModule() const { return CurrentCXXNamedModule; }
+  Module *getNamedModuleForCodeGen() const { return TopLevelCXXNamedModule; }
 
   TranslationUnitDecl *getTranslationUnitDecl() const {
     return TUDecl->getMostRecentDecl();

clang/include/clang/AST/DeclBase.h

@@ -644,9 +644,6 @@ class alignas(8) Decl {
     return getModuleOwnershipKind() > ModuleOwnershipKind::VisibleWhenImported;
   }
 
-  /// Whether this declaration comes from another module unit.
-  bool isInAnotherModuleUnit() const;
-
   /// FIXME: Implement discarding declarations actually in global module
   /// fragment. See [module.global.frag]p3,4 for details.
   bool isDiscardedInGlobalModuleFragment() const { return false; }

clang/include/clang/Sema/Sema.h

@@ -2358,6 +2358,9 @@ class Sema final {
     return Entity->getOwningModule();
   }
 
+  // Determine whether the module M belongs to the  current TU.
+  bool isModuleUnitOfCurrentTU(const Module *M) const;
+
   /// Make a merged definition of an existing hidden definition \p ND
   /// visible at the specified location.
   void makeMergedDefinitionVisible(NamedDecl *ND);

clang/lib/AST/ASTContext.cpp

@@ -1153,13 +1153,6 @@ ArrayRef<Decl *> ASTContext::getModuleInitializers(Module *M) {
   return Inits->Initializers;
 }
 
-void ASTContext::setCurrentNamedModule(Module *M) {
-  assert(M->isModulePurview());
-  assert(!CurrentCXXNamedModule &&
-         "We should set named module for ASTContext for only once");
-  CurrentCXXNamedModule = M;
-}
-
 ExternCContextDecl *ASTContext::getExternCContextDecl() const {
   if (!ExternCContext)
     ExternCContext = ExternCContextDecl::Create(*this, getTranslationUnitDecl());
@@ -11929,7 +11922,7 @@ bool ASTContext::DeclMustBeEmitted(const Decl *D) {
   // Variables in other module units shouldn't be forced to be emitted.
   auto *VM = VD->getOwningModule();
   if (VM && VM->getTopLevelModule()->isModulePurview() &&
-      VM->getTopLevelModule() != getCurrentNamedModule())
+      VM->getTopLevelModule() != getNamedModuleForCodeGen())
     return false;
 
   // Variables that can be needed in other TUs are required.

clang/lib/AST/DeclBase.cpp

@@ -30,7 +30,6 @@
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/LangOptions.h"
-#include "clang/Basic/Module.h"
 #include "clang/Basic/ObjCRuntime.h"
 #include "clang/Basic/PartialDiagnostic.h"
 #include "clang/Basic/SourceLocation.h"
@@ -1023,28 +1022,6 @@ bool Decl::isInExportDeclContext() const {
   return DC && isa<ExportDecl>(DC);
 }
 
-bool Decl::isInAnotherModuleUnit() const {
-  auto *M = getOwningModule();
-
-  if (!M)
-    return false;
-
-  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;
-
-  // 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;
-
-  assert(M->isModulePurview() && "New module kind?");
-  return M != getASTContext().getCurrentNamedModule();
-}
-
 static Decl::Kind getKind(const Decl *D) { return D->getKind(); }
 static Decl::Kind getKind(const DeclContext *DC) { return DC->getDeclKind(); }
 

clang/lib/CodeGen/CGDeclCXX.cpp

@@ -883,12 +883,12 @@ CodeGenModule::EmitCXXGlobalInitFunc() {
   // with priority emitted above.  Module implementation units behave the same
   // way as a non-modular TU with imports.
   llvm::Function *Fn;
-  if (CXX20ModuleInits && getContext().getCurrentNamedModule() &&
-      !getContext().getCurrentNamedModule()->isModuleImplementation()) {
+  if (CXX20ModuleInits && getContext().getNamedModuleForCodeGen() &&
+      !getContext().getNamedModuleForCodeGen()->isModuleImplementation()) {
     SmallString<256> InitFnName;
     llvm::raw_svector_ostream Out(InitFnName);
     cast<ItaniumMangleContext>(getCXXABI().getMangleContext())
-        .mangleModuleInitializer(getContext().getCurrentNamedModule(), Out);
+        .mangleModuleInitializer(getContext().getNamedModuleForCodeGen(), Out);
     Fn = CreateGlobalInitOrCleanUpFunction(
         FTy, llvm::Twine(InitFnName), FI, SourceLocation(), false,
         llvm::GlobalVariable::ExternalLinkage);

clang/lib/CodeGen/CodeGenModule.cpp

@@ -529,7 +529,7 @@ static void setVisibilityFromDLLStorageClass(const clang::LangOptions &LO,
 }
 
 void CodeGenModule::Release() {
-  Module *Primary = getContext().getCurrentNamedModule();
+  Module *Primary = getContext().getNamedModuleForCodeGen();
   if (CXX20ModuleInits && Primary && !Primary->isHeaderLikeModule())
     EmitModuleInitializers(Primary);
   EmitDeferred();

clang/lib/Frontend/ASTUnit.cpp

@@ -879,7 +879,7 @@ std::unique_ptr<ASTUnit> ASTUnit::LoadFromASTFile(
 
   Module *M = HeaderInfo.lookupModule(AST->getLangOpts().CurrentModule);
   if (M && AST->getLangOpts().isCompilingModule() && M->isModulePurview())
-    AST->Ctx->setCurrentNamedModule(M);
+    AST->Ctx->setNamedModuleForCodeGen(M);
 
   // Create an AST consumer, even though it isn't used.
   if (ToLoad >= LoadASTOnly)

clang/lib/Sema/SemaLookup.cpp

@@ -1905,11 +1905,14 @@ bool LookupResult::isReachableSlow(Sema &SemaRef, NamedDecl *D) {
   Module *DeclModule = SemaRef.getOwningModule(D);
   assert(DeclModule && "hidden decl has no owning module");
 
-  // Entities in header like modules are reachable only if they're visible.
-  if (DeclModule->isHeaderLikeModule())
+  // Entities in module map modules are reachable only if they're visible.
+  if (DeclModule->isModuleMapModule())
     return false;
 
-  if (!D->isInAnotherModuleUnit())
+  // If D comes from a module and SemaRef doesn't own a module, it implies D
+  // comes from another TU. In case SemaRef owns a module, we could judge if D
+  // comes from another TU by comparing the module unit.
+  if (SemaRef.isModuleUnitOfCurrentTU(DeclModule))
     return true;
 
   // [module.reach]/p3:
@@ -3890,7 +3893,7 @@ void Sema::ArgumentDependentLookup(DeclarationName Name, SourceLocation Loc,
                    "bad export context");
             // .. are attached to a named module M, do not appear in the
             // translation unit containing the point of the lookup..
-            if (D->isInAnotherModuleUnit() &&
+            if (!isModuleUnitOfCurrentTU(FM) &&
                 llvm::any_of(AssociatedClasses, [&](auto *E) {
                   // ... and have the same innermost enclosing non-inline
                   // namespace scope as a declaration of an associated entity

clang/lib/Sema/SemaModule.cpp

@@ -389,7 +389,7 @@ Sema::ActOnModuleDecl(SourceLocation StartLoc, SourceLocation ModuleLoc,
   // statements, so imports are allowed.
   ImportState = ModuleImportState::ImportAllowed;
 
-  getASTContext().setCurrentNamedModule(Mod);
+  getASTContext().setNamedModuleForCodeGen(Mod);
 
   // We already potentially made an implicit import (in the case of a module
   // implementation unit importing its interface).  Make this module visible
@@ -1021,3 +1021,16 @@ void Sema::PopImplicitGlobalModuleFragment() {
          "left the wrong module scope, which is not global module fragment");
   ModuleScopes.pop_back();
 }
+
+bool Sema::isModuleUnitOfCurrentTU(const Module *M) const {
+  assert(M);
+
+  Module *CurrentModuleUnit = getCurrentModule();
+
+  // If we are not in a module currently, M must not be the module unit of
+  // current TU.
+  if (!CurrentModuleUnit)
+    return false;
+
+  return M->isSubModuleOf(CurrentModuleUnit->getTopLevelModule());
+}

clang/lib/Sema/SemaOverload.cpp

@@ -6543,20 +6543,23 @@ void Sema::AddOverloadCandidate(
   }
 
   // Functions with internal linkage are only viable in the same module unit.
-  if (getLangOpts().CPlusPlusModules && Function->isInAnotherModuleUnit()) {
-    /// FIXME: Currently, the semantics of linkage in clang is slightly
-    /// different from the semantics in C++ spec. In C++ spec, only names
-    /// have linkage. So that all entities of the same should share one
-    /// linkage. But in clang, different entities of the same could have
-    /// different linkage.
-    NamedDecl *ND = Function;
-    if (auto *SpecInfo = Function->getTemplateSpecializationInfo())
-      ND = SpecInfo->getTemplate();
-
-    if (ND->getFormalLinkage() == Linkage::InternalLinkage) {
-      Candidate.Viable = false;
-      Candidate.FailureKind = ovl_fail_module_mismatched;
-      return;
+  if (auto *MF = Function->getOwningModule()) {
+    if (getLangOpts().CPlusPlusModules && !MF->isModuleMapModule() &&
+        !isModuleUnitOfCurrentTU(MF)) {
+      /// FIXME: Currently, the semantics of linkage in clang is slightly
+      /// different from the semantics in C++ spec. In C++ spec, only names
+      /// have linkage. So that all entities of the same should share one
+      /// linkage. But in clang, different entities of the same could have
+      /// different linkage.
+      NamedDecl *ND = Function;
+      if (auto *SpecInfo = Function->getTemplateSpecializationInfo())
+        ND = SpecInfo->getTemplate();
+
+      if (ND->getFormalLinkage() == Linkage::InternalLinkage) {
+        Candidate.Viable = false;
+        Candidate.FailureKind = ovl_fail_module_mismatched;
+        return;
+      }
     }
   }
 

clang/lib/Sema/SemaTemplate.cpp

@@ -2851,7 +2851,8 @@ bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
         NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
         SawDefaultArgument = true;
 
-        if (!OldTypeParm->isInAnotherModuleUnit())
+        if (!OldTypeParm->getOwningModule() ||
+            isModuleUnitOfCurrentTU(OldTypeParm->getOwningModule()))
           RedundantDefaultArg = true;
         else if (!getASTContext().isSameDefaultTemplateArgument(OldTypeParm,
                                                                 NewTypeParm)) {
@@ -2903,7 +2904,8 @@ bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
         OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
         NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
         SawDefaultArgument = true;
-        if (!OldNonTypeParm->isInAnotherModuleUnit())
+        if (!OldNonTypeParm->getOwningModule() ||
+            isModuleUnitOfCurrentTU(OldNonTypeParm->getOwningModule()))
           RedundantDefaultArg = true;
         else if (!getASTContext().isSameDefaultTemplateArgument(
                      OldNonTypeParm, NewNonTypeParm)) {
@@ -2954,7 +2956,8 @@ bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
         OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
         NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
         SawDefaultArgument = true;
-        if (!OldTemplateParm->isInAnotherModuleUnit())
+        if (!OldTemplateParm->getOwningModule() ||
+            isModuleUnitOfCurrentTU(OldTemplateParm->getOwningModule()))
           RedundantDefaultArg = true;
         else if (!getASTContext().isSameDefaultTemplateArgument(
                      OldTemplateParm, NewTemplateParm)) {