C++ Modules TS: Add parsing and some semantic analysis support for

export-declarations. These don't yet have an effect on name visibility;
we still export everything by default.

llvm-svn: 280999

13 files changed, 145 insertions, 27 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index cfdd5579c3f..fec7df0ffb7 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -4310,3 +4310,18 @@ SourceRange ImportDecl::getSourceRange() const {
 
   return SourceRange(getLocation(), getIdentifierLocs().back());
 }
+
+//===----------------------------------------------------------------------===//
+// ExportDecl Implementation
+//===----------------------------------------------------------------------===//
+
+void ExportDecl::anchor() {}
+
+ExportDecl *ExportDecl::Create(ASTContext &C, DeclContext *DC,
+                               SourceLocation ExportLoc) {
+  return new (C, DC) ExportDecl(DC, ExportLoc);
+}
+
+ExportDecl *ExportDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+  return new (C, ID) ExportDecl(nullptr, SourceLocation());
+}
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 4586d4bd2aa..4d4e725dbdd 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -672,6 +672,7 @@ unsigned Decl::getIdentifierNamespaceForKind(Kind DeclKind) {
     case FriendTemplate:
     case AccessSpec:
     case LinkageSpec:
+    case Export:
     case FileScopeAsm:
     case StaticAssert:
     case ObjCPropertyImpl:
@@ -957,7 +958,7 @@ bool DeclContext::isDependentContext() const {
 bool DeclContext::isTransparentContext() const {
   if (DeclKind == Decl::Enum)
     return !cast<EnumDecl>(this)->isScoped();
-  else if (DeclKind == Decl::LinkageSpec)
+  else if (DeclKind == Decl::LinkageSpec || DeclKind == Decl::Export)
     return true;
 
   return false;
@@ -996,6 +997,7 @@ DeclContext *DeclContext::getPrimaryContext() {
   case Decl::TranslationUnit:
   case Decl::ExternCContext:
   case Decl::LinkageSpec:
+  case Decl::Export:
   case Decl::Block:
   case Decl::Captured:
   case Decl::OMPDeclareReduction:
@@ -1408,8 +1410,8 @@ NamedDecl *const DeclContextLookupResult::SingleElementDummyList = nullptr;
 
 DeclContext::lookup_result
 DeclContext::lookup(DeclarationName Name) const {
-  assert(DeclKind != Decl::LinkageSpec &&
-         "Should not perform lookups into linkage specs!");
+  assert(DeclKind != Decl::LinkageSpec && DeclKind != Decl::Export &&
+         "should not perform lookups into transparent contexts");
 
   // If we have an external source, ensure that any later redeclarations of this
   // context have been loaded, since they may add names to the result of this
@@ -1472,8 +1474,8 @@ DeclContext::lookup(DeclarationName Name) const {
 
 DeclContext::lookup_result
 DeclContext::noload_lookup(DeclarationName Name) {
-  assert(DeclKind != Decl::LinkageSpec &&
-         "Should not perform lookups into linkage specs!");
+  assert(DeclKind != Decl::LinkageSpec && DeclKind != Decl::Export &&
+         "should not perform lookups into transparent contexts");
 
   DeclContext *PrimaryContext = getPrimaryContext();
   if (PrimaryContext != this)
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 5b4017cad37..a7920473d7c 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -78,6 +78,7 @@ void CodeGenFunction::EmitDecl(const Decl &D) {
   case Decl::PragmaDetectMismatch:
   case Decl::AccessSpec:
   case Decl::LinkageSpec:
+  case Decl::Export:
   case Decl::ObjCPropertyImpl:
   case Decl::FileScopeAsm:
   case Decl::Friend:
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index e296a4cc514..dad49f5dbca 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -3754,17 +3754,6 @@ void CodeGenModule::EmitObjCIvarInitializations(ObjCImplementationDecl *D) {
   D->setHasNonZeroConstructors(true);
 }
 
-/// EmitNamespace - Emit all declarations in a namespace.
-void CodeGenModule::EmitNamespace(const NamespaceDecl *ND) {
-  for (auto *I : ND->decls()) {
-    if (const auto *VD = dyn_cast<VarDecl>(I))
-      if (VD->getTemplateSpecializationKind() != TSK_ExplicitSpecialization &&
-          VD->getTemplateSpecializationKind() != TSK_Undeclared)
-        continue;
-    EmitTopLevelDecl(I);
-  }
-}
-
 // EmitLinkageSpec - Emit all declarations in a linkage spec.
 void CodeGenModule::EmitLinkageSpec(const LinkageSpecDecl *LSD) {
   if (LSD->getLanguage() != LinkageSpecDecl::lang_c &&
@@ -3773,13 +3762,21 @@ void CodeGenModule::EmitLinkageSpec(const LinkageSpecDecl *LSD) {
     return;
   }
 
-  for (auto *I : LSD->decls()) {
-    // Meta-data for ObjC class includes references to implemented methods.
-    // Generate class's method definitions first.
+  EmitDeclContext(LSD);
+}
+
+void CodeGenModule::EmitDeclContext(const DeclContext *DC) {
+  for (auto *I : DC->decls()) {
+    // Unlike other DeclContexts, the contents of an ObjCImplDecl at TU scope
+    // are themselves considered "top-level", so EmitTopLevelDecl on an
+    // ObjCImplDecl does not recursively visit them. We need to do that in
+    // case they're nested inside another construct (LinkageSpecDecl /
+    // ExportDecl) that does stop them from being considered "top-level".
     if (auto *OID = dyn_cast<ObjCImplDecl>(I)) {
       for (auto *M : OID->methods())
         EmitTopLevelDecl(M);
     }
+
     EmitTopLevelDecl(I);
   }
 }
@@ -3825,7 +3822,7 @@ void CodeGenModule::EmitTopLevelDecl(Decl *D) {
 
   // C++ Decls
   case Decl::Namespace:
-    EmitNamespace(cast<NamespaceDecl>(D));
+    EmitDeclContext(cast<NamespaceDecl>(D));
     break;
   case Decl::CXXRecord:
     // Emit any static data members, they may be definitions.
@@ -3976,6 +3973,10 @@ void CodeGenModule::EmitTopLevelDecl(Decl *D) {
     break;
   }
 
+  case Decl::Export:
+    EmitDeclContext(cast<ExportDecl>(D));
+    break;
+
   case Decl::OMPThreadPrivate:
     EmitOMPThreadPrivateDecl(cast<OMPThreadPrivateDecl>(D));
     break;
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index ed18156a082..a069ce1436e 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -1182,7 +1182,7 @@ private:
   
   // C++ related functions.
 
-  void EmitNamespace(const NamespaceDecl *D);
+  void EmitDeclContext(const DeclContext *DC);
   void EmitLinkageSpec(const LinkageSpecDecl *D);
   void CompleteDIClassType(const CXXMethodDecl* D);
 
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index ed99fedeab3..f7349b118f6 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -372,6 +372,53 @@ Decl *Parser::ParseLinkage(ParsingDeclSpec &DS, unsigned Context) {
                      : nullptr;
 }
 
+/// Parse a C++ Modules TS export-declaration.
+///
+///       export-declaration:
+///         'export' declaration
+///         'export' '{' declaration-seq[opt] '}'
+///
+Decl *Parser::ParseExportDeclaration() {
+  assert(Tok.is(tok::kw_export));
+  SourceLocation ExportLoc = ConsumeToken();
+
+  ParseScope ExportScope(this, Scope::DeclScope);
+  Decl *ExportDecl = Actions.ActOnStartExportDecl(
+      getCurScope(), ExportLoc,
+      Tok.is(tok::l_brace) ? Tok.getLocation() : SourceLocation());
+
+  if (Tok.isNot(tok::l_brace)) {
+    // FIXME: Factor out a ParseExternalDeclarationWithAttrs.
+    ParsedAttributesWithRange Attrs(AttrFactory);
+    MaybeParseCXX11Attributes(Attrs);
+    MaybeParseMicrosoftAttributes(Attrs);
+    ParseExternalDeclaration(Attrs);
+    return Actions.ActOnFinishExportDecl(getCurScope(), ExportDecl,
+                                         SourceLocation());
+  }
+
+  BalancedDelimiterTracker T(*this, tok::l_brace);
+  T.consumeOpen();
+
+  // The Modules TS draft says "An export-declaration shall declare at least one
+  // entity", but the intent is that it shall contain at least one declaration.
+  if (Tok.is(tok::r_brace))
+    Diag(ExportLoc, diag::err_export_empty)
+        << SourceRange(ExportLoc, Tok.getLocation());
+
+  while (!tryParseMisplacedModuleImport() && Tok.isNot(tok::r_brace) &&
+         Tok.isNot(tok::eof)) {
+    ParsedAttributesWithRange Attrs(AttrFactory);
+    MaybeParseCXX11Attributes(Attrs);
+    MaybeParseMicrosoftAttributes(Attrs);
+    ParseExternalDeclaration(Attrs);
+  }
+
+  T.consumeClose();
+  return Actions.ActOnFinishExportDecl(getCurScope(), ExportDecl,
+                                       T.getCloseLocation());
+}
+
 /// ParseUsingDirectiveOrDeclaration - Parse C++ using using-declaration or
 /// using-directive. Assumes that current token is 'using'.
 Decl *Parser::ParseUsingDirectiveOrDeclaration(unsigned Context,
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index 0a54ea0e6b8..8cc97e5f0d7 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -770,11 +770,17 @@ Parser::ParseExternalDeclaration(ParsedAttributesWithRange &attrs,
                                               : Sema::PCC_Namespace);
     cutOffParsing();
     return nullptr;
+  case tok::kw_export:
+    if (getLangOpts().ModulesTS) {
+      SingleDecl = ParseExportDeclaration();
+      break;
+    }
+    // This must be 'export template'. Parse it so we can diagnose our lack
+    // of support.
   case tok::kw_using:
   case tok::kw_namespace:
   case tok::kw_typedef:
   case tok::kw_template:
-  case tok::kw_export:    // As in 'export template'
   case tok::kw_static_assert:
   case tok::kw__Static_assert:
     // A function definition cannot start with any of these keywords.
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index e6381fbe49f..773d00bf2d7 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -15422,6 +15422,36 @@ void Sema::createImplicitModuleImportForErrorRecovery(SourceLocation Loc,
   VisibleModules.setVisible(Mod, Loc);
 }
 
+/// We have parsed the start of an export declaration, including the '{'
+/// (if present).
+Decl *Sema::ActOnStartExportDecl(Scope *S, SourceLocation ExportLoc,
+                                 SourceLocation LBraceLoc) {
+  // FIXME: C++ Modules TS:
+  //   An export-declaration [...] shall not contain more than one
+  //   export keyword.
+  //
+  // The intent here is that an export-declaration cannot appear within another
+  // export-declaration.
+
+  ExportDecl *D = ExportDecl::Create(Context, CurContext, ExportLoc);
+  CurContext->addDecl(D);
+  PushDeclContext(S, D);
+  return D;
+}
+
+/// Complete the definition of an export declaration.
+Decl *Sema::ActOnFinishExportDecl(Scope *S, Decl *D, SourceLocation RBraceLoc) {
+  auto *ED = cast<ExportDecl>(D);
+  if (RBraceLoc.isValid())
+    ED->setRBraceLoc(RBraceLoc);
+
+  // FIXME: Diagnose export of internal-linkage declaration (including
+  // anonymous namespace).
+
+  PopDeclContext();
+  return D;
+}
+
 void Sema::ActOnPragmaRedefineExtname(IdentifierInfo* Name,
                                       IdentifierInfo* AliasName,
                                       SourceLocation PragmaLoc,
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 40ad686321b..044a3aaa4bb 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -1538,8 +1538,8 @@ bool LookupResult::isVisibleSlow(Sema &SemaRef, NamedDecl *D) {
   // If this declaration is not at namespace scope nor module-private,
   // then it is visible if its lexical parent has a visible definition.
   DeclContext *DC = D->getLexicalDeclContext();
-  if (!D->isModulePrivate() &&
-      DC && !DC->isFileContext() && !isa<LinkageSpecDecl>(DC)) {
+  if (!D->isModulePrivate() && DC && !DC->isFileContext() &&
+      !isa<LinkageSpecDecl>(DC) && !isa<ExportDecl>(DC)) {
     // For a parameter, check whether our current template declaration's
     // lexical context is visible, not whether there's some other visible
     // definition of it, because parameters aren't "within" the definition.
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 7d573293f4e..bef36206e09 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -5892,9 +5892,7 @@ Sema::CheckTemplateDeclScope(Scope *S, TemplateParameterList *TemplateParams) {
   if (Ctx && Ctx->isExternCContext())
     return Diag(TemplateParams->getTemplateLoc(), diag::err_template_linkage)
              << TemplateParams->getSourceRange();
-
-  while (Ctx && isa<LinkageSpecDecl>(Ctx))
-    Ctx = Ctx->getParent();
+  Ctx = Ctx->getRedeclContext();
 
   // C++ [temp]p2:
   //   A template-declaration can appear only as a namespace scope or
diff --git a/clang/lib/Serialization/ASTCommon.cpp b/clang/lib/Serialization/ASTCommon.cpp
index 07d0c1c9ae5..79ccffc5abb 100644
--- a/clang/lib/Serialization/ASTCommon.cpp
+++ b/clang/lib/Serialization/ASTCommon.cpp
@@ -183,6 +183,7 @@ serialization::getDefinitiveDeclContext(const DeclContext *DC) {
   case Decl::ExternCContext:
   case Decl::Namespace:
   case Decl::LinkageSpec:
+  case Decl::Export:
     return nullptr;
 
   // C/C++ tag types can only be defined in one place.
@@ -291,6 +292,7 @@ bool serialization::isRedeclarableDeclKind(unsigned Kind) {
   case Decl::ObjCProperty:
   case Decl::ObjCCompatibleAlias:
   case Decl::LinkageSpec:
+  case Decl::Export:
   case Decl::ObjCPropertyImpl:
   case Decl::PragmaComment:
   case Decl::PragmaDetectMismatch:
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 620e1fed300..3cc54048188 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -327,6 +327,7 @@ namespace clang {
     void VisitUsingShadowDecl(UsingShadowDecl *D);
     void VisitConstructorUsingShadowDecl(ConstructorUsingShadowDecl *D);
     void VisitLinkageSpecDecl(LinkageSpecDecl *D);
+    void VisitExportDecl(ExportDecl *D);
     void VisitFileScopeAsmDecl(FileScopeAsmDecl *AD);
     void VisitImportDecl(ImportDecl *D);
     void VisitAccessSpecDecl(AccessSpecDecl *D);
@@ -1366,6 +1367,11 @@ void ASTDeclReader::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
   D->setRBraceLoc(ReadSourceLocation(Record, Idx));
 }
 
+void ASTDeclReader::VisitExportDecl(ExportDecl *D) {
+  VisitDecl(D);
+  D->RBraceLoc = ReadSourceLocation(Record, Idx);
+}
+
 void ASTDeclReader::VisitLabelDecl(LabelDecl *D) {
   VisitNamedDecl(D);
   D->setLocStart(ReadSourceLocation(Record, Idx));
@@ -3266,6 +3272,9 @@ Decl *ASTReader::ReadDeclRecord(DeclID ID) {
   case DECL_LINKAGE_SPEC:
     D = LinkageSpecDecl::CreateDeserialized(Context, ID);
     break;
+  case DECL_EXPORT:
+    D = ExportDecl::CreateDeserialized(Context, ID);
+    break;
   case DECL_LABEL:
     D = LabelDecl::CreateDeserialized(Context, ID);
     break;
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index 158123b1c06..a923d276fe9 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -110,6 +110,7 @@ namespace clang {
     void VisitUsingShadowDecl(UsingShadowDecl *D);
     void VisitConstructorUsingShadowDecl(ConstructorUsingShadowDecl *D);
     void VisitLinkageSpecDecl(LinkageSpecDecl *D);
+    void VisitExportDecl(ExportDecl *D);
     void VisitFileScopeAsmDecl(FileScopeAsmDecl *D);
     void VisitImportDecl(ImportDecl *D);
     void VisitAccessSpecDecl(AccessSpecDecl *D);
@@ -1080,6 +1081,12 @@ void ASTDeclWriter::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
   Code = serialization::DECL_LINKAGE_SPEC;
 }
 
+void ASTDeclWriter::VisitExportDecl(ExportDecl *D) {
+  VisitDecl(D);
+  Record.AddSourceLocation(D->getRBraceLoc());
+  Code = serialization::DECL_EXPORT;
+}
+
 void ASTDeclWriter::VisitLabelDecl(LabelDecl *D) {
   VisitNamedDecl(D);
   Record.AddSourceLocation(D->getLocStart());