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Diffstat (limited to 'lib/Sema/SemaModule.cpp')
| -rw-r--r-- | lib/Sema/SemaModule.cpp | 710 |
1 files changed, 710 insertions, 0 deletions
diff --git a/lib/Sema/SemaModule.cpp b/lib/Sema/SemaModule.cpp new file mode 100644 index 0000000000..68c2286cf4 --- /dev/null +++ b/lib/Sema/SemaModule.cpp @@ -0,0 +1,710 @@ +//===--- SemaModule.cpp - Semantic Analysis for Modules -------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file implements semantic analysis for modules (C++ modules syntax, +// Objective-C modules syntax, and Clang header modules). +// +//===----------------------------------------------------------------------===// + +#include "clang/AST/ASTConsumer.h" +#include "clang/Lex/HeaderSearch.h" +#include "clang/Lex/Preprocessor.h" +#include "clang/Sema/SemaInternal.h" + +using namespace clang; +using namespace sema; + +static void checkModuleImportContext(Sema &S, Module *M, + SourceLocation ImportLoc, DeclContext *DC, + bool FromInclude = false) { + SourceLocation ExternCLoc; + + if (auto *LSD = dyn_cast<LinkageSpecDecl>(DC)) { + switch (LSD->getLanguage()) { + case LinkageSpecDecl::lang_c: + if (ExternCLoc.isInvalid()) + ExternCLoc = LSD->getBeginLoc(); + break; + case LinkageSpecDecl::lang_cxx: + break; + } + DC = LSD->getParent(); + } + + while (isa<LinkageSpecDecl>(DC) || isa<ExportDecl>(DC)) + DC = DC->getParent(); + + if (!isa<TranslationUnitDecl>(DC)) { + S.Diag(ImportLoc, (FromInclude && S.isModuleVisible(M)) + ? diag::ext_module_import_not_at_top_level_noop + : diag::err_module_import_not_at_top_level_fatal) + << M->getFullModuleName() << DC; + S.Diag(cast<Decl>(DC)->getBeginLoc(), + diag::note_module_import_not_at_top_level) + << DC; + } else if (!M->IsExternC && ExternCLoc.isValid()) { + S.Diag(ImportLoc, diag::ext_module_import_in_extern_c) + << M->getFullModuleName(); + S.Diag(ExternCLoc, diag::note_extern_c_begins_here); + } +} + +Sema::DeclGroupPtrTy +Sema::ActOnGlobalModuleFragmentDecl(SourceLocation ModuleLoc) { + if (!ModuleScopes.empty() && + ModuleScopes.back().Module->Kind == Module::GlobalModuleFragment) { + // Under -std=c++2a -fmodules-ts, we can find an explicit 'module;' after + // already implicitly entering the global module fragment. That's OK. + assert(getLangOpts().CPlusPlusModules && getLangOpts().ModulesTS && + "unexpectedly encountered multiple global module fragment decls"); + ModuleScopes.back().BeginLoc = ModuleLoc; + return nullptr; + } + + // We start in the global module; all those declarations are implicitly + // module-private (though they do not have module linkage). + auto &Map = PP.getHeaderSearchInfo().getModuleMap(); + auto *GlobalModule = Map.createGlobalModuleFragmentForModuleUnit(ModuleLoc); + assert(GlobalModule && "module creation should not fail"); + + // Enter the scope of the global module. + ModuleScopes.push_back({}); + ModuleScopes.back().BeginLoc = ModuleLoc; + ModuleScopes.back().Module = GlobalModule; + VisibleModules.setVisible(GlobalModule, ModuleLoc); + + // All declarations created from now on are owned by the global module. + auto *TU = Context.getTranslationUnitDecl(); + TU->setModuleOwnershipKind(Decl::ModuleOwnershipKind::Visible); + TU->setLocalOwningModule(GlobalModule); + + // FIXME: Consider creating an explicit representation of this declaration. + return nullptr; +} + +Sema::DeclGroupPtrTy +Sema::ActOnModuleDecl(SourceLocation StartLoc, SourceLocation ModuleLoc, + ModuleDeclKind MDK, ModuleIdPath Path, bool IsFirstDecl) { + assert((getLangOpts().ModulesTS || getLangOpts().CPlusPlusModules) && + "should only have module decl in Modules TS or C++20"); + + // A module implementation unit requires that we are not compiling a module + // of any kind. A module interface unit requires that we are not compiling a + // module map. + switch (getLangOpts().getCompilingModule()) { + case LangOptions::CMK_None: + // It's OK to compile a module interface as a normal translation unit. + break; + + case LangOptions::CMK_ModuleInterface: + if (MDK != ModuleDeclKind::Implementation) + break; + + // We were asked to compile a module interface unit but this is a module + // implementation unit. That indicates the 'export' is missing. + Diag(ModuleLoc, diag::err_module_interface_implementation_mismatch) + << FixItHint::CreateInsertion(ModuleLoc, "export "); + MDK = ModuleDeclKind::Interface; + break; + + case LangOptions::CMK_ModuleMap: + Diag(ModuleLoc, diag::err_module_decl_in_module_map_module); + return nullptr; + + case LangOptions::CMK_HeaderModule: + Diag(ModuleLoc, diag::err_module_decl_in_header_module); + return nullptr; + } + + assert(ModuleScopes.size() <= 1 && "expected to be at global module scope"); + + // FIXME: Most of this work should be done by the preprocessor rather than + // here, in order to support macro import. + + // Only one module-declaration is permitted per source file. + if (!ModuleScopes.empty() && + ModuleScopes.back().Module->isModulePurview()) { + Diag(ModuleLoc, diag::err_module_redeclaration); + Diag(VisibleModules.getImportLoc(ModuleScopes.back().Module), + diag::note_prev_module_declaration); + return nullptr; + } + + // Find the global module fragment we're adopting into this module, if any. + Module *GlobalModuleFragment = nullptr; + if (!ModuleScopes.empty() && + ModuleScopes.back().Module->Kind == Module::GlobalModuleFragment) + GlobalModuleFragment = ModuleScopes.back().Module; + + // In C++20, the module-declaration must be the first declaration if there + // is no global module fragment. + if (getLangOpts().CPlusPlusModules && !IsFirstDecl && !GlobalModuleFragment) { + Diag(ModuleLoc, diag::err_module_decl_not_at_start); + SourceLocation BeginLoc = + ModuleScopes.empty() + ? SourceMgr.getLocForStartOfFile(SourceMgr.getMainFileID()) + : ModuleScopes.back().BeginLoc; + if (BeginLoc.isValid()) { + Diag(BeginLoc, diag::note_global_module_introducer_missing) + << FixItHint::CreateInsertion(BeginLoc, "module;\n"); + } + } + + // Flatten the dots in a module name. Unlike Clang's hierarchical module map + // modules, the dots here are just another character that can appear in a + // module name. + std::string ModuleName; + for (auto &Piece : Path) { + if (!ModuleName.empty()) + ModuleName += "."; + ModuleName += Piece.first->getName(); + } + + // If a module name was explicitly specified on the command line, it must be + // correct. + if (!getLangOpts().CurrentModule.empty() && + getLangOpts().CurrentModule != ModuleName) { + Diag(Path.front().second, diag::err_current_module_name_mismatch) + << SourceRange(Path.front().second, Path.back().second) + << getLangOpts().CurrentModule; + return nullptr; + } + const_cast<LangOptions&>(getLangOpts()).CurrentModule = ModuleName; + + auto &Map = PP.getHeaderSearchInfo().getModuleMap(); + Module *Mod; + + switch (MDK) { + case ModuleDeclKind::Interface: { + // We can't have parsed or imported a definition of this module or parsed a + // module map defining it already. + if (auto *M = Map.findModule(ModuleName)) { + Diag(Path[0].second, diag::err_module_redefinition) << ModuleName; + if (M->DefinitionLoc.isValid()) + Diag(M->DefinitionLoc, diag::note_prev_module_definition); + else if (const auto *FE = M->getASTFile()) + Diag(M->DefinitionLoc, diag::note_prev_module_definition_from_ast_file) + << FE->getName(); + Mod = M; + break; + } + + // Create a Module for the module that we're defining. + Mod = Map.createModuleForInterfaceUnit(ModuleLoc, ModuleName, + GlobalModuleFragment); + assert(Mod && "module creation should not fail"); + break; + } + + case ModuleDeclKind::Implementation: + std::pair<IdentifierInfo *, SourceLocation> ModuleNameLoc( + PP.getIdentifierInfo(ModuleName), Path[0].second); + Mod = getModuleLoader().loadModule(ModuleLoc, {ModuleNameLoc}, + Module::AllVisible, + /*IsIncludeDirective=*/false); + if (!Mod) { + Diag(ModuleLoc, diag::err_module_not_defined) << ModuleName; + // Create an empty module interface unit for error recovery. + Mod = Map.createModuleForInterfaceUnit(ModuleLoc, ModuleName, + GlobalModuleFragment); + } + break; + } + + if (!GlobalModuleFragment) { + ModuleScopes.push_back({}); + if (getLangOpts().ModulesLocalVisibility) + ModuleScopes.back().OuterVisibleModules = std::move(VisibleModules); + } else { + // We're done with the global module fragment now. + ActOnEndOfTranslationUnitFragment(TUFragmentKind::Global); + } + + // Switch from the global module fragment (if any) to the named module. + ModuleScopes.back().BeginLoc = StartLoc; + ModuleScopes.back().Module = Mod; + ModuleScopes.back().ModuleInterface = MDK != ModuleDeclKind::Implementation; + VisibleModules.setVisible(Mod, ModuleLoc); + + // From now on, we have an owning module for all declarations we see. + // However, those declarations are module-private unless explicitly + // exported. + auto *TU = Context.getTranslationUnitDecl(); + TU->setModuleOwnershipKind(Decl::ModuleOwnershipKind::ModulePrivate); + TU->setLocalOwningModule(Mod); + + // FIXME: Create a ModuleDecl. + return nullptr; +} + +Sema::DeclGroupPtrTy +Sema::ActOnPrivateModuleFragmentDecl(SourceLocation ModuleLoc, + SourceLocation PrivateLoc) { + // C++20 [basic.link]/2: + // A private-module-fragment shall appear only in a primary module + // interface unit. + switch (ModuleScopes.empty() ? Module::GlobalModuleFragment + : ModuleScopes.back().Module->Kind) { + case Module::ModuleMapModule: + case Module::GlobalModuleFragment: + Diag(PrivateLoc, diag::err_private_module_fragment_not_module); + return nullptr; + + case Module::PrivateModuleFragment: + Diag(PrivateLoc, diag::err_private_module_fragment_redefined); + Diag(ModuleScopes.back().BeginLoc, diag::note_previous_definition); + return nullptr; + + case Module::ModuleInterfaceUnit: + break; + } + + if (!ModuleScopes.back().ModuleInterface) { + Diag(PrivateLoc, diag::err_private_module_fragment_not_module_interface); + Diag(ModuleScopes.back().BeginLoc, + diag::note_not_module_interface_add_export) + << FixItHint::CreateInsertion(ModuleScopes.back().BeginLoc, "export "); + return nullptr; + } + + // FIXME: Check this isn't a module interface partition. + // FIXME: Check that this translation unit does not import any partitions; + // such imports would violate [basic.link]/2's "shall be the only module unit" + // restriction. + + // We've finished the public fragment of the translation unit. + ActOnEndOfTranslationUnitFragment(TUFragmentKind::Normal); + + auto &Map = PP.getHeaderSearchInfo().getModuleMap(); + Module *PrivateModuleFragment = + Map.createPrivateModuleFragmentForInterfaceUnit( + ModuleScopes.back().Module, PrivateLoc); + assert(PrivateModuleFragment && "module creation should not fail"); + + // Enter the scope of the private module fragment. + ModuleScopes.push_back({}); + ModuleScopes.back().BeginLoc = ModuleLoc; + ModuleScopes.back().Module = PrivateModuleFragment; + ModuleScopes.back().ModuleInterface = true; + VisibleModules.setVisible(PrivateModuleFragment, ModuleLoc); + + // All declarations created from now on are scoped to the private module + // fragment (and are neither visible nor reachable in importers of the module + // interface). + auto *TU = Context.getTranslationUnitDecl(); + TU->setModuleOwnershipKind(Decl::ModuleOwnershipKind::ModulePrivate); + TU->setLocalOwningModule(PrivateModuleFragment); + + // FIXME: Consider creating an explicit representation of this declaration. + return nullptr; +} + +DeclResult Sema::ActOnModuleImport(SourceLocation StartLoc, + SourceLocation ExportLoc, + SourceLocation ImportLoc, + ModuleIdPath Path) { + // Flatten the module path for a Modules TS module name. + std::pair<IdentifierInfo *, SourceLocation> ModuleNameLoc; + if (getLangOpts().ModulesTS) { + std::string ModuleName; + for (auto &Piece : Path) { + if (!ModuleName.empty()) + ModuleName += "."; + ModuleName += Piece.first->getName(); + } + ModuleNameLoc = {PP.getIdentifierInfo(ModuleName), Path[0].second}; + Path = ModuleIdPath(ModuleNameLoc); + } + + Module *Mod = + getModuleLoader().loadModule(ImportLoc, Path, Module::AllVisible, + /*IsIncludeDirective=*/false); + if (!Mod) + return true; + + return ActOnModuleImport(StartLoc, ExportLoc, ImportLoc, Mod, Path); +} + +/// Determine whether \p D is lexically within an export-declaration. +static const ExportDecl *getEnclosingExportDecl(const Decl *D) { + for (auto *DC = D->getLexicalDeclContext(); DC; DC = DC->getLexicalParent()) + if (auto *ED = dyn_cast<ExportDecl>(DC)) + return ED; + return nullptr; +} + +DeclResult Sema::ActOnModuleImport(SourceLocation StartLoc, + SourceLocation ExportLoc, + SourceLocation ImportLoc, + Module *Mod, ModuleIdPath Path) { + VisibleModules.setVisible(Mod, ImportLoc); + + checkModuleImportContext(*this, Mod, ImportLoc, CurContext); + + // FIXME: we should support importing a submodule within a different submodule + // of the same top-level module. Until we do, make it an error rather than + // silently ignoring the import. + // Import-from-implementation is valid in the Modules TS. FIXME: Should we + // warn on a redundant import of the current module? + // FIXME: Import of a module from an implementation partition of the same + // module is permitted. + if (Mod->getTopLevelModuleName() == getLangOpts().CurrentModule && + (getLangOpts().isCompilingModule() || !getLangOpts().ModulesTS)) { + Diag(ImportLoc, getLangOpts().isCompilingModule() + ? diag::err_module_self_import + : diag::err_module_import_in_implementation) + << Mod->getFullModuleName() << getLangOpts().CurrentModule; + } + + SmallVector<SourceLocation, 2> IdentifierLocs; + Module *ModCheck = Mod; + for (unsigned I = 0, N = Path.size(); I != N; ++I) { + // If we've run out of module parents, just drop the remaining identifiers. + // We need the length to be consistent. + if (!ModCheck) + break; + ModCheck = ModCheck->Parent; + + IdentifierLocs.push_back(Path[I].second); + } + + // If this was a header import, pad out with dummy locations. + // FIXME: Pass in and use the location of the header-name token in this case. + if (Path.empty()) { + for (; ModCheck; ModCheck = ModCheck->Parent) { + IdentifierLocs.push_back(SourceLocation()); + } + } + + ImportDecl *Import = ImportDecl::Create(Context, CurContext, StartLoc, + Mod, IdentifierLocs); + CurContext->addDecl(Import); + + // Sequence initialization of the imported module before that of the current + // module, if any. + if (!ModuleScopes.empty()) + Context.addModuleInitializer(ModuleScopes.back().Module, Import); + + // Re-export the module if needed. + if (!ModuleScopes.empty() && ModuleScopes.back().ModuleInterface) { + if (ExportLoc.isValid() || getEnclosingExportDecl(Import)) + getCurrentModule()->Exports.emplace_back(Mod, false); + } else if (ExportLoc.isValid()) { + Diag(ExportLoc, diag::err_export_not_in_module_interface); + } + + return Import; +} + +void Sema::ActOnModuleInclude(SourceLocation DirectiveLoc, Module *Mod) { + checkModuleImportContext(*this, Mod, DirectiveLoc, CurContext, true); + BuildModuleInclude(DirectiveLoc, Mod); +} + +void Sema::BuildModuleInclude(SourceLocation DirectiveLoc, Module *Mod) { + // Determine whether we're in the #include buffer for a module. The #includes + // in that buffer do not qualify as module imports; they're just an + // implementation detail of us building the module. + // + // FIXME: Should we even get ActOnModuleInclude calls for those? + bool IsInModuleIncludes = + TUKind == TU_Module && + getSourceManager().isWrittenInMainFile(DirectiveLoc); + + bool ShouldAddImport = !IsInModuleIncludes; + + // If this module import was due to an inclusion directive, create an + // implicit import declaration to capture it in the AST. + if (ShouldAddImport) { + TranslationUnitDecl *TU = getASTContext().getTranslationUnitDecl(); + ImportDecl *ImportD = ImportDecl::CreateImplicit(getASTContext(), TU, + DirectiveLoc, Mod, + DirectiveLoc); + if (!ModuleScopes.empty()) + Context.addModuleInitializer(ModuleScopes.back().Module, ImportD); + TU->addDecl(ImportD); + Consumer.HandleImplicitImportDecl(ImportD); + } + + getModuleLoader().makeModuleVisible(Mod, Module::AllVisible, DirectiveLoc); + VisibleModules.setVisible(Mod, DirectiveLoc); +} + +void Sema::ActOnModuleBegin(SourceLocation DirectiveLoc, Module *Mod) { + checkModuleImportContext(*this, Mod, DirectiveLoc, CurContext, true); + + ModuleScopes.push_back({}); + ModuleScopes.back().Module = Mod; + if (getLangOpts().ModulesLocalVisibility) + ModuleScopes.back().OuterVisibleModules = std::move(VisibleModules); + + VisibleModules.setVisible(Mod, DirectiveLoc); + + // The enclosing context is now part of this module. + // FIXME: Consider creating a child DeclContext to hold the entities + // lexically within the module. + if (getLangOpts().trackLocalOwningModule()) { + for (auto *DC = CurContext; DC; DC = DC->getLexicalParent()) { + cast<Decl>(DC)->setModuleOwnershipKind( + getLangOpts().ModulesLocalVisibility + ? Decl::ModuleOwnershipKind::VisibleWhenImported + : Decl::ModuleOwnershipKind::Visible); + cast<Decl>(DC)->setLocalOwningModule(Mod); + } + } +} + +void Sema::ActOnModuleEnd(SourceLocation EomLoc, Module *Mod) { + if (getLangOpts().ModulesLocalVisibility) { + VisibleModules = std::move(ModuleScopes.back().OuterVisibleModules); + // Leaving a module hides namespace names, so our visible namespace cache + // is now out of date. + VisibleNamespaceCache.clear(); + } + + assert(!ModuleScopes.empty() && ModuleScopes.back().Module == Mod && + "left the wrong module scope"); + ModuleScopes.pop_back(); + + // We got to the end of processing a local module. Create an + // ImportDecl as we would for an imported module. + FileID File = getSourceManager().getFileID(EomLoc); + SourceLocation DirectiveLoc; + if (EomLoc == getSourceManager().getLocForEndOfFile(File)) { + // We reached the end of a #included module header. Use the #include loc. + assert(File != getSourceManager().getMainFileID() && + "end of submodule in main source file"); + DirectiveLoc = getSourceManager().getIncludeLoc(File); + } else { + // We reached an EOM pragma. Use the pragma location. + DirectiveLoc = EomLoc; + } + BuildModuleInclude(DirectiveLoc, Mod); + + // Any further declarations are in whatever module we returned to. + if (getLangOpts().trackLocalOwningModule()) { + // The parser guarantees that this is the same context that we entered + // the module within. + for (auto *DC = CurContext; DC; DC = DC->getLexicalParent()) { + cast<Decl>(DC)->setLocalOwningModule(getCurrentModule()); + if (!getCurrentModule()) + cast<Decl>(DC)->setModuleOwnershipKind( + Decl::ModuleOwnershipKind::Unowned); + } + } +} + +void Sema::createImplicitModuleImportForErrorRecovery(SourceLocation Loc, + Module *Mod) { + // Bail if we're not allowed to implicitly import a module here. + if (isSFINAEContext() || !getLangOpts().ModulesErrorRecovery || + VisibleModules.isVisible(Mod)) + return; + + // Create the implicit import declaration. + TranslationUnitDecl *TU = getASTContext().getTranslationUnitDecl(); + ImportDecl *ImportD = ImportDecl::CreateImplicit(getASTContext(), TU, + Loc, Mod, Loc); + TU->addDecl(ImportD); + Consumer.HandleImplicitImportDecl(ImportD); + + // Make the module visible. + getModuleLoader().makeModuleVisible(Mod, Module::AllVisible, 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) { + ExportDecl *D = ExportDecl::Create(Context, CurContext, ExportLoc); + + // Set this temporarily so we know the export-declaration was braced. + D->setRBraceLoc(LBraceLoc); + + // C++2a [module.interface]p1: + // An export-declaration shall appear only [...] in the purview of a module + // interface unit. An export-declaration shall not appear directly or + // indirectly within [...] a private-module-fragment. + if (ModuleScopes.empty() || !ModuleScopes.back().Module->isModulePurview()) { + Diag(ExportLoc, diag::err_export_not_in_module_interface) << 0; + } else if (!ModuleScopes.back().ModuleInterface) { + Diag(ExportLoc, diag::err_export_not_in_module_interface) << 1; + Diag(ModuleScopes.back().BeginLoc, + diag::note_not_module_interface_add_export) + << FixItHint::CreateInsertion(ModuleScopes.back().BeginLoc, "export "); + } else if (ModuleScopes.back().Module->Kind == + Module::PrivateModuleFragment) { + Diag(ExportLoc, diag::err_export_in_private_module_fragment); + Diag(ModuleScopes.back().BeginLoc, diag::note_private_module_fragment); + } + + for (const DeclContext *DC = CurContext; DC; DC = DC->getLexicalParent()) { + if (const auto *ND = dyn_cast<NamespaceDecl>(DC)) { + // An export-declaration shall not appear directly or indirectly within + // an unnamed namespace [...] + if (ND->isAnonymousNamespace()) { + Diag(ExportLoc, diag::err_export_within_anonymous_namespace); + Diag(ND->getLocation(), diag::note_anonymous_namespace); + // Don't diagnose internal-linkage declarations in this region. + D->setInvalidDecl(); + break; + } + + // A declaration is exported if it is [...] a namespace-definition + // that contains an exported declaration. + // + // Defer exporting the namespace until after we leave it, in order to + // avoid marking all subsequent declarations in the namespace as exported. + if (!DeferredExportedNamespaces.insert(ND).second) + break; + } + } + + // [...] its declaration or declaration-seq shall not contain an + // export-declaration. + if (auto *ED = getEnclosingExportDecl(D)) { + Diag(ExportLoc, diag::err_export_within_export); + if (ED->hasBraces()) + Diag(ED->getLocation(), diag::note_export); + } + + CurContext->addDecl(D); + PushDeclContext(S, D); + D->setModuleOwnershipKind(Decl::ModuleOwnershipKind::VisibleWhenImported); + return D; +} + +static bool checkExportedDeclContext(Sema &S, DeclContext *DC, + SourceLocation BlockStart); + +namespace { +enum class UnnamedDeclKind { + Empty, + StaticAssert, + Asm, + UsingDirective, + Context +}; +} + +static llvm::Optional<UnnamedDeclKind> getUnnamedDeclKind(Decl *D) { + if (isa<EmptyDecl>(D)) + return UnnamedDeclKind::Empty; + if (isa<StaticAssertDecl>(D)) + return UnnamedDeclKind::StaticAssert; + if (isa<FileScopeAsmDecl>(D)) + return UnnamedDeclKind::Asm; + if (isa<UsingDirectiveDecl>(D)) + return UnnamedDeclKind::UsingDirective; + // Everything else either introduces one or more names or is ill-formed. + return llvm::None; +} + +unsigned getUnnamedDeclDiag(UnnamedDeclKind UDK, bool InBlock) { + switch (UDK) { + case UnnamedDeclKind::Empty: + case UnnamedDeclKind::StaticAssert: + // Allow empty-declarations and static_asserts in an export block as an + // extension. + return InBlock ? diag::ext_export_no_name_block : diag::err_export_no_name; + + case UnnamedDeclKind::UsingDirective: + // Allow exporting using-directives as an extension. + return diag::ext_export_using_directive; + + case UnnamedDeclKind::Context: + // Allow exporting DeclContexts that transitively contain no declarations + // as an extension. + return diag::ext_export_no_names; + + case UnnamedDeclKind::Asm: + return diag::err_export_no_name; + } + llvm_unreachable("unknown kind"); +} + +static void diagExportedUnnamedDecl(Sema &S, UnnamedDeclKind UDK, Decl *D, + SourceLocation BlockStart) { + S.Diag(D->getLocation(), getUnnamedDeclDiag(UDK, BlockStart.isValid())) + << (unsigned)UDK; + if (BlockStart.isValid()) + S.Diag(BlockStart, diag::note_export); +} + +/// Check that it's valid to export \p D. +static bool checkExportedDecl(Sema &S, Decl *D, SourceLocation BlockStart) { + // C++2a [module.interface]p3: + // An exported declaration shall declare at least one name + if (auto UDK = getUnnamedDeclKind(D)) + diagExportedUnnamedDecl(S, *UDK, D, BlockStart); + + // [...] shall not declare a name with internal linkage. + if (auto *ND = dyn_cast<NamedDecl>(D)) { + // Don't diagnose anonymous union objects; we'll diagnose their members + // instead. + if (ND->getDeclName() && ND->getFormalLinkage() == InternalLinkage) { + S.Diag(ND->getLocation(), diag::err_export_internal) << ND; + if (BlockStart.isValid()) + S.Diag(BlockStart, diag::note_export); + } + } + + // C++2a [module.interface]p5: + // all entities to which all of the using-declarators ultimately refer + // shall have been introduced with a name having external linkage + if (auto *USD = dyn_cast<UsingShadowDecl>(D)) { + NamedDecl *Target = USD->getUnderlyingDecl(); + if (Target->getFormalLinkage() == InternalLinkage) { + S.Diag(USD->getLocation(), diag::err_export_using_internal) << Target; + S.Diag(Target->getLocation(), diag::note_using_decl_target); + if (BlockStart.isValid()) + S.Diag(BlockStart, diag::note_export); + } + } + + // Recurse into namespace-scope DeclContexts. (Only namespace-scope + // declarations are exported.) + if (auto *DC = dyn_cast<DeclContext>(D)) + if (DC->getRedeclContext()->isFileContext() && !isa<EnumDecl>(D)) + return checkExportedDeclContext(S, DC, BlockStart); + return false; +} + +/// Check that it's valid to export all the declarations in \p DC. +static bool checkExportedDeclContext(Sema &S, DeclContext *DC, + SourceLocation BlockStart) { + bool AllUnnamed = true; + for (auto *D : DC->decls()) + AllUnnamed &= checkExportedDecl(S, D, BlockStart); + return AllUnnamed; +} + +/// 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); + + PopDeclContext(); + + if (!D->isInvalidDecl()) { + SourceLocation BlockStart = + ED->hasBraces() ? ED->getBeginLoc() : SourceLocation(); + for (auto *Child : ED->decls()) { + if (checkExportedDecl(*this, Child, BlockStart)) { + // If a top-level child is a linkage-spec declaration, it might contain + // no declarations (transitively), in which case it's ill-formed. + diagExportedUnnamedDecl(*this, UnnamedDeclKind::Context, Child, + BlockStart); + } + } + } + + return D; +} |