Implement Itanium name mangling support for C++ Modules TS.

This follows the scheme agreed with Nathan Sidwell, which can be found here:

  https://gcc.gnu.org/wiki/cxx-modules?action=AttachFile

This will be proposed to the itanium-cxx-abi list once we have some experience
with how well it works; the ABI for this TS should be considered unstable until
it is part of the Itanium C++ ABI.

llvm-svn: 312467

2 files changed, 28 insertions, 10 deletions

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index e99e73fc8da..66cb4976dac 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -766,10 +766,24 @@ void Sema::emitAndClearUnusedLocalTypedefWarnings() {
 /// declarations.
 void Sema::ActOnStartOfTranslationUnit() {
   if (getLangOpts().ModulesTS) {
+    SourceLocation StartOfTU =
+        SourceMgr.getLocForStartOfFile(SourceMgr.getMainFileID());
+
     // We start in the global module; all those declarations are implicitly
     // module-private (though they do not have module linkage).
-    Context.getTranslationUnitDecl()->setModuleOwnershipKind(
-        Decl::ModuleOwnershipKind::ModulePrivate);
+    auto &Map = PP.getHeaderSearchInfo().getModuleMap();
+    auto *GlobalModule = Map.createGlobalModuleForInterfaceUnit(StartOfTU);
+    assert(GlobalModule && "module creation should not fail");
+
+    // Enter the scope of the global module.
+    ModuleScopes.push_back({});
+    ModuleScopes.back().Module = GlobalModule;
+    VisibleModules.setVisible(GlobalModule, StartOfTU);
+
+    // All declarations created from now on are owned by the global module.
+    auto *TU = Context.getTranslationUnitDecl();
+    TU->setModuleOwnershipKind(Decl::ModuleOwnershipKind::Visible);
+    TU->setLocalOwningModule(GlobalModule);
   }
 }
 
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 8334adbbc07..d6de97feb08 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -16052,6 +16052,9 @@ Sema::DeclGroupPtrTy Sema::ActOnModuleDecl(SourceLocation StartLoc,
                                            SourceLocation ModuleLoc,
                                            ModuleDeclKind MDK,
                                            ModuleIdPath Path) {
+  assert(getLangOpts().ModulesTS &&
+         "should only have module decl in modules TS");
+
   // 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.
@@ -16104,10 +16107,10 @@ Sema::DeclGroupPtrTy Sema::ActOnModuleDecl(SourceLocation StartLoc,
   auto &Map = PP.getHeaderSearchInfo().getModuleMap();
   Module *Mod;
 
+  assert(ModuleScopes.size() == 1 && "expected to be at global module scope");
+
   switch (MDK) {
   case ModuleDeclKind::Module: {
-    // FIXME: Check we're not in a submodule.
-
     // 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)) {
@@ -16121,7 +16124,8 @@ Sema::DeclGroupPtrTy Sema::ActOnModuleDecl(SourceLocation StartLoc,
     }
 
     // Create a Module for the module that we're defining.
-    Mod = Map.createModuleForInterfaceUnit(ModuleLoc, ModuleName);
+    Mod = Map.createModuleForInterfaceUnit(ModuleLoc, ModuleName,
+                                           ModuleScopes.front().Module);
     assert(Mod && "module creation should not fail");
     break;
   }
@@ -16140,16 +16144,16 @@ Sema::DeclGroupPtrTy Sema::ActOnModuleDecl(SourceLocation StartLoc,
     break;
   }
 
-  // Enter the semantic scope of the module.
-  ModuleScopes.push_back({});
+  // Switch from the global module to the named module.
   ModuleScopes.back().Module = Mod;
-  ModuleScopes.back().OuterVisibleModules = std::move(VisibleModules);
   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.
-  Context.getTranslationUnitDecl()->setLocalOwningModule(Mod);
+  auto *TU = Context.getTranslationUnitDecl();
+  TU->setModuleOwnershipKind(Decl::ModuleOwnershipKind::ModulePrivate);
+  TU->setLocalOwningModule(Mod);
 
   // FIXME: Create a ModuleDecl.
   return nullptr;
@@ -16327,7 +16331,7 @@ Decl *Sema::ActOnStartExportDecl(Scope *S, SourceLocation ExportLoc,
   // C++ Modules TS draft:
   //   An export-declaration shall appear in the purview of a module other than
   //   the global module.
-  if (ModuleScopes.empty() || !ModuleScopes.back().Module ||
+  if (ModuleScopes.empty() ||
       ModuleScopes.back().Module->Kind != Module::ModuleInterfaceUnit)
     Diag(ExportLoc, diag::err_export_not_in_module_interface);