P0629R0: Switch to latest proposal for distinguishing module interface from implementation.

This switches from the prototype syntax in P0273R0 ('module' and 'module
implementation') to the consensus syntax 'export module' and 'module'.

In passing, drop the "module declaration must be first" enforcement, since EWG
seems to have changed its mind on that.

llvm-svn: 301056

1 files changed, 27 insertions, 16 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 6269c9fe391..6138cbb114e 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -15688,30 +15688,41 @@ static void checkModuleImportContext(Sema &S, Module *M,
   }
 }
 
-Sema::DeclGroupPtrTy Sema::ActOnModuleDecl(SourceLocation ModuleLoc,
+Sema::DeclGroupPtrTy Sema::ActOnModuleDecl(SourceLocation StartLoc,
+                                           SourceLocation ModuleLoc,
                                            ModuleDeclKind MDK,
                                            ModuleIdPath Path) {
-  // 'module implementation' requires that we are not compiling a module of any
-  // kind. 'module' and 'module partition' require that we are compiling a
-  // module inteface (not a module map).
-  auto CMK = getLangOpts().getCompilingModule();
-  if (MDK == ModuleDeclKind::Implementation
-          ? CMK != LangOptions::CMK_None
-          : CMK != LangOptions::CMK_ModuleInterface) {
+  // 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)
-      << (unsigned)MDK;
+      << FixItHint::CreateInsertion(ModuleLoc, "export ");
+    break;
+
+  case LangOptions::CMK_ModuleMap:
+    Diag(ModuleLoc, diag::err_module_decl_in_module_map_module);
     return nullptr;
   }
 
   // FIXME: Create a ModuleDecl and return it.
 
   // FIXME: Most of this work should be done by the preprocessor rather than
-  // here, in case we look ahead across something where the current
-  // module matters (eg a #include).
+  // here, in order to support macro import.
 
-  // The dots in a module name in the Modules TS are a lie. Unlike Clang's
-  // hierarchical module map modules, the dots here are just another character
-  // that can appear in a module name. Flatten down to the actual module name.
+  // 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())
@@ -15736,8 +15747,8 @@ Sema::DeclGroupPtrTy Sema::ActOnModuleDecl(SourceLocation ModuleLoc,
   case ModuleDeclKind::Module: {
     // FIXME: Check we're not in a submodule.
 
-    // We can't have imported a definition of this module or parsed a module
-    // map defining it already.
+    // 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())