[Modules TS] Diagnose 'export' declaration within 'export' declaration.

llvm-svn: 282443

2 files changed, 21 insertions, 2 deletions

diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index cea511b5118..77e74b044fd 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -377,6 +377,22 @@ bool Decl::isReferenced() const {
   return false; 
 }
 
+bool Decl::isExported() const {
+  if (isModulePrivate())
+    return false;
+  // Namespaces are always exported.
+  if (isa<TranslationUnitDecl>(this) || isa<NamespaceDecl>(this))
+    return true;
+  // Otherwise, this is a strictly lexical check.
+  for (auto *DC = getLexicalDeclContext(); DC; DC = DC->getLexicalParent()) {
+    if (cast<Decl>(DC)->isModulePrivate())
+      return false;
+    if (isa<ExportDecl>(DC))
+      return true;
+  }
+  return false;
+}
+
 bool Decl::hasDefiningAttr() const {
   return hasAttr<AliasAttr>() || hasAttr<IFuncAttr>();
 }
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 3eb00625a45..cfb1f99b07c 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -15465,14 +15465,17 @@ void Sema::createImplicitModuleImportForErrorRecovery(SourceLocation Loc,
 /// (if present).
 Decl *Sema::ActOnStartExportDecl(Scope *S, SourceLocation ExportLoc,
                                  SourceLocation LBraceLoc) {
-  // FIXME: C++ Modules TS:
+  ExportDecl *D = ExportDecl::Create(Context, CurContext, ExportLoc);
+
+  // C++ Modules TS draft:
   //   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.
+  if (D->isExported())
+    Diag(ExportLoc, diag::err_export_within_export);
 
-  ExportDecl *D = ExportDecl::Create(Context, CurContext, ExportLoc);
   CurContext->addDecl(D);
   PushDeclContext(S, D);
   return D;