1 files changed, 7 insertions, 0 deletions
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index fdf5346d92e..08133d68899 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -681,6 +681,13 @@ static bool LookupBuiltin(Sema &S, LookupResult &R) {
       NameKind == Sema::LookupRedeclarationWithLinkage) {
     IdentifierInfo *II = R.getLookupName().getAsIdentifierInfo();
     if (II) {
+      if (S.getLangOpts().CPlusPlus11 && S.getLangOpts().GNUMode &&
+          II == S.getFloat128Identifier()) {
+        // libstdc++4.7's type_traits expects type __float128 to exist, so
+        // insert a dummy type to make that header build in gnu++11 mode.
+        R.addDecl(S.getASTContext().getFloat128StubType());
+        return true;
+      }
       if (S.getLangOpts().CPlusPlus && NameKind == Sema::LookupOrdinaryName &&
           II == S.getASTContext().getMakeIntegerSeqName()) {
         R.addDecl(S.getASTContext().getMakeIntegerSeqDecl());