Lazily provide a __float128 dummy type in -std=gnu++11 mode.

This is needed to parse libstdc++ 4.7's type_traits, see PR13530.

llvm-svn: 184476

4 files changed, 35 insertions, 2 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index c76ed5fdb98..870e09cc674 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -698,7 +698,7 @@ ASTContext::ASTContext(LangOptions& LOpts, SourceManager &SM,
     DependentTemplateSpecializationTypes(this_()),
     SubstTemplateTemplateParmPacks(this_()),
     GlobalNestedNameSpecifier(0), 
-    Int128Decl(0), UInt128Decl(0),
+    Int128Decl(0), UInt128Decl(0), Float128StubDecl(0),
     BuiltinVaListDecl(0),
     ObjCIdDecl(0), ObjCSelDecl(0), ObjCClassDecl(0), ObjCProtocolClassDecl(0),
     BOOLDecl(0),
@@ -857,6 +857,19 @@ TypedefDecl *ASTContext::getUInt128Decl() const {
   return UInt128Decl;
 }
 
+TypeDecl *ASTContext::getFloat128StubType() const {
+  if (!Float128StubDecl) {
+    Float128StubDecl = RecordDecl::Create(const_cast<ASTContext &>(*this), 
+                                          TTK_Struct,
+                                          getTranslationUnitDecl(),
+                                          SourceLocation(),
+                                          SourceLocation(),
+                                          &Idents.get("__float128"));
+  }
+  
+  return Float128StubDecl;
+}
+
 void ASTContext::InitBuiltinType(CanQualType &R, BuiltinType::Kind K) {
   BuiltinType *Ty = new (*this, TypeAlignment) BuiltinType(K);
   R = CanQualType::CreateUnsafe(QualType(Ty, 0));
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index e55524b1062..954091d6177 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -90,7 +90,7 @@ Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
     AccessCheckingSFINAE(false), InNonInstantiationSFINAEContext(false),
     NonInstantiationEntries(0), ArgumentPackSubstitutionIndex(-1),
     CurrentInstantiationScope(0), TyposCorrected(0),
-    AnalysisWarnings(*this), CurScope(0), Ident_super(0)
+    AnalysisWarnings(*this), CurScope(0), Ident_super(0), Ident___float128(0)
 {
   TUScope = 0;
 
@@ -1320,6 +1320,12 @@ IdentifierInfo *Sema::getSuperIdentifier() const {
   return Ident_super;
 }
 
+IdentifierInfo *Sema::getFloat128Identifier() const {
+  if (!Ident___float128)
+    Ident___float128 = &Context.Idents.get("__float128");
+  return Ident___float128;
+}
+
 void Sema::PushCapturedRegionScope(Scope *S, CapturedDecl *CD, RecordDecl *RD,
                                    CapturedRegionKind K) {
   CapturingScopeInfo *CSI = new CapturedRegionScopeInfo(getDiagnostics(), S, CD, RD,
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index c70367691f3..6ae040ffd7d 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -511,6 +511,14 @@ 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 this is a builtin on this (or all) targets, create the decl.
       if (unsigned BuiltinID = II->getBuiltinID()) {
         // In C++, we don't have any predefined library functions like
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 279a6e34823..f5a28966f86 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -4939,6 +4939,12 @@ bool Sema::RequireCompleteType(SourceLocation Loc, QualType T,
     return true;
 
   // We have an incomplete type. Produce a diagnostic.
+  if (Ident___float128 &&
+      T == Context.getTypeDeclType(Context.getFloat128StubType())) {
+    Diag(Loc, diag::err_typecheck_decl_incomplete_type___float128);
+    return true;
+  }
+
   Diagnoser.diagnose(*this, Loc, T);
 
   // If the type was a forward declaration of a class/struct/union