C++1y constexpr extensions, round 1: Allow most forms of declaration and
statement in constexpr functions. Everything which doesn't require variable
mutation is also allowed as an extension in C++11. 'void' becomes a literal
type to support constexpr functions which return 'void'.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180022 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index ece8315..c2b7513 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -186,7 +186,7 @@
       data().IsStandardLayout = false;
 
     // Record if this base is the first non-literal field or base.
-    if (!hasNonLiteralTypeFieldsOrBases() && !BaseType->isLiteralType())
+    if (!hasNonLiteralTypeFieldsOrBases() && !BaseType->isLiteralType(C))
       data().HasNonLiteralTypeFieldsOrBases = true;
     
     // Now go through all virtual bases of this base and add them.
@@ -676,7 +676,7 @@
     }
 
     // Record if this field is the first non-literal or volatile field or base.
-    if (!T->isLiteralType() || T.isVolatileQualified())
+    if (!T->isLiteralType(Context) || T.isVolatileQualified())
       data().HasNonLiteralTypeFieldsOrBases = true;
 
     if (Field->hasInClassInitializer()) {
@@ -845,7 +845,7 @@
       }
     } else {
       // Base element type of field is a non-class type.
-      if (!T->isLiteralType() ||
+      if (!T->isLiteralType(Context) ||
           (!Field->hasInClassInitializer() && !isUnion()))
         data().DefaultedDefaultConstructorIsConstexpr = false;
 
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 1303fb0..cf7ddbc 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -289,7 +289,7 @@
   //          expression that is value-dependent [C++11]
   if (VarDecl *Var = dyn_cast<VarDecl>(D)) {
     if ((Ctx.getLangOpts().CPlusPlus11 ?
-           Var->getType()->isLiteralType() :
+           Var->getType()->isLiteralType(Ctx) :
            Var->getType()->isIntegralOrEnumerationType()) &&
         (Var->getType().isConstQualified() ||
          Var->getType()->isReferenceType())) {
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index c02df9a..2a7e8a7 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -290,7 +290,7 @@
 
     // Note that we intentionally use std::map here so that references to
     // values are stable.
-    typedef std::map<const Expr*, APValue> MapTy;
+    typedef std::map<const void*, APValue> MapTy;
     typedef MapTy::const_iterator temp_iterator;
     /// Temporaries - Temporary lvalues materialized within this stack frame.
     MapTy Temporaries;
@@ -913,6 +913,14 @@
 // Misc utilities
 //===----------------------------------------------------------------------===//
 
+/// Evaluate an expression to see if it had side-effects, and discard its
+/// result.
+static void EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
+  APValue Scratch;
+  if (!Evaluate(Scratch, Info, E))
+    Info.EvalStatus.HasSideEffects = true;
+}
+
 /// Should this call expression be treated as a string literal?
 static bool IsStringLiteralCall(const CallExpr *E) {
   unsigned Builtin = E->isBuiltinCall();
@@ -1046,7 +1054,7 @@
 /// Check that this core constant expression is of literal type, and if not,
 /// produce an appropriate diagnostic.
 static bool CheckLiteralType(EvalInfo &Info, const Expr *E) {
-  if (!E->isRValue() || E->getType()->isLiteralType())
+  if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx))
     return true;
 
   // Prvalue constant expressions must be of literal types.
@@ -1461,6 +1469,15 @@
     return true;
   }
 
+  // If this is a local variable, dig out its value.
+  if (VD->hasLocalStorage() && Frame && Frame->Index > 1) {
+    Result = Frame->Temporaries[VD];
+    // If we've carried on past an unevaluatable local variable initializer,
+    // we can't go any further. This can happen during potential constant
+    // expression checking.
+    return !Result.isUninit();
+  }
+
   // Dig out the initializer, and use the declaration which it's attached to.
   const Expr *Init = VD->getAnyInitializer(VD);
   if (!Init || Init->isValueDependent()) {
@@ -1803,7 +1820,9 @@
       return false;
     }
 
-    if (!isa<ParmVarDecl>(VD)) {
+    // Unless we're looking at a local variable or argument in a constexpr call,
+    // the variable we're reading must be const.
+    if (LVal.CallIndex <= 1 || !VD->hasLocalStorage()) {
       if (VD->isConstexpr()) {
         // OK, we can read this variable.
       } else if (VT->isIntegralOrEnumerationType()) {
@@ -1911,7 +1930,7 @@
   if (Object->isGLValue())
     return EvaluateLValue(Object, This, Info);
 
-  if (Object->getType()->isLiteralType())
+  if (Object->getType()->isLiteralType(Info.Ctx))
     return EvaluateTemporary(Object, This, Info);
 
   return false;
@@ -2060,20 +2079,61 @@
 };
 }
 
+static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
+  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
+    // We don't need to evaluate the initializer for a static local.
+    if (!VD->hasLocalStorage())
+      return true;
+
+    LValue Result;
+    Result.set(VD, Info.CurrentCall->Index);
+    APValue &Val = Info.CurrentCall->Temporaries[VD];
+
+    if (!EvaluateInPlace(Val, Info, Result, VD->getInit())) {
+      // Wipe out any partially-computed value, to allow tracking that this
+      // evaluation failed.
+      Val = APValue();
+      return false;
+    }
+  }
+
+  return true;
+}
+
 // Evaluate a statement.
 static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info,
                                    const Stmt *S) {
+  // FIXME: Mark all temporaries in the current frame as destroyed at
+  // the end of each full-expression.
   switch (S->getStmtClass()) {
   default:
+    if (const Expr *E = dyn_cast<Expr>(S)) {
+      EvaluateIgnoredValue(Info, E);
+      // Don't bother evaluating beyond an expression-statement which couldn't
+      // be evaluated.
+      if (Info.EvalStatus.HasSideEffects && !Info.keepEvaluatingAfterFailure())
+        return ESR_Failed;
+      return ESR_Succeeded;
+    }
+
+    Info.Diag(S->getLocStart());
     return ESR_Failed;
 
   case Stmt::NullStmtClass:
-  case Stmt::DeclStmtClass:
     return ESR_Succeeded;
 
+  case Stmt::DeclStmtClass: {
+    const DeclStmt *DS = cast<DeclStmt>(S);
+    for (DeclStmt::const_decl_iterator DclIt = DS->decl_begin(),
+           DclEnd = DS->decl_end(); DclIt != DclEnd; ++DclIt)
+      if (!EvaluateDecl(Info, *DclIt) && !Info.keepEvaluatingAfterFailure())
+        return ESR_Failed;
+    return ESR_Succeeded;
+  }
+
   case Stmt::ReturnStmtClass: {
     const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
-    if (!Evaluate(Result, Info, RetExpr))
+    if (RetExpr && !Evaluate(Result, Info, RetExpr))
       return ESR_Failed;
     return ESR_Returned;
   }
@@ -2088,6 +2148,28 @@
     }
     return ESR_Succeeded;
   }
+
+  case Stmt::IfStmtClass: {
+    const IfStmt *IS = cast<IfStmt>(S);
+
+    // Evaluate the condition, as either a var decl or as an expression.
+    bool Cond;
+    if (VarDecl *CondDecl = IS->getConditionVariable()) {
+      if (!EvaluateDecl(Info, CondDecl))
+        return ESR_Failed;
+      if (!HandleConversionToBool(Info.CurrentCall->Temporaries[CondDecl],
+                                  Cond))
+        return ESR_Failed;
+    } else if (!EvaluateAsBooleanCondition(IS->getCond(), Cond, Info))
+      return ESR_Failed;
+
+    if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
+      EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
+      if (ESR != ESR_Succeeded)
+        return ESR;
+    }
+    return ESR_Succeeded;
+  }
   }
 }
 
@@ -2181,7 +2263,10 @@
     return false;
 
   CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data());
-  return EvaluateStmt(Result, Info, Body) == ESR_Returned;
+  EvalStmtResult ESR = EvaluateStmt(Result, Info, Body);
+  if (ESR == ESR_Succeeded)
+    Info.Diag(Callee->getLocEnd(), diag::note_constexpr_no_return);
+  return ESR == ESR_Returned;
 }
 
 /// Evaluate a constructor call.
@@ -2207,7 +2292,9 @@
   // If it's a delegating constructor, just delegate.
   if (Definition->isDelegatingConstructor()) {
     CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
-    return EvaluateInPlace(Result, Info, This, (*I)->getInit());
+    if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()))
+      return false;
+    return EvaluateStmt(Result, Info, Definition->getBody()) != ESR_Failed;
   }
 
   // For a trivial copy or move constructor, perform an APValue copy. This is
@@ -2307,7 +2394,8 @@
     }
   }
 
-  return Success;
+  return Success &&
+         EvaluateStmt(Result, Info, Definition->getBody()) != ESR_Failed;
 }
 
 //===----------------------------------------------------------------------===//
@@ -2660,9 +2748,7 @@
 
   /// Visit a value which is evaluated, but whose value is ignored.
   void VisitIgnoredValue(const Expr *E) {
-    APValue Scratch;
-    if (!Evaluate(Scratch, Info, E))
-      Info.EvalStatus.HasSideEffects = true;
+    EvaluateIgnoredValue(Info, E);
   }
 };
 
@@ -2868,7 +2954,7 @@
 
 bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
   if (!VD->getType()->isReferenceType()) {
-    if (isa<ParmVarDecl>(VD)) {
+    if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) {
       Result.set(VD, Info.CurrentCall->Index);
       return true;
     }
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 0c5636d..7922c33 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -1142,16 +1142,20 @@
 
 
 
-bool Type::isLiteralType() const {
+bool Type::isLiteralType(ASTContext &Ctx) const {
   if (isDependentType())
     return false;
 
-  // C++0x [basic.types]p10:
+  // C++1y [basic.types]p10:
+  //   A type is a literal type if it is:
+  //   -- cv void; or
+  if (Ctx.getLangOpts().CPlusPlus1y && isVoidType())
+    return true;
+
+  // C++11 [basic.types]p10:
   //   A type is a literal type if it is:
   //   [...]
-  //   -- an array of literal type.
-  // Extension: variable arrays cannot be literal types, since they're
-  // runtime-sized.
+  //   -- an array of literal type other than an array of runtime bound; or
   if (isVariableArrayType())
     return false;
   const Type *BaseTy = getBaseElementTypeUnsafe();
@@ -1162,7 +1166,7 @@
   if (BaseTy->isIncompleteType())
     return false;
 
-  // C++0x [basic.types]p10:
+  // C++11 [basic.types]p10:
   //   A type is a literal type if it is:
   //    -- a scalar type; or
   // As an extension, Clang treats vector types and complex types as
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 6ecc84f..380b53f 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -7626,7 +7626,7 @@
       }
 
     // Suggest adding 'constexpr' in C++11 for literal types.
-    } else if (getLangOpts().CPlusPlus11 && DclT->isLiteralType()) {
+    } else if (getLangOpts().CPlusPlus11 && DclT->isLiteralType(Context)) {
       Diag(VDecl->getLocation(), diag::err_in_class_initializer_literal_type)
         << DclT << Init->getSourceRange()
         << FixItHint::CreateInsertion(VDecl->getLocStart(), "constexpr ");
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index b29ce23..d18b9d3 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -775,12 +775,13 @@
 }
 
 /// Check the given declaration statement is legal within a constexpr function
-/// body. C++0x [dcl.constexpr]p3,p4.
+/// body. C++11 [dcl.constexpr]p3,p4, and C++1y [dcl.constexpr]p3.
 ///
-/// \return true if the body is OK, false if we have diagnosed a problem.
+/// \return true if the body is OK (maybe only as an extension), false if we
+///         have diagnosed a problem.
 static bool CheckConstexprDeclStmt(Sema &SemaRef, const FunctionDecl *Dcl,
-                                   DeclStmt *DS) {
-  // C++0x [dcl.constexpr]p3 and p4:
+                                   DeclStmt *DS, SourceLocation &Cxx1yLoc) {
+  // C++11 [dcl.constexpr]p3 and p4:
   //  The definition of a constexpr function(p3) or constructor(p4) [...] shall
   //  contain only
   for (DeclStmt::decl_iterator DclIt = DS->decl_begin(),
@@ -791,6 +792,7 @@
     case Decl::UsingShadow:
     case Decl::UsingDirective:
     case Decl::UnresolvedUsingTypename:
+    case Decl::UnresolvedUsingValue:
       //   - static_assert-declarations
       //   - using-declarations,
       //   - using-directives,
@@ -814,20 +816,62 @@
 
     case Decl::Enum:
     case Decl::CXXRecord:
-      // As an extension, we allow the declaration (but not the definition) of
-      // classes and enumerations in all declarations, not just in typedef and
-      // alias declarations.
-      if (cast<TagDecl>(*DclIt)->isThisDeclarationADefinition()) {
-        SemaRef.Diag(DS->getLocStart(), diag::err_constexpr_type_definition)
+      // C++1y allows types to be defined, not just declared.
+      if (cast<TagDecl>(*DclIt)->isThisDeclarationADefinition())
+        SemaRef.Diag(DS->getLocStart(),
+                     SemaRef.getLangOpts().CPlusPlus1y
+                       ? diag::warn_cxx11_compat_constexpr_type_definition
+                       : diag::ext_constexpr_type_definition)
           << isa<CXXConstructorDecl>(Dcl);
-        return false;
-      }
       continue;
 
-    case Decl::Var:
-      SemaRef.Diag(DS->getLocStart(), diag::err_constexpr_var_declaration)
+    case Decl::EnumConstant:
+    case Decl::IndirectField:
+    case Decl::ParmVar:
+      // These can only appear with other declarations which are banned in
+      // C++11 and permitted in C++1y, so ignore them.
+      continue;
+
+    case Decl::Var: {
+      // C++1y [dcl.constexpr]p3 allows anything except:
+      //   a definition of a variable of non-literal type or of static or
+      //   thread storage duration or for which no initialization is performed.
+      VarDecl *VD = cast<VarDecl>(*DclIt);
+      if (VD->isThisDeclarationADefinition()) {
+        if (VD->isStaticLocal()) {
+          SemaRef.Diag(VD->getLocation(),
+                       diag::err_constexpr_local_var_static)
+            << isa<CXXConstructorDecl>(Dcl)
+            << (VD->getTLSKind() == VarDecl::TLS_Dynamic);
+          return false;
+        }
+        if (SemaRef.RequireLiteralType(
+              VD->getLocation(), VD->getType(),
+              diag::err_constexpr_local_var_non_literal_type,
+              isa<CXXConstructorDecl>(Dcl)))
+          return false;
+        if (!VD->hasInit()) {
+          SemaRef.Diag(VD->getLocation(),
+                       diag::err_constexpr_local_var_no_init)
+            << isa<CXXConstructorDecl>(Dcl);
+          return false;
+        }
+      }
+      SemaRef.Diag(VD->getLocation(),
+                   SemaRef.getLangOpts().CPlusPlus1y
+                    ? diag::warn_cxx11_compat_constexpr_local_var
+                    : diag::ext_constexpr_local_var)
         << isa<CXXConstructorDecl>(Dcl);
-      return false;
+      continue;
+    }
+
+    case Decl::NamespaceAlias:
+    case Decl::Function:
+      // These are disallowed in C++11 and permitted in C++1y. Allow them
+      // everywhere as an extension.
+      if (!Cxx1yLoc.isValid())
+        Cxx1yLoc = DS->getLocStart();
+      continue;
 
     default:
       SemaRef.Diag(DS->getLocStart(), diag::err_constexpr_body_invalid_stmt)
@@ -876,6 +920,124 @@
   }
 }
 
+/// Check the provided statement is allowed in a constexpr function
+/// definition.
+static bool
+CheckConstexprFunctionStmt(Sema &SemaRef, const FunctionDecl *Dcl, Stmt *S,
+                           llvm::SmallVectorImpl<SourceLocation> &ReturnStmts,
+                           SourceLocation &Cxx1yLoc) {
+  // - its function-body shall be [...] a compound-statement that contains only
+  switch (S->getStmtClass()) {
+  case Stmt::NullStmtClass:
+    //   - null statements,
+    return true;
+
+  case Stmt::DeclStmtClass:
+    //   - static_assert-declarations
+    //   - using-declarations,
+    //   - using-directives,
+    //   - typedef declarations and alias-declarations that do not define
+    //     classes or enumerations,
+    if (!CheckConstexprDeclStmt(SemaRef, Dcl, cast<DeclStmt>(S), Cxx1yLoc))
+      return false;
+    return true;
+
+  case Stmt::ReturnStmtClass:
+    //   - and exactly one return statement;
+    if (isa<CXXConstructorDecl>(Dcl)) {
+      // C++1y allows return statements in constexpr constructors.
+      if (!Cxx1yLoc.isValid())
+        Cxx1yLoc = S->getLocStart();
+      return true;
+    }
+
+    ReturnStmts.push_back(S->getLocStart());
+    return true;
+
+  case Stmt::CompoundStmtClass: {
+    // C++1y allows compound-statements.
+    if (!Cxx1yLoc.isValid())
+      Cxx1yLoc = S->getLocStart();
+
+    CompoundStmt *CompStmt = cast<CompoundStmt>(S);
+    for (CompoundStmt::body_iterator BodyIt = CompStmt->body_begin(),
+           BodyEnd = CompStmt->body_end(); BodyIt != BodyEnd; ++BodyIt) {
+      if (!CheckConstexprFunctionStmt(SemaRef, Dcl, *BodyIt, ReturnStmts,
+                                      Cxx1yLoc))
+        return false;
+    }
+    return true;
+  }
+
+  case Stmt::AttributedStmtClass:
+    if (!Cxx1yLoc.isValid())
+      Cxx1yLoc = S->getLocStart();
+    return true;
+
+  case Stmt::IfStmtClass: {
+    // C++1y allows if-statements.
+    if (!Cxx1yLoc.isValid())
+      Cxx1yLoc = S->getLocStart();
+
+    IfStmt *If = cast<IfStmt>(S);
+    if (!CheckConstexprFunctionStmt(SemaRef, Dcl, If->getThen(), ReturnStmts,
+                                    Cxx1yLoc))
+      return false;
+    if (If->getElse() &&
+        !CheckConstexprFunctionStmt(SemaRef, Dcl, If->getElse(), ReturnStmts,
+                                    Cxx1yLoc))
+      return false;
+    return true;
+  }
+
+  case Stmt::WhileStmtClass:
+  case Stmt::DoStmtClass:
+  case Stmt::ForStmtClass:
+  case Stmt::CXXForRangeStmtClass:
+  case Stmt::ContinueStmtClass:
+    // C++1y allows all of these. We don't allow them as extensions in C++11,
+    // because they don't make sense without variable mutation.
+    if (!SemaRef.getLangOpts().CPlusPlus1y)
+      break;
+    if (!Cxx1yLoc.isValid())
+      Cxx1yLoc = S->getLocStart();
+    for (Stmt::child_range Children = S->children(); Children; ++Children)
+      if (*Children &&
+          !CheckConstexprFunctionStmt(SemaRef, Dcl, *Children, ReturnStmts,
+                                      Cxx1yLoc))
+        return false;
+    return true;
+
+  case Stmt::SwitchStmtClass:
+  case Stmt::CaseStmtClass:
+  case Stmt::DefaultStmtClass:
+  case Stmt::BreakStmtClass:
+    // C++1y allows switch-statements, and since they don't need variable
+    // mutation, we can reasonably allow them in C++11 as an extension.
+    if (!Cxx1yLoc.isValid())
+      Cxx1yLoc = S->getLocStart();
+    for (Stmt::child_range Children = S->children(); Children; ++Children)
+      if (*Children &&
+          !CheckConstexprFunctionStmt(SemaRef, Dcl, *Children, ReturnStmts,
+                                      Cxx1yLoc))
+        return false;
+    return true;
+
+  default:
+    if (!isa<Expr>(S))
+      break;
+
+    // C++1y allows expression-statements.
+    if (!Cxx1yLoc.isValid())
+      Cxx1yLoc = S->getLocStart();
+    return true;
+  }
+
+  SemaRef.Diag(S->getLocStart(), diag::err_constexpr_body_invalid_stmt)
+    << isa<CXXConstructorDecl>(Dcl);
+  return false;
+}
+
 /// Check the body for the given constexpr function declaration only contains
 /// the permitted types of statement. C++11 [dcl.constexpr]p3,p4.
 ///
@@ -896,44 +1058,25 @@
     return false;
   }
 
-  // - its function-body shall be [...] a compound-statement that contains only
-  CompoundStmt *CompBody = cast<CompoundStmt>(Body);
-
   SmallVector<SourceLocation, 4> ReturnStmts;
+
+  // - its function-body shall be [...] a compound-statement that contains only
+  //   [... list of cases ...]
+  CompoundStmt *CompBody = cast<CompoundStmt>(Body);
+  SourceLocation Cxx1yLoc;
   for (CompoundStmt::body_iterator BodyIt = CompBody->body_begin(),
          BodyEnd = CompBody->body_end(); BodyIt != BodyEnd; ++BodyIt) {
-    switch ((*BodyIt)->getStmtClass()) {
-    case Stmt::NullStmtClass:
-      //   - null statements,
-      continue;
-
-    case Stmt::DeclStmtClass:
-      //   - static_assert-declarations
-      //   - using-declarations,
-      //   - using-directives,
-      //   - typedef declarations and alias-declarations that do not define
-      //     classes or enumerations,
-      if (!CheckConstexprDeclStmt(*this, Dcl, cast<DeclStmt>(*BodyIt)))
-        return false;
-      continue;
-
-    case Stmt::ReturnStmtClass:
-      //   - and exactly one return statement;
-      if (isa<CXXConstructorDecl>(Dcl))
-        break;
-
-      ReturnStmts.push_back((*BodyIt)->getLocStart());
-      continue;
-
-    default:
-      break;
-    }
-
-    Diag((*BodyIt)->getLocStart(), diag::err_constexpr_body_invalid_stmt)
-      << isa<CXXConstructorDecl>(Dcl);
-    return false;
+    if (!CheckConstexprFunctionStmt(*this, Dcl, *BodyIt, ReturnStmts, Cxx1yLoc))
+      return false;
   }
 
+  if (Cxx1yLoc.isValid())
+    Diag(Cxx1yLoc,
+         getLangOpts().CPlusPlus1y
+           ? diag::warn_cxx11_compat_constexpr_body_invalid_stmt
+           : diag::ext_constexpr_body_invalid_stmt)
+      << isa<CXXConstructorDecl>(Dcl);
+
   if (const CXXConstructorDecl *Constructor
         = dyn_cast<CXXConstructorDecl>(Dcl)) {
     const CXXRecordDecl *RD = Constructor->getParent();
@@ -988,14 +1131,23 @@
     }
   } else {
     if (ReturnStmts.empty()) {
-      Diag(Dcl->getLocation(), diag::err_constexpr_body_no_return);
+      // C++1y doesn't require constexpr functions to contain a 'return'
+      // statement. We still do, unless the return type is void, because
+      // otherwise if there's no return statement, the function cannot
+      // be used in a core constant expression.
+      Diag(Dcl->getLocation(),
+           getLangOpts().CPlusPlus1y && Dcl->getResultType()->isVoidType()
+             ? diag::warn_cxx11_compat_constexpr_body_no_return
+             : diag::err_constexpr_body_no_return);
       return false;
     }
     if (ReturnStmts.size() > 1) {
-      Diag(ReturnStmts.back(), diag::err_constexpr_body_multiple_return);
+      Diag(ReturnStmts.back(),
+           getLangOpts().CPlusPlus1y
+             ? diag::warn_cxx11_compat_constexpr_body_multiple_return
+             : diag::ext_constexpr_body_multiple_return);
       for (unsigned I = 0; I < ReturnStmts.size() - 1; ++I)
         Diag(ReturnStmts[I], diag::note_constexpr_body_previous_return);
-      return false;
     }
   }
 
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 89c1bc5..ba2291e 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -3137,7 +3137,7 @@
   case UTT_IsPOD:
     return T.isPODType(Self.Context);
   case UTT_IsLiteral:
-    return T->isLiteralType();
+    return T->isLiteralType(Self.Context);
   case UTT_IsEmpty:
     if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
       return !RD->isUnion() && RD->isEmpty();
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 699265c..5289d15 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -4809,7 +4809,7 @@
   QualType ElemType = Context.getBaseElementType(T);
   RequireCompleteType(Loc, ElemType, 0);
 
-  if (T->isLiteralType())
+  if (T->isLiteralType(Context))
     return false;
 
   if (Diagnoser.Suppressed)
@@ -4851,7 +4851,7 @@
   } else if (RD->hasNonLiteralTypeFieldsOrBases()) {
     for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
          E = RD->bases_end(); I != E; ++I) {
-      if (!I->getType()->isLiteralType()) {
+      if (!I->getType()->isLiteralType(Context)) {
         Diag(I->getLocStart(),
              diag::note_non_literal_base_class)
           << RD << I->getType() << I->getSourceRange();
@@ -4860,7 +4860,7 @@
     }
     for (CXXRecordDecl::field_iterator I = RD->field_begin(),
          E = RD->field_end(); I != E; ++I) {
-      if (!I->getType()->isLiteralType() ||
+      if (!I->getType()->isLiteralType(Context) ||
           I->getType().isVolatileQualified()) {
         Diag(I->getLocation(), diag::note_non_literal_field)
           << RD << *I << I->getType()