Implement a rudimentary form of generic lambdas.

Specifically, the following features are not included in this commit:
  - any sort of capturing within generic lambdas 
  - nested lambdas
  - conversion operator for captureless lambdas
  - ensuring all visitors are generic lambda aware


As an example of what compiles:

template <class F1, class F2>
struct overload : F1, F2 {
    using F1::operator();
    using F2::operator();
    overload(F1 f1, F2 f2) : F1(f1), F2(f2) { }
  };

  auto Recursive = [](auto Self, auto h, auto ... rest) {
    return 1 + Self(Self, rest...);
  };
  auto Base = [](auto Self, auto h) {
      return 1;
  };
  overload<decltype(Base), decltype(Recursive)> O(Base, Recursive);
  int num_params =  O(O, 5, 3, "abc", 3.14, 'a');

Please see attached tests for more examples.

Some implementation notes:

  - Add a new Declarator context => LambdaExprParameterContext to 
    clang::Declarator to allow the use of 'auto' in declaring generic
    lambda parameters
    
  - Augment AutoType's constructor (similar to how variadic 
    template-type-parameters ala TemplateTypeParmDecl are implemented) to 
    accept an IsParameterPack to encode a generic lambda parameter pack.
  
  - Add various helpers to CXXRecordDecl to facilitate identifying
    and querying a closure class
  
  - LambdaScopeInfo (which maintains the current lambda's Sema state)
    was augmented to house the current depth of the template being
    parsed (id est the Parser calls Sema::RecordParsingTemplateParameterDepth)
    so that Sema::ActOnLambdaAutoParameter may use it to create the 
    appropriate list of corresponding TemplateTypeParmDecl for each
    auto parameter identified within the generic lambda (also stored
    within the current LambdaScopeInfo).  Additionally, 
    a TemplateParameterList data-member was added to hold the invented
    TemplateParameterList AST node which will be much more useful
    once we teach TreeTransform how to transform generic lambdas.
    
  - SemaLambda.h was added to hold some common lambda utility
    functions (this file is likely to grow ...)
    
  - Teach Sema::ActOnStartOfFunctionDef to check whether it
    is being called to instantiate a generic lambda's call
    operator, and if so, push an appropriately prepared
    LambdaScopeInfo object on the stack.
    
  - Teach Sema::ActOnStartOfLambdaDefinition to set the
    return type of a lambda without a trailing return type
    to 'auto' in C++1y mode, and teach the return type
    deduction machinery in SemaStmt.cpp to process either
    C++11 and C++14 lambda's correctly depending on the flag.    

  - various tests were added - but much more will be needed.

A greatful thanks to all reviewers including Eli Friedman,  
James Dennett and the ever illuminating Richard Smith.  And 
yet I am certain that I have allowed unidentified bugs to creep in; 
bugs, that I will do my best to slay, once identified!

Thanks!

llvm-svn: 188977

clang/include/clang/AST/ASTContext.h

@@ -1115,7 +1115,7 @@ public:
 
   /// \brief C++11 deduced auto type.
   QualType getAutoType(QualType DeducedType, bool IsDecltypeAuto,
-                       bool IsDependent = false) const;
+                       bool IsDependent, bool IsParameterPack) const;
 
   /// \brief C++11 deduction pattern for 'auto' type.
   QualType getAutoDeductType() const;

clang/include/clang/AST/DeclCXX.h

@@ -516,8 +516,8 @@ class CXXRecordDecl : public RecordDecl {
     
     LambdaDefinitionData(CXXRecordDecl *D, TypeSourceInfo *Info, bool Dependent) 
       : DefinitionData(D), Dependent(Dependent), NumCaptures(0), 
-        NumExplicitCaptures(0), ManglingNumber(0), ContextDecl(0), Captures(0),
+        NumExplicitCaptures(0), ManglingNumber(0), ContextDecl(0), 
-        MethodTyInfo(Info) 
+        Captures(0), MethodTyInfo(Info), TheLambdaExpr(0) 
     {
       IsLambda = true;
     }
@@ -529,7 +529,7 @@ class CXXRecordDecl : public RecordDecl {
     /// within the default argument of a function template, because the
     /// lambda will have been created with the enclosing context as its
     /// declaration context, rather than function. This is an unfortunate
-    /// artifact of having to parse the default arguments before 
+    /// artifact of having to parse the default arguments before. 
     unsigned Dependent : 1;
     
     /// \brief The number of captures in this lambda.
@@ -554,6 +554,10 @@ class CXXRecordDecl : public RecordDecl {
 
     /// \brief The type of the call method.
     TypeSourceInfo *MethodTyInfo;
+
+    /// \brief The AST node of the lambda expression.
+    LambdaExpr *TheLambdaExpr;
+       
   };
 
   struct DefinitionData &data() {
@@ -989,6 +993,36 @@ public:
   /// \brief Determine whether this class describes a lambda function object.
   bool isLambda() const { return hasDefinition() && data().IsLambda; }
 
+  /// \brief Determine whether this class describes a generic 
+  /// lambda function object (i.e. function call operator is
+  /// a template). 
+  bool isGenericLambda() const; 
+
+  /// \brief Retrieve the lambda call operator of the closure type
+  /// if this is a closure type.
+  CXXMethodDecl* getLambdaCallOperator() const; 
+
+  /// \brief Retrieve the lambda static invoker, the address of which
+  /// is returned by the conversion operator, and the body of which
+  /// is forwarded to the lambda call operator. 
+  CXXMethodDecl* getLambdaStaticInvoker() const; 
+
+  /// \brief Retrieve the generic lambda's template parameter list.
+  /// Returns null if the class does not represent a lambda or a generic 
+  /// lambda.
+  TemplateParameterList* getGenericLambdaTemplateParameterList() const;
+
+  /// \brief Assign the member call operator of the lambda. 
+  void setLambdaExpr(LambdaExpr *E) {
+    getLambdaData().TheLambdaExpr = E;
+  }
+
+  /// \brief Retrieve the parent lambda expression.
+  LambdaExpr* getLambdaExpr() const {
+    return isLambda() ? getLambdaData().TheLambdaExpr : 0;
+  }
+
+
   /// \brief For a closure type, retrieve the mapping from captured
   /// variables and \c this to the non-static data members that store the
   /// values or references of the captures.

clang/include/clang/AST/ExprCXX.h

@@ -1605,6 +1605,13 @@ public:
   /// lambda expression. 
   CXXMethodDecl *getCallOperator() const;
 
+  /// \brief If this is a generic lambda expression, retrieve the template 
+  /// parameter list associated with it, or else return null. 
+  TemplateParameterList *getTemplateParameterList() const;
+
+  /// \brief Whether this is a generic lambda.
+  bool isGenericLambda() const { return !!getTemplateParameterList(); }
+
   /// \brief Retrieve the body of the lambda.
   CompoundStmt *getBody() const;
 

clang/include/clang/AST/Type.h

@@ -3614,10 +3614,11 @@ public:
 /// is no deduced type and an auto type is canonical. In the latter case, it is
 /// also a dependent type.
 class AutoType : public Type, public llvm::FoldingSetNode {
-  AutoType(QualType DeducedType, bool IsDecltypeAuto, bool IsDependent)
+  AutoType(QualType DeducedType, bool IsDecltypeAuto, 
+           bool IsDependent, bool IsParameterPack)
     : Type(Auto, DeducedType.isNull() ? QualType(this, 0) : DeducedType,
            /*Dependent=*/IsDependent, /*InstantiationDependent=*/IsDependent,
-           /*VariablyModified=*/false, /*ContainsParameterPack=*/false) {
+           /*VariablyModified=*/false, /*ContainsParameterPack=*/IsParameterPack) {
     assert((DeducedType.isNull() || !IsDependent) &&
            "auto deduced to dependent type");
     AutoTypeBits.IsDecltypeAuto = IsDecltypeAuto;
@@ -3641,14 +3642,17 @@ public:
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
-    Profile(ID, getDeducedType(), isDecltypeAuto(), isDependentType());
+    Profile(ID, getDeducedType(), isDecltypeAuto(), 
+		    isDependentType(), containsUnexpandedParameterPack());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType Deduced,
-                      bool IsDecltypeAuto, bool IsDependent) {
+                      bool IsDecltypeAuto, bool IsDependent, 
+                      bool IsParameterPack) {
     ID.AddPointer(Deduced.getAsOpaquePtr());
     ID.AddBoolean(IsDecltypeAuto);
     ID.AddBoolean(IsDependent);
+    ID.AddBoolean(IsParameterPack);
   }
 
   static bool classof(const Type *T) {

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -5050,6 +5050,10 @@ let CategoryName = "Lambda Issue" in {
     "cannot deduce type for lambda capture %0 from initializer list">;
 }
 
+// C++1y Generic Lambdas
+def err_glambda_not_fully_implemented : Error<
+  "unimplemented generic lambda feature: %0">;
+    
 def err_return_in_captured_stmt : Error<
   "cannot return from %0">;
 def err_capture_block_variable : Error<

clang/include/clang/Sema/DeclSpec.h

@@ -1502,6 +1502,7 @@ public:
     ObjCCatchContext,    // Objective-C catch exception-declaration
     BlockLiteralContext, // Block literal declarator.
     LambdaExprContext,   // Lambda-expression declarator.
+    LambdaExprParameterContext, // Lambda-expression parameter declarator.
     ConversionIdContext, // C++ conversion-type-id.
     TrailingReturnContext, // C++11 trailing-type-specifier.
     TemplateTypeArgContext, // Template type argument.
@@ -1577,7 +1578,6 @@ public:
   ~Declarator() {
     clear();
   }
-
   /// getDeclSpec - Return the declaration-specifier that this declarator was
   /// declared with.
   const DeclSpec &getDeclSpec() const { return DS; }
@@ -1606,7 +1606,8 @@ public:
   bool isPrototypeContext() const {
     return (Context == PrototypeContext ||
             Context == ObjCParameterContext ||
-            Context == ObjCResultContext);
+            Context == ObjCResultContext ||
+            Context == LambdaExprParameterContext);
   }
 
   /// \brief Get the source range that spans this declarator.
@@ -1670,6 +1671,7 @@ public:
     case AliasDeclContext:
     case AliasTemplateContext:
     case PrototypeContext:
+    case LambdaExprParameterContext:
     case ObjCParameterContext:
     case ObjCResultContext:
     case TemplateParamContext:
@@ -1698,6 +1700,7 @@ public:
     case ForContext:
     case ConditionContext:
     case PrototypeContext:
+    case LambdaExprParameterContext:
     case TemplateParamContext:
     case CXXCatchContext:
     case ObjCCatchContext:
@@ -1730,6 +1733,7 @@ public:
     case ForContext:
     case ConditionContext:
     case PrototypeContext:
+    case LambdaExprParameterContext:
     case TemplateParamContext:
     case CXXCatchContext:
     case ObjCCatchContext:
@@ -1782,6 +1786,7 @@ public:
     case KNRTypeListContext:
     case MemberContext:
     case PrototypeContext:
+    case LambdaExprParameterContext:
     case ObjCParameterContext:
     case ObjCResultContext:
     case TemplateParamContext:
@@ -1968,6 +1973,7 @@ public:
     case AliasDeclContext:
     case AliasTemplateContext:
     case PrototypeContext:
+    case LambdaExprParameterContext:
     case ObjCParameterContext:
     case ObjCResultContext:
     case TemplateParamContext:

clang/include/clang/Sema/ScopeInfo.h

@@ -35,6 +35,8 @@ class LabelDecl;
 class ReturnStmt;
 class Scope;
 class SwitchStmt;
+class TemplateTypeParmDecl;
+class TemplateParameterList;
 class VarDecl;
 class DeclRefExpr;
 class ObjCIvarRefExpr;
@@ -613,12 +615,27 @@ public:
   /// \brief Offsets into the ArrayIndexVars array at which each capture starts
   /// its list of array index variables.
   SmallVector<unsigned, 4> ArrayIndexStarts;
+  
+  /// \brief If this is a generic lambda, use this as the depth of 
+  /// each 'auto' parameter, during initial AST construction.
+  unsigned AutoTemplateParameterDepth;
 
-  LambdaScopeInfo(DiagnosticsEngine &Diag, CXXRecordDecl *Lambda,
+  // If this is a generic lambda, store the list of the auto 
-                  CXXMethodDecl *CallOperator)
+  // parameters converted into TemplateTypeParmDecls into a vector
-    : CapturingScopeInfo(Diag, ImpCap_None), Lambda(Lambda),
+  // that can be used to construct the generic lambda's template
-      CallOperator(CallOperator), NumExplicitCaptures(0), Mutable(false),
+  // parameter list, during initial AST construction.
-      ExprNeedsCleanups(false), ContainsUnexpandedParameterPack(false)
+  /// \brief Store the list of the auto parameters for a generic lambda.
+  SmallVector<TemplateTypeParmDecl*, 4> AutoTemplateParams;
+
+  // If this is a generic lambda, store its template parameter list.
+  TemplateParameterList *GLTemplateParameterList;
+  
+  LambdaScopeInfo(DiagnosticsEngine &Diag)
+    : CapturingScopeInfo(Diag, ImpCap_None), Lambda(0),
+      CallOperator(0), NumExplicitCaptures(0), Mutable(false),
+      ExprNeedsCleanups(false), ContainsUnexpandedParameterPack(false),
+      AutoTemplateParameterDepth(0),
+      GLTemplateParameterList(0)
   {
     Kind = SK_Lambda;
   }
@@ -631,8 +648,10 @@ public:
   }
 
   static bool classof(const FunctionScopeInfo *FSI) {
-    return FSI->Kind == SK_Lambda;
+    return FSI->Kind == SK_Lambda; 
   }
+
+
 };
 
 

clang/include/clang/Sema/Sema.h

@@ -969,7 +969,13 @@ public:
 
   void PushFunctionScope();
   void PushBlockScope(Scope *BlockScope, BlockDecl *Block);
-  void PushLambdaScope(CXXRecordDecl *Lambda, CXXMethodDecl *CallOperator);
+  void PushLambdaScope();
+  
+  // This is used to inform Sema what the current TemplateParameterDepth
+  // is during Parsing.  Currently it is used to pass on the depth
+  // when parsing generic lambda 'auto' parameters.
+  void RecordParsingTemplateParameterDepth(unsigned Depth);
+  
   void PushCapturedRegionScope(Scope *RegionScope, CapturedDecl *CD,
                                RecordDecl *RD,
                                CapturedRegionKind K);
@@ -996,9 +1002,12 @@ public:
   /// \brief Retrieve the current block, if any.
   sema::BlockScopeInfo *getCurBlock();
 
-  /// \brief Retrieve the current lambda expression, if any.
+  /// \brief Retrieve the current lambda scope info, if any.
   sema::LambdaScopeInfo *getCurLambda();
 
+  /// \brief Retrieve the current generic lambda info, if any.
+  sema::LambdaScopeInfo *getCurGenericLambda();
+
   /// \brief Retrieve the current captured region, if any.
   sema::CapturedRegionScopeInfo *getCurCapturedRegion();
 
@@ -4402,6 +4411,10 @@ public:
   /// initializer for the declaration 'Dcl'.
   void ActOnCXXExitDeclInitializer(Scope *S, Decl *Dcl);
 
+  /// \brief Invoked when an auto parameter is parsed
+  /// in a lambda's parameter declaration clause.
+  ParmVarDecl *ActOnLambdaAutoParameter(ParmVarDecl *P);
+
   /// \brief Create a new lambda closure type.
   CXXRecordDecl *createLambdaClosureType(SourceRange IntroducerRange,
                                          TypeSourceInfo *Info,
@@ -4414,14 +4427,15 @@ public:
                                        SourceLocation EndLoc,
                                        ArrayRef<ParmVarDecl *> Params);
 
-  /// \brief Introduce the scope for a lambda expression.
+  /// \brief Endow the lambda scope info with the relevant properties.
-  sema::LambdaScopeInfo *enterLambdaScope(CXXMethodDecl *CallOperator,
+  void buildLambdaScope(sema::LambdaScopeInfo *LSI, 
-                                          SourceRange IntroducerRange,
+                        CXXMethodDecl *CallOperator,
-                                          LambdaCaptureDefault CaptureDefault,
+                        SourceRange IntroducerRange,
-                                          SourceLocation CaptureDefaultLoc,
+                        LambdaCaptureDefault CaptureDefault,
-                                          bool ExplicitParams,
+                        SourceLocation CaptureDefaultLoc,
-                                          bool ExplicitResultType,
+                        bool ExplicitParams,
-                                          bool Mutable);
+                        bool ExplicitResultType,
+                        bool Mutable);
 
   /// \brief Check and build an init-capture with the specified name and
   /// initializer.
@@ -5806,6 +5820,12 @@ public:
                           sema::TemplateDeductionInfo &Info,
                           bool InOverloadResolution = false);
 
+  /// \brief Substitute Replacement for \p auto in \p TypeWithAuto
+  QualType SubstAutoType(QualType TypeWithAuto, QualType Replacement);
+  /// \brief Substitute Replacement for auto in TypeWithAuto
+  TypeSourceInfo* SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto, 
+                                          QualType Replacement);
+
   /// \brief Result type of DeduceAutoType.
   enum DeduceAutoResult {
     DAR_Succeeded,
@@ -5817,7 +5837,6 @@ public:
                                   QualType &Result);
   DeduceAutoResult DeduceAutoType(TypeLoc AutoTypeLoc, Expr *&Initializer,
                                   QualType &Result);
-  QualType SubstAutoType(QualType TypeWithAuto, QualType Replacement);
   void DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init);
   bool DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
                         bool Diagnose = true);

clang/include/clang/Sema/SemaLambda.h

@@ -0,0 +1,44 @@
+//===--- SemaLambda.h - Lambda Helper Functions --------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file provides some common utility functions for processing
+/// Lambdas.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_SEMA_LAMBDA_H
+#define LLVM_CLANG_SEMA_LAMBDA_H
+
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclTemplate.h"
+#include "clang/Sema/ScopeInfo.h"
+
+namespace clang {
+static inline const char *getLambdaStaticInvokerName() {
+  return "__invoke";
+}
+static inline bool isGenericLambdaCallOperatorSpecialization(CXXMethodDecl *MD) {
+  if (MD) {
+    CXXRecordDecl *LambdaClass = MD->getParent();
+    if (LambdaClass && LambdaClass->isGenericLambda()) {
+      return LambdaClass->getLambdaCallOperator() 
+                  == MD->getTemplateInstantiationPattern();
+    }
+  }
+  return false;
+}
+
+static inline bool isGenericLambdaCallOperatorSpecialization(Decl *D) {
+  return isGenericLambdaCallOperatorSpecialization(
+                                dyn_cast<CXXMethodDecl>(D));
+}
+} // clang
+
+#endif // LLVM_CLANG_SEMA_LAMBDA_H

clang/lib/AST/ASTContext.cpp

@@ -3649,20 +3649,24 @@ QualType ASTContext::getUnaryTransformType(QualType BaseType,
 /// deduced to the given type, or to the canonical undeduced 'auto' type, or the
 /// canonical deduced-but-dependent 'auto' type.
 QualType ASTContext::getAutoType(QualType DeducedType, bool IsDecltypeAuto,
-                                 bool IsDependent) const {
+                             bool IsDependent, bool IsParameterPack) const {
-  if (DeducedType.isNull() && !IsDecltypeAuto && !IsDependent)
+  if (DeducedType.isNull() && !IsDecltypeAuto && !IsDependent && 
+                              !IsParameterPack)
     return getAutoDeductType();
-
+  assert(!IsParameterPack || DeducedType.isNull() 
+           && "Auto parameter pack: auto ... a should always be undeduced!");
   // Look in the folding set for an existing type.
   void *InsertPos = 0;
   llvm::FoldingSetNodeID ID;
-  AutoType::Profile(ID, DeducedType, IsDecltypeAuto, IsDependent);
+  AutoType::Profile(ID, DeducedType, IsDecltypeAuto, IsDependent, 
+     IsParameterPack);
   if (AutoType *AT = AutoTypes.FindNodeOrInsertPos(ID, InsertPos))
     return QualType(AT, 0);
 
   AutoType *AT = new (*this, TypeAlignment) AutoType(DeducedType,
                                                      IsDecltypeAuto,
-                                                     IsDependent);
+                                                     IsDependent, 
+                                                     IsParameterPack);
   Types.push_back(AT);
   if (InsertPos)
     AutoTypes.InsertNode(AT, InsertPos);
@@ -3702,7 +3706,8 @@ QualType ASTContext::getAutoDeductType() const {
   if (AutoDeductTy.isNull())
     AutoDeductTy = QualType(
       new (*this, TypeAlignment) AutoType(QualType(), /*decltype(auto)*/false,
-                                          /*dependent*/false),
+                                          /*dependent*/false, 
+                                          /*IsParameterPack*/false),
       0);
   return AutoDeductTy;
 }

clang/lib/AST/ASTImporter.cpp

@@ -1709,7 +1709,9 @@ QualType ASTNodeImporter::VisitAutoType(const AutoType *T) {
       return QualType();
   }
   
-  return Importer.getToContext().getAutoType(ToDeduced, T->isDecltypeAuto());
+  return Importer.getToContext().getAutoType(ToDeduced, T->isDecltypeAuto(), 
+                                             /*IsDependent*/false,
+                                      T->containsUnexpandedParameterPack());
 }
 
 QualType ASTNodeImporter::VisitRecordType(const RecordType *T) {

clang/lib/AST/DeclCXX.cpp

@@ -20,6 +20,7 @@
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/IdentifierTable.h"
+#include "clang/Sema/SemaLambda.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.h"
 using namespace clang;
@@ -930,6 +931,40 @@ bool CXXRecordDecl::isCLike() const {
   return isPOD() && data().HasOnlyCMembers;
 }
 
+bool CXXRecordDecl::isGenericLambda() const { 
+  return isLambda() && 
+      getLambdaCallOperator()->getDescribedFunctionTemplate(); 
+}
+
+CXXMethodDecl* CXXRecordDecl::getLambdaCallOperator() const {
+  if (!isLambda()) return 0;
+  DeclarationName Name = 
+    getASTContext().DeclarationNames.getCXXOperatorName(OO_Call);
+  DeclContext::lookup_const_result Calls = lookup(Name);
+
+  assert(!Calls.empty() && "Missing lambda call operator!");
+  assert(Calls.size() == 1 && "More than one lambda call operator!"); 
+   
+  NamedDecl *CallOp = Calls.front();
+  if (FunctionTemplateDecl *CallOpTmpl = 
+                    dyn_cast<FunctionTemplateDecl>(CallOp)) 
+    return cast<CXXMethodDecl>(CallOpTmpl->getTemplatedDecl());
+  
+  return cast<CXXMethodDecl>(CallOp);
+}
+
+CXXMethodDecl* CXXRecordDecl::getLambdaStaticInvoker() const {
+  if (!isLambda()) return 0;
+  DeclarationName Name = 
+    &getASTContext().Idents.get(getLambdaStaticInvokerName());
+  DeclContext::lookup_const_result Invoker = lookup(Name);
+  if (Invoker.empty()) return 0;
+  assert(Invoker.size() == 1 && "More than one static invoker operator!");  
+  CXXMethodDecl *Result = cast<CXXMethodDecl>(Invoker.front());  
+  return Result;
+
+}
+
 void CXXRecordDecl::getCaptureFields(
        llvm::DenseMap<const VarDecl *, FieldDecl *> &Captures,
        FieldDecl *&ThisCapture) const {
@@ -947,6 +982,14 @@ void CXXRecordDecl::getCaptureFields(
   }
 }
 
+TemplateParameterList* 
+        CXXRecordDecl::getGenericLambdaTemplateParameterList() const {
+  if (!isLambda()) return 0;
+  CXXMethodDecl *CallOp = getLambdaCallOperator();     
+  if (FunctionTemplateDecl *Tmpl = CallOp->getDescribedFunctionTemplate())
+    return Tmpl->getTemplateParameters();
+  return 0;
+}
 
 static CanQualType GetConversionType(ASTContext &Context, NamedDecl *Conv) {
   QualType T;
@@ -1493,7 +1536,7 @@ bool CXXMethodDecl::hasInlineBody() const {
 
 bool CXXMethodDecl::isLambdaStaticInvoker() const {
   return getParent()->isLambda() && 
-         getIdentifier() && getIdentifier()->getName() == "__invoke";
+         getParent()->getLambdaStaticInvoker() == this;
 }
 
 

clang/lib/AST/ExprCXX.cpp

@@ -1026,13 +1026,13 @@ CXXRecordDecl *LambdaExpr::getLambdaClass() const {
 
 CXXMethodDecl *LambdaExpr::getCallOperator() const {
   CXXRecordDecl *Record = getLambdaClass();
-  DeclarationName Name
+  return Record->getLambdaCallOperator();  
-    = Record->getASTContext().DeclarationNames.getCXXOperatorName(OO_Call);
+}
-  DeclContext::lookup_result Calls = Record->lookup(Name);
+
-  assert(!Calls.empty() && "Missing lambda call operator!");
+TemplateParameterList *LambdaExpr::getTemplateParameterList() const {
-  assert(Calls.size() == 1 && "More than one lambda call operator!");
+  CXXRecordDecl *Record = getLambdaClass();
-  CXXMethodDecl *Result = cast<CXXMethodDecl>(Calls.front());
+  return Record->getGenericLambdaTemplateParameterList();
-  return Result;
+
 }
 
 CompoundStmt *LambdaExpr::getBody() const {

clang/lib/AST/Type.cpp

@@ -589,6 +589,10 @@ namespace {
     AutoType *VisitAttributedType(const AttributedType *T) {
       return Visit(T->getModifiedType());
     }
+    AutoType *VisitPackExpansionType(const PackExpansionType *T) {
+      return Visit(T->getPattern());
+    }
+
   };
 }
 

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -700,7 +700,7 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
     EmitLambdaToBlockPointerBody(Args);
   } else if (isa<CXXMethodDecl>(FD) &&
              cast<CXXMethodDecl>(FD)->isLambdaStaticInvoker()) {
-    // The lambda "__invoke" function is special, because it forwards or
+    // The lambda static invoker function is special, because it forwards or
     // clones the body of the function call operator (but is actually static).
     EmitLambdaStaticInvokeFunction(cast<CXXMethodDecl>(FD));
   } else if (FD->isDefaulted() && isa<CXXMethodDecl>(FD) &&

clang/lib/Parse/ParseDecl.cpp

@@ -4670,6 +4670,7 @@ void Parser::ParseDirectDeclarator(Declarator &D) {
     //   as part of the parameter-declaration-clause.
     if (Tok.is(tok::ellipsis) && D.getCXXScopeSpec().isEmpty() &&
         !((D.getContext() == Declarator::PrototypeContext ||
+           D.getContext() == Declarator::LambdaExprParameterContext ||
            D.getContext() == Declarator::BlockLiteralContext) &&
           NextToken().is(tok::r_paren) &&
           !D.hasGroupingParens() &&
@@ -4988,7 +4989,6 @@ void Parser::ParseFunctionDeclarator(Declarator &D,
   TypeResult TrailingReturnType;
 
   Actions.ActOnStartFunctionDeclarator();
-
   /* LocalEndLoc is the end location for the local FunctionTypeLoc.
      EndLoc is the end location for the function declarator.
      They differ for trailing return types. */
@@ -5009,7 +5009,8 @@ void Parser::ParseFunctionDeclarator(Declarator &D,
     EndLoc = RParenLoc;
   } else {
     if (Tok.isNot(tok::r_paren))
-      ParseParameterDeclarationClause(D, FirstArgAttrs, ParamInfo, EllipsisLoc);
+      ParseParameterDeclarationClause(D, FirstArgAttrs, ParamInfo, 
+                                      EllipsisLoc);
     else if (RequiresArg)
       Diag(Tok, diag::err_argument_required_after_attribute);
 
@@ -5240,7 +5241,6 @@ void Parser::ParseParameterDeclarationClause(
        ParsedAttributes &FirstArgAttrs,
        SmallVectorImpl<DeclaratorChunk::ParamInfo> &ParamInfo,
        SourceLocation &EllipsisLoc) {
-
   while (1) {
     if (Tok.is(tok::ellipsis)) {
       // FIXME: Issue a diagnostic if we parsed an attribute-specifier-seq
@@ -5270,16 +5270,21 @@ void Parser::ParseParameterDeclarationClause(
 
     ParseDeclarationSpecifiers(DS);
 
-    // Parse the declarator.  This is "PrototypeContext", because we must
+
-    // accept either 'declarator' or 'abstract-declarator' here.
+    // Parse the declarator.  This is "PrototypeContext" or 
-    Declarator ParmDecl(DS, Declarator::PrototypeContext);
+    // "LambdaExprParameterContext", because we must accept either 
-    ParseDeclarator(ParmDecl);
+    // 'declarator' or 'abstract-declarator' here.
+    Declarator ParmDeclarator(DS, 
+              D.getContext() == Declarator::LambdaExprContext ?
+                                  Declarator::LambdaExprParameterContext : 
+                                                Declarator::PrototypeContext);
+    ParseDeclarator(ParmDeclarator);
 
     // Parse GNU attributes, if present.
-    MaybeParseGNUAttributes(ParmDecl);
+    MaybeParseGNUAttributes(ParmDeclarator);
 
     // Remember this parsed parameter in ParamInfo.
-    IdentifierInfo *ParmII = ParmDecl.getIdentifier();
+    IdentifierInfo *ParmII = ParmDeclarator.getIdentifier();
 
     // DefArgToks is used when the parsing of default arguments needs
     // to be delayed.
@@ -5287,8 +5292,8 @@ void Parser::ParseParameterDeclarationClause(
 
     // If no parameter was specified, verify that *something* was specified,
     // otherwise we have a missing type and identifier.
-    if (DS.isEmpty() && ParmDecl.getIdentifier() == 0 &&
+    if (DS.isEmpty() && ParmDeclarator.getIdentifier() == 0 &&
-        ParmDecl.getNumTypeObjects() == 0) {
+        ParmDeclarator.getNumTypeObjects() == 0) {
       // Completely missing, emit error.
       Diag(DSStart, diag::err_missing_param);
     } else {
@@ -5297,8 +5302,8 @@ void Parser::ParseParameterDeclarationClause(
 
       // Inform the actions module about the parameter declarator, so it gets
       // added to the current scope.
-      Decl *Param = Actions.ActOnParamDeclarator(getCurScope(), ParmDecl);
+      Decl *Param = Actions.ActOnParamDeclarator(getCurScope(), 
-
+                                                       ParmDeclarator);
       // Parse the default argument, if any. We parse the default
       // arguments in all dialects; the semantic analysis in
       // ActOnParamDefaultArgument will reject the default argument in
@@ -5359,8 +5364,8 @@ void Parser::ParseParameterDeclarationClause(
       }
 
       ParamInfo.push_back(DeclaratorChunk::ParamInfo(ParmII,
-                                          ParmDecl.getIdentifierLoc(), Param,
+                                          ParmDeclarator.getIdentifierLoc(), 
-                                          DefArgToks));
+                                          Param, DefArgToks));
     }
 
     // If the next token is a comma, consume it and keep reading arguments.

clang/lib/Parse/ParseExprCXX.cpp

@@ -20,6 +20,7 @@
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "clang/AST/DeclTemplate.h"
 
 using namespace clang;
 
@@ -908,12 +909,16 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
   PrettyStackTraceLoc CrashInfo(PP.getSourceManager(), LambdaBeginLoc,
                                 "lambda expression parsing");
 
+ 
+
   // FIXME: Call into Actions to add any init-capture declarations to the
   // scope while parsing the lambda-declarator and compound-statement.
 
   // Parse lambda-declarator[opt].
   DeclSpec DS(AttrFactory);
   Declarator D(DS, Declarator::LambdaExprContext);
+  TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
+  Actions.PushLambdaScope();    
 
   if (Tok.is(tok::l_paren)) {
     ParseScope PrototypeScope(this,
@@ -931,9 +936,17 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
     SmallVector<DeclaratorChunk::ParamInfo, 16> ParamInfo;
     SourceLocation EllipsisLoc;
 
-    if (Tok.isNot(tok::r_paren))
+    
+    if (Tok.isNot(tok::r_paren)) {
+      sema::LambdaScopeInfo *LSI = Actions.getCurLambda(); 
+      if (getLangOpts().CPlusPlus1y)
+        Actions.RecordParsingTemplateParameterDepth(TemplateParameterDepth);
       ParseParameterDeclarationClause(D, Attr, ParamInfo, EllipsisLoc);
-
+      // For a generic lambda, each 'auto' within the parameter declaration 
+      // clause creates a template type parameter, so increment the depth.
+      if (getLangOpts().CPlusPlus1y && Actions.getCurGenericLambda()) 
+        ++CurTemplateDepthTracker;
+    }
     T.consumeClose();
     SourceLocation RParenLoc = T.getCloseLocation();
     DeclEndLoc = RParenLoc;

clang/lib/Parse/Parser.cpp

@@ -1175,7 +1175,6 @@ void Parser::ParseKNRParamDeclarations(Declarator &D) {
       // Ask the actions module to compute the type for this declarator.
       Decl *Param =
         Actions.ActOnParamDeclarator(getCurScope(), ParmDeclarator);
-
       if (Param &&
           // A missing identifier has already been diagnosed.
           ParmDeclarator.getIdentifier()) {

clang/lib/Sema/Sema.cpp

@@ -1007,10 +1007,17 @@ void Sema::PushBlockScope(Scope *BlockScope, BlockDecl *Block) {
                                               BlockScope, Block));
 }
 
-void Sema::PushLambdaScope(CXXRecordDecl *Lambda,
+void Sema::PushLambdaScope() {
-                           CXXMethodDecl *CallOperator) {
+  FunctionScopes.push_back(new LambdaScopeInfo(getDiagnostics()));
-  FunctionScopes.push_back(new LambdaScopeInfo(getDiagnostics(), Lambda,
+}
-                                               CallOperator));
+
+void Sema::RecordParsingTemplateParameterDepth(unsigned Depth) {
+  if (LambdaScopeInfo *const LSI = getCurLambda()) {
+    LSI->AutoTemplateParameterDepth = Depth;
+    return;
+  } 
+  assert(false && 
+      "Remove assertion if intentionally called in a non-lambda context.");
 }
 
 void Sema::PopFunctionScopeInfo(const AnalysisBasedWarnings::Policy *WP,
@@ -1066,6 +1073,16 @@ LambdaScopeInfo *Sema::getCurLambda() {
 
   return dyn_cast<LambdaScopeInfo>(FunctionScopes.back());
 }
+// We have a generic lambda if we parsed auto parameters, or we have 
+// an associated template parameter list.
+LambdaScopeInfo *Sema::getCurGenericLambda() {
+  if (LambdaScopeInfo *LSI =  getCurLambda()) {
+    return (LSI->AutoTemplateParams.size() ||
+                    LSI->GLTemplateParameterList) ? LSI : 0;
+  }
+  return 0;
+}
+
 
 void Sema::ActOnComment(SourceRange Comment) {
   if (!LangOpts.RetainCommentsFromSystemHeaders &&

clang/lib/Sema/SemaDecl.cpp

@@ -35,6 +35,7 @@
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/DelayedDiagnostic.h"
 #include "clang/Sema/Initialization.h"
+#include "clang/Sema/SemaLambda.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
@@ -8909,6 +8910,7 @@ Decl *Sema::ActOnParamDeclarator(Scope *S, Declarator &D) {
   const DeclSpec &DS = D.getDeclSpec();
 
   // Verify C99 6.7.5.3p2: The only SCS allowed is 'register'.
+
   // C++03 [dcl.stc]p2 also permits 'auto'.
   VarDecl::StorageClass StorageClass = SC_None;
   if (DS.getStorageClassSpec() == DeclSpec::SCS_register) {
@@ -9015,6 +9017,14 @@ Decl *Sema::ActOnParamDeclarator(Scope *S, Declarator &D) {
   if (New->hasAttr<BlocksAttr>()) {
     Diag(New->getLocation(), diag::err_block_on_nonlocal);
   }
+
+  // Handle 'auto' within a generic lambda.
+  QualType ParamType = New->getType();
+  if (getLangOpts().CPlusPlus1y && ParamType->getContainedAutoType()) { 
+    assert(getCurLambda() && 
+                  "'auto' in parameter type only allowed in lambdas!");
+    New = ActOnLambdaAutoParameter(New);
+  } 
   return New;
 }
 
@@ -9268,9 +9278,38 @@ Decl *Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Decl *D) {
     FD = FunTmpl->getTemplatedDecl();
   else
     FD = cast<FunctionDecl>(D);
+  // If we are instantiating a generic lambda call operator, push
+  // a LambdaScopeInfo onto the function stack.  But use the information
+  // that's already been calculated (ActOnLambdaExpr) when analyzing the
+  // template version, to prime the current LambdaScopeInfo. 
+  if (getLangOpts().CPlusPlus1y 
+                        && isGenericLambdaCallOperatorSpecialization(D)) {
+    CXXMethodDecl *CallOperator = cast<CXXMethodDecl>(D);
+    CXXRecordDecl *LambdaClass = CallOperator->getParent();
+    LambdaExpr    *LE = LambdaClass->getLambdaExpr();
+    assert(LE && 
+     "No LambdaExpr of closure class when instantiating a generic lambda!");
+    assert(ActiveTemplateInstantiations.size() &&
+      "There should be an active template instantiation on the stack " 
+      "when instantiating a generic lambda!");
+    PushLambdaScope();
+    LambdaScopeInfo *LSI = getCurLambda();
+    LSI->CallOperator = CallOperator;
+    LSI->Lambda = LambdaClass;
+    LSI->ReturnType = CallOperator->getResultType();
 
-  // Enter a new function scope
+    if (LE->getCaptureDefault() == LCD_None)
-  PushFunctionScope();
+      LSI->ImpCaptureStyle = CapturingScopeInfo::ImpCap_None;
+    else if (LE->getCaptureDefault() == LCD_ByCopy)
+      LSI->ImpCaptureStyle = CapturingScopeInfo::ImpCap_LambdaByval;
+    else if (LE->getCaptureDefault() == LCD_ByRef)
+      LSI->ImpCaptureStyle = CapturingScopeInfo::ImpCap_LambdaByref;
+    
+    LSI->IntroducerRange = LE->getIntroducerRange();
+  }
+  else
+    // Enter a new function scope
+    PushFunctionScope();
 
   // See if this is a redefinition.
   if (!FD->isLateTemplateParsed())

clang/lib/Sema/SemaDeclCXX.cpp

@@ -32,6 +32,7 @@
 #include "clang/Sema/CXXFieldCollector.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/Initialization.h"
+#include "clang/Sema/SemaLambda.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
@@ -10015,29 +10016,27 @@ void Sema::DefineImplicitLambdaToFunctionPointerConversion(
        SourceLocation CurrentLocation,
        CXXConversionDecl *Conv) 
 {
-  CXXRecordDecl *Lambda = Conv->getParent();
+  CXXRecordDecl *LambdaClass = Conv->getParent();
   
   // Make sure that the lambda call operator is marked used.
-  markLambdaCallOperatorUsed(*this, Lambda);
+  markLambdaCallOperatorUsed(*this, LambdaClass);
   
   Conv->setUsed();
   
   SynthesizedFunctionScope Scope(*this, Conv);
   DiagnosticErrorTrap Trap(Diags);
   
-  // Return the address of the __invoke function.
+  CXXMethodDecl *Invoke = LambdaClass->getLambdaStaticInvoker();
-  DeclarationName InvokeName = &Context.Idents.get("__invoke");
+
-  CXXMethodDecl *Invoke 
-    = cast<CXXMethodDecl>(Lambda->lookup(InvokeName).front());
   Expr *FunctionRef = BuildDeclRefExpr(Invoke, Invoke->getType(),
                                        VK_LValue, Conv->getLocation()).take();
-  assert(FunctionRef && "Can't refer to __invoke function?");
+  assert(FunctionRef && "Can't refer to lambda static invoker function?");
   Stmt *Return = ActOnReturnStmt(Conv->getLocation(), FunctionRef).take();
   Conv->setBody(new (Context) CompoundStmt(Context, Return,
                                            Conv->getLocation(),
                                            Conv->getLocation()));
     
-  // Fill in the __invoke function with a dummy implementation. IR generation
+  // Fill in the invoke function with a dummy implementation. IR generation
   // will fill in the actual details.
   Invoke->setUsed();
   Invoke->setReferenced();

clang/lib/Sema/SemaLambda.cpp

@@ -14,6 +14,7 @@
 #include "clang/AST/ExprCXX.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/Initialization.h"
+#include "clang/Sema/SemaLambda.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/ScopeInfo.h"
@@ -120,11 +121,69 @@ Sema::getCurrentMangleNumberContext(const DeclContext *DC,
   llvm_unreachable("unexpected context");
 }
 
+
+ParmVarDecl *Sema::ActOnLambdaAutoParameter(ParmVarDecl *PVD) {
+  LambdaScopeInfo *LSI = getCurLambda();
+  assert(LSI && "No LambdaScopeInfo on the stack!");
+  const unsigned TemplateParameterDepth = LSI->AutoTemplateParameterDepth;
+  const unsigned AutoParameterPosition = LSI->AutoTemplateParams.size();
+  // Invent a template type parameter corresponding to the auto 
+  // containing parameter.
+  TemplateTypeParmDecl *TemplateParam =
+    TemplateTypeParmDecl::Create(Context, 
+      // Temporarily add to the TranslationUnit DeclContext.  When the 
+      // associated TemplateParameterList is attached to a template
+      // declaration (such as FunctionTemplateDecl), the DeclContext 
+      // for each template parameter gets updated appropriately via
+      // a call to AdoptTemplateParameterList. 
+      Context.getTranslationUnitDecl(), 
+      SourceLocation(), 
+      PVD->getLocation(), 
+      TemplateParameterDepth, 
+      AutoParameterPosition,  // our template param index 
+      /* Identifier*/ 0, false, PVD->isParameterPack());
+  LSI->AutoTemplateParams.push_back(TemplateParam);
+  QualType AutoTy = PVD->getType();
+  // Now replace the 'auto' in the function parameter with this invented 
+  // template type parameter.
+  QualType TemplParamType = QualType(TemplateParam->getTypeForDecl(), 0);    
+  
+  TypeSourceInfo *AutoTSI = PVD->getTypeSourceInfo();
+  TypeSourceInfo *NewTSI = SubstAutoTypeSourceInfo(AutoTSI, TemplParamType);
+  PVD->setType(NewTSI->getType());
+  PVD->setTypeSourceInfo(NewTSI);
+  return PVD;
+}
+
+
+static inline TemplateParameterList *
+              getGenericLambdaTemplateParameterList(LambdaScopeInfo *LSI, 
+                            Sema &SemaRef) {
+  if (LSI->GLTemplateParameterList)
+    return LSI->GLTemplateParameterList;
+  else if (LSI->AutoTemplateParams.size()) {
+    SourceRange IntroRange = LSI->IntroducerRange;
+    SourceLocation LAngleLoc = IntroRange.getBegin();
+    SourceLocation RAngleLoc = IntroRange.getEnd();
+    LSI->GLTemplateParameterList = 
+          TemplateParameterList::Create(SemaRef.Context, 
+            /* Template kw loc */ SourceLocation(), 
+            LAngleLoc,
+            (NamedDecl**)LSI->AutoTemplateParams.data(), 
+            LSI->AutoTemplateParams.size(), RAngleLoc);  
+  }
+  return LSI->GLTemplateParameterList;
+}
+
+
+
 CXXMethodDecl *Sema::startLambdaDefinition(CXXRecordDecl *Class,
                  SourceRange IntroducerRange,
                  TypeSourceInfo *MethodType,
                  SourceLocation EndLoc,
                  ArrayRef<ParmVarDecl *> Params) {
+  TemplateParameterList *TemplateParams = 
+            getGenericLambdaTemplateParameterList(getCurLambda(), *this);
   // C++11 [expr.prim.lambda]p5:
   //   The closure type for a lambda-expression has a public inline function 
   //   call operator (13.5.4) whose parameters and return type are described by
@@ -152,6 +211,17 @@ CXXMethodDecl *Sema::startLambdaDefinition(CXXRecordDecl *Class,
   // Temporarily set the lexical declaration context to the current
   // context, so that the Scope stack matches the lexical nesting.
   Method->setLexicalDeclContext(CurContext);  
+  // Create a function template if we have a template parameter list
+  FunctionTemplateDecl *const TemplateMethod = TemplateParams ?
+            FunctionTemplateDecl::Create(Context, Class,
+                                         Method->getLocation(), MethodName, 
+                                         TemplateParams,
+                                         Method) : 0;
+  if (TemplateMethod) {
+    TemplateMethod->setLexicalDeclContext(CurContext);
+    TemplateMethod->setAccess(AS_public);
+    Method->setDescribedFunctionTemplate(TemplateMethod);
+  }
   
   // Add parameters.
   if (!Params.empty()) {
@@ -177,15 +247,16 @@ CXXMethodDecl *Sema::startLambdaDefinition(CXXRecordDecl *Class,
   return Method;
 }
 
-LambdaScopeInfo *Sema::enterLambdaScope(CXXMethodDecl *CallOperator,
+void Sema::buildLambdaScope(LambdaScopeInfo *LSI,
+                                        CXXMethodDecl *CallOperator,
                                         SourceRange IntroducerRange,
                                         LambdaCaptureDefault CaptureDefault,
                                         SourceLocation CaptureDefaultLoc,
                                         bool ExplicitParams,
                                         bool ExplicitResultType,
                                         bool Mutable) {
-  PushLambdaScope(CallOperator->getParent(), CallOperator);
+  LSI->CallOperator = CallOperator;
-  LambdaScopeInfo *LSI = getCurLambda();
+  LSI->Lambda = CallOperator->getParent();
   if (CaptureDefault == LCD_ByCopy)
     LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
   else if (CaptureDefault == LCD_ByRef)
@@ -208,8 +279,6 @@ LambdaScopeInfo *Sema::enterLambdaScope(CXXMethodDecl *CallOperator,
   } else {
     LSI->HasImplicitReturnType = true;
   }
-
-  return LSI;
 }
 
 void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
@@ -358,7 +427,7 @@ static void adjustBlockReturnsToEnum(Sema &S, ArrayRef<ReturnStmt*> returns,
 }
 
 void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
-  assert(CSI.HasImplicitReturnType);
+  assert(CSI.HasImplicitReturnType || CSI.ReturnType->isUndeducedType());
 
   // C++ Core Issue #975, proposed resolution:
   //   If a lambda-expression does not include a trailing-return-type,
@@ -392,7 +461,7 @@ void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
   // Second case: at least one return statement has dependent type.
   // Delay type checking until instantiation.
   assert(!CSI.ReturnType.isNull() && "We should have a tentative return type.");
-  if (CSI.ReturnType->isDependentType())
+  if (CSI.ReturnType->isDependentType() || CSI.ReturnType->isUndeducedType())
     return;
 
   // Try to apply the enum-fuzz rule.
@@ -519,15 +588,25 @@ FieldDecl *Sema::checkInitCapture(SourceLocation Loc, bool ByRef,
 }
 
 void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
-                                        Declarator &ParamInfo,
+                  Declarator &ParamInfo, Scope *CurScope) {
-                                        Scope *CurScope) {
   // Determine if we're within a context where we know that the lambda will
   // be dependent, because there are template parameters in scope.
   bool KnownDependent = false;
-  if (Scope *TmplScope = CurScope->getTemplateParamParent())
+  LambdaScopeInfo *const LSI = getCurLambda();
-    if (!TmplScope->decl_empty())
+  assert(LSI && "LambdaScopeInfo should be on stack!");
+  TemplateParameterList *TemplateParams = 
+            getGenericLambdaTemplateParameterList(LSI, *this);
+
+  if (Scope *TmplScope = CurScope->getTemplateParamParent()) {
+    // Since we have our own TemplateParams, so check if an outer scope
+    // has template params, only then are we in a dependent scope.
+    if (TemplateParams)  {
+      TmplScope = TmplScope->getParent();
+      TmplScope = TmplScope ? TmplScope->getTemplateParamParent() : 0;
+    }
+    if (TmplScope && !TmplScope->decl_empty())
       KnownDependent = true;
-  
+  }
   // Determine the signature of the call operator.
   TypeSourceInfo *MethodTyInfo;
   bool ExplicitParams = true;
@@ -542,7 +621,11 @@ void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
     FunctionProtoType::ExtProtoInfo EPI;
     EPI.HasTrailingReturn = true;
     EPI.TypeQuals |= DeclSpec::TQ_const;
-    QualType MethodTy = Context.getFunctionType(Context.DependentTy, None,
+    // For C++1y, use the new return type deduction machinery, by imaginging
+    // 'auto' if no trailing return type.
+    QualType DefaultTypeForNoTrailingReturn = getLangOpts().CPlusPlus1y ?
+                    Context.getAutoDeductType() : Context.DependentTy;
+    QualType MethodTy = Context.getFunctionType(DefaultTypeForNoTrailingReturn, None,
                                                 EPI);
     MethodTyInfo = Context.getTrivialTypeSourceInfo(MethodTy);
     ExplicitParams = false;
@@ -560,14 +643,15 @@ void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
     if (!FTI.hasMutableQualifier())
       FTI.TypeQuals |= DeclSpec::TQ_const;
     
+    ExplicitResultType = FTI.hasTrailingReturnType();
+    // In C++11 if there is no explicit return type, the return type is
+    // artificially set to DependentTy, whereas in C++1y it is set to AutoTy
+    // (through ConvertDeclSpecToType) which allows us to support both
+    // C++11 and C++1y return type deduction semantics.
     MethodTyInfo = GetTypeForDeclarator(ParamInfo, CurScope);
     assert(MethodTyInfo && "no type from lambda-declarator");
     EndLoc = ParamInfo.getSourceRange().getEnd();
     
-    ExplicitResultType
-      = MethodTyInfo->getType()->getAs<FunctionType>()->getResultType() 
-                                                        != Context.DependentTy;
-
     if (FTI.NumArgs == 1 && !FTI.isVariadic && FTI.ArgInfo[0].Ident == 0 &&
         cast<ParmVarDecl>(FTI.ArgInfo[0].Param)->getType()->isVoidType()) {
       // Empty arg list, don't push any params.
@@ -588,7 +672,6 @@ void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
 
   CXXMethodDecl *Method = startLambdaDefinition(Class, Intro.Range,
                                                 MethodTyInfo, EndLoc, Params);
-  
   if (ExplicitParams)
     CheckCXXDefaultArguments(Method);
   
@@ -598,9 +681,8 @@ void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
   // Introduce the function call operator as the current declaration context.
   PushDeclContext(CurScope, Method);
     
-  // Introduce the lambda scope.
+  // Build the lambda scope.
-  LambdaScopeInfo *LSI
+  buildLambdaScope(LSI, Method,
-    = enterLambdaScope(Method,
                        Intro.Range,
                        Intro.Default, Intro.DefaultLoc,
                        ExplicitParams,
@@ -812,6 +894,8 @@ static void addFunctionPointerConversion(Sema &S,
                                          SourceRange IntroducerRange,
                                          CXXRecordDecl *Class,
                                          CXXMethodDecl *CallOperator) {
+  // FIXME: The conversion operator needs to be fixed for generic lambdas.
+  if (Class->isGenericLambda()) return;
   // Add the conversion to function pointer.
   const FunctionProtoType *Proto
     = CallOperator->getType()->getAs<FunctionProtoType>(); 
@@ -849,10 +933,9 @@ static void addFunctionPointerConversion(Sema &S,
   Conversion->setAccess(AS_public);
   Conversion->setImplicit(true);
   Class->addDecl(Conversion);
-  
+  // Add a non-static member function that will be the result of
-  // Add a non-static member function "__invoke" that will be the result of
+  // the conversion with a certain unique ID.
-  // the conversion.
+  Name = &S.Context.Idents.get(getLambdaStaticInvokerName());
-  Name = &S.Context.Idents.get("__invoke");
   CXXMethodDecl *Invoke
     = CXXMethodDecl::Create(S.Context, Class, Loc, 
                             DeclarationNameInfo(Name, Loc), FunctionTy, 
@@ -1000,8 +1083,11 @@ ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
     //   If a lambda-expression does not include a
     //   trailing-return-type, it is as if the trailing-return-type
     //   denotes the following type:
+    // Skip for C++1y return type deduction semantics which uses
+    // different machinery currently.
+    // FIXME: Refactor and Merge the return type deduction machinery.
     // FIXME: Assumes current resolution to core issue 975.
-    if (LSI->HasImplicitReturnType) {
+    if (LSI->HasImplicitReturnType && !getLangOpts().CPlusPlus1y) {
       deduceClosureReturnType(*LSI);
 
       //   - if there are no return statements in the
@@ -1019,13 +1105,18 @@ ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
           LSI->ReturnType, Proto->getArgTypes(), Proto->getExtProtoInfo());
       CallOperator->setType(FunctionTy);
     }
-
     // C++ [expr.prim.lambda]p7:
     //   The lambda-expression's compound-statement yields the
     //   function-body (8.4) of the function call operator [...].
     ActOnFinishFunctionBody(CallOperator, Body, IsInstantiation);
     CallOperator->setLexicalDeclContext(Class);
-    Class->addDecl(CallOperator);
+    Decl *TemplateOrNonTemplateCallOperatorDecl = 
+      !CallOperator->getDescribedFunctionTemplate() ? cast<Decl>(CallOperator)
+        : CallOperator->getDescribedFunctionTemplate();
+
+    TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
+    Class->addDecl(TemplateOrNonTemplateCallOperatorDecl);
+
     PopExpressionEvaluationContext();
 
     // C++11 [expr.prim.lambda]p6:
@@ -1065,7 +1156,7 @@ ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
                                           CaptureInits, ArrayIndexVars, 
                                           ArrayIndexStarts, Body->getLocEnd(),
                                           ContainsUnexpandedParameterPack);
-
+  Class->setLambdaExpr(Lambda);
   // C++11 [expr.prim.lambda]p2:
   //   A lambda-expression shall not appear in an unevaluated operand
   //   (Clause 5).
@@ -1085,7 +1176,15 @@ ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
       break;
     }
   }
-  
+  // TODO: Implement capturing.
+  if (Lambda->isGenericLambda()) {
+    if (Lambda->getCaptureDefault() != LCD_None) {
+      Diag(Lambda->getIntroducerRange().getBegin(), 
+        diag::err_glambda_not_fully_implemented) 
+        << " capturing not implemented yet";
+      return ExprError();
+    }
+  }
   return MaybeBindToTemporary(Lambda);
 }
 

clang/lib/Sema/SemaOverload.cpp

@@ -8670,6 +8670,10 @@ void DiagnoseBadDeduction(Sema &S, Decl *Templated,
         }
       }
     }
+    // FIXME: For generic lambda parameters, check if the function is a lambda
+    // call operator, and if so, emit a prettier and more informative 
+    // diagnostic that mentions 'auto' and lambda in addition to 
+    // (or instead of?) the canonical template type parameters.
     S.Diag(Templated->getLocation(),
            diag::note_ovl_candidate_non_deduced_mismatch)
         << FirstTA << SecondTA;

clang/lib/Sema/SemaStmt.cpp

@@ -2487,12 +2487,31 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
   // [expr.prim.lambda]p4 in C++11; block literals follow the same rules.
   CapturingScopeInfo *CurCap = cast<CapturingScopeInfo>(getCurFunction());
   QualType FnRetType = CurCap->ReturnType;
-
+  LambdaScopeInfo *const LambdaSI = getCurLambda();
-  // For blocks/lambdas with implicit return types, we check each return
+  // In C++1y, an implicit return type behaves as if 'auto' was
-  // statement individually, and deduce the common return type when the block
+  // the return type.
-  // or lambda is completed.
+  if (FnRetType.isNull() && getLangOpts().CPlusPlus1y) {
-  if (CurCap->HasImplicitReturnType) {
+    if (LambdaSI) {
-    // FIXME: Fold this into the 'auto' codepath below.
+      FunctionDecl *CallOp = LambdaSI->CallOperator; 
+      FnRetType = CallOp->getResultType();
+      assert(FnRetType->getContainedAutoType());
+    }
+  }
+  
+  // For blocks/lambdas with implicit return types in C++11, we check each 
+  // return statement individually, and deduce the common return type when 
+  // the block or lambda is completed.  In C++1y, the return type deduction
+  // of a lambda is specified in terms of auto.
+  // Notably, in C++11, we take the type of the expression after decay and
+  // lvalue-to-rvalue conversion, so a class type can be cv-qualified.
+  // In C++1y, we perform template argument deduction as if the return
+  // type were 'auto', so an implicit return type is never cv-qualified.
+  // i.e if (getLangOpts().CPlusPlus1y && FnRetType.hasQualifiers())
+  //   FnRetType = FnRetType.getUnqualifiedType();
+  // Return type deduction is unchanged for blocks in C++1y.
+  // FIXME: Fold this into the 'auto' codepath below.
+  if (CurCap->HasImplicitReturnType && 
+                            (!LambdaSI || !getLangOpts().CPlusPlus1y)) {
     if (RetValExp && !isa<InitListExpr>(RetValExp)) {
       ExprResult Result = DefaultFunctionArrayLvalueConversion(RetValExp);
       if (Result.isInvalid())
@@ -2500,13 +2519,7 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
       RetValExp = Result.take();
 
       if (!CurContext->isDependentContext()) {
-        FnRetType = RetValExp->getType();
+        FnRetType = RetValExp->getType();       
-        // In C++11, we take the type of the expression after decay and
-        // lvalue-to-rvalue conversion, so a class type can be cv-qualified.
-        // In C++1y, we perform template argument deduction as if the return
-        // type were 'auto', so an implicit return type is never cv-qualified.
-        if (getLangOpts().CPlusPlus1y && FnRetType.hasQualifiers())
-          FnRetType = FnRetType.getUnqualifiedType();
       } else
         FnRetType = CurCap->ReturnType = Context.DependentTy;
     } else {
@@ -2517,7 +2530,6 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
         Diag(ReturnLoc, diag::err_lambda_return_init_list)
           << RetValExp->getSourceRange();
       }
-
       FnRetType = Context.VoidTy;
     }
 
@@ -2526,7 +2538,8 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
     if (CurCap->ReturnType.isNull())
       CurCap->ReturnType = FnRetType;
   } else if (AutoType *AT =
-                 FnRetType.isNull() ? 0 : FnRetType->getContainedAutoType()) {
+                 (FnRetType.isNull() || !LambdaSI) ? 0 
+                      : FnRetType->getContainedAutoType()) {
     // In C++1y, the return type may involve 'auto'.
     FunctionDecl *FD = cast<LambdaScopeInfo>(CurCap)->CallOperator;
     if (CurContext->isDependentContext()) {
@@ -2534,7 +2547,7 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
       //   Return type deduction [...] occurs when the definition is
       //   instantiated even if the function body contains a return
       //   statement with a non-type-dependent operand.
-      CurCap->ReturnType = FnRetType = Context.DependentTy;
+      CurCap->ReturnType = FnRetType;
     } else if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) {
       FD->setInvalidDecl();
       return StmtError();
@@ -2564,7 +2577,7 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
   // pickier with blocks than for normal functions because we don't have GCC
   // compatibility to worry about here.
   const VarDecl *NRVOCandidate = 0;
-  if (FnRetType->isDependentType()) {
+  if (FnRetType->isDependentType() || FnRetType->isUndeducedType()) {
     // Delay processing for now.  TODO: there are lots of dependent
     // types we can conclusively prove aren't void.
   } else if (FnRetType->isVoidType()) {
@@ -2624,7 +2637,6 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
 
   return Owned(Result);
 }
-
 /// Deduce the return type for a function from a returned expression, per
 /// C++1y [dcl.spec.auto]p6.
 bool Sema::DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
@@ -2634,7 +2646,6 @@ bool Sema::DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
   TypeLoc OrigResultType = FD->getTypeSourceInfo()->getTypeLoc().
     IgnoreParens().castAs<FunctionProtoTypeLoc>().getResultLoc();
   QualType Deduced;
-
   if (RetExpr && isa<InitListExpr>(RetExpr)) {
     //  If the deduction is for a return statement and the initializer is
     //  a braced-init-list, the program is ill-formed.
@@ -2692,9 +2703,18 @@ bool Sema::DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
     AutoType *NewAT = Deduced->getContainedAutoType();
     if (!FD->isDependentContext() &&
         !Context.hasSameType(AT->getDeducedType(), NewAT->getDeducedType())) {
-      Diag(ReturnLoc, diag::err_auto_fn_different_deductions)
+      LambdaScopeInfo *const LambdaSI = getCurLambda();
-        << (AT->isDecltypeAuto() ? 1 : 0)
+      if (LambdaSI && LambdaSI->HasImplicitReturnType) {
-        << NewAT->getDeducedType() << AT->getDeducedType();
+        Diag(ReturnLoc,
+          diag::err_typecheck_missing_return_type_incompatible)
+          << NewAT->getDeducedType() << AT->getDeducedType()
+          << true /*IsLambda*/;
+      }
+      else {  
+        Diag(ReturnLoc, diag::err_auto_fn_different_deductions)
+          << (AT->isDecltypeAuto() ? 1 : 0)
+          << NewAT->getDeducedType() << AT->getDeducedType();
+      }
       return true;
     }
   } else if (!FD->isInvalidDecl()) {
@@ -2710,10 +2730,8 @@ Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
   // Check for unexpanded parameter packs.
   if (RetValExp && DiagnoseUnexpandedParameterPack(RetValExp))
     return StmtError();
-
   if (isa<CapturingScopeInfo>(getCurFunction()))
     return ActOnCapScopeReturnStmt(ReturnLoc, RetValExp);
-
   QualType FnRetType;
   QualType RelatedRetType;
   if (const FunctionDecl *FD = getCurFunctionDecl()) {

clang/lib/Sema/SemaTemplateDeduction.cpp

@@ -3766,7 +3766,8 @@ namespace {
         QualType Result =
           SemaRef.Context.getAutoType(Dependent ? QualType() : Replacement,
                                       TL.getTypePtr()->isDecltypeAuto(),
-                                      Dependent);
+                                      Dependent, TL.getTypePtr()->
+                                        containsUnexpandedParameterPack());
         AutoTypeLoc NewTL = TLB.push<AutoTypeLoc>(Result);
         NewTL.setNameLoc(TL.getNameLoc());
         return Result;
@@ -3907,8 +3908,16 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result) {
   return DAR_Succeeded;
 }
 
-QualType Sema::SubstAutoType(QualType Type, QualType Deduced) {
+QualType Sema::SubstAutoType(QualType TypeWithAuto, 
-  return SubstituteAutoTransform(*this, Deduced).TransformType(Type);
+                             QualType TypeToReplaceAuto) {
+  return SubstituteAutoTransform(*this, TypeToReplaceAuto).
+               TransformType(TypeWithAuto);
+}
+
+TypeSourceInfo* Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto, 
+                             QualType TypeToReplaceAuto) {
+    return SubstituteAutoTransform(*this, TypeToReplaceAuto).
+               TransformType(TypeWithAuto);
 }
 
 void Sema::DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init) {

clang/lib/Sema/SemaType.cpp

@@ -781,7 +781,13 @@ static QualType ConvertDeclSpecToType(TypeProcessingState &state) {
     // specified with a trailing return type or inferred.
     if (declarator.getContext() == Declarator::LambdaExprContext ||
         isOmittedBlockReturnType(declarator)) {
-      Result = Context.DependentTy;
+      // In C++1y (n3690 CD), 5.1.2 [expr.prim.lambda]/4 : The lambda return 
+      // type is auto, which is replaced by the trailing-return-type if 
+      // provided and/or deduced from return statements as described 
+      // in 7.1.6.4. 
+      Result = S.getLangOpts().CPlusPlus1y &&
+               declarator.getContext() == Declarator::LambdaExprContext 
+                  ? Context.getAutoDeductType() : Context.DependentTy;
       break;
     }
 
@@ -1006,11 +1012,17 @@ static QualType ConvertDeclSpecToType(TypeProcessingState &state) {
 
   case DeclSpec::TST_auto:
     // TypeQuals handled by caller.
-    Result = Context.getAutoType(QualType(), /*decltype(auto)*/false);
+    Result = Context.getAutoType(QualType(), 
+                                /*decltype(auto)*/false, 
+                                /*IsDependent*/   false, 
+                                /*IsParameterPack*/ declarator.hasEllipsis());
     break;
 
   case DeclSpec::TST_decltype_auto:
-    Result = Context.getAutoType(QualType(), /*decltype(auto)*/true);
+    Result = Context.getAutoType(QualType(), 
+                                 /*decltype(auto)*/true, 
+                                 /*IsDependent*/   false, 
+                                 /*IsParameterPack*/ false);
     break;
 
   case DeclSpec::TST_unknown_anytype:
@@ -1557,7 +1569,7 @@ QualType Sema::BuildArrayType(QualType T, ArrayType::ArraySizeModifier ASM,
         ASM = ArrayType::Normal;
       }
     } else if (!T->isDependentType() && !T->isVariablyModifiedType() &&
-               !T->isIncompleteType()) {
+               !T->isIncompleteType() && !T->isUndeducedType()) {
       // Is the array too large?
       unsigned ActiveSizeBits
         = ConstantArrayType::getNumAddressingBits(Context, T, ConstVal);
@@ -2097,6 +2109,7 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
   // In C++11, a function declarator using 'auto' must have a trailing return
   // type (this is checked later) and we can skip this. In other languages
   // using auto, we need to check regardless.
+  // Generic Lambdas (C++14) allow 'auto' in their parameters.
   if (ContainsPlaceholderType &&
       (!SemaRef.getLangOpts().CPlusPlus11 || !D.isFunctionDeclarator())) {
     int Error = -1;
@@ -2109,7 +2122,12 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
     case Declarator::ObjCParameterContext:
     case Declarator::ObjCResultContext:
     case Declarator::PrototypeContext:
-      Error = 0; // Function prototype
+      Error = 0;  
+      break;
+    case Declarator::LambdaExprParameterContext:
+      if (!(SemaRef.getLangOpts().CPlusPlus1y 
+              && D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_auto))
+        Error = 0;
       break;
     case Declarator::MemberContext:
       if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static)
@@ -2189,8 +2207,13 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
       AutoRange = D.getName().getSourceRange();
 
     if (Error != -1) {
+      if (D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_decltype_auto) {
+        SemaRef.Diag(AutoRange.getBegin(), 
+            diag::err_decltype_auto_function_declarator_not_declaration);
+      } else {
       SemaRef.Diag(AutoRange.getBegin(), diag::err_auto_not_allowed)
         << Error << AutoRange;
+      }
       T = SemaRef.Context.IntTy;
       D.setInvalidType(true);
     } else
@@ -2240,6 +2263,7 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
       D.setInvalidType(true);
       break;
     case Declarator::PrototypeContext:
+    case Declarator::LambdaExprParameterContext:
     case Declarator::ObjCParameterContext:
     case Declarator::ObjCResultContext:
     case Declarator::KNRTypeListContext:
@@ -2613,8 +2637,11 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
           }
         }
       }
-
+      const AutoType *AT = T->getContainedAutoType();
-      if (const AutoType *AT = T->getContainedAutoType()) {
+      // Allow arrays of auto if we are a generic lambda parameter.
+      // i.e. [](auto (&array)[5]) { return array[0]; }; OK
+      if (AT && !(S.getLangOpts().CPlusPlus1y && 
+                  D.getContext() == Declarator::LambdaExprParameterContext)) {
         // We've already diagnosed this for decltype(auto).
         if (!AT->isDecltypeAuto())
           S.Diag(DeclType.Loc, diag::err_illegal_decl_array_of_auto)
@@ -3110,6 +3137,7 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
     //   is a parameter pack (14.5.3). [...]
     switch (D.getContext()) {
     case Declarator::PrototypeContext:
+    case Declarator::LambdaExprParameterContext:
       // C++0x [dcl.fct]p13:
       //   [...] When it is part of a parameter-declaration-clause, the
       //   parameter pack is a function parameter pack (14.5.3). The type T
@@ -3128,7 +3156,6 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
         T = Context.getPackExpansionType(T, None);
       }
       break;
-
     case Declarator::TemplateParamContext:
       // C++0x [temp.param]p15:
       //   If a template-parameter is a [...] is a parameter-declaration that

clang/lib/Sema/TreeTransform.h

@@ -782,7 +782,10 @@ public:
     // Note, IsDependent is always false here: we implicitly convert an 'auto'
     // which has been deduced to a dependent type into an undeduced 'auto', so
     // that we'll retry deduction after the transformation.
-    return SemaRef.Context.getAutoType(Deduced, IsDecltypeAuto);
+    // FIXME: Can we assume the same about IsParameterPack?
+    return SemaRef.Context.getAutoType(Deduced, IsDecltypeAuto, 
+                                       /*IsDependent*/ false, 
+                                       /*IsParameterPack*/ false);
   }
 
   /// \brief Build a new template specialization type.
@@ -3494,7 +3497,9 @@ TreeTransform<Derived>::TransformQualifiedType(TypeLocBuilder &TLB,
         Qs.removeObjCLifetime();
         Deduced = SemaRef.Context.getQualifiedType(Deduced.getUnqualifiedType(),
                                                    Qs);
-        Result = SemaRef.Context.getAutoType(Deduced, AutoTy->isDecltypeAuto());
+        Result = SemaRef.Context.getAutoType(Deduced, AutoTy->isDecltypeAuto(), 
+                                AutoTy->isDependentType(), 
+                                AutoTy->containsUnexpandedParameterPack());
         TLB.TypeWasModifiedSafely(Result);
       } else {
         // Otherwise, complain about the addition of a qualifier to an
@@ -8193,6 +8198,14 @@ TreeTransform<Derived>::TransformCXXTemporaryObjectExpr(
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
+ 
+  // FIXME: Implement nested generic lambda transformations.
+  if (E->isGenericLambda()) {
+    getSema().Diag(E->getIntroducerRange().getBegin(), 
+      diag::err_glambda_not_fully_implemented) 
+      << " nested lambdas not implemented yet";
+    return ExprError();
+  }
   // Transform the type of the lambda parameters and start the definition of
   // the lambda itself.
   TypeSourceInfo *MethodTy
@@ -8215,7 +8228,10 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
         E->getCallOperator()->param_size(),
         0, ParamTypes, &Params))
     return ExprError();
-
+  getSema().PushLambdaScope();
+  LambdaScopeInfo *LSI = getSema().getCurLambda();
+  // TODO: Fix for nested lambdas
+  LSI->GLTemplateParameterList = 0;
   // Build the call operator.
   CXXMethodDecl *CallOperator
     = getSema().startLambdaDefinition(Class, E->getIntroducerRange(),
@@ -8250,9 +8266,9 @@ TreeTransform<Derived>::TransformLambdaScope(LambdaExpr *E,
   // Introduce the context of the call operator.
   Sema::ContextRAII SavedContext(getSema(), CallOperator);
 
+  LambdaScopeInfo *const LSI = getSema().getCurLambda();
   // Enter the scope of the lambda.
-  sema::LambdaScopeInfo *LSI
+  getSema().buildLambdaScope(LSI, CallOperator, E->getIntroducerRange(),
-    = getSema().enterLambdaScope(CallOperator, E->getIntroducerRange(),
                                  E->getCaptureDefault(),
                                  E->getCaptureDefaultLoc(),
                                  E->hasExplicitParameters(),

clang/lib/Serialization/ASTReader.cpp

@@ -4740,7 +4740,9 @@ QualType ASTReader::readTypeRecord(unsigned Index) {
     QualType Deduced = readType(*Loc.F, Record, Idx);
     bool IsDecltypeAuto = Record[Idx++];
     bool IsDependent = Deduced.isNull() ? Record[Idx++] : false;
-    return Context.getAutoType(Deduced, IsDecltypeAuto, IsDependent);
+    bool IsParameterPack = Record[Idx++];
+    return Context.getAutoType(Deduced, IsDecltypeAuto, IsDependent, 
+                                                      IsParameterPack);
   }
 
   case TYPE_RECORD: {

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -1201,6 +1201,7 @@ void ASTDeclReader::ReadCXXDefinitionData(
       = (Capture*)Reader.Context.Allocate(sizeof(Capture)*Lambda.NumCaptures);
     Capture *ToCapture = Lambda.Captures;
     Lambda.MethodTyInfo = GetTypeSourceInfo(Record, Idx);
+    Lambda.TheLambdaExpr = cast<LambdaExpr>(Reader.ReadExpr(F));
     for (unsigned I = 0, N = Lambda.NumCaptures; I != N; ++I) {
       SourceLocation Loc = ReadSourceLocation(Record, Idx);
       bool IsImplicit = Record[Idx++];

clang/lib/Serialization/ASTWriter.cpp

@@ -253,6 +253,7 @@ void ASTTypeWriter::VisitAutoType(const AutoType *T) {
   Record.push_back(T->isDecltypeAuto());
   if (T->getDeducedType().isNull())
     Record.push_back(T->isDependentType());
+  Record.push_back(T->containsUnexpandedParameterPack());
   Code = TYPE_AUTO;
 }
 
@@ -5136,6 +5137,7 @@ void ASTWriter::AddCXXDefinitionData(const CXXRecordDecl *D, RecordDataImpl &Rec
     Record.push_back(Lambda.ManglingNumber);
     AddDeclRef(Lambda.ContextDecl, Record);
     AddTypeSourceInfo(Lambda.MethodTyInfo, Record);
+    AddStmt(Lambda.TheLambdaExpr);
     for (unsigned I = 0, N = Lambda.NumCaptures; I != N; ++I) {
       LambdaExpr::Capture &Capture = Lambda.Captures[I];
       AddSourceLocation(Capture.getLocation(), Record);

clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p3-generic-lambda-1y.cpp

@@ -0,0 +1,75 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++1y -DCXX1Y
+
+//FIXME: These tests were written when return type deduction had not been implemented
+// for generic lambdas, hence
+template<class T> T id(T t);
+template<class ... Ts> int vfoo(Ts&& ... ts);
+auto GL1 = [](auto a, int i) -> int { return id(a); };
+
+auto GL2 = [](auto ... As) -> int { return vfoo(As...); };
+auto GL3 = [](int i, char c, auto* ... As) -> int { return vfoo(As...); };
+
+auto GL4 = [](int i, char c, auto* ... As) -> int { return vfoo(As...); };
+
+
+void foo() {
+  auto GL1 = [](auto a, int i) -> int { return id(a); };
+
+  auto GL2 = [](auto ... As) -> int { return vfoo(As...); };
+}
+
+ 
+int main()
+{
+  auto l1 = [](auto a) -> int { return a + 5; };
+  auto l2 = [](auto *p) -> int { return p + 5; };
+ 
+  struct A { int i; char f(int) { return 'c'; } };
+  auto l3 = [](auto &&ur, 
+                auto &lr, 
+                auto v, 
+                int i, 
+                auto* p,
+                auto A::*memvar,
+                auto (A::*memfun)(int),
+                char c,
+                decltype (v)* pv
+                , auto (&array)[5] 
+              ) -> int { return v + i + c
+                          + array[0]; 
+                       };
+  int arr[5] = {0, 1, 2, 3, 4 };
+  int lval = 0;
+  double d = 3.14;
+  l3(3, lval, d, lval, &lval, &A::i, &A::f, 'c', &d, arr);
+  auto l4 = [](decltype(auto) a) -> int { return 0; }; //expected-error{{decltype(auto)}}
+  {
+    struct Local {
+      static int ifi(int i) { return i; }
+      static char cfi(int) { return 'a'; }
+      static double dfi(int i) { return i + 3.14; }
+      static Local localfi(int) { return Local{}; }
+    };
+    auto l4 = [](auto (*fp)(int)) -> int { return fp(3); }; //expected-error{{no viable conversion from 'Local' to 'int'}} 
+    l4(&Local::ifi);
+    l4(&Local::cfi);
+    l4(&Local::dfi);
+    l4(&Local::localfi); //expected-note{{in instantiation of function template specialization}}  
+  }
+  {
+    auto unnamed_parameter = [](auto, auto) -> void { };
+    unnamed_parameter(3, '4');
+  }
+  {
+    auto l = [](auto 
+                      (*)(auto)) { }; //expected-error{{'auto' not allowed}}
+    //FIXME: These diagnostics might need some work.
+    auto l2 = [](char auto::*pm) { };  //expected-error{{cannot combine with previous}}\
+                                         expected-error{{'pm' does not point into a class}}
+    auto l3 = [](char (auto::*pmf)()) { };  //expected-error{{'auto' not allowed}}\
+                                              expected-error{{'pmf' does not point into a class}}\
+                                              expected-error{{function cannot return function type 'char ()'}}
+  }
+}
+
+

clang/test/CXX/expr/expr.prim/expr.prim.lambda/generic-lambda-unimplemented-1y.cpp

@@ -0,0 +1,50 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c++1y %s -verify -emit-llvm
+namespace return_type_deduction_ok {
+// FIXME: Once return type deduction is implemented for generic lambdas
+// this will need to be updated.
+ auto l = [](auto a) ->auto { return a; }(2); 
+ auto l2 = [](auto a) ->decltype(auto) { return a; }(2);  
+ auto l3 = [](auto a) { return a; }(2); 
+
+
+}
+
+namespace lambda_capturing {
+// FIXME: Once return type deduction is implemented for generic lambdas
+// this will need to be updated.
+void test() {
+  int i = 10;
+  auto L = [=](auto a) -> int { //expected-error{{unimplemented}}
+    return i + a;
+  };
+  L(3); 
+}
+
+}
+
+namespace nested_generic_lambdas {
+void test() {
+  auto L = [](auto a) -> int {
+    auto M = [](auto b, decltype(a) b2) -> int { //expected-error{{unimplemented}}
+      return 1;
+    };
+    M(a, a);
+  };
+  L(3); //expected-note{{in instantiation of}}
+}
+}
+
+namespace conversion_operator {
+void test() {
+    auto L = [](auto a) -> int { return a; };
+    int (*fp)(int) = L;  //expected-error{{no viable conversion}}
+  }
+}
+
+namespace generic_lambda_as_default_argument_ok {
+  void test(int i = [](auto a)->int { return a; }(3)) {
+  
+  }
+  
+}
+

clang/test/CXX/expr/expr.prim/expr.prim.lambda/p2-generic-lambda-1y.cpp

@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++1y -DCXX1Y
+
+// prvalue
+void prvalue() {
+  auto&& x = [](auto a)->void { };
+  auto& y = [](auto *a)->void { }; // expected-error{{cannot bind to a temporary of type}}
+}
+
+namespace std {
+  class type_info;
+}
+
+struct P {
+  virtual ~P();
+};
+
+void unevaluated_operand(P &p, int i) {
+  // FIXME: this should only emit one error.
+  int i2 = sizeof([](auto a, auto b)->void{}(3, '4')); // expected-error{{lambda expression in an unevaluated operand}} \
+                                                       // expected-error{{invalid application of 'sizeof'}}
+  const std::type_info &ti1 = typeid([](auto &a) -> P& { static P p; return p; }(i));
+  const std::type_info &ti2 = typeid([](auto) -> int { return i; }(i));  // expected-error{{lambda expression in an unevaluated operand}}
+}

clang/test/CXX/expr/expr.prim/expr.prim.lambda/p4-1y.cpp

@@ -7,3 +7,60 @@ int &d = [] (int &r) -> auto & { return r; } (a);
 int &e = [] (int &r) -> auto { return r; } (a); // expected-error {{cannot bind to a temporary}}
 int &f = [] (int r) -> decltype(auto) { return r; } (a); // expected-error {{cannot bind to a temporary}}
 int &g = [] (int r) -> decltype(auto) { return (r); } (a); // expected-warning {{reference to stack}}
+
+
+int test_explicit_auto_return() 
+{
+    struct X {};
+    auto L = [](auto F, auto a) { return F(a); };
+    auto M = [](auto a) -> auto { return a; }; // OK
+    auto MRef = [](auto b) -> auto& { return b; }; //expected-warning{{reference to stack}}
+    auto MPtr = [](auto c) -> auto* { return &c; }; //expected-warning{{address of stack}}
+    auto MDeclType = [](auto&& d) -> decltype(auto) { return static_cast<decltype(d)>(d); }; //OK
+    M(3);
+    
+    auto &&x = MDeclType(X{});
+    auto &&x1 = M(X{});
+    auto &&x2 = MRef(X{});//expected-note{{in instantiation of}}
+    auto &&x3 = MPtr(X{}); //expected-note{{in instantiation of}}
+    return 0;    
+}
+
+int test_implicit_auto_return() 
+{  
+  {
+    auto M = [](auto a) { return a; };
+    struct X {};
+    X x = M(X{});
+    
+  }
+}
+ 
+int test_multiple_returns()  {
+    auto M = [](auto a) { 
+      bool k;
+      if (k)
+        return a;
+      else
+        return 5; //expected-error{{deduced as 'int' here}}
+    }; 
+    M(3); // OK
+    M('a'); //expected-note{{in instantiation of}}
+  return 0;
+}
+int test_no_parameter_list()
+{
+  static int si = 0;
+    auto M = [] { return 5; }; // OK
+    auto M2 = [] -> auto&& { return si; }; // expected-error{{lambda requires '()'}}
+    M();
+}
+
+int test_conditional_in_return() {
+  auto Fac = [](auto f, auto n) { 
+    return n <= 0 ? n : f(f, n - 1) * n;
+  };
+  // FIXME: this test causes a recursive limit - need to error more gracefully.
+  //Fac(Fac, 3);
+
+}

clang/test/CXX/expr/expr.prim/expr.prim.lambda/p4.cpp

@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only -std=c++11 %s -verify
-// RUN: %clang_cc1 -fsyntax-only -std=c++1y %s -verify
+// RUN: %clang_cc1 -fsyntax-only -std=c++1y %s -verify -DCPP1Y
 
 void missing_lambda_declarator() {
   [](){}();
@@ -18,7 +18,7 @@ void infer_void_return_type(int i) {
     switch (x) {
     case 0: return get<void>();
     case 1: return;
-    case 2: return { 1, 2.0 }; // expected-error{{cannot deduce lambda return type from initializer list}}
+    case 2: return { 1, 2.0 }; //expected-error{{cannot deduce}}
     }
   }(7);
 }

clang/test/CXX/expr/expr.prim/expr.prim.lambda/p5-generic-lambda-1y.cpp

@@ -0,0 +1,135 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++1y -DCXX1Y -emit-llvm
+
+namespace test_factorial {
+
+auto Fact = [](auto Self, unsigned n) -> unsigned {
+    return !n ? 1 : Self(Self, n - 1) * n;
+};
+
+auto six = Fact(Fact, 3);
+
+}
+
+namespace overload_generic_lambda {
+  template <class F1, class F2> struct overload : F1, F2 {
+    using F1::operator();
+    using F2::operator();
+    overload(F1 f1, F2 f2) : F1(f1), F2(f2) { }
+  };
+
+  auto NumParams = [](auto Self, auto h, auto ... rest) -> unsigned {
+    return 1 + Self(Self, rest...);
+  };
+  auto Base = [](auto Self, auto h) -> unsigned {
+      return 1;
+  };
+  overload<decltype(Base), decltype(NumParams)> O(Base, NumParams);
+  int num_params =  O(O, 5, 3, "abc", 3.14, 'a');
+}
+
+
+namespace overload_generic_lambda_return_type_deduction {
+  template <class F1, class F2> struct overload : F1, F2 {
+    using F1::operator();
+    using F2::operator();
+    overload(F1 f1, F2 f2) : F1(f1), F2(f2) { }
+  };
+
+  auto NumParams = [](auto Self, auto h, auto ... rest) {
+    return 1 + Self(Self, rest...);
+  };
+  auto Base = [](auto Self, auto h) {
+      return 1;
+  };
+  overload<decltype(Base), decltype(NumParams)> O(Base, NumParams);
+  int num_params =  O(O, 5, 3, "abc", 3.14, 'a');
+}
+
+namespace test_standard_p5 {
+// FIXME: This test should eventually compile without an explicit trailing return type
+auto glambda = [](auto a, auto&& b) ->bool { return a < b; };
+bool b = glambda(3, 3.14); // OK
+
+}
+namespace test_deduction_failure {
+ int test() {
+   auto g = [](auto *a) { //expected-note{{candidate template ignored}}
+    return a;
+   };
+   struct X { };
+   X *x;
+   g(x);
+   g(3); //expected-error{{no matching function}}
+   return 0;
+ }
+
+}
+  
+namespace test_instantiation_or_sfinae_failure {
+int test2() {
+  {
+    auto L = [](auto *a) { 
+                return (*a)(a); }; //expected-error{{called object type 'double' is not a function}}
+    //l(&l);
+    double d;
+    L(&d); //expected-note{{in instantiation of}}
+    auto M = [](auto b) { return b; };
+    L(&M); // ok
+  }
+  {
+    auto L = [](auto *a) ->decltype (a->foo()) { //expected-note2{{candidate template ignored:}}
+                return (*a)(a); }; 
+    //l(&l);
+    double d;
+    L(&d); //expected-error{{no matching function for call}} 
+    auto M = [](auto b) { return b; };
+    L(&M); //expected-error{{no matching function for call}} 
+ 
+  }
+  return 0;
+}
+
+
+}
+  
+namespace test_misc {
+auto GL = [](auto a, decltype(a) b) //expected-note{{candidate function}} 
+                -> int { return a + b; };
+
+void test() {
+   struct X { };
+   GL(3, X{}); //expected-error{{no matching function}}
+}
+
+void test2() {
+  auto l = [](auto *a) -> int { 
+              (*a)(a); return 0; }; //expected-error{{called object type 'double' is not a function}}
+  l(&l);
+  double d;
+  l(&d); //expected-note{{in instantiation of}}
+}
+
+}
+
+namespace nested_lambdas {
+  int test() {
+    auto L = [](auto a) {
+                 return [=](auto b) {  //expected-error{{unimplemented}}
+                           return a + b;
+                        };
+              };
+   // auto M = L(3.14);
+   // return M('4');    
+  }
+  auto get_lambda() {
+    return [](auto a) {
+      return a; 
+    };
+  };
+  
+  int test2() {
+    auto L = get_lambda();
+    L(3);
+  }
+}
+