8 files changed, 72 insertions, 2 deletions
diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
index a16c74ed511..72bbb606df0 100644
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -70,6 +70,7 @@ namespace clang {
   class VTableContextBase;
 
   namespace Builtin { class Context; }
+  enum BuiltinTemplateKind : int;
 
   namespace comments {
     class FullComment;
@@ -246,6 +247,9 @@ class ASTContext : public RefCountedBase<ASTContext> {
   /// The identifier 'NSCopying'.
   IdentifierInfo *NSCopyingName = nullptr;
 
+  /// The identifier '__make_integer_seq'.
+  mutable IdentifierInfo *MakeIntegerSeqName = nullptr;
+
   QualType ObjCConstantStringType;
   mutable RecordDecl *CFConstantStringTypeDecl;
   
@@ -399,6 +403,7 @@ private:
   
   TranslationUnitDecl *TUDecl;
   mutable ExternCContextDecl *ExternCContext;
+  mutable BuiltinTemplateDecl *MakeIntegerSeqDecl;
 
   /// \brief The associated SourceManager object.a
   SourceManager &SourceMgr;
@@ -868,6 +873,7 @@ public:
   TranslationUnitDecl *getTranslationUnitDecl() const { return TUDecl; }
 
   ExternCContextDecl *getExternCContextDecl() const;
+  BuiltinTemplateDecl *getMakeIntegerSeqDecl() const;
 
   // Builtin Types.
   CanQualType VoidTy;
@@ -941,6 +947,9 @@ public:
   void PrintStats() const;
   const SmallVectorImpl<Type *>& getTypes() const { return Types; }
 
+  BuiltinTemplateDecl *buildBuiltinTemplateDecl(BuiltinTemplateKind BTK,
+                                                const IdentifierInfo *II) const;
+
   /// \brief Create a new implicit TU-level CXXRecordDecl or RecordDecl
   /// declaration.
   RecordDecl *buildImplicitRecord(StringRef Name,
@@ -1444,6 +1453,12 @@ public:
     return NSCopyingName;
   }
 
+  IdentifierInfo *getMakeIntegerSeqName() const {
+    if (!MakeIntegerSeqName)
+      MakeIntegerSeqName = &Idents.get("__make_integer_seq");
+    return MakeIntegerSeqName;
+  }
+
   /// \brief Retrieve the Objective-C "instancetype" type, if already known;
   /// otherwise, returns a NULL type;
   QualType getObjCInstanceType() {
diff --git a/clang/include/clang/AST/DataRecursiveASTVisitor.h b/clang/include/clang/AST/DataRecursiveASTVisitor.h
index 25e2c069baf..cc80a684366 100644
--- a/clang/include/clang/AST/DataRecursiveASTVisitor.h
+++ b/clang/include/clang/AST/DataRecursiveASTVisitor.h
@@ -1551,6 +1551,10 @@ DEF_TRAVERSE_DECL(FunctionTemplateDecl, {
     TRY_TO(TraverseFunctionInstantiations(D));
 })
 
+DEF_TRAVERSE_DECL(BuiltinTemplateDecl, {
+  TRY_TO(TraverseTemplateParameterListHelper(D->getTemplateParameters()));
+})
+
 DEF_TRAVERSE_DECL(TemplateTemplateParmDecl, {
   // D is the "T" in something like
   //   template <template <typename> class T> class container { };
diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
index bd38ac88238..a23fe4b5e52 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -25,6 +25,7 @@
 
 namespace clang {
 
+enum BuiltinTemplateKind : int;
 class TemplateParameterList;
 class TemplateDecl;
 class RedeclarableTemplateDecl;
@@ -1490,6 +1491,35 @@ public:
   friend TrailingObjects;
 };
 
+/// \brief Represents the builtin template declaration which is used to
+/// implement __make_integer_seq.  It serves no real purpose beyond existing as
+/// a place to hold template parameters.
+class BuiltinTemplateDecl : public TemplateDecl {
+  void anchor() override;
+
+  BuiltinTemplateDecl(const ASTContext &C, DeclContext *DC,
+                      DeclarationName Name, BuiltinTemplateKind BTK);
+
+  BuiltinTemplateKind BTK;
+
+public:
+  // Implement isa/cast/dyncast support
+  static bool classof(const Decl *D) { return classofKind(D->getKind()); }
+  static bool classofKind(Kind K) { return K == BuiltinTemplate; }
+
+  static BuiltinTemplateDecl *Create(const ASTContext &C, DeclContext *DC,
+                                     DeclarationName Name,
+                                     BuiltinTemplateKind BTK) {
+    return new (C, DC) BuiltinTemplateDecl(C, DC, Name, BTK);
+  }
+
+  SourceRange getSourceRange() const override LLVM_READONLY {
+    return SourceRange();
+  }
+
+  BuiltinTemplateKind getBuiltinTemplateKind() const { return BTK; }
+};
+
 /// \brief Represents a class template specialization, which refers to
 /// a class template with a given set of template arguments.
 ///
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 341acd99e06..ab0aa968765 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -1603,6 +1603,10 @@ DEF_TRAVERSE_DECL(TemplateTemplateParmDecl, {
   TRY_TO(TraverseTemplateParameterListHelper(D->getTemplateParameters()));
 })
 
+DEF_TRAVERSE_DECL(BuiltinTemplateDecl, {
+  TRY_TO(TraverseTemplateParameterListHelper(D->getTemplateParameters()));
+})
+
 DEF_TRAVERSE_DECL(TemplateTypeParmDecl, {
   // D is the "T" in something like "template<typename T> class vector;"
   if (D->getTypeForDecl())
diff --git a/clang/include/clang/Basic/Builtins.h b/clang/include/clang/Basic/Builtins.h
index 13849fd5f2d..41f19e7cbfe 100644
--- a/clang/include/clang/Basic/Builtins.h
+++ b/clang/include/clang/Basic/Builtins.h
@@ -205,5 +205,12 @@ private:
 };
 
 }
+
+/// \brief Kinds of BuiltinTemplateDecl.
+enum BuiltinTemplateKind : int {
+  /// \brief This names the __make_integer_seq BuiltinTemplateDecl.
+  BTK__make_integer_seq
+};
+
 } // end namespace clang
 #endif
diff --git a/clang/include/clang/Basic/DeclNodes.td b/clang/include/clang/Basic/DeclNodes.td
index e1a23120c18..723ea547d8a 100644
--- a/clang/include/clang/Basic/DeclNodes.td
+++ b/clang/include/clang/Basic/DeclNodes.td
@@ -59,6 +59,7 @@ def Named : Decl<1>;
       def VarTemplate : DDecl<RedeclarableTemplate>;
       def TypeAliasTemplate : DDecl<RedeclarableTemplate>;
     def TemplateTemplateParm : DDecl<Template>;
+    def BuiltinTemplate : DDecl<Template>;
   def Using : DDecl<Named>;
   def UsingShadow : DDecl<Named>;
   def ObjCMethod : DDecl<Named>, DeclContext;
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 542ccbef769..0862a96eb26 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1995,7 +1995,13 @@ def err_concept_decl_invalid_specifiers : Error<
 def warn_cxx98_compat_unicode_type : Warning<
   "'%0' type specifier is incompatible with C++98">,
   InGroup<CXX98Compat>, DefaultIgnore;
- 
+
+// __make_integer_seq
+def err_integer_sequence_negative_length : Error<
+  "integer sequences must have non-negative sequence length">;
+def err_integer_sequence_integral_element_type : Error<
+  "integer sequences must have integral element type">;
+
 // Objective-C++
 def err_objc_decls_may_only_appear_in_global_scope : Error<
   "Objective-C declarations may only appear in global scope">;
diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 7af3c628556..a37bafdbe0e 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -982,13 +982,16 @@ namespace clang {
 
       /// \brief The extern "C" context.
       PREDEF_DECL_EXTERN_C_CONTEXT_ID = 12,
+
+      /// \brief The internal '__make_integer_seq' template.
+      PREDEF_DECL_MAKE_INTEGER_SEQ_ID = 13,
     };
 
     /// \brief The number of declaration IDs that are predefined.
     ///
     /// For more information about predefined declarations, see the
     /// \c PredefinedDeclIDs type and the PREDEF_DECL_*_ID constants.
-    const unsigned int NUM_PREDEF_DECL_IDS = 13;
+    const unsigned int NUM_PREDEF_DECL_IDS = 14;
 
     /// \brief Record code for a list of local redeclarations of a declaration.
     const unsigned int LOCAL_REDECLARATIONS = 50;