Do not create a template parameter list for the index

Author: Sirraide

clang/include/clang/AST/DeclTemplate.h

@@ -3432,18 +3432,18 @@ class TemplateParamObjectDecl : public ValueDecl,
 /// \see CXXExpansionStmtInstantiation
 class CXXExpansionStmtDecl : public Decl, public DeclContext {
   CXXExpansionStmtPattern *Expansion = nullptr;
-  TemplateParameterList *TParams;
+  NonTypeTemplateParmDecl *IndexNTTP = nullptr;
   CXXExpansionStmtInstantiation *Instantiations = nullptr;
 
   CXXExpansionStmtDecl(DeclContext *DC, SourceLocation Loc,
-                       TemplateParameterList *TParams);
+                       NonTypeTemplateParmDecl *NTTP);
 
 public:
   friend class ASTDeclReader;
 
   static CXXExpansionStmtDecl *Create(ASTContext &C, DeclContext *DC,
                                       SourceLocation Loc,
-                                      TemplateParameterList *TParams);
+                                      NonTypeTemplateParmDecl *NTTP);
   static CXXExpansionStmtDecl *CreateDeserialized(ASTContext &C,
                                                   GlobalDeclID ID);
 
@@ -3462,10 +3462,10 @@ class CXXExpansionStmtDecl : public Decl, public DeclContext {
     Instantiations = S;
   }
 
-  NonTypeTemplateParmDecl *getIndexTemplateParm() const {
-    return cast<NonTypeTemplateParmDecl>(TParams->getParam(0));
+  NonTypeTemplateParmDecl *getIndexTemplateParm() { return IndexNTTP; }
+  const NonTypeTemplateParmDecl *getIndexTemplateParm() const {
+    return IndexNTTP;
   }
-  TemplateParameterList *getTemplateParameters() const { return TParams; }
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 

clang/lib/AST/ASTImporter.cpp

@@ -2879,14 +2879,14 @@ ASTNodeImporter::VisitCXXExpansionStmtDecl(CXXExpansionStmtDecl *D) {
   Error Err = Error::success();
   auto ToLocation = importChecked(Err, D->getLocation());
   auto ToExpansion = importChecked(Err, D->getExpansionPattern());
-  auto ToTemplateParams = importChecked(Err, D->getTemplateParameters());
+  auto ToIndex = importChecked(Err, D->getIndexTemplateParm());
   auto ToInstantiations = importChecked(Err, D->getInstantiations());
   if (Err)
     return std::move(Err);
 
   CXXExpansionStmtDecl *ToD;
   if (GetImportedOrCreateDecl(ToD, D, Importer.getToContext(), DC, ToLocation,
-                              ToTemplateParams))
+                              ToIndex))
     return ToD;
 
   ToD->setExpansionPattern(ToExpansion);

clang/lib/AST/DeclTemplate.cpp

@@ -1718,9 +1718,8 @@ clang::getReplacedTemplateParameter(Decl *D, unsigned Index) {
         cast<FunctionDecl>(D)->getTemplateSpecializationInfo()->getTemplate(),
         Index);
   case Decl::Kind::CXXExpansionStmt:
-    return {
-        cast<CXXExpansionStmtDecl>(D)->getTemplateParameters()->getParam(Index),
-        {}};
+    assert(Index == 0 && "expansion stmts only have a single template param");
+    return {cast<CXXExpansionStmtDecl>(D)->getIndexTemplateParm(), {}};
   default:
     llvm_unreachable("Unhandled templated declaration kind");
   }
@@ -1794,14 +1793,14 @@ const Decl &clang::adjustDeclToTemplate(const Decl &D) {
 }
 
 CXXExpansionStmtDecl::CXXExpansionStmtDecl(DeclContext *DC, SourceLocation Loc,
-                                           TemplateParameterList *TParams)
+                                           NonTypeTemplateParmDecl *NTTP)
     : Decl(CXXExpansionStmt, DC, Loc), DeclContext(CXXExpansionStmt),
-      TParams(TParams) {}
+      IndexNTTP(NTTP) {}
 
 CXXExpansionStmtDecl *
 CXXExpansionStmtDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation Loc,
-                             TemplateParameterList *TParams) {
-  return new (C, DC) CXXExpansionStmtDecl(DC, Loc, TParams);
+                             NonTypeTemplateParmDecl *NTTP) {
+  return new (C, DC) CXXExpansionStmtDecl(DC, Loc, NTTP);
 }
 CXXExpansionStmtDecl *
 CXXExpansionStmtDecl::CreateDeserialized(ASTContext &C, GlobalDeclID ID) {

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -2775,7 +2775,7 @@ void ASTDeclReader::VisitCXXExpansionStmtDecl(CXXExpansionStmtDecl *D) {
   D->Expansion = cast<CXXExpansionStmtPattern>(Record.readStmt());
   D->Instantiations =
       cast_or_null<CXXExpansionStmtInstantiation>(Record.readStmt());
-  D->TParams = Record.readTemplateParameterList();
+  D->IndexNTTP = cast<NonTypeTemplateParmDecl>(Record.readDeclRef());
 }
 
 void ASTDeclReader::VisitEmptyDecl(EmptyDecl *D) {

clang/lib/Serialization/ASTWriterDecl.cpp

@@ -2193,7 +2193,7 @@ void ASTDeclWriter::VisitCXXExpansionStmtDecl(CXXExpansionStmtDecl *D) {
   VisitDecl(D);
   Record.AddStmt(D->getExpansionPattern());
   Record.AddStmt(D->getInstantiations());
-  Record.AddTemplateParameterList(D->getTemplateParameters());
+  Record.AddDeclRef(D->getIndexTemplateParm());
   Code = serialization::DECL_EXPANSION_STMT;
 }