[NFC][SYCL] Add const to some uses of CXXRecordDecl (#2153)

This adds const-correctness to a bit of the visitor, as brought up in
review on #1785.

clang/lib/Sema/SemaSYCL.cpp

@@ -729,7 +729,7 @@ getKernelInvocationKind(FunctionDecl *KernelCallerFunc) {
       .Default(InvokeUnknown);
 }
 
-static CXXRecordDecl *getKernelObjectType(FunctionDecl *Caller) {
+static const CXXRecordDecl *getKernelObjectType(FunctionDecl *Caller) {
   return (*Caller->param_begin())->getType()->getAsCXXRecordDecl();
 }
 
@@ -878,12 +878,12 @@ class KernelObjVisitor {
   }
 
   template <typename ParentTy, typename... Handlers>
-  void VisitRecord(CXXRecordDecl *Owner, ParentTy &Parent,
-                   CXXRecordDecl *Wrapper, Handlers &... handlers);
+  void VisitRecord(const CXXRecordDecl *Owner, ParentTy &Parent,
+                   const CXXRecordDecl *Wrapper, Handlers &... handlers);
 
   template <typename... Handlers>
-  void VisitRecordHelper(CXXRecordDecl *Owner,
-                         clang::CXXRecordDecl::base_class_range Range,
+  void VisitRecordHelper(const CXXRecordDecl *Owner,
+                         clang::CXXRecordDecl::base_class_const_range Range,
                          Handlers &... handlers) {
     for (const auto &Base : Range) {
       (void)std::initializer_list<int>{
@@ -906,15 +906,15 @@ class KernelObjVisitor {
   }
 
   template <typename... Handlers>
-  void VisitRecordHelper(CXXRecordDecl *Owner,
-                         clang::RecordDecl::field_range Range,
+  void VisitRecordHelper(const CXXRecordDecl *Owner,
+                         RecordDecl::field_range Range,
                          Handlers &... handlers) {
     VisitRecordFields(Owner, handlers...);
   }
 
   // FIXME: Can this be refactored/handled some other way?
   template <typename ParentTy, typename... Handlers>
-  void VisitStreamRecord(CXXRecordDecl *Owner, ParentTy &Parent,
+  void VisitStreamRecord(const CXXRecordDecl *Owner, ParentTy &Parent,
                          CXXRecordDecl *Wrapper, Handlers &... handlers) {
     (void)std::initializer_list<int>{
         (handlers.enterStruct(Owner, Parent), 0)...};
@@ -933,14 +933,15 @@ class KernelObjVisitor {
   }
 
   template <typename... Handlers>
-  void VisitRecordBases(CXXRecordDecl *KernelFunctor, Handlers &... handlers) {
+  void VisitRecordBases(const CXXRecordDecl *KernelFunctor,
+                        Handlers &... handlers) {
     VisitRecordHelper(KernelFunctor, KernelFunctor->bases(), handlers...);
   }
 
   // A visitor function that dispatches to functions as defined in
   // SyclKernelFieldHandler for the purposes of kernel generation.
   template <typename... Handlers>
-  void VisitRecordFields(CXXRecordDecl *Owner, Handlers &... handlers) {
+  void VisitRecordFields(const CXXRecordDecl *Owner, Handlers &... handlers) {
 
     for (const auto Field : Owner->fields()) {
       (void)std::initializer_list<int>{
@@ -987,8 +988,8 @@ class KernelObjVisitor {
 // type (which doesn't exist in cases where it is a FieldDecl in the
 // 'root'), and Wrapper is the current struct being unwrapped.
 template <typename ParentTy, typename... Handlers>
-void KernelObjVisitor::VisitRecord(CXXRecordDecl *Owner, ParentTy &Parent,
-                                   CXXRecordDecl *Wrapper,
+void KernelObjVisitor::VisitRecord(const CXXRecordDecl *Owner, ParentTy &Parent,
+                                   const CXXRecordDecl *Wrapper,
                                    Handlers &... handlers) {
   (void)std::initializer_list<int>{(handlers.enterStruct(Owner, Parent), 0)...};
   VisitRecordHelper(Wrapper, Wrapper->bases(), handlers...);
@@ -1357,7 +1358,7 @@ class SyclKernelBodyCreator : public SyclKernelFieldHandler {
   llvm::SmallVector<Expr *, 16> InitExprs;
   VarDecl *KernelObjClone;
   InitializedEntity VarEntity;
-  CXXRecordDecl *KernelObj;
+  const CXXRecordDecl *KernelObj;
   llvm::SmallVector<Expr *, 16> MemberExprBases;
   uint64_t ArrayIndex;
   FunctionDecl *KernelCallerFunc;
@@ -1524,7 +1525,7 @@ class SyclKernelBodyCreator : public SyclKernelFieldHandler {
   // FIXME Avoid creation of kernel obj clone.
   // See https://github.com/intel/llvm/issues/1544 for details.
   static VarDecl *createKernelObjClone(ASTContext &Ctx, DeclContext *DC,
-                                       CXXRecordDecl *KernelObj) {
+                                       const CXXRecordDecl *KernelObj) {
     TypeSourceInfo *TSInfo =
         KernelObj->isLambda() ? KernelObj->getLambdaTypeInfo() : nullptr;
     VarDecl *VD = VarDecl::Create(
@@ -1572,7 +1573,7 @@ class SyclKernelBodyCreator : public SyclKernelFieldHandler {
 
 public:
   SyclKernelBodyCreator(Sema &S, SyclKernelDeclCreator &DC,
-                        CXXRecordDecl *KernelObj,
+                        const CXXRecordDecl *KernelObj,
                         FunctionDecl *KernelCallerFunc)
       : SyclKernelFieldHandler(S), DeclCreator(DC),
         KernelObjClone(createKernelObjClone(S.getASTContext(),
@@ -1934,7 +1935,7 @@ class SyclKernelIntHeaderCreator : public SyclKernelFieldHandler {
 void Sema::ConstructOpenCLKernel(FunctionDecl *KernelCallerFunc,
                                  MangleContext &MC) {
   // The first argument to the KernelCallerFunc is the lambda object.
-  CXXRecordDecl *KernelObj = getKernelObjectType(KernelCallerFunc);
+  const CXXRecordDecl *KernelObj = getKernelObjectType(KernelCallerFunc);
   assert(KernelObj && "invalid kernel caller");
 
   // Calculate both names, since Integration headers need both.