[flang][OpenMP] Treat ClassType as BoxType in COPYPRIVATE (#141844)

This fixes the second problem reported in
#141481

Author: kparzysz

flang/lib/Lower/OpenMP/ClauseProcessor.cpp

@@ -743,6 +743,9 @@ void TypeInfo::typeScan(mlir::Type ty) {
   } else if (auto bty = mlir::dyn_cast<fir::BoxType>(ty)) {
     inBox = true;
     typeScan(bty.getEleTy());
+  } else if (auto cty = mlir::dyn_cast<fir::ClassType>(ty)) {
+    inBox = true;
+    typeScan(cty.getEleTy());
   } else if (auto cty = mlir::dyn_cast<fir::CharacterType>(ty)) {
     charLen = cty.getLen();
   } else if (auto hty = mlir::dyn_cast<fir::HeapType>(ty)) {

flang/test/Lower/OpenMP/copyprivate4.f90

@@ -0,0 +1,18 @@
+!RUN: %flang_fc1 -emit-hlfir -fopenmp -o - %s 2>&1 | FileCheck %s
+
+!The second testcase from https://github.com/llvm/llvm-project/issues/141481
+
+!Check that we don't crash on this.
+
+!CHECK: omp.single copyprivate(%6#0 -> @_copy_class_ptr_rec__QFf01Tt : !fir.ref<!fir.class<!fir.ptr<!fir.type<_QFf01Tt>>>>) {
+!CHECK:   omp.terminator
+!CHECK: }
+
+subroutine f01
+  type t
+  end type
+  class(t), pointer :: tt
+
+!$omp single copyprivate(tt)
+!$omp end single
+end