[Flang][OpenMP] Compile error of end single copyprivate statement written within parallel private construct within task construct

[ohno-fj]

Version of flang : 21.0.0(8c7c791284877e36f73c41ffa56b52c13e613993)/AArch64

end single statement with copyprivate clause written in parallel construct with private clause in task construct results in compilation errors.
The above program is sngtomp028_21.f90.
When task construct is removed, the compilation succeeds.
The above program is sngtomp028_22.f90.

The following are the test program, Flang, Gfortran and ifx compilation/execution result.

sngtomp028_21.f90:

program main
  real, dimension(:), allocatable :: a
  real, dimension(:), pointer :: b
!$omp task
!$omp parallel private (a, b)
  allocate (a(5))
  allocate (b(10))
!$omp single
  a = 22
  b = 33
!$omp end single copyprivate (a, b)
  if(any(a/=(/(22,j=1,5)/))) print *,'err1'
  if(any(b/=(/(33,k=1,10)/))) print *,'err2'
!$omp end parallel
!$omp end task
  print *,'pass'
end program main

$ flang -fopenmp sngtomp028_21.f90
flang-20: warning: OpenMP support in flang is still experimental [-Wexperimental-option]
error: Semantic errors in sngtomp028_21.f90
./sngtomp028_21.f90:11:31: error: COPYPRIVATE variable 'a' is not PRIVATE or THREADPRIVATE in outer context
  !$omp end single copyprivate (a, b)
                                ^
./sngtomp028_21.f90:11:34: error: COPYPRIVATE variable 'b' is not PRIVATE or THREADPRIVATE in outer context
  !$omp end single copyprivate (a, b)
                                   ^
$

$ export OMP_NUM_THREADS=2; gfortran -fopenmp sngtomp028_21.f90; ./a.out
 pass
$

$ export OMP_NUM_THREADS=2; ifx -qopenmp sngtomp028_21.f90; ./a.out
 pass
$

sngtomp028_22.f90:

program main
  real, dimension(:), allocatable :: a
  real, dimension(:), pointer :: b
! !$omp task
!$omp parallel private (a, b)
  allocate (a(5))
  allocate (b(10))
!$omp single
  a = 22
  b = 33
!$omp end single copyprivate (a, b)
  if(any(a/=(/(22,j=1,5)/))) print *,'err1'
  if(any(b/=(/(33,k=1,10)/))) print *,'err2'
!$omp end parallel
! !$omp end task
  print *,'pass'
end program main

$ export OMP_NUM_THREADS=2; flang -fopenmp sngtomp028_21.f90; ./a.out
flang-20: warning: OpenMP support in flang is still experimental [-Wexperimental-option]
 pass
$

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: None (ohno-fj)

``` Version of flang : 21.0.0(8c7c791)/AArch64 ```

end single statement with copyprivate clause written in parallel construct with private clause in task construct results in compilation errors.
The above program is sngtomp028_21.f90.
When task construct is removed, the compilation succeeds.
The above program is sngtomp028_22.f90.

The following are the test program, Flang, Gfortran and ifx compilation/execution result.

sngtomp028_21.f90:

program main
  real, dimension(:), allocatable :: a
  real, dimension(:), pointer :: b
!$omp task
!$omp parallel private (a, b)
  allocate (a(5))
  allocate (b(10))
!$omp single
  a = 22
  b = 33
!$omp end single copyprivate (a, b)
  if(any(a/=(/(22,j=1,5)/))) print *,'err1'
  if(any(b/=(/(33,k=1,10)/))) print *,'err2'
!$omp end parallel
!$omp end task
  print *,'pass'
end program main

$ flang -fopenmp sngtomp028_21.f90
flang-20: warning: OpenMP support in flang is still experimental [-Wexperimental-option]
error: Semantic errors in sngtomp028_21.f90
./sngtomp028_21.f90:11:31: error: COPYPRIVATE variable 'a' is not PRIVATE or THREADPRIVATE in outer context
  !$omp end single copyprivate (a, b)
                                ^
./sngtomp028_21.f90:11:34: error: COPYPRIVATE variable 'b' is not PRIVATE or THREADPRIVATE in outer context
  !$omp end single copyprivate (a, b)
                                   ^
$

$ export OMP_NUM_THREADS=2; gfortran -fopenmp sngtomp028_21.f90; ./a.out
 pass
$

$ export OMP_NUM_THREADS=2; ifx -qopenmp sngtomp028_21.f90; ./a.out
 pass
$

sngtomp028_22.f90:

program main
  real, dimension(:), allocatable :: a
  real, dimension(:), pointer :: b
! !$omp task
!$omp parallel private (a, b)
  allocate (a(5))
  allocate (b(10))
!$omp single
  a = 22
  b = 33
!$omp end single copyprivate (a, b)
  if(any(a/=(/(22,j=1,5)/))) print *,'err1'
  if(any(b/=(/(33,k=1,10)/))) print *,'err2'
!$omp end parallel
! !$omp end task
  print *,'pass'
end program main

$ export OMP_NUM_THREADS=2; flang -fopenmp sngtomp028_21.f90; ./a.out
flang-20: warning: OpenMP support in flang is still experimental [-Wexperimental-option]
 pass
$