[flang][OpenMP] Variable may not appear on both MAP and SHARED clauses on a TARGET construct

[mrkajetanp]

real :: a(100)
integer :: i

!$omp task shared(a)
!$omp target map(tofrom: a)
  !$omp parallel do
  do i = 1, size(a)
  end do
!$omp end target
!$omp end task
end

Reproducible on godbolt: https://godbolt.org/z/5dcahc5Gh

[mrkajetanp]

More specifically, any data sharing clause on task for this program will break. Leaving it to choose the default data sharing attribute does work, but the symbol table still appears wrong:

  MainProgram scope:  size=404 alignment=4 sourceRange=145 bytes
    a (OmpMapToFrom) size=400 offset=0: ObjectEntity type: REAL(4) shape: 1_8:100_8
    i size=4 offset=400: ObjectEntity type: INTEGER(4)
    size, INTRINSIC, PURE (Function): ProcEntity
    OtherConstruct scope: size=0 alignment=1 sourceRange=107 bytes
      a (OmpFirstPrivate, OmpImplicit): HostAssoc
      i (OmpFirstPrivate, OmpImplicit): HostAssoc
      OtherConstruct scope: size=0 alignment=1 sourceRange=81 bytes
        OtherClause scope: size=0 alignment=1 sourceRange=0 bytes
        OtherConstruct scope: size=0 alignment=1 sourceRange=36 bytes
          a (OmpShared): HostAssoc
          i (OmpPrivate, OmpPreDetermined): HostAssoc

It seems that target should be creating new host-associated implicit symbols and attaching the attributes to them, which it's currently not doing. I think it's better for someone with experience and background on target to look at this.