a.f90

module foo
    interface
      integer function bar(A)
        INTEGER :: A
      end function
    end interface
    type baz
      procedure(bar), pointer, nopass :: proc
    end type baz
  contains
    integer function implement_bar(A)
      integer :: A

      print *, 'Hello, World!', A

      implement_bar = 42
    end function
    subroutine use_baz(b)
      type(baz) :: b

      call b%proc(42)
    end subroutine
end module foo

program main
  use foo

  type(baz) :: obj

  obj%proc => implement_bar

  call use_baz(obj)
end program main

a.mlir

module attributes {fir.defaultkind = "a1c4d8i4l4r4", fir.kindmap = "", llvm.target_triple = "x86_64-unknown-linux-gnu"} {
  func.func @_QMfooPimplement_bar(%arg0: !fir.ref<i32> {fir.bindc_name = "a"}) -> i32 {
    %0 = fir.alloca i32 {bindc_name = "implement_bar", uniq_name = "_QMfooFimplement_barEimplement_bar"}
    %c-1_i32 = arith.constant -1 : i32
    %1 = fir.address_of(@_QQcl.2E2F612E66393000) : !fir.ref<!fir.char<1,8>>
    %2 = fir.convert %1 : (!fir.ref<!fir.char<1,8>>) -> !fir.ref<i8>
    %c14_i32 = arith.constant 14 : i32
    %3 = fir.call @_FortranAioBeginExternalListOutput(%c-1_i32, %2, %c14_i32) : (i32, !fir.ref<i8>, i32) -> !fir.ref<i8>
    %4 = fir.address_of(@_QQcl.48656C6C6F2C20576F726C6421) : !fir.ref<!fir.char<1,13>>
    %c13 = arith.constant 13 : index
    %5 = fir.convert %4 : (!fir.ref<!fir.char<1,13>>) -> !fir.ref<i8>
    %6 = fir.convert %c13 : (index) -> i64
    %7 = fir.call @_FortranAioOutputAscii(%3, %5, %6) : (!fir.ref<i8>, !fir.ref<i8>, i64) -> i1
    %8 = fir.load %arg0 : !fir.ref<i32>
    %9 = fir.call @_FortranAioOutputInteger32(%3, %8) : (!fir.ref<i8>, i32) -> i1
    %10 = fir.call @_FortranAioEndIoStatement(%3) : (!fir.ref<i8>) -> i32
    %c42_i32 = arith.constant 42 : i32
    fir.store %c42_i32 to %0 : !fir.ref<i32>
    %11 = fir.load %0 : !fir.ref<i32>
    return %11 : i32
  }
  func.func @_QMfooPuse_baz(%arg0: !fir.ref<!fir.type<_QMfooTbaz{proc:!fir.boxproc<(!fir.ref<i32>) -> i32>}>> {fir.bindc_name = "b"}) {
    return
  }
  func.func @_QQmain() {
    %0 = fir.alloca !fir.type<_QMfooTbaz{proc:!fir.boxproc<(!fir.ref<i32>) -> i32>}> {bindc_name = "obj", uniq_name = "_QFEobj"}
    %1 = fir.field_index proc, !fir.type<_QMfooTbaz{proc:!fir.boxproc<(!fir.ref<i32>) -> i32>}>
    %2 = fir.coordinate_of %0, %1 : (!fir.ref<!fir.type<_QMfooTbaz{proc:!fir.boxproc<(!fir.ref<i32>) -> i32>}>>, !fir.field) -> !fir.ref<!fir.boxproc<(!fir.ref<i32>) -> i32>>
    %3 = fir.address_of(@_QMfooPimplement_bar) : (!fir.ref<i32>) -> i32
    %4 = fir.emboxproc %3 : ((!fir.ref<i32>) -> i32) -> !fir.boxproc<(!fir.ref<i32>) -> i32>
    fir.store %4 to %2 : !fir.ref<!fir.boxproc<(!fir.ref<i32>) -> i32>>
    fir.call @_QMfooPuse_baz(%0) : (!fir.ref<!fir.type<_QMfooTbaz{proc:!fir.boxproc<(!fir.ref<i32>) -> i32>}>>) -> ()
    return
  }
  func.func private @_FortranAioBeginExternalListOutput(i32, !fir.ref<i8>, i32) -> !fir.ref<i8> attributes {fir.io, fir.runtime}
  fir.global linkonce @_QQcl.2E2F612E66393000 constant : !fir.char<1,8> {
    %0 = fir.string_lit "./a.f90\00"(8) : !fir.char<1,8>
    fir.has_value %0 : !fir.char<1,8>
  }
  func.func private @_FortranAioOutputAscii(!fir.ref<i8>, !fir.ref<i8>, i64) -> i1 attributes {fir.io, fir.runtime}
  fir.global linkonce @_QQcl.48656C6C6F2C20576F726C6421 constant : !fir.char<1,13> {
    %0 = fir.string_lit "Hello, World!"(13) : !fir.char<1,13>
    fir.has_value %0 : !fir.char<1,13>
  }
  func.func private @_FortranAioOutputInteger32(!fir.ref<i8>, i32) -> i1 attributes {fir.io, fir.runtime}
  func.func private @_FortranAioEndIoStatement(!fir.ref<i8>) -> i32 attributes {fir.io, fir.runtime}
}