[Flang] fails to diagnose invalid write statement in forall construct

[k-arrows]

Reproducer:
https://godbolt.org/z/chnoPWx4e

integer :: i
forall (i = 1:1)
  print *, i
end forall
end

Gfortran and Ifx can diagnose the reproducer as follows:

Gfortran:

/app/example.f90:3:12:

    3 |   print *, i
      |            1
Error: Unexpected WRITE statement in FORALL block at (1)

Ifx:

/app/example.f90(3): error #7086: This statement in a FORALL construct is invalid.
  print *, i
--^
compilation aborted for /app/example.f90 (code 1)

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: None (k-arrows)

Reproducer: https://godbolt.org/z/chnoPWx4e ```f90 integer :: i forall (i = 1:1) print *, i end forall end ```

Gfortran and Ifx can diagnose the reproducer as follows:

Gfortran:

/app/example.f90:3:12:

    3 |   print *, i
      |            1
Error: Unexpected WRITE statement in FORALL block at (1)

Ifx:

/app/example.f90(3): error #<!-- -->7086: This statement in a FORALL construct is invalid.
  print *, i
--^
compilation aborted for /app/example.f90 (code 1)

[klausler]

What version of flang-new are you using to compile that code? It gets fatal parsing errors with the current main. And the godbolt link that you supplied also demonstrates fatal error messages?

[k-arrows]

My local flang is a bit old, and the flang on godbolt is newer. Parsing errors occur with both flangs as follows:

error: Could not parse /app/example.f90
/app/example.f90:3:3: error: expected 'END FORALL'
    print *, i
    ^
/app/example.f90:3:3: in the context: END FORALL statement
    print *, i
    ^
/app/example.f90:2:1: in the context: FORALL construct
  forall (i = 1:1)
  ^
/app/example.f90:3:3: error: expected end of statement
    print *, i
    ^
/app/example.f90:2:1: in the context: FORALL construct
  forall (i = 1:1)
  ^
/app/example.f90:1:1: in the context: main program
  integer :: i
  ^
/app/example.f90:4:5: error: expected end of statement
  end forall
      ^
/app/example.f90:4:1: in the context: END PROGRAM statement
  end forall
  ^
/app/example.f90:1:1: in the context: main program
  integer :: i
  ^
Compiler returned: 1