[Flang] Irritating warning about NUMERIC_STORAGE_SIZE while not used

[mjklemm]

In the following code, NUMERIC_STORAGE_SIZE is not being used (and technically not visible):

program reproducer
    use iso_fortran_env, only: output_unit
    implicit none
end program reproducer

Flang still a warning, when compiling the file like this:

> flang-new -fdefault-real-8 -c reproducer.f90
reproducer.f90:2:9: warning: NUMERIC_STORAGE_SIZE from ISO_FORTRAN_ENV is not well-defined when default INTEGER and REAL are not consistent due to compiler options
      use iso_fortran_env, only: output_unit
          ^^^^^^^^^^^^^^^

Should this warning be issued when NUMERIC_STORAGE_SIZE is not visible?

[mjklemm]

@klausler @kiranchandramohan @clementval @tblah Can you please comment? I think this may be a bug. Is it?

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: Michael Klemm (mjklemm)

In the following code, `NUMERIC_STORAGE_SIZE` is not being used (and technically not visible):

program reproducer
    use iso_fortran_env, only: output_unit
    implicit none
end program reproducer

Flang still a warning, when compiling the file like this:

> flang-new -fdefault-real-8 -c reproducer.f90
reproducer.f90:2:9: warning: NUMERIC_STORAGE_SIZE from ISO_FORTRAN_ENV is not well-defined when default INTEGER and REAL are not consistent due to compiler options
      use iso_fortran_env, only: output_unit
          ^^^^^^^^^^^^^^^

Should this warning be issued when NUMERIC_STORAGE_SIZE is not visible?

[klausler]

Yes, it's a bug, and probably caused by your recent rearrangement of the contents of the ISO_FORTRAN_ENV module.

[mjklemm]

I'd like to plea not guilty, as the warning still appears with commit 22eb290 which is the one before I merged the ISO_FORTRAN_ENV stuff. When looking at the code it seems to be a static warning that only depends on the sizes of of INTEGER and REAL depending on the compiler options picked.

[klausler]

Can confirm, it shows up earlier.

[tarunprabhu]

As of bba40ab, a warning message is no longer emitted.