[Bug fortran/119656] New: [12/13/14/15 Regression] Wrong code with impure elemental subroutine and interface

[anlauf at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119656

            Bug ID: 119656
           Summary: [12/13/14/15 Regression] Wrong code with impure
                    elemental subroutine and interface
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: anlauf at gcc dot gnu.org
  Target Milestone: ---

The attached code is derived from:

https://fortran-lang.discourse.group/t/problem-with-impure-elemental-subroutine-in-interface-with-gfortran/9545

Compiled with gfortran 12+ I get:

 in foo_df, len(xstr) =           2
 in foo_df, len(xstr) =           0

while with version 7-11 I get the correct:

 in foo_df, len(xstr) =           2
 in foo_df, len(xstr) =           2

Remarks:

- as noted in the above discussion, commenting 'use m1_mod' avoids the issue

- impure AND elemental are needed to reproduce

- the dump tree shows that the failing translated calls has a wrong number of
  arguments:

void MAIN__ ()
{
  {
    static integer(kind=4) C.4688 = 5;

    foo_df (&C.4688, 0B, &"ab"[1]{lb: 1 sz: 1}, 2);
  }
  {
    static integer(kind=4) C.4689 = 5;

    foo_df (&C.4689, 0B, &"ab"[1]{lb: 1 sz: 1}, 0, 2);
  }
}

The additional 0 in the argument list is taken as string length.