[Bug fortran/88486] ICE in gfc_conv_scalarized_array_ref, at fortran/trans-array.c:3401

["kargl at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88486

--- Comment #5 from kargl at gcc dot gnu.org ---
(In reply to G. Steinmetz from comment #0)
> Affects versions down to at least gfortran-5.
> Under the hood related to pr85686.
> 
> 
> $ cat z1.f90
> subroutine s(x)
>    character(:), allocatable :: x(:)
>    x = ['bcd']
>    x = ['a'//x//'e']
>    print *, x
> end
> 

This compiles with GNU Fortran (GCC) 13.0.1 20230408 (experimental).
This has an ICE with GNU Fortran (FreeBSD Ports Collection) 12.2.0.

Filling out the code to something that actually does something
reveals a wrong-code issue with an array constructor.  There are
a boat load of warnings of uninitialized variables, e.g., 
a.f90:53:34:

   53 |          x = [ ('a' // x // 'e') ]
      |                                  ^
Warning: '__var_1_realloc_string.dim[0].ubound' is used uninitialized
[-Wuninitialized]
a.f90:1:11:

    1 | program foo
      |           ^
note: '__var_1_realloc_string' declared here
a.f90:3:36:

    3 |    character(:), allocatable :: a(:)
      |                                    ^
Warning: '.a' is used uninitialized [-Wuninitialized]
a.f90:34:22:

   34 |       end subroutine s
      |                      ^
note: '.a' declared here


program foo

   character(:), allocatable :: a(:)

   call s(a)
   print '(A,1X,2(I0,1X),/)', 'a: >>' // a // '<<', size(a), len(a(1))
   if (allocated(a)) deallocate(a)

   call t(a)
   print '(A,1X,2(I0,1X),/)', 'a: >>' // a // '<<', size(a), len(a(1))
   if (allocated(a)) deallocate(a)

   call u(a)
   print '(A,1X,2(I0,1X),/)', 'a: >>' // a // '<<', size(a), len(a(1))
   if (allocated(a)) deallocate(a)

   call v(a)
   print '(A,1X,2(I0,1X),/)', 'a: >>' // a // '<<', size(a), len(a(1))
   if (allocated(a)) deallocate(a)

   call w(a)
   print '(A,1X,2(I0,1X),/)', 'a: >>' // a // '<<', size(a), len(a(1))
   if (allocated(a)) deallocate(a)

   contains

      subroutine s(x)
         character(:), allocatable :: x(:)
         x = ['bcd']
         x = ['a' // x // 'e']
         print '(A,1X,2(I0,1X))', 's: >>' // x // '<<', size(x), len(x(1))
      end subroutine s

      subroutine t(x)
         character(:), allocatable :: x(:)
         x = ['bcd']
         x = 'a' // x // 'e'
         print '(A,1X,2(I0,1X))', 't: >>' // x // '<<', size(x), len(x(1))
      end subroutine t

      subroutine u(x)
         character(:), allocatable :: x(:)
         x = ['bcd']
         x = [ ('a' // x // 'e') ]
         print '(A,1X,2(I0,1X))', 'u: >>' // x // '<<', size(x), len(x(1))
      end subroutine u

      subroutine v(x)
         character(:), allocatable, intent(out) :: x(:)
         x = ['bcd']
         x = [ ('a' // x // 'e') ]
         print '(A,1X,2(I0,1X))', 'v: >>' // x // '<<', size(x), len(x(1))
      end subroutine v

      subroutine w(x)
         character(:), allocatable, intent(out) :: x(:)
         x = [ 'a' // ['bcd'] // 'e' ]
         print '(A,1X,2(I0,1X))', 'w: >>' // x // '<<', size(x), len(x(1))
      end subroutine w

end program foo


s: >>abcde<< 1 5
a: >>abc<< 1 3    <--- whoops

t: >>abcde<< 1 5
a: >>abcde<< 1 5

u: >>abcde<< 1 5
a: >>abc<< 1 3    <--- whoops

v: >>abcde<< 1 5
a: >>abc<< 1 3    <--- whoops

w: >>abcde<< 1 5
a: >>abcde<< 1 5