Re: Need a hint or more likely help

[Steve Kargl <sgk@troutmask.apl.washington.edu>]

On Sat, Feb 10, 2024 at 06:00:42PM -0800, Steve Kargl wrote:
> All, consider this simple code:
> 
>   module foo
>     contains
>       subroutine bar 
>         character(len=:), allocatable :: s(:)
>         call bah(s)
>      end subroutine bar
>   end module foo
> 
> If one compiles with -fdump-tree-original, one see (with some pruning)
> 
>   void bar ()
>   {
>     integer(kind=8) .s;
>     struct array01_character(kind=1) s;
> 
> The above two lines seem to be ok.
> 
>     bitsizetype D.4319;
>     sizetype D.4320;
> 
>     try
>       {
>         D.4319 = (bitsizetype) (sizetype) NON_LVALUE_EXPR <.s> * 8;
>         D.4320 = (sizetype) NON_LVALUE_EXPR <.s>;
>         s.data = 0B;
>         s.dtype = {.elem_len=(unsigned long) .s, .version=0, .rank=1, .type=6};
>         bah ((character(kind=1)[0:][1:.s] * restrict) s.data, .s);
>     }
> 
> This is bad. .s is undefined.  I've trace this to trans-array.cc:11531

I have created PR113883 with the patch suggested by Mikael and
a testcase.   I have bootstrapped and regression tested the result.
Could I ask someone to commit it?

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113883


* trans-array.cc (gfc_trans_deferred_array): Set length of an unallocated
  character entity to zero to prevent reference to undefined variable.

* testsuite/gfortran.dg/allocatable_length.f90: New test. 




-- 
Steve