Re: [PATCH] Fix Bug 79524 - [Regression] valgrind error for gcc/testsuite/gfortran.dg/fimplicit_none_2.f90

commit r16-8479-g7660e3067481159acc3ad76cfae22f71606670c7
Author: Christopher Albert <[email protected]>
Date:   Fri Apr 3 12:45:57 2026 +0200

     fortran: Clean up charlens after rejected parameter arrays [PR79524]

I will backport after some time.

Jerry

On 4/4/26 10:32 AM, Jerry D wrote:
> Hi all,
> 
> As stated in the PR, I was able to verify the valgrind error and after applying 
> the patch, confirmed the errors go away.
> 
> Regression tested on X86_64.
> 
> I plan to commit this in the next day or so unless additional comments.
> 
> Regards,
> 
> Jerry
> 
> ---
> 
> fortran: Clean up charlens after rejected parameter arrays
>   [PR79524]
> 
> When a parameter array declaration such as
> character(*), parameter :: z(2) = [character(n) :: 'x', 'y']
> is rejected, declaration-local charlen nodes from that statement can remain on
> cl_list and later be resolved again.  The charlen's length expression still
> references the symbol 'n' whose symtree was already freed by gfc_undo_symbols,
> causing a heap-use-after-free in resolve_charlen.
> 
> Clean up those statement-local charlens at the rejection point in decl.cc,
> after clearing the surviving owners in that path.
> 
>      PR fortran/79524
> 
> gcc/fortran/ChangeLog:
> 
>      PR fortran/79524
>      * decl.cc (discard_pending_charlens): New helper.
>      (add_init_expr_to_sym): Drop statement-local charlens when
>      rejecting variable-length parameter arrays.
>      (variable_decl, do_parm, enumerator_decl): Save the current
>      namespace charlen list before parsing declarations with
>      initializers.
>      (match_procedure_decl): Adjust call to add_init_expr_to_sym.
> 
> gcc/testsuite/ChangeLog:
> 
>      PR fortran/79524
>      * gfortran.dg/pr79524.f90: New test.
> 
> Signed-off-by: Christopher Albert <[email protected]>