Re: [PATCH] Fortran: use name of array component in runtime error message [PR30802]

[Harald Anlauf <anlauf@gmx.de>]

Am 29.01.24 um 18:25 schrieb Harald Anlauf:
> I was talking about the generated format strings of runtime error
> messages.
>
> program p
>    implicit none
>    type t
>       real :: zzz(10) = 42
>    end type t
>    class(t), allocatable :: xx(:)
>    integer :: j
>    j = 0
>    allocate (t :: xx(1))
>    print *, xx(1)% zzz(j)
> end
>
> This is generating the following error at runtime since at least gcc-7:
>
> Fortran runtime error: Index '0' of dimension 1 of array 'xx%_data%zzz'
> below lower bound of 1

Of course this is easily suppressed by:

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index 1e0d698a949..fa0e00a28a6 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -4054,7 +4054,8 @@ gfc_conv_array_ref (gfc_se * se, gfc_array_ref *
ar, gfc_expr *expr,
  	{
  	  if (ref->type == REF_ARRAY && &ref->u.ar == ar)
  	    break;
-	  if (ref->type == REF_COMPONENT)
+	  if (ref->type == REF_COMPONENT
+	      && strcmp (ref->u.c.component->name, "_data") != 0)
  	    {
  	      strcat (var_name, "%%");
  	      strcat (var_name, ref->u.c.component->name);


I have been contemplating the generation the full chain of references as
suggested by Mikael and supported by NAG.  The main issue is: how do I
easily generate that call?

gfc_trans_runtime_check is a vararg function, but what I would rather
have is a function that takes either a (chained?) list of trees or
an array of trees holding the (co-)indices of the reference.

Is there an example, or a recommendation which variant to prefer?

Thanks,
Harald