[Bug fortran/93339] [9/10 Regression] ICE in gimplify_var_or_parm_decl, at gimplify.c:2830

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93339

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |burnus at gcc dot gnu.org

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> ---
Created attachment 48243
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48243&action=edit
Extended test case

I have tried with GCC 7 – while some variants to not crash, others do and it
also does not work at run time. The full test case shows the same compile-time
error as trunk (see last item in this comment). Hence, it is not a "real"
regression.

 * * * 

The problem is at
     associate (y => x%a)
here,
  expr = "x%a"
but
  expr->ts.u.cl->backend_decl == ".z".

When processing "associate (y => x%a)", gfc_get_array_span() gets the
descriptor (desc) and the "expr" from above as input. (When called from
trans_associate_var.)

Thus, one ends up with:
    integer(kind=8) .y;
    struct array01_unknown y;

    y = x.a;
    y.span = .z;  // should be .y instead (+ at some point initialized)

If one uses "y => x%a(:)(1:3)", one gets:
  .z = 3
Hence, .z is no longer uninitialized. Still, '.z' is not defined in this scope
→ which causes the ICE.

If one only has only one ASSOCIATE, this works has there is only a '.y'.

In the attached test case (when commenting the two inner associate):
  'y = x%a(:)(1:3)' works
  but 'y2 => x%a' fails at the run-time check as 'y == ['AB','CD'] instead of
['ABC','DEF'] (why?)

 * * *

Additionally, there are odd errors for the inner associate, which does not show
up for the outer associate; it might be well related to the expr->ts.u.cl
issue, but could also be an issue of its own.  

     associate (z => x%a(:)(1:2))
                           1
Error: Substring end index at (1) exceeds the string length
foo3.f90:18:31:

     associate (z => x%a(:)(1:2))
                               1
Error: Entity ‘z’ at (1) has a deferred type parameter and requires either the
POINTER or ALLOCATABLE attribute