[Bug fortran/94048] New: ICE and other problems using rank intrinsic to set array size

[jrfsousa at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94048

            Bug ID: 94048
           Summary: ICE and other problems using rank intrinsic to set
                    array size
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jrfsousa at gmail dot com
  Target Milestone: ---

Created attachment 47978
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47978&action=edit
Code demonstrating problems.

Hi all!

ICE using rank to set the size of an array.

Both in:

GNU Fortran (GCC) 9.2.1 20200303

and

GNU Fortran (GCC) 10.0.1 20200303 (experimental)

The ICE is easy to fix:

diff --git a/gcc/fortran/expr.c b/gcc/fortran/expr.c
index 79e00b4..a5993ea 100644
--- a/gcc/fortran/expr.c
+++ b/gcc/fortran/expr.c
@@ -3253,7 +3253,7 @@ check_references (gfc_ref* ref, bool (*checker)
(gfc_expr*))
   switch (ref->type)
     {
     case REF_ARRAY:
-      for (dim = 0; dim != ref->u.ar.dimen; ++dim)
+      for (dim = 0; dim < ref->u.ar.dimen; ++dim)
        {
          if (!checker (ref->u.ar.start[dim]))
            return false;

On x86_64-pc-linux-gnu it tests OK.

The real problems start after that... :-)

Using the module generates:

f951: Fatal Error: Reading module ‘ice2_m.mod’ at line 23 column 6: Bad name
compilation terminated.

Using the function by itself returns a malformed array, compiling with
-fbounds-check generates the error:

At line 11 of file ./ice2.f90
Fortran runtime error: Dimension 1 of array 'bar' has extent 1 instead of -1

I belive that the error is at the interface and the ifm.n artificial variable
is not properly generated.

Thank you very much.

Best regards,
José Rui