[Bug fortran/56007] Remarkably bad error message with DO array=1,2

["anlauf at gmx dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56007

--- Comment #4 from Harald Anlauf <anlauf at gmx dot de> ---
(In reply to Tobias SchlÃter from comment #3)
> Just for the fun of it, another confusing way this error message appears:
> $ cat t3.f90
> character c(5)
> 
> do c=2,3
> end do
> 
> END 
> $ gfortran t3.f90
> t3.f90:3.4:
> 
> do c=2,3
>     1
> Error: Loop variable at (1) cannot be a sub-component
> t3.f90:4.3:
> 
> end do
>    1
> Error: Expecting END PROGRAM statement at (1)
> $ 
> 
> Of course this behavior is expected once you look at the code.

The above error message is somewhat improved with the following patch:

Index: gcc/fortran/match.c
===================================================================
--- gcc/fortran/match.c (revision 232904)
+++ gcc/fortran/match.c (working copy)
@@ -877,6 +877,12 @@
   if (m != MATCH_YES)
     return MATCH_NO;

+  if (var->ts.type == BT_CHARACTER)
+    {
+      gfc_error ("Loop variable at %C cannot be of type CHARACTER");
+      goto cleanup;
+    }
+
   /* F2008, C617 & C565.  */
   if (var->symtree->n.sym->attr.codimension)
     {

I now get:

t3.f90:3:4:

 do c=2,3
    1
Error: Loop variable at (1) cannot be of type CHARACTER
t3.f90:4:3:

 end do
   1
Error: Expecting END PROGRAM statement at (1)