[PR fortran/89077, patch] - ICE using * as len specifier for character parameter

[Thomas Koenig]

Hi Harald,

> ==> f1.f90 <==
>    character(1), parameter :: u = transfer ([('a'(i:i),i=1,1)], 'x')
>    print *, u
> end

This one is really strange.  Looking at the tree dump, it seems we
manage to encode the expression (this also works in a module file)
without actually simplifying this.

Having said that, I think one of the things we can do is to
look at gfc_resolve_substring_charlen, which has

   /* Length = (end - start + 1).  */
   e->ts.u.cl->length = gfc_subtract (end, start);
   e->ts.u.cl->length = gfc_add (e->ts.u.cl->length,
				gfc_get_int_expr (gfc_charlen_int_kind,
						  NULL, 1));

You could try using gfc_dep_difference (in dependency.c) to try to
calculate the string length.  If that does not succeed, you can then
fall back to the gfc_subtract function.

This should work to simplify the string length for a(i:i) to one.

I think we do something like this somewhere in trans-*, but it
would be much better do do it early.

Regards

	Thomas