Fix ICE due to map typespecs with different sized charlens being copied

[Steve Kargl]

On Wed, Oct 05, 2016 at 04:40:50PM -0400, Fritz Reese wrote:
> When union type symbols are compared and they contain maps containing
> characters with different lengths, their type symbols should have
> different backend declarations otherwise the gimple tree explodes.
> Strangely enough the gimple checker only explodes with '-g' enabled
> and certain other specific conditions, however the problem seems
> clear. See the attached testcase for an example, and the attached
> patch for a fix.
> 
> RFC: My only concern is that this patch would technically also change
> the way components are compared between derived types and class types,
> not just union/map types. However from what I can tell if two derived
> types are declared with character components of different lengths then
> the two types should have distinct backend declarations anyway. If
> anyone can think of any issues this patch might cause with derived
> types/class types then I'd be okay guarding the new if statement to
> only run for union/structure types. But with all my tests it doesn't
> seem to result in any concrete differences.
> 
> The patch does pass all regression tests on x86_64-redhat-linux. I
> will give it a couple days for the RFC before committing.
> 
> ---
> Fritz Reese
> 
> 2016-10-05  Fritz Reese  <fritzoreese@gmail.com>
> 
>         Fix ICE due to map typespecs with different sized charlens being copied.
> 
>         * gcc/fortran/interface.c (compare_components): Check charlens.
> 
>         * gcc/testsuite/gfortran.dg/dec_union_11.f90: New testcase.
> 

Patch looks ok to me. 

-- 
Steve