Re: potential patch for gdb bug c++/20020

[Andrew Burgess <andrew.burgess@embecosm.com>]

* Bob Steagall <bob.steagall.cpp@gmail.com> [2018-12-06 13:29:31 -0500]:

> Description: This patch, against released version 8.2, fixes the
> problem reported in gdb bug c++/20020, using the approach described in
> comment 1 of that report.
> 
> Changelog entry:
> 
> 2018-12-06  Bob Steagall   <bob.steagall.cpp@gmail.com>
> 
>         * cp-valprint.c: Fixes bug c++/20020.

> --- gdb/cp-valprint.c	2018-09-05 03:27:13.000000000 -0400
> +++ gdb/cp-valprint.c.new	2018-12-06 13:01:06.819266165 -0500
> @@ -326,12 +326,16 @@ cp_print_value_fields (struct type *type
>  		      fprintf_filtered (stream,
>  					_("<error reading variable: %s>"),
>  					ex.message);
> +                      v = NULL;

I don't think this NULL assignment should be needed.  `v` starts as
NULL, and we only end in this block if `value_static_field` throws an
exception, which will be before `v` is assigned too.

>  		    }
>  		  END_CATCH
>  
> -		  cp_print_static_field (TYPE_FIELD_TYPE (type, i),
> -					 v, stream, recurse + 1,
> -					 options);
> +                  if (v != NULL)
> +                    {

You should drop the '{' and '}' here for a single statement block.

> +                      cp_print_static_field (TYPE_FIELD_TYPE (type, i),
> +                                             v, stream, recurse + 1,
> +                                             options);
> +                    }
>  		}
>  	      else if (i == vptr_fieldno && type == vptr_basetype)
>  		{

I'm not a maintainer so can't approve patches, but this seems sensible
to me.

Thanks,
Andrew