[PATCH 2/2] Better system header location detection for built-in macro tokens

[Jason Merrill]

On 06/02/2012 12:40 PM, Paolo Carlini wrote:
> That said, the tricks we are playing with the global input_location vs the loc we are passing around still confuse me quite a lot. Actually any *assignment* to input_location makes me a bit more nervous than I was already ;) Do you have any idea whether just passing down to build_x_modify_expr a different value for loc instead of assigning to input_location would also work for you? Maybe together with more throughly forwarding the loc from build_x_modify_expr itself to the build_min* functions (ie the project I mentioned above)??

We already pass to build_x_modify_expr the location that he is assigning 
to input_location.  I would guess that the issue in this case is with 
the "in_system_header" macro, which uses input_location.

I think the input_location hack here is OK until we improve our use of 
explicit locations to make it unnecessary.

> -  s = s; // { dg-message "synthesized|deleted" }
> +  s = s;

Why do we lose this error?

Jason