is re-running bootstrap after a change safe?

[Jeff Law]

On 4/5/19 2:50 PM, Eric Botcazou wrote:
>> Say if the first bootstrap succeeds and I then change a single
>> GCC .c file and rerun make bootstrap, am I guaranteed to see
>> the same fallout of the change as I would if I did a pristine
>> build in a clean directory?
> 
> No, this would imply deleting the stage2 and stage3 compilers and that isn't 
> what happens.  Instead the compiler of each stage is updated in isolation.
> 
RIght.  Thus I always blow away stage2-* stage3-*, and stage1 target
directories along with the "compare" stamp file.

Jeff