Makefile change to restart bootstraps

[Eric W. Biederman]

kenner@vlsi1.ultra.nyu.edu (Richard Kenner) writes:

>     I can see it's advisable to do it when testing GCC, but remember that
>     these rules are also for people who're going to build GCC to use.
> 
> Right.
> 
>     They used to get quite frustrated when `make bootstrap' re-started the
>     build pretty much from scratch, and it would be quite annoying to have
>     the bootstrap restarted just because you tweak something in a config.h
>     file.
> 
> But remember that machines are much faster than when people "used to"
> compain!  The bootstrap shouldn't *need* to be "restarted". I'd argue
> quite the opposite: if a bootstrap failed for some reason, it's
> necessary to understand why and fix it so that it can run completely
> through.  Otherwise, how can you have confidence in the result?
> 
> And *certainly* if somebody other than a developer "teawked" something in
> config.h, I'd want the bootstrap to *definitely* restart from the beginning
> since he can't be sure how much it affects.

So why aren't dependencies set up correctly in the makefile?

> In fact the "normal user" argument makes it even stronger that we should not
> have this sort of restarting bootstrap since it's much harder for normal
> users to know they have to take steps to start over than for dvelopers.

Again set the dependencies up properly and make knows what needs to be rebuilt
because that's it's job.

Eric