Re: Annoyingly cautious make rules

[Stephen J. Turnbull]

Paul Eggert writes:
 > On 12/02/11 08:14, Stefan Monnier wrote:
 > > IIUC it's because the expectation is that it's not run very often and
 > > that current machines are fast enough to make it bearable,
 > 
 > Both assumptions are false for me.

But the assumption that you can find "configure -C" easily is true,
no?  Let's optimize the default for the people for whom doing the
wrong thing can be quite expensive.  It costs you and Richard minutes
waiting for configure, and from a few seconds to a day to learn about
"-C", but it can cost an occasional tester days if their build breaks
and they have no idea that it's a configure bug rather than a real
build issue.

 > And another part of this problem is that "configure -C" is poorly
 > publicized.  (Perhaps -C should be the default, but that's a bigger
 > change.)

It used to be default.  But for reasons given elsewhere, that really
sucked for people who should *never* need to worry about autoconf's
foot-shooting proclivities.  It took years to get that changed.

 > Here's a patch that addresses the above issues, without making
 > -C the default.

Thank you!

 > --- INSTALL.BZR      2011-06-25 17:51:03 +0000
 > +++ INSTALL.BZR      2011-12-02 17:54:11 +0000
 > @@ -26,7 +26,7 @@
 >  You can then configure your build (use `./configure --help' to see
 >  options you can set):
 >  
 > -  $ ./configure
 > +  $ ./configure -C

Please, no.  "-C" is an heuristic, not an optimization.  Write this
instead:

    You can then configure your build (use `./configure --help' to see
    options you can set):

    $ ./configure

    (If you run configure often, it can be annoyingly slow.  You can
    use "./configure -C" to enable a cache, which does speed things up
    dramatically, but at the cost of correctness: your build *will*
    break occasionally over a period of months if you use "-C".)

BTW, in

$ ./configure -C
$ ./configure

does the second configure step read the cache?  Does it leave an
existing cache behind?

 > -echo "You can now run \`./configure'."
 > +echo "You can now run \`./configure -C'."

Please, no.  "-C" is an heuristic, not an optimization.  It should be
available to those who need it, but advertising it is inviting trouble
for the testers and the folks who help testers on this list and others.