ghc configure

[Sven Panne]

On Tuesday 01 May 2007 13:02, Claus Reinke wrote:
> [...] would it be possible
> to have a "configuration package" with nothing but the common checks? then
> every package, and ghc itself, could depend on that package being there,
> and every package configure could modularly use the information from that
> package. [...]

That would be the wrong approach, autoconf already has the relevant 
mechanisms:

   http://www.gnu.org/software/autoconf/manual/html_node/Caching-Results.html
   http://www.gnu.org/software/autoconf/manual/html_node/Cache-Files.html

Basically, this boils down to using the AC_CACHE_BLAH macros in all 
time-consuming places (we do this, at least most of the time) and pass down 
the cache file location through the directory hierarchy (You won't achieve 
caching between siblings in the build hierarchy, but I am not sure if this is 
a real problem). This is what configure usually does, but I guess that some 
things have been broken by the recent changes in the build system, so that 
currently caching is not very effective.

My personal opinion is: Compared to the whole build time, the configuration 
checks are ridiculously fast, and doing arcane things to speed this up is not 
worth the trouble.

Cheers,
   S.