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Re: It's (PCH) merging time!
- From: Geoff Keating <geoffk at geoffk dot org>
- To: Tim Josling <tej at melbpc dot org dot au>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: 07 Oct 2002 11:33:00 -0700
- Subject: Re: It's (PCH) merging time!
- References: <1033932057.27106.ezmlm@gcc.gnu.org><3DA110ED.C0AA1D1@melbpc.org.au>
Tim Josling <tej@melbpc.org.au> writes:
> The problem is that the output of gengtype$(exe) depends on all the
> files it scans. In particular the file gtype-desc.h has stuff from
> potentially all the files it scans, and it is included by many
> files. So this creates a many->many dependency. gtype-desc.h only
> has a new change date/time if it actually gets changed.
>
> So, if the dependencies are set up writing, changing one of many files causes
> many files to be recompiled.
>
> Maybe the solution is worse than the disease because you generate a lot of
> recompiles that are useless but I don't know how to avoid it.
What's wrong with the current solution for this, using s-gtype? All
the dependencies seem to be specified correctly (other than the
Makefile:ada/config-lang.in dependency, which would seem to be a
long-standing bug easily fixed by changing ada/Make-lang.in).
--
- Geoffrey Keating <geoffk@geoffk.org>