Re: Debugging dependencies

[Bob Sidebotham]

I think that most, if not all, problems of this nature come down to
Cons believing that a file is a source file even though it is actually
derived somehow, explicitly or implicitly, in the process of a build.
This could be for various reasons (multiple names for files, hidden
circularities, explicit code to touch files, etc.). There are two
things that could be done that would make these easy to find:

1. Patch -d to show the signature of each file. Then you can figure out
which source files changed by simply diffing the output from two runs.
I'll bet you a nickel that this simple change would pinpoint Eric's
problem.

2. Cache source signatures. Then cons *knows* which source files have
changed, and this information can be displayed directly, rather than
having to resort to a diff (the only problem with this is the problem
of caching information for read-only trees using the existing .consign
mechanism. Of course, if they're *truly* read-only, then magic updating
of those source files wouldn't be a problem in the first place).

Bob

--- Steven Knight <address@hidden> wrote:
> On Mon, 26 Feb 2001, Eric Brown wrote:
> > Is there any way to get cons to print out why it decided to rebuild
> a file?
> > My current project rebuilds certain files every time Cons runs. 
> You can
> > even run cons twice in a row, and the files will get rebuilt. 
> Running with
> > the -d option yields an interesting set of dependencies, but
> doesn't signal
> > which file caused the rebuild.
> 
> Unfortunately, this is part of the information that gets lost in
> aggregating all of the dependencies into a single MD5 signature. 
> Cons
> can only tell that the calculated signature is different from the
> old one, and that the file must therefore be rebuilt.  It can't tell
> directly which dependency's signature is the one that caused the
> aggregate signature to be different.  I'd welcome suggestions for
> ways
> this could be accomplished...
> 
>       --SK
> 
> 
> 
> _______________________________________________
> address@hidden
> http://mail.gnu.org/mailman/listinfo/cons-discuss
> Cons URL: http://www.dsmit.com/cons/


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