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Subject: Re: [boost] [build] [config] check_target_builds and feature.subfeature composition
From: Stefan Seefeld (stefan_at_[hidden])
Date: 2017-01-24 09:13:31

On 24.01.2017 03:30, John Maddock wrote:
>>> Yes I have, I brought it up, nothing happened. I stopped using
>>> check_target_builds.
>> The problem is that check_target_builds tries to
>> guess which features are important, and does it
>> badly (via a hard-coded list).
> IMO this is just plain wrong - any command line change could change
> the behaviour of the compile - I would rather loose the caching (which
> itself is problematic at times) that have it yield the wrong answer.

Allow me to tie this back to an earlier conversation:

It seems this issue arises because b2 allows multiple build variants to
be built at once, so (at least theoretically) each would need to run its
own set of config checks.
I understand that there are features that may take on different values
within a single build, but to open that door widely and let multiple
feature values be set at build time just makes the whole process so much
more complex. Wouldn't there be a way to simplify this to get the
complexity in check ?
Alternatively, config checks need to become (intermediate) build targets
by themselves, and "caching" would need to be handled the same as for
any other target (such as object files).


      ...ich hab' noch einen Koffer in Berlin...

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