Re: [Boost-build] allowing targets to fail

Subject: Re: [Boost-build] allowing targets to fail
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2017-03-31 14:47:26

AMDG

On 03/31/2017 08:22 AM, Stefan Seefeld via Boost-build wrote:
> Here is a related question:
> 
> I'm looking at the "try_compile" example, which seems to use a similar
> feature: It runs a configure check ("check_target_builds foo") and
> allows it to fail, i.e.
> the result is captured in a log file rather than on the console, in
> addition to a conditional definition of feature sets.
> 
> How is this implemented in the engine, i.e. what is the underlying
> target definition (as seen by the engine) and what causes the engine not
> to report it as an "updated" or "failed target" on the console ?
> 

  The target as seen by the engine is a normal target.
The only thing special is that it's built using a
call to UPDATE_NOW with a file descriptor for the log file.
See the documentation of UPDATE_NOW here:
http://www.boost.org/build/doc/html/jam/language.html#jam.language.rules.builtins.utility

> Oh, and how does the caching work, i.e. where is that implemented ?
> 

config-cache.jam

In Christ,
Steven Watanabe