Re: [Boost-bugs] [Boost C++ Libraries] #10248: Understanding generated files / targets.

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #10248: Understanding generated files / targets.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-02-27 01:38:18

#10248: Understanding generated files / targets.
  Reporter: anonymous | Owner: vladimir_prus
      Type: Support Requests | Status: new
 Milestone: To Be Determined | Component: build
   Version: Boost 1.51.0 | Severity: Not Applicable
Resolution: | Keywords:

Comment (by steven_watanabe):

 * t1:
   Boost.Build assumes that if a target is updated, all
   dependent targets must be updated. It does not recheck
   the timestamp after building a target to determine whether
   it really changed. Instead of always-generate-main, you can
   use the print module, which will only update the target
   when its contents change.

 * t2:
   Boost.Build ignores t2.hpp because there's no rule for
   building an exe from a header. You really do need
   <implicit-dependency> for this. <implicit-dependency>
   does two things for you. It forces the jam target for t2.hpp
   to be generated, so that t2.hpp can be found by the #include scanner,
   and it also adds an appropriate -I directive to the compile
   command line. Remember that Boost.Build will put t2.hpp
   in some directory under bin/

 * t5:
   The reason that it doesn't relink is that there is no #include <t5.hpp>.
   <implicit-dependency> doesn't set up an actual dependency. It only
   says that there's a possible dependency which should be found by
   scanning the source. If you want an unconditional dependency, then
   use the <dependency> feature instead.

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