Re: [Boost-build] Projects requirements and alternative selection

Subject: Re: [Boost-build] Projects requirements and alternative selection
From: Vladimir Prus (ghost_at_[hidden])
Date: 2009-04-16 02:33:58

On Wednesday 15 April 2009 16:38:28 Johan Nilsson wrote:
> Hi,
> 
> I'm experiencing some "problems" with target selection. A simplified 
> example:
> 
> -------------------- Jamroot ------------------
> project foo
>  : requirements
>  <link>static
>  <threading>multi
>  <runtime-link>shared
> 
>  : default-build
>  debug
> 
>  ;
> 
> # release
> lib bar
>  :
>  : <file>a.lib <threading>multi <link>static <runtime-link>shared 
> <variant>release
>  ;
> 
> # debug
> lib bar
>  :
>  : <file>a_d.lib <threading>multi <link>static <runtime-link>shared 
> <variant>debug
>  ;
> ------------------ Build output -----------------------
> >bjam
> error: No best alternative for ./bar
>     next alternative: required properties: <link>static <runtime-link>shared 
> <threading>multi <variant>release
>         not matched
>     next alternative: required properties: <link>static <runtime-link>shared 
> <threading>multi <variant>debug
>         not matched
> ...found 1 target...
> ----------------------------------------------------
> 
> Note that if I declare e.g. an exe target that references the 'bar' lib, the 
> correct library is selected and linked with, but the above error messages 
> still appear (build is not aborted). What seems to be the culprit is that 
> threading defaults to "single" and link to "static" and that this is added 
> to the build request. This is the output from some tracing added to 
> select-alternatives in targets.jam:
> 
> Original: <debug-symbols>on
> <inlining>off
> <optimization>off
> <runtime-debugging>on
> <variant>debug
> 
> With defaults: <asynch-exceptions>off
> <debug-store>object
> <debug-symbols>on
> <embed-manifest>on
> <exception-handling>on
> <extern-c-nothrow>off
> <hardcode-dll-paths>true
> <host-os>windows
> <inlining>off
> <install-dependencies>off
> <link>shared
> <midl-robust>yes
> <midl-stubless-proxy>yes
> <optimization>off
> <os>NT
> <pch>on
> <profiling>off
> <rtti>on
> <runtime-debugging>on
> <runtime-link>shared
> <stdlib>native
> <suppress-import-lib>false
> <symlink-location>project-relative
> <target-os>windows
> <threading>single
> <toolset-msvc:version>8.0
> <toolset>msvc
> <user-interface>console
> <variant>debug
> <warnings-as-errors>off
> <warnings>on
> 
> Is this as expected - I had a gut feeling that the requirements set by 
> "project" should be added to the "build" request for the bar lib in the 
> above scenario?
> 
> I've tried the above using Boost.Build from trunk as well as from 1.34.1. 
> Toolset is msvc (set in user-config.jam).

You are hitting:

        http://zigzag.lvk.cs.msu.su/boost.build/ticket/16

I'd recommend that instead of alternatives, you use one target with
indirect conditional requirements that computes <file> property as
necessary.

HTH,
Volodya