Re: [Boost-build] BUMPITTY BUMP: [git] genrating forward headers

Subject: Re: [Boost-build] BUMPITTY BUMP: [git] genrating forward headers
From: Dave Abrahams (dave_at_[hidden])
Date: 2013-08-22 09:01:59

on Wed Aug 21 2013, Steven Watanabe <watanabesj-AT-gmail.com> wrote:

> AMDG
>
> On 08/21/2013 07:12 PM, Dave Abrahams wrote:
>> 
>> Perhaps, but these posts assume a great deal of background that I don't
>> have.  I need details filled in, please.  
>> For instance, in that post Steven says:
>> 
>>> I've applied the Boost.Build changes.  
>> 
>> Applied them where?  What do these changes do?
>> 
>
> In Boost.Build. (mostly tools/build/v2/tools/link.jam).
> These changes specify /how/ to create the header links.
> The remaining changes are to create the link targets
> and modify the rest of Boost to get the dependencies right.

OK, but in trunk?  release?  somwehere else?

>>> I don't want to apply the changes to Boost proper in svn, since it'll
>>> break without the git layout.
>>>
>>> Here are the changes that need to happen in git:
>> 
>> What does he mean by "need to happen in git?"  We are not making any
>> git-specific commits.
>> 
>>> - Use the original boost-root patch (i.e. no <dependency>)
>> 
>> Sorry, which patch is that?
>> 
>
> It's somewhere in the archives.  I think Jürgen
> and Bjørn both posted it earlier in this thread.
>
>>> - Change all uses of boost//headers to
>>> <implicit-dependency>/boost//headers.  <use> <source> and <library> do not
>>>   work correctly for handling generated headers.
>>>   This is the cause of the build problems with
>>>   the original patch.
>> 
>> Is this a simple search-and-replace, or does it require some specialized
>> knowledge?
>> 
>
> A search and replace won't quite work.  e.g.
>
> lib A : a.cpp boost//headers ;
> becomes
> lib A : a.cpp : <implicit-dependency>/boost//headers ;
>
> lib B : b.cpp : <library>/boost//headers ;
> becomes
> lib B : b.cpp : <implicit-dependency>/boost//headers ;
>
> <implicit-dependency> needs to be in the target requirements.

So, a regexp search.  Is there any other relevant prefix other than
<library>?

>>> - Add <implicit-dependency>/boost//headers to all library and test
>>> targets.  
>> 
>> I /think/ I understand what that means.
>> 
>
> It can be added at the project level:
>
> project : requirements <implicit-dependency>/boost//headers ;

Good to know, thaks.

>>> - Change the header install glob to search the correct include
>>> directories
>> 
>> I have no idea what that means.  Please explain.
>> 
>
> The install target has to copy all the boost headers.
> Currently it looks something like:
> headers = [ path.glob-recursive boost : *.hpp *.ipp : .svn ]
> It will need to be changed to search the library specific
> include directories instead, under the git layout only.

What layout should the headers follow in this copy?

>>> The fact that we need to disable everything that is specific for the
>>> modularized layout when building in the monolithic layout complicates
>>> the process of proceeding.  
>> 
>> Huh; from what I'm reading here it seems like maybe it could be done
>> with a few project-wide bjam variables.  Something like:
>> 
>>   if $(BOOST_SVNLAYOUT)
>>   {
>>     BOOST_HEADER_DEPENDENCY = boost//headers ;
>>   }
>>   else
>>   {
>>     BOOST_HEADER_DEPENDENCY = <implicit-dependency>boost//headers ;
>>   }
>> 
>> then replace uses of "boost//headers" with "$(BOOST_HEADER_DEPENDENCY)".
>> Is the problem more complicated than I'm guessing?
>> 
>
> This doesn't need to be conditionalized.
> <implicit-dependency> will work correctly in svn.

Great.

>>> I imagine that some test may be used as a config step that allow new
>>> or changed rules to be conditioned or targets to be disabled.
>> 
>> Sorry, I don't know what that means.
>> 
>
> I think he means exactly what you just described
> (if $(BOOST_SVNLAYOUT)).
>
> BOOST_SVNLAYOUT = [ path.glob . :
>   path/to/file/that/only/exists/in/git ] ;

OK, great.

Cheers,

-- 
Dave Abrahams