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

Subject: Re: [Boost-build] BUMPITTY BUMP: [git] genrating forward headers
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2013-08-21 23:39:46

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.

>> 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.

>> - 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 ;

>> - 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.

>> 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.

>> 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 ] ;

In Christ,
Steven Watanabe