Re: [Boost-build] Building library with flex/bison inputs with dependencies

Subject: Re: [Boost-build] Building library with flex/bison inputs with dependencies
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2015-12-01 14:13:44

AMDG

On 12/01/2015 09:16 AM, Jim Hague wrote:
> 
> I'm building a project with includes the following library rule:
> 
> lib e2kmapparse
>     : e2kmapyacc.yy e2kmaplex.ll
>      ...
>     ;
> 
> As it not usual, e2kmaplex.ll includes a header defining token values 
> generated by e2kmapyacc.yy. In other words, e2kmaplex.ll starts thus:
> 
> %{
> #include <cstdlib>
> #include <cstring>
> 
> #include "e2kmapyacc.hpp"
> %}
> 
> But it looks like the CPP file output by flex is not scanned for include 
> dependencies before compiling; so on random -j builds, GCC will be launched 
> long before Bison is run on e2kmapyacc.yy, with unhappy results.
> 

  This is supposed to work automatically.
If it doesn't it's probably a bug.  I
reworked parts of the header scanning
algorithm significantly in 2012-2013,
so your problem may have been fixed.

  Of particular interest are:
https://github.com/boostorg/build/commit/64add142e14d5fdfccb7361fed2ea37fb2fd2f5b
(The end of a long series of patches,
to fix handling of cyclic INCLUDES,
which was seriously broken before.)

https://github.com/boostorg/build/commit/c1395b49614ed5c4b0958355ffaa0f794fb760a2
(Handles actions, such as bison, which
generate multiple targets in a cleaner
way.  The original code relied on
marking the outputs as INCLUDing
each other.  Processing of cyclic
INCLUDES used to be broken.  See above.)

In Christ,
Steven Watanabe