Re: Failing to use gnulib bootstrap in libtool

[Eric Blake]

On 09/03/2010 04:03 AM, Bruno Haible wrote:
> It is well possible to use gnulib without using 'bootstrap'. As examples,
> please see the 'autogen.sh' scripts of some packages:
>    - libunistring
>      
> <http://git.savannah.gnu.org/gitweb/?p=libunistring.git;a=blob;f=autogen.sh>

Also GNU M4, which uses 'gnulib-tool --update' rather than --import in 
its bootstrap script.

> The contents of gnulib-cache.m4 is an output of the invocation of gnulib-tool,
> and therefore a derivative of the parameters that you pass to gnulib-tool.

But the current documentation says that 'gnulib-cache.m4' is the ONE 
output that you SHOULD be keeping in version control.  In fact, that is 
precisely how m4 works - by versioning just gnulib-cache.m4, it is 
sufficient to have bootstrap run 'gnulib-tool --update' so that all 
other developers will pick up the same set of modules as the last 
developer that made a modification via gnulib-tool --import.

> 'gnulib-tool --update' is equivalent to 'gnulib-tool --import ...' where the
> options and list of modules are fetched from gnulib-cache.m4. Because of the
> principle to not mix inputs and outputs (see above), and because
> gnulib-cache.m4 is an output (produced by the previous gnulib-tool execution),
> you must ensure that gnulib-cache.m4 is not used by subsequent gnulib-tool
> invocations.

That advice goes counter to how M4 is currently using gnulib-tool.

> This means
>    1. You must not use 'gnulib-tool --update'.

Then why does it exist?  I frequently rerun bootstrap on an existing 
tree in order to pick up the new modules that have been added by other 
developers, and gnulib-tool --update is faster than gnulib-tool --import 
at doing so.

--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org