Re: Using automake to change gcc build

[Ralf Wildenhues <Ralf dot Wildenhues at gmx dot de>]

Hello Amittai,

* Amittai Aviram wrote on Tue, Jan 11, 2011 at 08:17:39AM CET:
> I want to add a few files to the gcc source tree and build and test
> the resulting gcc, but I am having trouble finding my way around the
> Automake system.  
[...]

> Then I ran automake in order to produce (I thought) the corresponding
> Makefile.in, and got this error:
> 
> $ automake
[...]
> configure.ac:5: error: Please use exactly Autoconf 2.64 instead of 2.65.
> ../config/override.m4:34: _GCC_AUTOCONF_VERSION_CHECK is expanded from...
> configure.ac:5: the top level
> autom4te: /usr/bin/m4 failed with exit status: 1
> automake: autoconf failed with exit status: 1
[...]

> It seems to me that a version 2.65 autoconf should be sufficiently
> backward compatible to deal with input for the previous minor version.
> So why am I running into this problem and what can I do about it?

The GCC tree requires an exact version, rather than a minimal version of
Autoconf, because the generated files are committed into version control
and there would be spurious differences due to version skew all the time
otherwise; this used to be the case before the check was put into place.

However, the config/override.m4 macro file also documents how this check
can be overridden (at the location given in the error message): by
m4_define'ing _GCC_AUTOCONF_VERSION to the version you use early.  Thus,
you could either patch override.m4 right away and enter your version
there, or do that in the configure.ac file (before AC_INIT) which
belongs to the part of the GCC tree you are working on.

Hope that helps.

Cheers,
Ralf