If you want to build PHP from the SVN repository, you have to run buildconf [--force].

But depending on the version of autoconf you have on your machine you can get the very annoying warning message :

[...]
buildconf: Your version of autoconf likely contains buggy cache code.
Running vcsclean for you.
To avoid this, install autoconf-2.13.
[...]

If you do not have autoconf 2.13 installed, then you have to install it first.

On RedHat running sudo yum install autoconf213 should work. On Debian, the autoconf2.13 package is available.

Once autoconf2.13 install, you can instruct buildconf to use this new version of autoconf by runing :

export PHP_AUTOCONF=`which autoconf-2.13`

You can check the value is correct by running :

echo $PHP_AUTOCONF

Which should give you something like (depending on your system)

/usr/bin/autoconf-2.13

Now retry to run ./buildconf –force. The annoying message is gone, joy

‘Hope that helps.