WARNING: This bison version is not supported for regeneration of the Zend/PHP parsers (found: 3.0, min: 204, excluded: 3.0).

PHP 5.4: 1.28, 1.35, 1.75, 1.875, 2.0, 2.1, 2.2, 2.3, 2.4, 2.4.1, 2.4.2, 2.4.3, 2.5, 2.5.1, 2.6, 2.6.1, 2.6.2, 2.6.4
PHP 5.5: 2.4, 2.4.1, 2.4.2, 2.4.3, 2.5, 2.5.1, 2.6, 2.6.1, 2.6.2, 2.6.3, 2.6.4, 2.6.5, 2.7
PHP 5.6: 2.4 or later, excluding 3.0 only (3.0.1 and later are OK)
PHP 7.0: 2.4 or later

~/php-src# git checkout PHP-5.6
...
checking for bison... bison -y
checking for bison version... invalid
configure: WARNING: This bison version is not supported for regeneration of the Zend/PHP parsers (found: 3.0, min: 204, excluded: 3.0).
checking for re2c... re2c
checking for re2c version... 0.16 (ok)
configure: error: bison is required to build PHP/Zend when building a GIT checkout!

wget http://ftp.gnu.org/gnu/bison/bison-2.4.1.tar.gz
tar -zxvf bison-2.4.1.tar.gz
cd bison-2.4.1/
./configure
make
make install