SWIG PHP Bindings can't be built on Travis

[geographika]

After several failed attempts at building the new PHPNG SWIG bindings with Travis, I think I have found the reason.

The same version of PHP and SWIG builds fine on a clean Ubuntu Trusy machine, but not on Travis.

After trying to find the differences between the two setups using;

php -r 'echo phpinfo();'

The most likely culprit seems to be:

# Travis
Thread Safety => enabled
# local
Thread Safety => disabled

travis-ci/php-src-builder#24 mentions that

the current implementation only builds ZTS (Zend Thread Safety) builds of PHP.

And also:

PHP being ZTS by default is quite annoying for extension developers. Its not the default in PHP world.

Which is why Debian and local builds seem to be fine.

There is a pull request to add non-ZTS builds at travis-ci/php-src-builder#24

The error messages caused by this seem to match the ones mentioned by @AlexanderGabriel in swig/swig#1238 which he encountered with ZTS on Windows builds.

[ 94%] Building C object mapscript/phpng/CMakeFiles/php_mapscriptng.dir/mapscriptPHP7_wrap.c.o
/home/travis/build/geographika/mapserver/build/mapscript/phpng/mapscriptPHP7_wrap.c: In function ‘SWIG_FAIL’:
/home/travis/build/geographika/mapserver/build/mapscript/phpng/mapscriptPHP7_wrap.c:1045:27: error: ‘mapscript_globals’ undeclared (first use in this function)
 #define SWIG_ErrorCode() (mapscript_globals.error_code)

There seem to be a couple of options to get this working:

• install PHP from another source and ignore the prebuilt Travis machines

sudo add-apt-repository -y ppa:ondrej/php
sudo apt-get install -y --allow-unauthenticated php7.0-dev

• update to SWIG 4.0 (currently in beta, and seems to break the Python MapScript builds):

cd /tmp
sudo wget http://prdownloads.sourceforge.net/swig/swig-4.0.0-beta1.tar.gz
tar xf swig-4.0.0-beta1.tar.gz
cd swig-4.0.0-beta1 && ./configure --prefix=/usr && make && sudo make install
swig -version

[geographika]

Fixed by updating to SWIG 4 in #5983