add php 7.3 to travis config

[samsonasik]

since php: nightly already use php 7.4dev

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[samsonasik]

it seems php 7.4dev on nightly currently only on dist: trusty. Current travis config uses dist: precise which show as 7.3.0-dev in nightly.

The details is as follow:

1. When using precise, the 7.3 will be shown as 7.3.0RC3 and the nightly will be shown as 7.3.0-dev.

2. When using trusty, the 7.3 will be shown as 7.3.0RC3 and the nightly will be shown as 7.4.0-dev.

[samsonasik]

the reason seems by use group: edge, it will be shown as 7.3 => 7.3.0RC3, and nightly => 7.4.0-dev. I also updated to dist: trusty as the Precise is in the process of being decommissioned.

• 7.3.0RC3 travis build: https://travis-ci.org/bcit-ci/CodeIgniter4/jobs/449022333
• 7.4.0-dev travis build: https://travis-ci.org/bcit-ci/CodeIgniter4/jobs/449022338

[jim-parry]

It looks like memcached is not supported on 7.3 or 7.4 yet ? :(

[samsonasik]

yes, it seems not yet supported, but probably, we can manually install something like:

   - if [[ $TRAVIS_PHP_VERSION = 7.3 ]]; then git clone https://github.com/php-memcached-dev/php-memcached.git && cd php-memcached && phpize && ./configure  && make && make install && echo "zend_extension = memcached.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini && cd ..; fi 

worth a try ?

[jim-parry]

with memcached not supported yet (per their website), I am not convinced that it makes sense to add 7.3 to the list of versions. We know it will fail.
Using "dist: trusty" makes sense, given that "dist:trusty" is being phased out.
I can't find an explanaiton of "group:edge" on the travis-site, and only some allusions to behaviour when it is used. What does this buy us?

[samsonasik]

I only got reference from this https://blog.travis-ci.com/2017-06-19-trusty-updates-2017-Q2 .
For some tests: with group:edge, I can got 7.4.0dev for nightly, and without it, I got only 7.3.0dev for nightly.

[jim-parry]

I see that you specified that the 7.3 build is allowed to fail, so it won't prevent us from moving forward with 7.1 & 7.2 ... will merge