MDEV-10750 - travis: gcc-5 and gcc-6

[grooverdan]

depends on no_ipv6 PR to succeed.

I submit this under the MCA.

[svoj]

@grooverdan, thanks for your contribution!

@ottok, could you handle this PR?

[ottok]

Thanks @grooverdan ! Unfortunately the test suite failed. Should you force push a fixed version before anybody reviews the details?

@svoj Please assign this to yourself, I have no particular domain knowledge about GCC versions or how they affect MariaDB.

[svoj]

Hi Daniel,

Thanks for your contribution. JIRA task has been created to track this pull request: https://jira.mariadb.org/browse/MDEV-10750

This task was added to 10.2.3 backlog, which is planned to be handled between 2016-09-22 and 2016-09-29.

Thanks,
Sergey

[svoj]

@ottok, FWICS test suite failure doesn't relate to this PR. Also I believe this PR is properply assigned: you have best domain knowledge of Travis, current Travis configuration is yours too.

@grooverdan, what was the rationale of this PR?

[grooverdan]

rational is to test against modern a variety of gcc version, particularly later versions, to ensure that warnings or errors can be corrected as code gets developed. This makes the code merged future resistant and reduces the development burden by avoid revisiting and re-factoring code in 6+ months when some user tries it against a modern gcc version.

[grooverdan]

@cvicentiu , have the gcc-6 issues related to this pointers been resolved?

[svoj]

@grooverdan, is this change still relevant? Does it depend on other PR's?

[grooverdan]

Still relevent. doesn't depend on other PRs.