build: Treat all warnings as errors

[plexoos]

These changes do not affect how the code is built by default using cons but allows one to interrupt compilation when the compiler (GCC 4.8.5) produces a warning.

cons EXTRA_CXXFLAGS="-Werror"

The source files matching the regex patterns in mgr/warnoff_dirs.txt are excluded from the above rule in order to let CI pass with known problems. We hope this will prevent introduction of questionable code in all other directories or new packages.

See issue #392

[plexoos]

Ready for review

[plexoos]

Any comments from the code owners?

[genevb]

To clarify, this allows pre-existing warnings in old codes to not trigger an alert in CI, while new codes will be monitored for such warnings and either fixed or added to this exclusion list?

Is there a clear (documented?) place to make change that would allow someone compiling the whole library to see the warnings for all codes again?

[plexoos]

Excellent questions, Gene. The answer to the first question is yes, that is how it is intended to work. With only one comment that the goal should be to shrink the exclusion list rather than adding new codes with questionable constructs. Warnings detect real bugs #431

For the second one, no special action needs to be taken, the warnings for the excluded paths will still appear in the build log, they just won't fail CI.

[plexoos]

If no more comments can we merge?

[plexoos]

@klendathu2k your last word 🥺

[klendathu2k]

Should be fine, and if/when it breaks the build we will fix.

[DanielWielanek]

Actually is a funny story.
For over two weeks, I had a problem with getting only the list of modified files. The script that worked on my local computer didn't work on GitHub servers. Then I found this plugin. As far as I remember, I was not able to connect both plugins correctly (I do not remember why). However, when I removed the plugin for getting the list of modified files, surprisingly, I noticed that the older script is working now. I suppose that by accident, I enabled some flags during tests :)
So in principle, this plugin actually helped me :)

[plexoos]

Cool story, wrong thread 🤣

Moved to #436 (comment)