[mrout]

-pedantic-errors -Wall -Werror isn't used in the wild because it breaks whenever a new compiler comes out. New compilers often come out with new warnings, new cases for old warnings, etc. It's not forwards-compatible to make warnings errors.

You should release your code with no warnings on the current compiler, but new warnings shouldn't break everything.

[aumerle]

-Werror is used only when building on the continuous integration servers, not in the released code. That way, you get the best of both worlds. Your code wont break on new compiler releases, but it also wont have neglected warnings.