The gnulib manywarnings module is useful to add as many warnings as appropriate in a portable manner

https://www.gnu.org/software/gnulib/manual/html_node/manywar...

That's used in dev mode for various projects like GNU coreutils etc.

When distros etc. are building though these warnings are not used. It's worth stating as I've seen this issue many times, that -Werror at least should not be used by default for third parties building your code