[Heads-up] ECM 5.96 KDECompilerSettings will add -Werror=undef to GCC/Clang build flags

[Ahmad Samir]

This[1] should catch undefined preprocessor expressions, i.e. instead of
showing a warning if FOO_BAR_H is undefined:
  #if FOO_BAR_H

make the build fail with an error instead.

This combined with using #cmakedefine01 (instead of #cmakedefine), could
catch things like:
https://invent.kde.org/pim/kdepim-runtime/-/commit/05a0e5bbfbb06ed6aa88640f25f563cf7e5b1330


[1]https://invent.kde.org/frameworks/extra-cmake-modules/-/commit/25bbb2a4776d36b542857709bb0448a7ea030b59

Regards
Ahmad Samir