BC guidelines don't tell about static methods

[nicolas-grekas]

So that we give no promise nor instruction on how static methods can or not become non-static, and vice versa

[wouterj]

Ping @webmozart @fabpot

[stof]

A static method cannot become non-static. It is a BC break (you cannot call it statically anymore).

for the opposite, it cannot change in @api as it would break child classes. for non @api classes, we need to decide what we allow

[nicolas-grekas]

After testing, when extending a class, it's a fatal error when static is added or removed.
So we should maybe just say it's always forbidden.

[stof]

if it is a fatal error, it is indeed forbidden

[cordoval]

do we add a note on this then or this settles it?

[cordoval]

😊 thanks folks!