`bevy_platform` depends on `getrandom` but doesn't need to

[kpreid]

What problem does this solve or what need does it fill?

Newly in Bevy 0.17, bevy_platform depends on getrandom 0.3, solely for the purpose of enabling the wasm_js feature. This means that all dependents of bevy_platform compiling for the web must do the RUSTFLAGS=--cfg thing, even if they are not using getrandom anywhere else at all — such as if they using bevy_ecs but not bevy_math.

It would be nice if users of bevy_ecs alone did not have to deal with rustflags configuration, since it composes poorly — for example, RUSTFLAGS=-Dwarnings, such as one might do in CI, will overwrite the configuration.

(Also, from a build performance perspective, it's an unnecessary dependency on getrandom.)

What solution would you like?

One of:

• Remove this dependency on getrandom entirely — obligate application developers to have a dep and a rustflags config instead of just a dep. This would be a breaking change, so it can't happen for 0.17.
• Move the dependency on getrandom somewhere more root-ward in the dependency graph of bevy, such as bevy_math. This might manage to not be a breaking change, at least for users of bevy as a whole, but I don’t know if the overall dependency graph is such that this is possible.

What alternative(s) have you considered?

Do nothing; continue to obligate all users of bevy_ecs to depend on getrandom and do the configuration.

Additional context

I regret not having noticed this issue — or at least, not having thought to check whether it would be possible to fix as opposed to necessary to live with — sooner so as to report it in the release candidate period.

[alice-i-cecile]

Indeed :( I am generally pretty malcontent with this situation. I think that bevy_ecs is the wrong place for this. bevy itself might make sense, or bevy_math.

[cwfitzgerald]

rust-random/getrandom#730 May also make this better

[NaHCO3-code]

Additionally, the current guide for examples is missing these setup instructions. Therefore, following the guide exactly will result in compilation failure, which is confusing.