Bevy's HashSet missing some functionality

[TheLeonsver1]

Bevy version

0.5

Operating system & version

Windows 10.

What you did

tried to initiate a HashSet with with_capactity()

What you expected to happen

A HashSet to be initiated with the wanted capacity.

What actually happened

rustc error https://doc.rust-lang.org/error-index.html#E0599

Additional information

no.

[TehPers]

The standard implementations for HashSet and HashMap implement new() and with_capacity() only for std's RandomState. Since bevy re-exports them with ahash's RandomState, we lose those implementations. This could be worked around by creating an extension trait when working with ahash versions of those data structures.

[cart]

We actually used to have this, but @bjorn3 removed it in #1235 to cut down on compile times. I'll let them respond here with rationale for / against.

[bjorn3]

It was just a slight improvement if I recall correctly. The majority of the change was in the last commit of that PR. I replaced a HashMap::with_capacity(size) (where with_capacity came from AHashExt) with HashMap::with_capacity_and_hasher(size, Default::default()). The former is more elegant than the later so I guess it is fine to reintroduce AHashExt for just with_capacity. HashMap::new() is not significantly nicer than HashMap::default() so I have a slight preference for not reintroducing AHashExt::new.

[cart]

Cool cool. Then I think its worth adding it back, as the whole point is to abstract out the hasher. I also agree that we don't need new().