Deprecate type aliases for WorldQuery::Fetch

[joseph-gio]

Objective

WorldQuery::Fetch is a type used to optimize the implementation of queries. These types are hidden and not intended to be outside of the engine, so there is no need to provide type aliases to make it easier to refer to them. If a user absolutely needs to refer to one of these types, they can always just refer to the associated type directly.

Solution

Deprecate these type aliases.

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Changelog

• Deprecated the type aliases QueryFetch and ROQueryFetch.

Migration Guide

The type aliases bevy_ecs::query::QueryFetch and ROQueryFetch have been deprecated. If you need to refer to a WorldQuery struct's fetch type, refer to the associated type defined on WorldQuery directly:

// Before:
type MyFetch<'w> = QueryFetch<'w, MyQuery>;
type MyFetchReadOnly<'w> = ROQueryFetch<'w, MyQuery>;

// After:
type MyFetch<'w> = <MyQuery as WorldQuery>::Fetch;
type MyFetchReadOnly<'w> = <<MyQuery as WorldQuery>::ReadOnly as WorldQuery>::Fetch;

[james7132]

Have you tried removing these from the codebase? I remember it cropping up a lot in generated code from WorldQuery derive macros. Removing these may actually end up with much less readable code, and that's a feat given the readability status of that macro right now.

[joseph-gio]

Everything still compiles when I remove them. Neither of these type aliases are currently used anywhere in the engine.

[alice-i-cecile]

I'm glad to see we no longer need this :)

[james7132]

If we can remove these without too much fuss, then I'm all for removing them.