`BevyManifest` incorrectly assumes that all crates starting with `bevy_` are exposed through `::bevy::`

[raldone01]

bevy/crates/bevy_macro_utils/src/bevy_manifest.rs

Lines 14 to 18 in 153ce46

	fn get_re_exported_crate_path(&self, crate_name: &str) -> Option<PathPiece> {
	crate_name.strip_prefix("bevy_").map(|s| {
	let mut path = PathPiece::new();
	path.push(syn::parse_str::<syn::PathSegment>(s).unwrap());
	path

When I modified BevyManifest, I thought that it was bevy internal. However it is also used by https://github.com/bevyengine/bevy_editor_prototypes/blob/f41e2240174e29f1c9206bb6b080431463466ea5/crates/bevy_bsn/src/macros/src/derive_construct.rs#L14-L16 and possibly in other crates too. As long as only official bevy crates are resolved though it, there are no issues.

However, should a user crate that extends bevy and is named bevy_... use the BevyManifest in their proc macros, it will incorrectly assume their crate is available through ::bevy::.

A fix would be to only strip the prefix from the bevy_ crates that are actually available through ::bevy::.

I can create a pr for this and see two options:

1. List dir in crates/ to get all the bevy internal crates. More complex but should automatically keep up with bevy but possibly yield wrong results if crates are added that are not rexported through bevy.
2. Just using a manual string list. Simpler but needs to be kept in sync manually.

[alice-i-cecile]

I would prefer solution 1. We would definitely desync this pretty quickly.

[raldone01]

I investigated solution 1.

Unfortunately bevy_macro_utils has no way of knowing which bevy crates are official and re-exported through the bevy crate. I have attached an image of all the files bevy_macro_utils has access to, if it is downloaded as a dependency.

I can write a script to generate rust source code with a static str slice of all official bevy crates. However, I don't know how to best hook it into the build process.