Harden proc macro path resolution and add integration tests. (#17330)

This pr uses the `extern crate self as` trick to make proc macros behave
the same way inside and outside bevy.

# Objective

- Removes noise introduced by `crate as` in the whole bevy repo.
- Fixes #17004.
- Hardens proc macro path resolution.

## TODO

- [x] `BevyManifest` needs cleanup.
- [x] Cleanup remaining `crate as`.
- [x] Add proper integration tests to the ci.

## Notes

- `cargo-manifest-proc-macros` is written by me and based/inspired by
the old `BevyManifest` implementation and
[`bkchr/proc-macro-crate`](https://github.com/bkchr/proc-macro-crate).
- What do you think about the new integration test machinery I added to
the `ci`?
  More and better integration tests can be added at a later stage.
The goal of these integration tests is to simulate an actual separate
crate that uses bevy. Ideally they would lightly touch all bevy crates.

## Testing

- Needs RA test
- Needs testing from other users
- Others need to run at least `cargo run -p ci integration-test` and
verify that they work.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>

Author: raldone01

.gitignore

@@ -7,6 +7,7 @@ crates/**/target
 benches/**/target
 tools/**/target
 **/*.rs.bk
+rustc-ice-*.txt
 
 # DX12 wgpu backend
 dxcompiler.dll

Cargo.toml

@@ -29,6 +29,10 @@ members = [
   # Bevy's error codes. This is a crate so we can automatically check all of the code blocks.
   "errors",
 ]
+exclude = [
+  # Integration tests are not part of the workspace
+  "tests-integration",
+]
 
 [workspace.lints.clippy]
 doc_markdown = "warn"
@@ -494,6 +498,13 @@ serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 bytemuck = "1.7"
 bevy_render = { path = "crates/bevy_render", version = "0.16.0-dev", default-features = false }
+# The following explicit dependencies are needed for proc macros to work inside of examples as they are part of the bevy crate itself.
+bevy_ecs = { path = "crates/bevy_ecs", version = "0.16.0-dev", default-features = false }
+bevy_state = { path = "crates/bevy_state", version = "0.16.0-dev", default-features = false }
+bevy_asset = { path = "crates/bevy_asset", version = "0.16.0-dev", default-features = false }
+bevy_reflect = { path = "crates/bevy_reflect", version = "0.16.0-dev", default-features = false }
+bevy_image = { path = "crates/bevy_image", version = "0.16.0-dev", default-features = false }
+bevy_gizmos = { path = "crates/bevy_gizmos", version = "0.16.0-dev", default-features = false }
 # Needed to poll Task examples
 futures-lite = "2.0.1"
 async-std = "1.13"

benches/benches/bevy_ecs/change_detection.rs

@@ -267,7 +267,7 @@ fn none_changed_detection(criterion: &mut Criterion) {
     }
 }
 fn insert_if_bit_enabled<const B: u16>(entity: &mut EntityWorldMut, i: u16) {
-    if i & 1 << B != 0 {
+    if i & (1 << B) != 0 {
         entity.insert(Data::<B>(1.0));
     }
 }

benches/benches/bevy_ecs/components/archetype_updates.rs

@@ -22,7 +22,7 @@ fn setup(system_count: usize) -> (World, Schedule) {
 }
 
 fn insert_if_bit_enabled<const B: u16>(entity: &mut EntityWorldMut, i: u16) {
-    if i & 1 << B != 0 {
+    if i & (1 << B) != 0 {
         entity.insert(A::<B>(1.0));
     }
 }

benches/benches/bevy_ecs/empty_archetypes.rs

@@ -105,49 +105,49 @@ fn add_archetypes(world: &mut World, count: u16) {
         e.insert(A::<10>(1.0));
         e.insert(A::<11>(1.0));
         e.insert(A::<12>(1.0));
-        if i & 1 << 1 != 0 {
+        if i & (1 << 1) != 0 {
             e.insert(A::<13>(1.0));
         }
-        if i & 1 << 2 != 0 {
+        if i & (1 << 2) != 0 {
             e.insert(A::<14>(1.0));
         }
-        if i & 1 << 3 != 0 {
+        if i & (1 << 3) != 0 {
             e.insert(A::<15>(1.0));
         }
-        if i & 1 << 4 != 0 {
+        if i & (1 << 4) != 0 {
             e.insert(A::<16>(1.0));
         }
-        if i & 1 << 5 != 0 {
+        if i & (1 << 5) != 0 {
             e.insert(A::<18>(1.0));
         }
-        if i & 1 << 6 != 0 {
+        if i & (1 << 6) != 0 {
             e.insert(A::<19>(1.0));
         }
-        if i & 1 << 7 != 0 {
+        if i & (1 << 7) != 0 {
             e.insert(A::<20>(1.0));
         }
-        if i & 1 << 8 != 0 {
+        if i & (1 << 8) != 0 {
             e.insert(A::<21>(1.0));
         }
-        if i & 1 << 9 != 0 {
+        if i & (1 << 9) != 0 {
             e.insert(A::<22>(1.0));
         }
-        if i & 1 << 10 != 0 {
+        if i & (1 << 10) != 0 {
             e.insert(A::<23>(1.0));
         }
-        if i & 1 << 11 != 0 {
+        if i & (1 << 11) != 0 {
             e.insert(A::<24>(1.0));
         }
-        if i & 1 << 12 != 0 {
+        if i & (1 << 12) != 0 {
             e.insert(A::<25>(1.0));
         }
-        if i & 1 << 13 != 0 {
+        if i & (1 << 13) != 0 {
             e.insert(A::<26>(1.0));
         }
-        if i & 1 << 14 != 0 {
+        if i & (1 << 14) != 0 {
             e.insert(A::<27>(1.0));
         }
-        if i & 1 << 15 != 0 {
+        if i & (1 << 15) != 0 {
             e.insert(A::<28>(1.0));
         }
     }

benches/benches/bevy_ecs/iteration/par_iter_simple.rs

@@ -19,7 +19,7 @@ struct Data<const X: u16>(f32);
 pub struct Benchmark<'w>(World, QueryState<(&'w Velocity, &'w mut Position)>);
 
 fn insert_if_bit_enabled<const B: u16>(entity: &mut EntityWorldMut, i: u16) {
-    if i & 1 << B != 0 {
+    if i & (1 << B) != 0 {
         entity.insert(Data::<B>(1.0));
     }
 }

crates/bevy_app/src/app.rs

@@ -1532,7 +1532,6 @@ mod tests {
     #[test]
     fn test_derive_app_label() {
         use super::AppLabel;
-        use crate::{self as bevy_app};
 
         #[derive(AppLabel, Debug, Default, Clone, Copy, PartialEq, Eq, Hash)]
         struct UnitLabel;
@@ -1664,7 +1663,6 @@ mod tests {
     #[test]
     fn test_extract_sees_changes() {
         use super::AppLabel;
-        use crate::{self as bevy_app};
 
         #[derive(AppLabel, Clone, Copy, Hash, PartialEq, Eq, Debug)]
         struct MySubApp;

crates/bevy_app/src/lib.rs

@@ -20,6 +20,9 @@ extern crate std;
 
 extern crate alloc;
 
+// Required to make proc macros work in bevy itself.
+extern crate self as bevy_app;
+
 mod app;
 mod main_schedule;
 mod panic_handler;

crates/bevy_asset/src/asset_changed.rs

@@ -282,7 +282,7 @@ unsafe impl<A: AsAssetId> QueryFilter for AssetChanged<A> {
 
 #[cfg(test)]
 mod tests {
-    use crate::{self as bevy_asset, AssetEvents, AssetPlugin, Handle};
+    use crate::{AssetEvents, AssetPlugin, Handle};
     use alloc::{vec, vec::Vec};
     use core::num::NonZero;
     use std::println;

crates/bevy_asset/src/assets.rs

@@ -1,8 +1,5 @@
 use crate::asset_changed::AssetChanges;
-use crate::{
-    self as bevy_asset, Asset, AssetEvent, AssetHandleProvider, AssetId, AssetServer, Handle,
-    UntypedHandle,
-};
+use crate::{Asset, AssetEvent, AssetHandleProvider, AssetId, AssetServer, Handle, UntypedHandle};
 use alloc::{sync::Arc, vec::Vec};
 use bevy_ecs::{
     prelude::EventWriter,