From daa8bf20dfb0d5e3e2c8dbd032d532bde133f221 Mon Sep 17 00:00:00 2001
From: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
Date: Tue, 28 Nov 2023 18:46:09 -0700
Subject: [PATCH] Fix nested generics in Reflect derive (#10791)

# Objective

> Issue raised on
[Discord](https://discord.com/channels/691052431525675048/1002362493634629796/1179182488787103776)

Currently the following code fails due to a missing `TypePath` bound:

```rust
#[derive(Reflect)] struct Foo<T>(T);
#[derive(Reflect)] struct Bar<T>(Foo<T>);
#[derive(Reflect)] struct Baz<T>(Bar<Foo<T>>);
```

## Solution

Add `TypePath` to the per-field bounds instead of _just_ the generic
type parameter bounds.

### Related Work

It should be noted that #9046 would help make these kinds of issues
easier to work around and/or avoid entirely.

---

## Changelog

- Fixes missing `TypePath` requirement when deriving `Reflect` on nested
generics
---
 .../bevy_reflect_derive/src/utility.rs           |  4 ++--
 .../tests/reflect_derive/nested.pass.rs          | 16 ++++++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 crates/bevy_reflect_compile_fail_tests/tests/reflect_derive/nested.pass.rs

diff --git a/crates/bevy_reflect/bevy_reflect_derive/src/utility.rs b/crates/bevy_reflect/bevy_reflect_derive/src/utility.rs
index 0cd4c88b4c..1adc5787e5 100644
--- a/crates/bevy_reflect/bevy_reflect_derive/src/utility.rs
+++ b/crates/bevy_reflect/bevy_reflect_derive/src/utility.rs
@@ -132,9 +132,9 @@ impl WhereClauseOptions {
                 let custom_bounds = active_bounds(field).map(|bounds| quote!(+ #bounds));
 
                 let bounds = if is_from_reflect {
-                    quote!(#bevy_reflect_path::FromReflect #custom_bounds)
+                    quote!(#bevy_reflect_path::FromReflect + #bevy_reflect_path::TypePath #custom_bounds)
                 } else {
-                    quote!(#bevy_reflect_path::Reflect #custom_bounds)
+                    quote!(#bevy_reflect_path::Reflect + #bevy_reflect_path::TypePath #custom_bounds)
                 };
 
                 (ty, bounds)
diff --git a/crates/bevy_reflect_compile_fail_tests/tests/reflect_derive/nested.pass.rs b/crates/bevy_reflect_compile_fail_tests/tests/reflect_derive/nested.pass.rs
new file mode 100644
index 0000000000..8be4d79e41
--- /dev/null
+++ b/crates/bevy_reflect_compile_fail_tests/tests/reflect_derive/nested.pass.rs
@@ -0,0 +1,16 @@
+use bevy_reflect::Reflect;
+
+mod nested_generics {
+    use super::*;
+
+    #[derive(Reflect)]
+    struct Foo<T>(T);
+
+    #[derive(Reflect)]
+    struct Bar<T>(Foo<T>);
+
+    #[derive(Reflect)]
+    struct Baz<T>(Bar<Foo<T>>);
+}
+
+fn main() {}