Curves: FromReflect boogaloo part 2 (#15714)

# Objective

Allow curve adaptors to be reliably `Reflect` even if the curves they
hold are not `FromReflect`. This allows them, for example, to be used in
`bevy_animation`. I previously addressed this with the functional
adaptors, but I forgot to address this in the case of fields that hold
other curves and not arbitrary functions.

## Solution

Do the following on every curve adaptor that holds another curve:
```rust
// old:
#[derive(Reflect)]
```

```rust
// new:
#[derive(Reflect, FromReflect)]
#[reflect(from_reflect = false)]
```

This looks inane, but it's necessary because the default
`#[derive(Reflect)]` macro places `FromReflect` bounds on everything. To
avoid this, we opt out of deriving `FromReflect` with that macro by
adding `#[reflect(from_reflect = false)]`, then separately derive
`FromReflect`. (Of course, the latter still has the `FromReflect`
bounds, which is fine.)

crates/bevy_math/src/curve/adaptors.rs

@@ -9,7 +9,7 @@ use core::fmt::{self, Debug};
 use core::marker::PhantomData;
 
 #[cfg(feature = "bevy_reflect")]
-use bevy_reflect::{utility::GenericTypePathCell, Reflect, TypePath};
+use bevy_reflect::{utility::GenericTypePathCell, FromReflect, Reflect, TypePath};
 
 #[cfg(feature = "bevy_reflect")]
 mod paths {
@@ -368,7 +368,7 @@ where
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
 #[cfg_attr(
     feature = "bevy_reflect",
-    derive(Reflect),
+    derive(Reflect, FromReflect),
     reflect(from_reflect = false)
 )]
 pub struct LinearReparamCurve<T, C> {
@@ -401,7 +401,11 @@ where
 /// sample times before sampling. Curves of this type are produced by [`Curve::reparametrize_by_curve`].
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[cfg_attr(feature = "bevy_reflect", derive(Reflect))]
+#[cfg_attr(
+    feature = "bevy_reflect",
+    derive(Reflect, FromReflect),
+    reflect(from_reflect = false)
+)]
 pub struct CurveReparamCurve<T, C, D> {
     pub(crate) base: C,
     pub(crate) reparam_curve: D,
@@ -430,7 +434,11 @@ where
 /// produced by [`Curve::graph`].
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[cfg_attr(feature = "bevy_reflect", derive(Reflect))]
+#[cfg_attr(
+    feature = "bevy_reflect",
+    derive(Reflect, FromReflect),
+    reflect(from_reflect = false)
+)]
 pub struct GraphCurve<T, C> {
     pub(crate) base: C,
     #[cfg_attr(feature = "bevy_reflect", reflect(ignore))]
@@ -456,7 +464,11 @@ where
 /// of this type are produced by [`Curve::zip`].
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[cfg_attr(feature = "bevy_reflect", derive(Reflect))]
+#[cfg_attr(
+    feature = "bevy_reflect",
+    derive(Reflect, FromReflect),
+    reflect(from_reflect = false)
+)]
 pub struct ZipCurve<S, T, C, D> {
     pub(crate) domain: Interval,
     pub(crate) first: C,
@@ -493,7 +505,11 @@ where
 /// Curves of this type are produced by [`Curve::chain`].
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[cfg_attr(feature = "bevy_reflect", derive(Reflect))]
+#[cfg_attr(
+    feature = "bevy_reflect",
+    derive(Reflect, FromReflect),
+    reflect(from_reflect = false)
+)]
 pub struct ChainCurve<T, C, D> {
     pub(crate) first: C,
     pub(crate) second: D,
@@ -539,7 +555,11 @@ where
 /// The original curve's domain must be bounded to get a valid [`ReverseCurve`].
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[cfg_attr(feature = "bevy_reflect", derive(Reflect))]
+#[cfg_attr(
+    feature = "bevy_reflect",
+    derive(Reflect, FromReflect),
+    reflect(from_reflect = false)
+)]
 pub struct ReverseCurve<T, C> {
     pub(crate) curve: C,
     #[cfg_attr(feature = "bevy_reflect", reflect(ignore))]
@@ -576,7 +596,11 @@ where
 /// The original curve's domain must be bounded to get a valid [`RepeatCurve`].
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[cfg_attr(feature = "bevy_reflect", derive(Reflect))]
+#[cfg_attr(
+    feature = "bevy_reflect",
+    derive(Reflect, FromReflect),
+    reflect(from_reflect = false)
+)]
 pub struct RepeatCurve<T, C> {
     pub(crate) domain: Interval,
     pub(crate) curve: C,
@@ -621,7 +645,11 @@ where
 /// The original curve's domain must be bounded to get a valid [`ForeverCurve`].
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[cfg_attr(feature = "bevy_reflect", derive(Reflect))]
+#[cfg_attr(
+    feature = "bevy_reflect",
+    derive(Reflect, FromReflect),
+    reflect(from_reflect = false)
+)]
 pub struct ForeverCurve<T, C> {
     pub(crate) curve: C,
     #[cfg_attr(feature = "bevy_reflect", reflect(ignore))]
@@ -661,7 +689,11 @@ where
 /// The original curve's domain must be right-finite to get a valid [`PingPongCurve`].
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[cfg_attr(feature = "bevy_reflect", derive(Reflect))]
+#[cfg_attr(
+    feature = "bevy_reflect",
+    derive(Reflect, FromReflect),
+    reflect(from_reflect = false)
+)]
 pub struct PingPongCurve<T, C> {
     pub(crate) curve: C,
     #[cfg_attr(feature = "bevy_reflect", reflect(ignore))]
@@ -711,7 +743,11 @@ where
 /// valid [`ContinuationCurve`].
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[cfg_attr(feature = "bevy_reflect", derive(Reflect))]
+#[cfg_attr(
+    feature = "bevy_reflect",
+    derive(Reflect, FromReflect),
+    reflect(from_reflect = false)
+)]
 pub struct ContinuationCurve<T, C, D> {
     pub(crate) first: C,
     pub(crate) second: D,

crates/bevy_math/src/curve/easing.rs

@@ -31,7 +31,11 @@ impl Easing<f32> for ElasticCurve {}
 /// [unit interval]: `Interval::UNIT`
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[cfg_attr(feature = "bevy_reflect", derive(bevy_reflect::Reflect))]
+#[cfg_attr(
+    feature = "bevy_reflect",
+    derive(bevy_reflect::Reflect, bevy_reflect::FromReflect),
+    reflect(from_reflect = false)
+)]
 pub struct EasingCurve<T, E>
 where
     T: VectorSpace,