Fix debug printing for dynamic types (#10740)

# Objective

Printing `DynamicStruct` with a debug format does not show the contained
type anymore. For instance, in `examples/reflection/reflection.rs`,
adding `dbg!(&reflect_value);` to line 96 will print:
```rust
[examples/reflection/reflection.rs:96] &reflect_value = DynamicStruct(bevy_reflect::DynamicStruct {
    a: 4,
    nested: DynamicStruct(bevy_reflect::DynamicStruct {
        b: 8,
    }),
})
```

## Solution

Show the represented type instead (`reflection::Foo` and
`reflection::Bar` in this case):
```rust
[examples/reflection/reflection.rs:96] &reflect_value = DynamicStruct(reflection::Foo {
    a: 4,
    nested: DynamicStruct(reflection::Bar {
        b: 8,
    }),
})
```

---------

Co-authored-by: Gino Valente <[email protected]>

crates/bevy_reflect/src/array.rs

@@ -5,7 +5,7 @@ use crate::{
 use bevy_reflect_derive::impl_type_path;
 use std::{
     any::{Any, TypeId},
-    fmt::Debug,
+    fmt::{Debug, Formatter},
     hash::{Hash, Hasher},
 };
 
@@ -301,6 +301,12 @@ impl Reflect for DynamicArray {
     fn is_dynamic(&self) -> bool {
         true
     }
+
+    fn debug(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "DynamicArray(")?;
+        array_debug(self, f)?;
+        write!(f, ")")
+    }
 }
 
 impl Array for DynamicArray {

crates/bevy_reflect/src/lib.rs

@@ -1927,6 +1927,73 @@ bevy_reflect::tests::Test {
         );
     }
 
+    #[test]
+    fn dynamic_types_debug_format() {
+        #[derive(Debug, Reflect)]
+        struct TestTupleStruct(u32);
+
+        #[derive(Debug, Reflect)]
+        enum TestEnum {
+            A(u32),
+            B,
+        }
+
+        #[derive(Debug, Reflect)]
+        // test DynamicStruct
+        struct TestStruct {
+            // test DynamicTuple
+            tuple: (u32, u32),
+            // test DynamicTupleStruct
+            tuple_struct: TestTupleStruct,
+            // test DynamicList
+            list: Vec<u32>,
+            // test DynamicArray
+            array: [u32; 3],
+            // test DynamicEnum
+            e: TestEnum,
+            // test DynamicMap
+            map: HashMap<u32, u32>,
+            // test reflected value
+            value: u32,
+        }
+        let mut map = HashMap::new();
+        map.insert(9, 10);
+        let mut test_struct = TestStruct {
+            tuple: (0, 1),
+            list: vec![2, 3, 4],
+            array: [5, 6, 7],
+            tuple_struct: TestTupleStruct(8),
+            e: TestEnum::A(11),
+            map,
+            value: 12,
+        }
+        .clone_value();
+        let test_struct = test_struct.downcast_mut::<DynamicStruct>().unwrap();
+
+        // test unknown DynamicStruct
+        let mut test_unknown_struct = DynamicStruct::default();
+        test_unknown_struct.insert("a", 13);
+        test_struct.insert("unknown_struct", test_unknown_struct);
+        // test unknown DynamicTupleStruct
+        let mut test_unknown_tuple_struct = DynamicTupleStruct::default();
+        test_unknown_tuple_struct.insert(14);
+        test_struct.insert("unknown_tuplestruct", test_unknown_tuple_struct);
+        assert_eq!(
+            format!("{:?}", test_struct),
+            "DynamicStruct(bevy_reflect::tests::TestStruct { \
+                tuple: DynamicTuple((0, 1)), \
+                tuple_struct: DynamicTupleStruct(bevy_reflect::tests::TestTupleStruct(8)), \
+                list: DynamicList([2, 3, 4]), \
+                array: DynamicArray([5, 6, 7]), \
+                e: DynamicEnum(A(11)), \
+                map: DynamicMap({9: 10}), \
+                value: 12, \
+                unknown_struct: DynamicStruct(_ { a: 13 }), \
+                unknown_tuplestruct: DynamicTupleStruct(_(14)) \
+            })"
+        );
+    }
+
     #[cfg(feature = "glam")]
     mod glam {
         use super::*;

crates/bevy_reflect/src/struct_trait.rs

@@ -543,7 +543,12 @@ pub fn struct_partial_eq<S: Struct>(a: &S, b: &dyn Reflect) -> Option<bool> {
 /// ```
 #[inline]
 pub fn struct_debug(dyn_struct: &dyn Struct, f: &mut Formatter<'_>) -> std::fmt::Result {
-    let mut debug = f.debug_struct(dyn_struct.reflect_type_path());
+    let mut debug = f.debug_struct(
+        dyn_struct
+            .get_represented_type_info()
+            .map(|s| s.type_path())
+            .unwrap_or("_"),
+    );
     for field_index in 0..dyn_struct.field_len() {
         let field = dyn_struct.field_at(field_index).unwrap();
         debug.field(

crates/bevy_reflect/src/tuple_struct.rs

@@ -453,7 +453,12 @@ pub fn tuple_struct_debug(
     dyn_tuple_struct: &dyn TupleStruct,
     f: &mut Formatter<'_>,
 ) -> std::fmt::Result {
-    let mut debug = f.debug_tuple(dyn_tuple_struct.reflect_type_path());
+    let mut debug = f.debug_tuple(
+        dyn_tuple_struct
+            .get_represented_type_info()
+            .map(|s| s.type_path())
+            .unwrap_or("_"),
+    );
     for field in dyn_tuple_struct.iter_fields() {
         debug.field(&field as &dyn Debug);
     }