Replace Coerce with RefCast in ListRef and TupleRef

Summary: Following diff D56123012 removes `#[derive(Coerce)]` for inner.

Reviewed By: JakobDegen

Differential Revision: D56123010

fbshipit-source-id: fae8bfb56e69dee1cfca3c9340cc6ebb7861cf0b

starlark/Cargo.toml

@@ -34,6 +34,7 @@ num-bigint = "0.4.3"
 num-traits = "0.2"
 once_cell = "1.8"
 paste = "1.0"
+ref-cast = "1.0.18"
 regex = "1.5.4"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"

starlark/src/values/types/list/refs.rs

@@ -19,30 +19,31 @@ use std::fmt;
 use std::fmt::Display;
 use std::ops::Deref;
 
-use crate as starlark;
+use ref_cast::ref_cast_custom;
+use ref_cast::RefCastCustom;
+
 use crate::coerce::coerce;
 use crate::typing::Ty;
 use crate::values::list::value::display_list;
 use crate::values::list::value::FrozenListData;
 use crate::values::list::value::ListGen;
 use crate::values::type_repr::StarlarkTypeRepr;
 use crate::values::types::list::value::ListData;
-use crate::values::Coerce;
 use crate::values::FrozenValue;
 use crate::values::UnpackValue;
 use crate::values::Value;
 use crate::values::ValueLike;
 
 /// Reference to list content (mutable or frozen).
 #[repr(transparent)]
-#[derive(Coerce)]
+#[derive(RefCastCustom)]
 pub struct ListRef<'v> {
     pub(crate) content: [Value<'v>],
 }
 
 /// Reference to frozen list content.
 #[repr(transparent)]
-#[derive(Coerce)]
+#[derive(RefCastCustom)]
 pub struct FrozenListRef {
     pub(crate) content: [FrozenValue],
 }
@@ -51,9 +52,8 @@ impl<'v> ListRef<'v> {
     /// `type([])`, which is `"list"`.
     pub const TYPE: &'static str = ListData::TYPE;
 
-    pub(crate) fn new<'a>(slice: &'a [Value<'v>]) -> &'a ListRef<'v> {
-        coerce(slice)
-    }
+    #[ref_cast_custom]
+    pub(crate) fn new<'a>(slice: &'a [Value<'v>]) -> &'a ListRef<'v>;
 
     /// List elements.
     pub fn content(&self) -> &[Value<'v>] {
@@ -90,9 +90,8 @@ impl FrozenListRef {
     /// `type([])`, which is `"list"`.
     pub const TYPE: &'static str = ListRef::TYPE;
 
-    fn new(slice: &[FrozenValue]) -> &FrozenListRef {
-        coerce(slice)
-    }
+    #[ref_cast_custom]
+    fn new(slice: &[FrozenValue]) -> &FrozenListRef;
 
     /// Downcast to the frozen list.
     ///

starlark/src/values/types/tuple/refs.rs

@@ -15,9 +15,9 @@
  * limitations under the License.
  */
 
-use crate as starlark;
-use crate::coerce::coerce;
-use crate::coerce::Coerce;
+use ref_cast::ref_cast_custom;
+use ref_cast::RefCastCustom;
+
 use crate::typing::Ty;
 use crate::values::type_repr::StarlarkTypeRepr;
 use crate::values::types::tuple::value::FrozenTuple;
@@ -28,15 +28,15 @@ use crate::values::Value;
 use crate::values::ValueLike;
 
 /// Reference to tuple data in Starlark heap.
-#[derive(Coerce, Debug)]
+#[derive(RefCastCustom, Debug)]
 #[repr(transparent)]
 pub struct TupleRef<'v> {
     contents: [Value<'v>],
 }
 
 /// Reference to tuple data in frozen Starlark heap.
 #[repr(transparent)]
-#[derive(Coerce, Debug)]
+#[derive(RefCastCustom, Debug)]
 pub struct FrozenTupleRef {
     contents: [FrozenValue],
 }
@@ -45,9 +45,12 @@ impl<'v> TupleRef<'v> {
     /// `type(())`, which is `"tuple"`.
     pub const TYPE: &'static str = FrozenTupleRef::TYPE;
 
+    #[ref_cast_custom]
+    fn new(slice: &'v [Value<'v>]) -> &'v TupleRef<'v>;
+
     /// Downcast a value to a tuple.
     pub fn from_value(value: Value<'v>) -> Option<&'v TupleRef<'v>> {
-        Some(coerce(Tuple::from_value(value)?.content()))
+        Some(Self::new(Tuple::from_value(value)?.content()))
     }
 
     /// Downcast a value to a tuple.
@@ -75,9 +78,12 @@ impl FrozenTupleRef {
     /// `type(())`, which is `"tuple"`.
     pub const TYPE: &'static str = FrozenTuple::TYPE;
 
+    #[ref_cast_custom]
+    fn new(slice: &'static [FrozenValue]) -> &'static FrozenTupleRef;
+
     /// Downcast a value to a tuple.
     pub fn from_frozen_value(value: FrozenValue) -> Option<&'static FrozenTupleRef> {
-        Some(coerce(value.downcast_ref::<FrozenTuple>()?.content()))
+        Some(Self::new(value.downcast_ref::<FrozenTuple>()?.content()))
     }
 
     /// Number of elements.