1 files changed, 73 insertions, 0 deletions
diff --git a/vendor/chalk-ir/src/fold/binder_impls.rs b/vendor/chalk-ir/src/fold/binder_impls.rs
new file mode 100644
index 000000000..1f44c1629
--- /dev/null
+++ b/vendor/chalk-ir/src/fold/binder_impls.rs
@@ -0,0 +1,73 @@
+//! This module contains impls of `TypeFoldable` for those types that
+//! introduce binders.
+//!
+//! The more interesting impls of `TypeFoldable` remain in the `fold` module.
+
+use crate::*;
+
+impl<I: Interner> TypeFoldable<I> for FnPointer<I> {
+    fn try_fold_with<E>(
+        self,
+        folder: &mut dyn FallibleTypeFolder<I, Error = E>,
+        outer_binder: DebruijnIndex,
+    ) -> Result<Self, E> {
+        let FnPointer {
+            num_binders,
+            substitution,
+            sig,
+        } = self;
+        Ok(FnPointer {
+            num_binders,
+            substitution: substitution.try_fold_with(folder, outer_binder.shifted_in())?,
+            sig: FnSig {
+                abi: sig.abi,
+                safety: sig.safety,
+                variadic: sig.variadic,
+            },
+        })
+    }
+}
+
+impl<T, I: Interner> TypeFoldable<I> for Binders<T>
+where
+    T: HasInterner<Interner = I> + TypeFoldable<I>,
+    I: Interner,
+{
+    fn try_fold_with<E>(
+        self,
+        folder: &mut dyn FallibleTypeFolder<I, Error = E>,
+        outer_binder: DebruijnIndex,
+    ) -> Result<Self, E> {
+        let Binders {
+            binders: self_binders,
+            value: self_value,
+        } = self;
+        let value = self_value.try_fold_with(folder, outer_binder.shifted_in())?;
+        let binders = VariableKinds {
+            interned: self_binders.interned().clone(),
+        };
+        Ok(Binders::new(binders, value))
+    }
+}
+
+impl<I, T> TypeFoldable<I> for Canonical<T>
+where
+    I: Interner,
+    T: HasInterner<Interner = I> + TypeFoldable<I>,
+{
+    fn try_fold_with<E>(
+        self,
+        folder: &mut dyn FallibleTypeFolder<I, Error = E>,
+        outer_binder: DebruijnIndex,
+    ) -> Result<Self, E> {
+        let Canonical {
+            binders: self_binders,
+            value: self_value,
+        } = self;
+        let value = self_value.try_fold_with(folder, outer_binder.shifted_in())?;
+        let binders = CanonicalVarKinds {
+            interned: self_binders.interned().clone(),
+        };
+        Ok(Canonical { binders, value })
+    }
+}