1 files changed, 99 insertions, 0 deletions
diff --git a/vendor/chalk-solve-0.87.0/src/clauses/generalize.rs b/vendor/chalk-solve-0.87.0/src/clauses/generalize.rs
new file mode 100644
index 000000000..bff05b369
--- /dev/null
+++ b/vendor/chalk-solve-0.87.0/src/clauses/generalize.rs
@@ -0,0 +1,99 @@
+//! This gets rid of free variables in a type by replacing them by fresh bound
+//! ones. We use this when building clauses that contain types passed to
+//! `program_clauses`; these may contain variables, and just copying those
+//! variables verbatim leads to problems. Instead, we return a slightly more
+//! general program clause, with new variables in those places. This can only
+//! happen with `dyn Trait` currently; that's the only case where we use the
+//! types passed to `program_clauses` in the clauses we generate.
+
+use chalk_derive::FallibleTypeFolder;
+use chalk_ir::{
+    fold::{TypeFoldable, TypeFolder},
+    interner::{HasInterner, Interner},
+    Binders, BoundVar, Const, ConstData, ConstValue, DebruijnIndex, Lifetime, LifetimeData, Ty,
+    TyKind, TyVariableKind, VariableKind, VariableKinds,
+};
+use rustc_hash::FxHashMap;
+
+#[derive(FallibleTypeFolder)]
+pub struct Generalize<I: Interner> {
+    binders: Vec<VariableKind<I>>,
+    mapping: FxHashMap<BoundVar, usize>,
+    interner: I,
+}
+
+impl<I: Interner> Generalize<I> {
+    pub fn apply<T>(interner: I, value: T) -> Binders<T>
+    where
+        T: HasInterner<Interner = I> + TypeFoldable<I>,
+    {
+        let mut generalize = Generalize {
+            binders: Vec::new(),
+            mapping: FxHashMap::default(),
+            interner,
+        };
+        let value = value
+            .try_fold_with(&mut generalize, DebruijnIndex::INNERMOST)
+            .unwrap();
+        Binders::new(
+            VariableKinds::from_iter(interner, generalize.binders),
+            value,
+        )
+    }
+}
+
+impl<I: Interner> TypeFolder<I> for Generalize<I> {
+    fn as_dyn(&mut self) -> &mut dyn TypeFolder<I> {
+        self
+    }
+
+    fn fold_free_var_ty(&mut self, bound_var: BoundVar, outer_binder: DebruijnIndex) -> Ty<I> {
+        let binder_vec = &mut self.binders;
+        let new_index = self.mapping.entry(bound_var).or_insert_with(|| {
+            let i = binder_vec.len();
+            binder_vec.push(VariableKind::Ty(TyVariableKind::General));
+            i
+        });
+        let new_var = BoundVar::new(outer_binder, *new_index);
+        TyKind::BoundVar(new_var).intern(TypeFolder::interner(self))
+    }
+
+    fn fold_free_var_const(
+        &mut self,
+        ty: Ty<I>,
+        bound_var: BoundVar,
+        outer_binder: DebruijnIndex,
+    ) -> Const<I> {
+        let binder_vec = &mut self.binders;
+        let new_index = self.mapping.entry(bound_var).or_insert_with(|| {
+            let i = binder_vec.len();
+            binder_vec.push(VariableKind::Const(ty.clone()));
+            i
+        });
+        let new_var = BoundVar::new(outer_binder, *new_index);
+        ConstData {
+            ty,
+            value: ConstValue::BoundVar(new_var),
+        }
+        .intern(TypeFolder::interner(self))
+    }
+
+    fn fold_free_var_lifetime(
+        &mut self,
+        bound_var: BoundVar,
+        outer_binder: DebruijnIndex,
+    ) -> Lifetime<I> {
+        let binder_vec = &mut self.binders;
+        let new_index = self.mapping.entry(bound_var).or_insert_with(|| {
+            let i = binder_vec.len();
+            binder_vec.push(VariableKind::Lifetime);
+            i
+        });
+        let new_var = BoundVar::new(outer_binder, *new_index);
+        LifetimeData::BoundVar(new_var).intern(TypeFolder::interner(self))
+    }
+
+    fn interner(&self) -> I {
+        self.interner
+    }
+}