Use extension trait derive

compiler/rustc_infer/src/infer/canonical/instantiate.rs

@@ -13,30 +13,10 @@ use rustc_middle::ty::{self, TyCtxt};
 
 /// FIXME(-Znext-solver): This or public because it is shared with the
 /// new trait solver implementation. We should deduplicate canonicalization.
-pub trait CanonicalExt<'tcx, V> {
+#[extension]
+pub impl<'tcx, V> CanonicalExt<'tcx, V> for Canonical<'tcx, V> {
     /// Instantiate the wrapped value, replacing each canonical value
     /// with the value given in `var_values`.
-    fn instantiate(&self, tcx: TyCtxt<'tcx>, var_values: &CanonicalVarValues<'tcx>) -> V
-    where
-        V: TypeFoldable<TyCtxt<'tcx>>;
-
-    /// Allows one to apply a instantiation to some subset of
-    /// `self.value`. Invoke `projection_fn` with `self.value` to get
-    /// a value V that is expressed in terms of the same canonical
-    /// variables bound in `self` (usually this extracts from subset
-    /// of `self`). Apply the instantiation `var_values` to this value
-    /// V, replacing each of the canonical variables.
-    fn instantiate_projected<T>(
-        &self,
-        tcx: TyCtxt<'tcx>,
-        var_values: &CanonicalVarValues<'tcx>,
-        projection_fn: impl FnOnce(&V) -> T,
-    ) -> T
-    where
-        T: TypeFoldable<TyCtxt<'tcx>>;
-}
-
-impl<'tcx, V> CanonicalExt<'tcx, V> for Canonical<'tcx, V> {
     fn instantiate(&self, tcx: TyCtxt<'tcx>, var_values: &CanonicalVarValues<'tcx>) -> V
     where
         V: TypeFoldable<TyCtxt<'tcx>>,
@@ -44,6 +24,12 @@ impl<'tcx, V> CanonicalExt<'tcx, V> for Canonical<'tcx, V> {
         self.instantiate_projected(tcx, var_values, |value| value.clone())
     }
 
+    /// Allows one to apply a instantiation to some subset of
+    /// `self.value`. Invoke `projection_fn` with `self.value` to get
+    /// a value V that is expressed in terms of the same canonical
+    /// variables bound in `self` (usually this extracts from subset
+    /// of `self`). Apply the instantiation `var_values` to this value
+    /// V, replacing each of the canonical variables.
     fn instantiate_projected<T>(
         &self,
         tcx: TyCtxt<'tcx>,

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -2786,19 +2786,8 @@ pub enum FailureCode {
     Error0644,
 }
 
-pub trait ObligationCauseExt<'tcx> {
-    fn as_failure_code(&self, terr: TypeError<'tcx>) -> FailureCode;
-
-    fn as_failure_code_diag(
-        &self,
-        terr: TypeError<'tcx>,
-        span: Span,
-        subdiags: Vec<TypeErrorAdditionalDiags>,
-    ) -> ObligationCauseFailureCode;
-    fn as_requirement_str(&self) -> &'static str;
-}
-
-impl<'tcx> ObligationCauseExt<'tcx> for ObligationCause<'tcx> {
+#[extension]
+pub impl<'tcx> ObligationCauseExt<'tcx> for ObligationCause<'tcx> {
     fn as_failure_code(&self, terr: TypeError<'tcx>) -> FailureCode {
         use self::FailureCode::*;
         use crate::traits::ObligationCauseCode::*;

compiler/rustc_infer/src/infer/mod.rs

@@ -626,11 +626,8 @@ pub struct InferCtxtBuilder<'tcx> {
     next_trait_solver: bool,
 }
 
-pub trait TyCtxtInferExt<'tcx> {
-    fn infer_ctxt(self) -> InferCtxtBuilder<'tcx>;
-}
-
-impl<'tcx> TyCtxtInferExt<'tcx> for TyCtxt<'tcx> {
+#[extension]
+pub impl<'tcx> TyCtxtInferExt<'tcx> for TyCtxt<'tcx> {
     fn infer_ctxt(self) -> InferCtxtBuilder<'tcx> {
         InferCtxtBuilder {
             tcx: self,

compiler/rustc_infer/src/traits/engine.rs

@@ -52,18 +52,8 @@ pub trait TraitEngine<'tcx>: 'tcx {
     ) -> Vec<PredicateObligation<'tcx>>;
 }
 
-pub trait TraitEngineExt<'tcx> {
-    fn register_predicate_obligations(
-        &mut self,
-        infcx: &InferCtxt<'tcx>,
-        obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
-    );
-
-    #[must_use]
-    fn select_all_or_error(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>>;
-}
-
-impl<'tcx, T: ?Sized + TraitEngine<'tcx>> TraitEngineExt<'tcx> for T {
+#[extension]
+pub impl<'tcx, T: ?Sized + TraitEngine<'tcx>> TraitEngineExt<'tcx> for T {
     fn register_predicate_obligations(
         &mut self,
         infcx: &InferCtxt<'tcx>,