Move trait into attr so it's greppable

compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs

@@ -131,8 +131,8 @@ pub enum GenerateProofTree {
     Never,
 }
 
-#[extension]
-pub impl<'tcx> InferCtxtEvalExt<'tcx> for InferCtxt<'tcx> {
+#[extension(pub trait InferCtxtEvalExt<'tcx>)]
+impl<'tcx> InferCtxt<'tcx> {
     /// Evaluates a goal from **outside** of the trait solver.
     ///
     /// Using this while inside of the solver is wrong as it uses a new

compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs

@@ -17,8 +17,8 @@ use crate::solve::inspect::ProofTreeBuilder;
 use crate::traits::StructurallyNormalizeExt;
 use crate::traits::TraitEngineExt;
 
-#[extension]
-pub impl<'tcx> InferCtxtSelectExt<'tcx> for InferCtxt<'tcx> {
+#[extension(pub trait InferCtxtSelectExt<'tcx>)]
+impl<'tcx> InferCtxt<'tcx> {
     fn select_in_new_trait_solver(
         &self,
         obligation: &PolyTraitObligation<'tcx>,

compiler/rustc_trait_selection/src/solve/inspect/analyse.rs

@@ -216,8 +216,8 @@ pub trait ProofTreeVisitor<'tcx> {
     fn visit_goal(&mut self, goal: &InspectGoal<'_, 'tcx>) -> ControlFlow<Self::BreakTy>;
 }
 
-#[extension]
-pub impl<'tcx> ProofTreeInferCtxtExt<'tcx> for InferCtxt<'tcx> {
+#[extension(pub trait ProofTreeInferCtxtExt<'tcx>)]
+impl<'tcx> InferCtxt<'tcx> {
     fn visit_proof_tree<V: ProofTreeVisitor<'tcx>>(
         &self,
         goal: Goal<'tcx, ty::Predicate<'tcx>>,

compiler/rustc_trait_selection/src/solve/mod.rs

@@ -61,8 +61,8 @@ enum GoalEvaluationKind {
     Nested { is_normalizes_to_hack: IsNormalizesToHack },
 }
 
-#[extension]
-impl<'tcx> CanonicalResponseExt for Canonical<'tcx, Response<'tcx>> {
+#[extension(trait CanonicalResponseExt)]
+impl<'tcx> Canonical<'tcx, Response<'tcx>> {
     fn has_no_inference_or_external_constraints(&self) -> bool {
         self.value.external_constraints.region_constraints.is_empty()
             && self.value.var_values.is_identity()