Move trait into attr so it's greppable

compiler/rustc_trait_selection/src/traits/query/evaluate_obligation.rs

@@ -4,8 +4,8 @@ use crate::infer::canonical::OriginalQueryValues;
 use crate::infer::InferCtxt;
 use crate::traits::{EvaluationResult, OverflowError, PredicateObligation, SelectionContext};
 
-#[extension]
-pub impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
+#[extension(pub trait InferCtxtExt<'tcx>)]
+impl<'tcx> InferCtxt<'tcx> {
     /// Evaluates whether the predicate can be satisfied (by any means)
     /// in the given `ParamEnv`.
     fn predicate_may_hold(&self, obligation: &PredicateObligation<'tcx>) -> bool {

compiler/rustc_trait_selection/src/traits/query/normalize.rs

@@ -22,8 +22,8 @@ use super::NoSolution;
 
 pub use rustc_middle::traits::query::NormalizationResult;
 
-#[extension]
-pub impl<'cx, 'tcx> QueryNormalizeExt<'tcx> for At<'cx, 'tcx> {
+#[extension(pub trait QueryNormalizeExt<'tcx>)]
+impl<'cx, 'tcx> At<'cx, 'tcx> {
     /// Normalize `value` in the context of the inference context,
     /// yielding a resulting type, or an error if `value` cannot be
     /// normalized. If you don't care about regions, you should prefer