Auto merge of #104063 - compiler-errors:ct-norm-unless, r=jackh726

Don't normalize constants unless they need normalization

Maybe makes normalization a bit faster when we have many constants in a type

r? `@ghost`

Author: bors

compiler/rustc_trait_selection/src/traits/project.rs

@@ -647,7 +647,7 @@ impl<'a, 'b, 'tcx> TypeFolder<'tcx> for AssocTypeNormalizer<'a, 'b, 'tcx> {
     #[instrument(skip(self), level = "debug")]
     fn fold_const(&mut self, constant: ty::Const<'tcx>) -> ty::Const<'tcx> {
         let tcx = self.selcx.tcx();
-        if tcx.lazy_normalization() {
+        if tcx.lazy_normalization() || !needs_normalization(&constant, self.param_env.reveal()) {
             constant
         } else {
             let constant = constant.super_fold_with(self);

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

@@ -353,6 +353,10 @@ impl<'cx, 'tcx> FallibleTypeFolder<'tcx> for QueryNormalizer<'cx, 'tcx> {
         &mut self,
         constant: ty::Const<'tcx>,
     ) -> Result<ty::Const<'tcx>, Self::Error> {
+        if !needs_normalization(&constant, self.param_env.reveal()) {
+            return Ok(constant);
+        }
+
         let constant = constant.try_super_fold_with(self)?;
         debug!(?constant, ?self.param_env);
         Ok(crate::traits::project::with_replaced_escaping_bound_vars(