Rollup merge of #125510 - lcnr:change-proof-trees-to-be-shallow, r=compiler-errors

remove proof tree formatting, make em shallow

Debugging via tracing `RUSTC_LOG=rustc_trait_selection::solve=debug` is now imo slightly more readable then the actual proof tree formatter. Removing everything that's not needed for the `analyse` visitor allows us to remove a bunch of code.

I personally believe that we should continue to use tracing over proof trees for debugging:
- it eagerly prints, allowing us to debug ICEs
- the proof tree builder ends up going out of sync with the actual runtime behavior, which is confusing
- using shallow proof trees is a lot more performant as we frequently do not recurse into all nested goals when using an analyse visitor
- this allows us to clean up the implementation and remove some code

r? ```@compiler-errors```

compiler/rustc_middle/src/arena.rs

@@ -61,7 +61,10 @@ macro_rules! arena_types {
             [] dtorck_constraint: rustc_middle::traits::query::DropckConstraint<'tcx>,
             [] candidate_step: rustc_middle::traits::query::CandidateStep<'tcx>,
             [] autoderef_bad_ty: rustc_middle::traits::query::MethodAutoderefBadTy<'tcx>,
-            [] canonical_goal_evaluation: rustc_next_trait_solver::solve::inspect::GoalEvaluationStep<rustc_middle::ty::TyCtxt<'tcx>>,
+            [] canonical_goal_evaluation:
+                rustc_next_trait_solver::solve::inspect::CanonicalGoalEvaluationStep<
+                    rustc_middle::ty::TyCtxt<'tcx>
+                >,
             [] query_region_constraints: rustc_middle::infer::canonical::QueryRegionConstraints<'tcx>,
             [] type_op_subtype:
                 rustc_middle::infer::canonical::Canonical<'tcx,

compiler/rustc_middle/src/traits/solve/cache.rs

@@ -17,7 +17,7 @@ pub struct EvaluationCache<'tcx> {
 #[derive(Debug, PartialEq, Eq)]
 pub struct CacheData<'tcx> {
     pub result: QueryResult<'tcx>,
-    pub proof_tree: Option<&'tcx [inspect::GoalEvaluationStep<TyCtxt<'tcx>>]>,
+    pub proof_tree: Option<&'tcx inspect::CanonicalGoalEvaluationStep<TyCtxt<'tcx>>>,
     pub additional_depth: usize,
     pub encountered_overflow: bool,
 }
@@ -28,7 +28,7 @@ impl<'tcx> EvaluationCache<'tcx> {
         &self,
         tcx: TyCtxt<'tcx>,
         key: CanonicalInput<'tcx>,
-        proof_tree: Option<&'tcx [inspect::GoalEvaluationStep<TyCtxt<'tcx>>]>,
+        proof_tree: Option<&'tcx inspect::CanonicalGoalEvaluationStep<TyCtxt<'tcx>>>,
         additional_depth: usize,
         encountered_overflow: bool,
         cycle_participants: FxHashSet<CanonicalInput<'tcx>>,
@@ -107,7 +107,7 @@ struct Success<'tcx> {
 #[derive(Clone, Copy)]
 pub struct QueryData<'tcx> {
     pub result: QueryResult<'tcx>,
-    pub proof_tree: Option<&'tcx [inspect::GoalEvaluationStep<TyCtxt<'tcx>>]>,
+    pub proof_tree: Option<&'tcx inspect::CanonicalGoalEvaluationStep<TyCtxt<'tcx>>>,
 }
 
 /// The cache entry for a goal `CanonicalInput`.

compiler/rustc_middle/src/ty/context.rs

@@ -103,7 +103,8 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
     type PredefinedOpaques = solve::PredefinedOpaques<'tcx>;
     type DefiningOpaqueTypes = &'tcx ty::List<LocalDefId>;
     type ExternalConstraints = ExternalConstraints<'tcx>;
-    type GoalEvaluationSteps = &'tcx [solve::inspect::GoalEvaluationStep<TyCtxt<'tcx>>];
+    type CanonicalGoalEvaluationStepRef =
+        &'tcx solve::inspect::CanonicalGoalEvaluationStep<TyCtxt<'tcx>>;
 
     type Ty = Ty<'tcx>;
     type Tys = &'tcx List<Ty<'tcx>>;