Auto merge of #119101 - compiler-errors:outlives, r=lcnr

Normalize region obligation in lexical region resolution with next-gen solver

This normalizes region obligations when we `resolve_regions`, since they may be unnormalized with deferred projection equality.

It's pretty hard to add tests that exercise this without also triggering MIR borrowck errors (because we don't normalize there yet). I've added one test with two revisions that should test that we both 1. normalize region obligations in the param env, and 2. normalize registered region obligations during lexical region resolution.

compiler/rustc_trait_selection/src/traits/auto_trait.rs

@@ -179,7 +179,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
         }
 
         let outlives_env = OutlivesEnvironment::new(full_env);
-        infcx.process_registered_region_obligations(&outlives_env);
+        let _ = infcx.process_registered_region_obligations::<!>(&outlives_env, |ty, _| Ok(ty));
 
         let region_data =
             infcx.inner.borrow_mut().unwrap_region_constraints().region_constraint_data().clone();

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -6,6 +6,7 @@
 
 use crate::infer::outlives::env::OutlivesEnvironment;
 use crate::infer::InferOk;
+use crate::regions::InferCtxtRegionExt;
 use crate::solve::inspect::{InspectGoal, ProofTreeInferCtxtExt, ProofTreeVisitor};
 use crate::solve::{deeply_normalize_for_diagnostics, inspect};
 use crate::traits::engine::TraitEngineExt;

compiler/rustc_trait_selection/src/traits/engine.rs

@@ -3,6 +3,7 @@ use std::fmt::Debug;
 
 use super::FulfillmentContext;
 use super::TraitEngine;
+use crate::regions::InferCtxtRegionExt;
 use crate::solve::FulfillmentCtxt as NextFulfillmentCtxt;
 use crate::traits::error_reporting::TypeErrCtxtExt;
 use crate::traits::NormalizeExt;

compiler/rustc_trait_selection/src/traits/misc.rs

@@ -1,5 +1,6 @@
 //! Miscellaneous type-system utilities that are too small to deserve their own modules.
 
+use crate::regions::InferCtxtRegionExt;
 use crate::traits::{self, ObligationCause, ObligationCtxt};
 
 use hir::LangItem;

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -25,6 +25,7 @@ pub mod wf;
 
 use crate::infer::outlives::env::OutlivesEnvironment;
 use crate::infer::{InferCtxt, TyCtxtInferExt};
+use crate::regions::InferCtxtRegionExt;
 use crate::traits::error_reporting::TypeErrCtxtExt as _;
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc_errors::ErrorGuaranteed;