Rollup merge of #127631 - compiler-errors:yeet-fully-norm, r=lcnr

Remove `fully_normalize`

Yeet this function and replace it w/ some `ObligationCtxt` instead. It wasn't called very often anyways.

r? lcnr

compiler/rustc_lint/src/opaque_hidden_inferred_bound.rs

@@ -5,8 +5,7 @@ use rustc_middle::ty::print::{PrintTraitPredicateExt as _, TraitPredPrintModifie
 use rustc_middle::ty::{self, fold::BottomUpFolder, Ty, TypeFoldable};
 use rustc_session::{declare_lint, declare_lint_pass};
 use rustc_span::{symbol::kw, Span};
-use rustc_trait_selection::traits;
-use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
+use rustc_trait_selection::traits::{self, ObligationCtxt};
 
 use crate::{LateContext, LateLintPass, LintContext};
 
@@ -130,24 +129,26 @@ impl<'tcx> LateLintPass<'tcx> for OpaqueHiddenInferredBound {
                     .iter_instantiated_copied(cx.tcx, proj.projection_term.args)
                 {
                     let assoc_pred = assoc_pred.fold_with(proj_replacer);
-                    let Ok(assoc_pred) = traits::fully_normalize(
-                        infcx,
+
+                    let ocx = ObligationCtxt::new(infcx);
+                    let assoc_pred =
+                        ocx.normalize(&traits::ObligationCause::dummy(), cx.param_env, assoc_pred);
+                    if !ocx.select_all_or_error().is_empty() {
+                        // Can't normalize for some reason...?
+                        continue;
+                    }
+
+                    ocx.register_obligation(traits::Obligation::new(
+                        cx.tcx,
                         traits::ObligationCause::dummy(),
                         cx.param_env,
                         assoc_pred,
-                    ) else {
-                        continue;
-                    };
+                    ));
 
                     // If that predicate doesn't hold modulo regions (but passed during type-check),
                     // then we must've taken advantage of the hack in `project_and_unify_types` where
                     // we replace opaques with inference vars. Emit a warning!
-                    if !infcx.predicate_must_hold_modulo_regions(&traits::Obligation::new(
-                        cx.tcx,
-                        traits::ObligationCause::dummy(),
-                        cx.param_env,
-                        assoc_pred,
-                    )) {
+                    if !ocx.select_all_or_error().is_empty() {
                         // If it's a trait bound and an opaque that doesn't satisfy it,
                         // then we can emit a suggestion to add the bound.
                         let add_bound = match (proj_term.kind(), assoc_pred.kind().skip_binder()) {

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -271,13 +271,14 @@ fn do_normalize_predicates<'tcx>(
     // them here too, and we will remove this function when
     // we move over to lazy normalization *anyway*.
     let infcx = tcx.infer_ctxt().ignoring_regions().build();
-    let predicates = match fully_normalize(&infcx, cause, elaborated_env, predicates) {
-        Ok(predicates) => predicates,
-        Err(errors) => {
-            let reported = infcx.err_ctxt().report_fulfillment_errors(errors);
-            return Err(reported);
-        }
-    };
+    let ocx = ObligationCtxt::new_with_diagnostics(&infcx);
+    let predicates = ocx.normalize(&cause, elaborated_env, predicates);
+
+    let errors = ocx.select_all_or_error();
+    if !errors.is_empty() {
+        let reported = infcx.err_ctxt().report_fulfillment_errors(errors);
+        return Err(reported);
+    }
 
     debug!("do_normalize_predicates: normalized predicates = {:?}", predicates);
 
@@ -465,37 +466,6 @@ pub fn normalize_param_env_or_error<'tcx>(
     ty::ParamEnv::new(tcx.mk_clauses(&predicates), unnormalized_env.reveal())
 }
 
-/// Normalize a type and process all resulting obligations, returning any errors.
-///
-/// FIXME(-Znext-solver): This should be replaced by `At::deeply_normalize`
-/// which has the same behavior with the new solver. Because using a separate
-/// fulfillment context worsens caching in the old solver, `At::deeply_normalize`
-/// is still lazy with the old solver as it otherwise negatively impacts perf.
-#[instrument(skip_all)]
-pub fn fully_normalize<'tcx, T>(
-    infcx: &InferCtxt<'tcx>,
-    cause: ObligationCause<'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
-    value: T,
-) -> Result<T, Vec<FulfillmentError<'tcx>>>
-where
-    T: TypeFoldable<TyCtxt<'tcx>>,
-{
-    let ocx = ObligationCtxt::new_with_diagnostics(infcx);
-    debug!(?value);
-    let normalized_value = ocx.normalize(&cause, param_env, value);
-    debug!(?normalized_value);
-    debug!("select_all_or_error start");
-    let errors = ocx.select_all_or_error();
-    if !errors.is_empty() {
-        return Err(errors);
-    }
-    debug!("select_all_or_error complete");
-    let resolved_value = infcx.resolve_vars_if_possible(normalized_value);
-    debug!(?resolved_value);
-    Ok(resolved_value)
-}
-
 /// Normalizes the predicates and checks whether they hold in an empty environment. If this
 /// returns true, then either normalize encountered an error or one of the predicates did not
 /// hold. Used when creating vtables to check for unsatisfiable methods.

compiler/rustc_trait_selection/src/traits/normalize.rs

@@ -42,11 +42,9 @@ impl<'tcx> At<'_, 'tcx> {
     /// same goals in both a temporary and the shared context which negatively impacts
     /// performance as these don't share caching.
     ///
-    /// FIXME(-Znext-solver): This has the same behavior as `traits::fully_normalize`
-    /// in the new solver, but because of performance reasons, we currently reuse an
-    /// existing fulfillment context in the old solver. Once we also eagerly prove goals with
-    /// the old solver or have removed the old solver, remove `traits::fully_normalize` and
-    /// rename this function to `At::fully_normalize`.
+    /// FIXME(-Znext-solver): For performance reasons, we currently reuse an existing
+    /// fulfillment context in the old solver. Once we have removed the old solver, we
+    /// can remove the `fulfill_cx` parameter on this function.
     fn deeply_normalize<T, E>(
         self,
         value: T,

compiler/rustc_trait_selection/src/traits/specialize/mod.rs

@@ -18,9 +18,7 @@ use crate::error_reporting::traits::to_pretty_impl_header;
 use crate::errors::NegativePositiveConflict;
 use crate::infer::{InferCtxt, InferOk, TyCtxtInferExt};
 use crate::traits::select::IntercrateAmbiguityCause;
-use crate::traits::{
-    self, coherence, FutureCompatOverlapErrorKind, ObligationCause, ObligationCtxt,
-};
+use crate::traits::{coherence, FutureCompatOverlapErrorKind, ObligationCause, ObligationCtxt};
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_errors::{codes::*, Diag, EmissionGuarantee};
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -219,19 +217,17 @@ fn fulfill_implication<'tcx>(
         param_env, source_trait_ref, target_impl
     );
 
-    let source_trait_ref =
-        match traits::fully_normalize(infcx, ObligationCause::dummy(), param_env, source_trait_ref)
-        {
-            Ok(source_trait_ref) => source_trait_ref,
-            Err(_errors) => {
-                infcx.dcx().span_delayed_bug(
-                    infcx.tcx.def_span(source_impl),
-                    format!("failed to fully normalize {source_trait_ref}"),
-                );
-                source_trait_ref
-            }
-        };
+    let ocx = ObligationCtxt::new(infcx);
+    let source_trait_ref = ocx.normalize(&ObligationCause::dummy(), param_env, source_trait_ref);
 
+    if !ocx.select_all_or_error().is_empty() {
+        infcx.dcx().span_delayed_bug(
+            infcx.tcx.def_span(source_impl),
+            format!("failed to fully normalize {source_trait_ref}"),
+        );
+    }
+
+    let source_trait_ref = infcx.resolve_vars_if_possible(source_trait_ref);
     let source_trait = ImplSubject::Trait(source_trait_ref);
 
     let selcx = SelectionContext::new(infcx);
@@ -253,9 +249,6 @@ fn fulfill_implication<'tcx>(
         return Err(());
     };
 
-    // Needs to be `in_snapshot` because this function is used to rebase
-    // generic parameters, which may happen inside of a select within a probe.
-    let ocx = ObligationCtxt::new(infcx);
     // attempt to prove all of the predicates for impl2 given those for impl1
     // (which are packed up in penv)
     ocx.register_obligations(obligations.chain(more_obligations));