Auto merge of #155767 - adwinwhite:eager-norm-outside, r=<try>

`-Znext-solver` Eager normalization outside of solver

Author: bors

compiler/rustc_borrowck/src/type_check/canonical.rs

@@ -8,9 +8,7 @@ use rustc_middle::mir::{Body, ConstraintCategory};
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, Unnormalized, Upcast};
 use rustc_span::Span;
 use rustc_span::def_id::DefId;
-use rustc_trait_selection::solve::NoSolution;
 use rustc_trait_selection::traits::ObligationCause;
-use rustc_trait_selection::traits::query::type_op::custom::CustomTypeOp;
 use rustc_trait_selection::traits::query::type_op::{self, TypeOpOutput};
 use tracing::{debug, instrument};
 
@@ -242,71 +240,9 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             body.source.def_id().expect_local(),
         );
 
-        if self.infcx.next_trait_solver() {
-            let param_env = self.infcx.param_env;
-            // FIXME: Make this into a real type op?
-            self.fully_perform_op(
-                location.to_locations(),
-                ConstraintCategory::Boring,
-                CustomTypeOp::new(
-                    |ocx| {
-                        let structurally_normalize = |ty| {
-                            ocx.structurally_normalize_ty(&cause, param_env, Unnormalized::new_wip(ty))
-                            .unwrap_or_else(|_| bug!("struct tail should have been computable, since we computed it in HIR"))
-                        };
-
-                        let tail = tcx.struct_tail_raw(
-                            ty,
-                            &cause,
-                            structurally_normalize,
-                            || {},
-                        );
-
-                        Ok(tail)
-                    },
-                    "normalizing struct tail",
-                ),
-            )
-            .unwrap_or_else(|guar| Ty::new_error(tcx, guar))
-        } else {
-            let mut normalize = |ty| self.normalize(ty, location);
-            let tail = tcx.struct_tail_raw(ty, &cause, &mut normalize, || {});
-            normalize(tail)
-        }
-    }
-
-    #[instrument(skip(self), level = "debug")]
-    pub(super) fn structurally_resolve(
-        &mut self,
-        ty: Ty<'tcx>,
-        location: impl NormalizeLocation,
-    ) -> Ty<'tcx> {
-        if self.infcx.next_trait_solver() {
-            let body = self.body;
-            let param_env = self.infcx.param_env;
-            // FIXME: Make this into a real type op?
-            self.fully_perform_op(
-                location.to_locations(),
-                ConstraintCategory::Boring,
-                CustomTypeOp::new(
-                    |ocx| {
-                        ocx.structurally_normalize_ty(
-                            &ObligationCause::misc(
-                                location.to_locations().span(body),
-                                body.source.def_id().expect_local(),
-                            ),
-                            param_env,
-                            Unnormalized::new_wip(ty),
-                        )
-                        .map_err(|_| NoSolution)
-                    },
-                    "normalizing struct tail",
-                ),
-            )
-            .unwrap_or_else(|guar| Ty::new_error(self.tcx(), guar))
-        } else {
-            self.normalize(ty, location)
-        }
+        let mut normalize = |ty| self.normalize(ty, location);
+        let tail = tcx.struct_tail_raw(ty, &cause, &mut normalize, || {});
+        normalize(tail)
     }
 
     #[instrument(skip(self), level = "debug")]

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -461,7 +461,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             let projected_ty = curr_projected_ty.projection_ty_core(
                 tcx,
                 proj,
-                |ty| self.structurally_resolve(ty, locations),
+                |ty| self.normalize(ty, locations),
                 |ty, variant_index, field, ()| PlaceTy::field_ty(tcx, ty, variant_index, field),
                 |_| unreachable!(),
             );

compiler/rustc_hir_analysis/src/autoderef.rs

@@ -90,16 +90,9 @@ impl<'a, 'tcx> Iterator for Autoderef<'a, 'tcx> {
                 // NOTE: we may still need to normalize the built-in deref in case
                 // we have some type like `&<Ty as Trait>::Assoc`, since users of
                 // autoderef expect this type to have been structurally normalized.
-                if self.infcx.next_trait_solver()
-                    && let ty::Alias(..) = ty.kind()
-                {
-                    let (normalized_ty, obligations) =
-                        self.structurally_normalize_ty(Unnormalized::new_wip(ty))?;
-                    self.state.obligations.extend(obligations);
-                    (AutoderefKind::Builtin, normalized_ty)
-                } else {
-                    (AutoderefKind::Builtin, ty)
-                }
+                let (normalized_ty, obligations) = self.normalize_ty(Unnormalized::new_wip(ty))?;
+                self.state.obligations.extend(obligations);
+                (AutoderefKind::Builtin, normalized_ty)
             } else if let Some(ty) = self.overloaded_deref_ty(self.state.cur_ty) {
                 // The overloaded deref check already normalizes the pointee type.
                 (AutoderefKind::Overloaded, ty)
@@ -177,35 +170,27 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
             return None;
         }
 
-        let (normalized_ty, obligations) = self.structurally_normalize_ty(Unnormalized::new(
-            Ty::new_projection(tcx, trait_target_def_id, [ty]),
-        ))?;
+        let (normalized_ty, obligations) = self
+            .normalize_ty(Unnormalized::new(Ty::new_projection(tcx, trait_target_def_id, [ty])))?;
         debug!("overloaded_deref_ty({:?}) = ({:?}, {:?})", ty, normalized_ty, obligations);
         self.state.obligations.extend(obligations);
 
         Some(self.infcx.resolve_vars_if_possible(normalized_ty))
     }
 
     #[instrument(level = "debug", skip(self), ret)]
-    pub fn structurally_normalize_ty(
+    pub fn normalize_ty(
         &self,
         ty: Unnormalized<'tcx, Ty<'tcx>>,
     ) -> Option<(Ty<'tcx>, PredicateObligations<'tcx>)> {
         let ocx = ObligationCtxt::new(self.infcx);
-        let Ok(normalized_ty) = ocx.structurally_normalize_ty(
+        let normalized_ty = ocx.normalize(
             &traits::ObligationCause::misc(self.span, self.body_id),
             self.param_env,
             ty,
-        ) else {
-            // We shouldn't have errors here in the old solver, except for
-            // evaluate/fulfill mismatches, but that's not a reason for an ICE.
-            return None;
-        };
+        );
         let errors = ocx.try_evaluate_obligations();
         if !errors.is_empty() {
-            if self.infcx.next_trait_solver() {
-                unreachable!();
-            }
             // We shouldn't have errors here in the old solver, except for
             // evaluate/fulfill mismatches, but that's not a reason for an ICE.
             debug!(?errors, "encountered errors while fulfilling");

compiler/rustc_hir_analysis/src/check/check.rs

@@ -923,6 +923,15 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
             res = res.and(enter_wf_checking_ctxt(tcx, def_id, |wfcx| {
                 let ty = tcx.type_of(def_id).instantiate_identity();
                 let ty_span = tcx.ty_span(def_id);
+                // FIXME: Unnormalized version can ill-formed even if the normalized one is well-formed.
+                // Don't break the old solver for now. See `tests/ui/wf/wf-normalization-sized.rs`.
+                if tcx.next_trait_solver_globally() {
+                    wfcx.register_wf_obligation(
+                        ty_span,
+                        Some(WellFormedLoc::Ty(def_id)),
+                        ty.skip_normalization().into(),
+                    );
+                }
                 let ty = wfcx.deeply_normalize(ty_span, Some(WellFormedLoc::Ty(def_id)), ty);
                 wfcx.register_wf_obligation(ty_span, Some(WellFormedLoc::Ty(def_id)), ty.into());
                 wfcx.register_bound(

compiler/rustc_hir_analysis/src/coherence/orphan.rs

@@ -315,17 +315,6 @@ fn orphan_check<'tcx>(
             return Ok(user_ty);
         }
 
-        let ty = if infcx.next_trait_solver() {
-            ocx.structurally_normalize_ty(
-                &cause,
-                ty::ParamEnv::empty(),
-                Unnormalized::new_wip(infcx.resolve_vars_if_possible(ty)),
-            )
-            .unwrap_or(ty)
-        } else {
-            ty
-        };
-
         Ok::<_, !>(ty)
     };
 

compiler/rustc_hir_typeck/src/_match.rs

@@ -60,8 +60,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // type in that case)
         let mut all_arms_diverge = Diverges::WarnedAlways;
 
-        let expected =
-            orig_expected.try_structurally_resolve_and_adjust_for_branches(self, expr.span);
+        let expected = orig_expected.try_structurally_resolve_and_adjust_for_branches(self);
         debug!(?expected);
 
         let mut coercion = {

compiler/rustc_hir_typeck/src/callee.rs

@@ -79,7 +79,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             _ => self.check_expr(callee_expr),
         };
 
-        let expr_ty = self.try_structurally_resolve_type(call_expr.span, original_callee_ty);
+        let expr_ty = self.resolve_vars_with_obligations(original_callee_ty);
 
         let mut autoderef = self.autoderef(callee_expr.span, expr_ty);
         let mut result = None;
@@ -211,8 +211,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         arg_exprs: &'tcx [hir::Expr<'tcx>],
         autoderef: &Autoderef<'a, 'tcx>,
     ) -> Option<CallStep<'tcx>> {
-        let adjusted_ty =
-            self.try_structurally_resolve_type(autoderef.span(), autoderef.final_ty());
+        let adjusted_ty = self.resolve_vars_with_obligations(autoderef.final_ty());
 
         // If the callee is a function pointer or a closure, then we're all set.
         match *adjusted_ty.kind() {

compiler/rustc_hir_typeck/src/cast.rs

@@ -102,7 +102,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             return Ok(Some(PointerKind::Thin));
         }
 
-        let t = self.try_structurally_resolve_type(span, t);
+        let t = self.resolve_vars_with_obligations(t);
 
         Ok(match *t.kind() {
             ty::Slice(_) | ty::Str => Some(PointerKind::Length),
@@ -1041,8 +1041,8 @@ impl<'a, 'tcx> CastCheck<'tcx> {
         mut m_cast: ty::TypeAndMut<'tcx>,
     ) -> Result<CastKind, CastError<'tcx>> {
         // array-ptr-cast: allow mut-to-mut, mut-to-const, const-to-const
-        m_expr.ty = fcx.try_structurally_resolve_type(self.expr_span, m_expr.ty);
-        m_cast.ty = fcx.try_structurally_resolve_type(self.cast_span, m_cast.ty);
+        m_expr.ty = fcx.resolve_vars_with_obligations(m_expr.ty);
+        m_cast.ty = fcx.resolve_vars_with_obligations(m_cast.ty);
 
         if m_expr.mutbl >= m_cast.mutbl
             && let ty::Array(ety, _) = m_expr.ty.kind()

compiler/rustc_hir_typeck/src/closure.rs

@@ -59,10 +59,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // closure sooner rather than later, so first examine the expected
         // type, and see if can glean a closure kind from there.
         let (expected_sig, expected_kind) = match expected.to_option(self) {
-            Some(ty) => self.deduce_closure_signature(
-                self.try_structurally_resolve_type(expr_span, ty),
-                closure.kind,
-            ),
+            Some(ty) => {
+                self.deduce_closure_signature(self.resolve_vars_with_obligations(ty), closure.kind)
+            }
             None => (None, None),
         };
 
@@ -963,7 +962,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         let closure_span = self.tcx.def_span(body_def_id);
         let ret_ty = ret_coercion.borrow().expected_ty();
-        let ret_ty = self.try_structurally_resolve_type(closure_span, ret_ty);
+        let ret_ty = self.resolve_vars_with_obligations(ret_ty);
 
         let get_future_output = |predicate: ty::Predicate<'tcx>, span| {
             // Search for a pending obligation like

compiler/rustc_hir_typeck/src/coercion.rs

@@ -1051,17 +1051,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         &self,
         expr: &'tcx hir::Expr<'tcx>,
         expr_ty: Ty<'tcx>,
-        mut target: Ty<'tcx>,
+        target: Ty<'tcx>,
         allow_two_phase: AllowTwoPhase,
         cause: Option<ObligationCause<'tcx>>,
     ) -> RelateResult<'tcx, Ty<'tcx>> {
-        let source = self.try_structurally_resolve_type(expr.span, expr_ty);
-        if self.next_trait_solver() {
-            target = self.try_structurally_resolve_type(
-                cause.as_ref().map_or(expr.span, |cause| cause.span),
-                target,
-            );
-        }
+        let source = self.resolve_vars_with_obligations(expr_ty);
         debug!("coercion::try({:?}: {:?} -> {:?})", expr, source, target);
 
         let cause =
@@ -1099,23 +1093,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // Make sure to structurally resolve the types, since we use
             // the `TyKind`s heavily in coercion.
             let ocx = ObligationCtxt::new(self);
-            let structurally_resolve = |ty| {
-                let ty = self.shallow_resolve(ty);
-                if self.next_trait_solver()
-                    && let ty::Alias(..) = ty.kind()
-                {
-                    ocx.structurally_normalize_ty(&cause, self.param_env, Unnormalized::new_wip(ty))
-                } else {
-                    Ok(ty)
-                }
-            };
-            let Ok(expr_ty) = structurally_resolve(expr_ty) else {
-                return false;
-            };
-            let Ok(target_ty) = structurally_resolve(target_ty) else {
-                return false;
-            };
-
             let Ok(ok) = coerce.coerce(expr_ty, target_ty) else {
                 return false;
             };
@@ -1261,8 +1238,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         new: &hir::Expr<'_>,
         new_ty: Ty<'tcx>,
     ) -> RelateResult<'tcx, Ty<'tcx>> {
-        let prev_ty = self.try_structurally_resolve_type(cause.span, prev_ty);
-        let new_ty = self.try_structurally_resolve_type(new.span, new_ty);
+        let prev_ty = self.resolve_vars_with_obligations(prev_ty);
+        let new_ty = self.resolve_vars_with_obligations(new_ty);
         debug!(
             "coercion::try_find_coercion_lub({:?}, {:?}, exprs={:?} exprs)",
             prev_ty,