Split `-Zchalk` flag into `-Ztrait-solver=(stock|chalk|next)` flag

3 files changed, 14 insertions, 11 deletions

diff --git a/compiler/rustc_trait_selection/src/traits/engine.rs b/compiler/rustc_trait_selection/src/traits/engine.rs
index c028e89e4ea..bd56d058a49 100644
--- a/compiler/rustc_trait_selection/src/traits/engine.rs
+++ b/compiler/rustc_trait_selection/src/traits/engine.rs
@@ -3,6 +3,7 @@ use std::fmt::Debug;
 
 use super::TraitEngine;
 use super::{ChalkFulfillmentContext, FulfillmentContext};
+use crate::solve::FulfillmentCtxt as NextFulfillmentCtxt;
 use crate::traits::NormalizeExt;
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -20,6 +21,7 @@ use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::ToPredicate;
 use rustc_middle::ty::TypeFoldable;
 use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_session::config::TraitSolver;
 use rustc_span::Span;
 
 pub trait TraitEngineExt<'tcx> {
@@ -29,18 +31,18 @@ pub trait TraitEngineExt<'tcx> {
 
 impl<'tcx> TraitEngineExt<'tcx> for dyn TraitEngine<'tcx> {
     fn new(tcx: TyCtxt<'tcx>) -> Box<Self> {
-        if tcx.sess.opts.unstable_opts.chalk {
-            Box::new(ChalkFulfillmentContext::new())
-        } else {
-            Box::new(FulfillmentContext::new())
+        match tcx.sess.opts.unstable_opts.trait_solver {
+            TraitSolver::Stock => Box::new(FulfillmentContext::new()),
+            TraitSolver::Chalk => Box::new(ChalkFulfillmentContext::new()),
+            TraitSolver::Next => Box::new(NextFulfillmentCtxt::new()),
         }
     }
 
     fn new_in_snapshot(tcx: TyCtxt<'tcx>) -> Box<Self> {
-        if tcx.sess.opts.unstable_opts.chalk {
-            Box::new(ChalkFulfillmentContext::new_in_snapshot())
-        } else {
-            Box::new(FulfillmentContext::new_in_snapshot())
+        match tcx.sess.opts.unstable_opts.trait_solver {
+            TraitSolver::Stock => Box::new(FulfillmentContext::new_in_snapshot()),
+            TraitSolver::Chalk => Box::new(ChalkFulfillmentContext::new_in_snapshot()),
+            TraitSolver::Next => Box::new(NextFulfillmentCtxt::new()),
         }
     }
 }
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
index 8a08c7533aa..ac52316d9c9 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -40,6 +40,7 @@ use rustc_middle::ty::{
     self, SubtypePredicate, ToPolyTraitRef, ToPredicate, TraitRef, Ty, TyCtxt, TypeFoldable,
     TypeVisitable,
 };
+use rustc_session::config::TraitSolver;
 use rustc_session::Limit;
 use rustc_span::def_id::LOCAL_CRATE;
 use rustc_span::symbol::sym;
@@ -1167,7 +1168,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     }
 
                     ty::PredicateKind::WellFormed(ty) => {
-                        if !self.tcx.sess.opts.unstable_opts.chalk {
+                        if self.tcx.sess.opts.unstable_opts.trait_solver != TraitSolver::Chalk {
                             // WF predicates cannot themselves make
                             // errors. They can only block due to
                             // ambiguity; otherwise, they always
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index 466641ea6df..15526b34ed2 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -15,6 +15,7 @@ use rustc_middle::ty::{
     self, Binder, GenericArg, GenericArgKind, GenericParamDefKind, InternalSubsts, SubstsRef,
     ToPolyTraitRef, ToPredicate, TraitRef, Ty, TyCtxt,
 };
+use rustc_session::config::TraitSolver;
 use rustc_span::def_id::DefId;
 
 use crate::traits::project::{normalize_with_depth, normalize_with_depth_to};
@@ -767,8 +768,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         debug!(?closure_def_id, ?trait_ref, ?nested, "confirm closure candidate obligations");
 
         // FIXME: Chalk
-
-        if !self.tcx().sess.opts.unstable_opts.chalk {
+        if self.tcx().sess.opts.unstable_opts.trait_solver != TraitSolver::Chalk {
             nested.push(obligation.with(
                 self.tcx(),
                 ty::Binder::dummy(ty::PredicateKind::ClosureKind(closure_def_id, substs, kind)),