Auto merge of #118937 - lcnr:rename-solver-flag, r=compiler-errors

`-Ztrait-solver=next` to `-Znext-solver`

renames the feature flag to enable the new trait solver.

still want some feedback before merging: https://rust-lang.zulipchat.com/#narrow/stream/364551-t-types.2Ftrait-system-refactor/topic/renaming.20the.20feature.20flag.20to.20.60-Znew-solver.60.

The idea is to make it easier to add another option, e.g. to enable the solver in wfcheck or to optionally change its behavior to our new coinduction approach.

r? `@compiler-errors`

274 files changed, 345 insertions, 333 deletions

diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
index c93cfa78832..3764e4c4008 100644
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
@@ -315,7 +315,7 @@ fn check_opaque_type_well_formed<'tcx>(
         parent_def_id = tcx.local_parent(parent_def_id);
     }
 
-    // FIXME(-Ztrait-solver=next): We probably should use `DefiningAnchor::Error`
+    // FIXME(-Znext-solver): We probably should use `DefiningAnchor::Error`
     // and prepopulate this `InferCtxt` with known opaque values, rather than
     // using the `Bind` anchor here. For now it's fine.
     let infcx = tcx
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index e782221a4c2..98c21693cf0 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -1003,16 +1003,16 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             reported_errors: Default::default(),
         };
 
-        // FIXME(-Ztrait-solver=next): A bit dubious that we're only registering
+        // FIXME(-Znext-solver): A bit dubious that we're only registering
         // predefined opaques in the typeck root.
         if infcx.next_trait_solver() && !infcx.tcx.is_typeck_child(body.source.def_id()) {
-            checker.register_predefined_opaques_in_new_solver();
+            checker.register_predefined_opaques_for_next_solver();
         }
 
         checker
     }
 
-    pub(super) fn register_predefined_opaques_in_new_solver(&mut self) {
+    pub(super) fn register_predefined_opaques_for_next_solver(&mut self) {
         // OK to use the identity arguments for each opaque type key, since
         // we remap opaques from HIR typeck back to their definition params.
         let opaques: Vec<_> = self
diff --git a/compiler/rustc_codegen_cranelift/example/gen_block_iterate.rs b/compiler/rustc_codegen_cranelift/example/gen_block_iterate.rs
index 14bd23e77ea..25bfe542d22 100644
--- a/compiler/rustc_codegen_cranelift/example/gen_block_iterate.rs
+++ b/compiler/rustc_codegen_cranelift/example/gen_block_iterate.rs
@@ -1,7 +1,7 @@
 // Copied from https://github.com/rust-lang/rust/blob/46455dc65069387f2dc46612f13fd45452ab301a/tests/ui/coroutine/gen_block_iterate.rs
 // revisions: next old
 //compile-flags: --edition 2024 -Zunstable-options
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // run-pass
 #![feature(gen_blocks)]
 
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
index 82419d782cd..00302ec831c 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -320,7 +320,7 @@ fn compare_method_predicate_entailment<'tcx>(
     if check_implied_wf == CheckImpliedWfMode::Check && !(impl_sig, trait_sig).references_error() {
         // Select obligations to make progress on inference before processing
         // the wf obligation below.
-        // FIXME(-Ztrait-solver=next): Not needed when the hack below is removed.
+        // FIXME(-Znext-solver): Not needed when the hack below is removed.
         let errors = ocx.select_where_possible();
         if !errors.is_empty() {
             let reported = infcx.err_ctxt().report_fulfillment_errors(errors);
@@ -333,7 +333,7 @@ fn compare_method_predicate_entailment<'tcx>(
         // trigger the lint. Instead, let's only consider type outlives and
         // region outlives obligations.
         //
-        // FIXME(-Ztrait-solver=next): Try removing this hack again once
+        // FIXME(-Znext-solver): Try removing this hack again once
         // the new solver is stable.
         let mut wf_args: smallvec::SmallVec<[_; 4]> =
             unnormalized_impl_sig.inputs_and_output.iter().map(|ty| ty.into()).collect();
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs
index d571e04a49a..22af79e02a7 100644
--- a/compiler/rustc_hir_typeck/src/coercion.rs
+++ b/compiler/rustc_hir_typeck/src/coercion.rs
@@ -1019,7 +1019,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// Returns false if the coercion creates any obligations that result in
     /// errors.
     pub fn can_coerce(&self, expr_ty: Ty<'tcx>, target: Ty<'tcx>) -> bool {
-        // FIXME(-Ztrait-solver=next): We need to structurally resolve both types here.
+        // FIXME(-Znext-solver): We need to structurally resolve both types here.
         let source = self.resolve_vars_with_obligations(expr_ty);
         debug!("coercion::can_with_predicates({:?} -> {:?})", source, target);
 
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
index 572a3312506..7744f75121e 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
@@ -83,7 +83,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// version (resolve_vars_if_possible), this version will
     /// also select obligations if it seems useful, in an effort
     /// to get more type information.
-    // FIXME(-Ztrait-solver=next): A lot of the calls to this method should
+    // FIXME(-Znext-solver): A lot of the calls to this method should
     // probably be `try_structurally_resolve_type` or `structurally_resolve_type` instead.
     #[instrument(skip(self), level = "debug", ret)]
     pub(in super::super) fn resolve_vars_with_obligations(&self, mut ty: Ty<'tcx>) -> Ty<'tcx> {
diff --git a/compiler/rustc_infer/src/infer/canonical/mod.rs b/compiler/rustc_infer/src/infer/canonical/mod.rs
index 3c4c4644fe6..386fdb09ba5 100644
--- a/compiler/rustc_infer/src/infer/canonical/mod.rs
+++ b/compiler/rustc_infer/src/infer/canonical/mod.rs
@@ -101,7 +101,7 @@ impl<'tcx> InferCtxt<'tcx> {
     /// variable, then you'll get a new inference variable; if it is a
     /// universally quantified variable, you get a placeholder.
     ///
-    /// FIXME(-Ztrait-solver=next): This is public because it's used by the
+    /// FIXME(-Znext-solver): This is public because it's used by the
     /// new trait solver which has a different canonicalization routine.
     /// We should somehow deduplicate all of this.
     pub fn instantiate_canonical_var(
diff --git a/compiler/rustc_infer/src/infer/canonical/substitute.rs b/compiler/rustc_infer/src/infer/canonical/substitute.rs
index f368b30fbd1..e0b97bb160c 100644
--- a/compiler/rustc_infer/src/infer/canonical/substitute.rs
+++ b/compiler/rustc_infer/src/infer/canonical/substitute.rs
@@ -11,7 +11,7 @@ use rustc_middle::ty::fold::{FnMutDelegate, TypeFoldable};
 use rustc_middle::ty::GenericArgKind;
 use rustc_middle::ty::{self, TyCtxt};
 
-/// FIXME(-Ztrait-solver=next): This or public because it is shared with the
+/// FIXME(-Znext-solver): This or public because it is shared with the
 /// new trait solver implementation. We should deduplicate canonicalization.
 pub trait CanonicalExt<'tcx, V> {
     /// Instantiate the wrapped value, replacing each canonical value
diff --git a/compiler/rustc_infer/src/traits/mod.rs b/compiler/rustc_infer/src/traits/mod.rs
index a26e676c521..b9be178916c 100644
--- a/compiler/rustc_infer/src/traits/mod.rs
+++ b/compiler/rustc_infer/src/traits/mod.rs
@@ -135,7 +135,7 @@ pub enum FulfillmentErrorCode<'tcx> {
     CodeSubtypeError(ExpectedFound<Ty<'tcx>>, TypeError<'tcx>), // always comes from a SubtypePredicate
     CodeConstEquateError(ExpectedFound<Const<'tcx>>, TypeError<'tcx>),
     CodeAmbiguity {
-        /// Overflow reported from the new solver `-Ztrait-solver=next`, which will
+        /// Overflow reported from the new solver `-Znext-solver`, which will
         /// be reported as an regular error as opposed to a fatal error.
         overflow: bool,
     },
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 25fa2b37547..d96b1ba88f5 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -6,10 +6,9 @@ use rustc_session::config::{
     build_configuration, build_session_options, rustc_optgroups, BranchProtection, CFGuard, Cfg,
     DebugInfo, DumpMonoStatsFormat, ErrorOutputType, ExternEntry, ExternLocation, Externs,
     FunctionReturn, InliningThreshold, Input, InstrumentCoverage, InstrumentXRay,
-    LinkSelfContained, LinkerPluginLto, LocationDetail, LtoCli, MirSpanview, OomStrategy, Options,
-    OutFileName, OutputType, OutputTypes, PAuthKey, PacRet, Passes, Polonius,
-    ProcMacroExecutionStrategy, Strip, SwitchWithOptPath, SymbolManglingVersion, TraitSolver,
-    WasiExecModel,
+    LinkSelfContained, LinkerPluginLto, LocationDetail, LtoCli, MirSpanview, NextSolverConfig,
+    OomStrategy, Options, OutFileName, OutputType, OutputTypes, PAuthKey, PacRet, Passes, Polonius,
+    ProcMacroExecutionStrategy, Strip, SwitchWithOptPath, SymbolManglingVersion, WasiExecModel,
 };
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
@@ -781,6 +780,10 @@ fn test_unstable_options_tracking_hash() {
     tracked!(mir_opt_level, Some(4));
     tracked!(move_size_limit, Some(4096));
     tracked!(mutable_noalias, false);
+    tracked!(
+        next_solver,
+        Some(NextSolverConfig { coherence: true, globally: false, dump_tree: Default::default() })
+    );
     tracked!(no_generate_arange_section, true);
     tracked!(no_jump_tables, true);
     tracked!(no_link, true);
@@ -822,7 +825,6 @@ fn test_unstable_options_tracking_hash() {
     tracked!(thir_unsafeck, true);
     tracked!(tiny_const_eval_limit, true);
     tracked!(tls_model, Some(TlsModel::GeneralDynamic));
-    tracked!(trait_solver, TraitSolver::NextCoherence);
     tracked!(translate_remapped_path_to_local_path, false);
     tracked!(trap_unreachable, Some(false));
     tracked!(treat_err_as_bug, NonZeroUsize::new(1));
diff --git a/compiler/rustc_middle/src/traits/solve/cache.rs b/compiler/rustc_middle/src/traits/solve/cache.rs
index e9e9cc418a6..4f90af0a27c 100644
--- a/compiler/rustc_middle/src/traits/solve/cache.rs
+++ b/compiler/rustc_middle/src/traits/solve/cache.rs
@@ -5,7 +5,7 @@ use rustc_data_structures::sync::Lock;
 use rustc_query_system::cache::WithDepNode;
 use rustc_query_system::dep_graph::DepNodeIndex;
 use rustc_session::Limit;
-/// The trait solver cache used by `-Ztrait-solver=next`.
+/// The trait solver cache used by `-Znext-solver`.
 ///
 /// FIXME(@lcnr): link to some official documentation of how
 /// this works.
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 6aa0016650d..8faf5811343 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -2240,15 +2240,11 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     pub fn next_trait_solver_globally(self) -> bool {
-        self.sess.opts.unstable_opts.trait_solver == rustc_session::config::TraitSolver::Next
+        self.sess.opts.unstable_opts.next_solver.map_or(false, |c| c.globally)
     }
 
     pub fn next_trait_solver_in_coherence(self) -> bool {
-        matches!(
-            self.sess.opts.unstable_opts.trait_solver,
-            rustc_session::config::TraitSolver::Next
-                | rustc_session::config::TraitSolver::NextCoherence
-        )
+        self.sess.opts.unstable_opts.next_solver.map_or(false, |c| c.coherence)
     }
 
     pub fn is_impl_trait_in_trait(self, def_id: DefId) -> bool {
diff --git a/compiler/rustc_middle/src/ty/fast_reject.rs b/compiler/rustc_middle/src/ty/fast_reject.rs
index f95ceeff150..38a9cabca97 100644
--- a/compiler/rustc_middle/src/ty/fast_reject.rs
+++ b/compiler/rustc_middle/src/ty/fast_reject.rs
@@ -62,7 +62,7 @@ pub enum TreatParams {
     ///
     /// N.B. during deep rejection, this acts identically to `ForLookup`.
     ///
-    /// FIXME(-Ztrait-solver=next): Remove this variant and cleanup
+    /// FIXME(-Znext-solver): Remove this variant and cleanup
     /// the code.
     NextSolverLookup,
 }
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 8dc9a29c2ad..6fda18d87e3 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -755,13 +755,14 @@ pub enum PrintKind {
 }
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
-pub enum TraitSolver {
-    /// Classic trait solver in `rustc_trait_selection::traits::select`
-    Classic,
-    /// Experimental trait solver in `rustc_trait_selection::solve`
-    Next,
-    /// Use the new trait solver during coherence
-    NextCoherence,
+pub struct NextSolverConfig {
+    /// Whether the new trait solver should be enabled in coherence.
+    pub coherence: bool,
+    /// Whether the new trait solver should be enabled everywhere.
+    /// This is only `true` if `coherence` is also enabled.
+    pub globally: bool,
+    /// Whether to dump proof trees after computing a proof tree.
+    pub dump_tree: DumpSolverProofTree,
 }
 
 #[derive(Default, Debug, Copy, Clone, Hash, PartialEq, Eq)]
@@ -3220,10 +3221,10 @@ pub(crate) mod dep_tracking {
     use super::{
         BranchProtection, CFGuard, CFProtection, CrateType, DebugInfo, DebugInfoCompression,
         ErrorOutputType, FunctionReturn, InliningThreshold, InstrumentCoverage, InstrumentXRay,
-        LinkerPluginLto, LocationDetail, LtoCli, OomStrategy, OptLevel, OutFileName, OutputType,
-        OutputTypes, Polonius, RemapPathScopeComponents, ResolveDocLinks, SourceFileHashAlgorithm,
-        SplitDwarfKind, SwitchWithOptPath, SymbolManglingVersion, TraitSolver, TrimmedDefPaths,
-        WasiExecModel,
+        LinkerPluginLto, LocationDetail, LtoCli, NextSolverConfig, OomStrategy, OptLevel,
+        OutFileName, OutputType, OutputTypes, Polonius, RemapPathScopeComponents, ResolveDocLinks,
+        SourceFileHashAlgorithm, SplitDwarfKind, SwitchWithOptPath, SymbolManglingVersion,
+        TrimmedDefPaths, WasiExecModel,
     };
     use crate::lint;
     use crate::utils::NativeLib;
@@ -3326,7 +3327,7 @@ pub(crate) mod dep_tracking {
         BranchProtection,
         OomStrategy,
         LanguageIdentifier,
-        TraitSolver,
+        NextSolverConfig,
         Polonius,
         InliningThreshold,
         FunctionReturn,
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index a3835c085da..e8ca556aa42 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -396,8 +396,7 @@ mod desc {
     pub const parse_instrument_xray: &str = "either a boolean (`yes`, `no`, `on`, `off`, etc), or a comma separated list of settings: `always` or `never` (mutually exclusive), `ignore-loops`, `instruction-threshold=N`, `skip-entry`, `skip-exit`";
     pub const parse_unpretty: &str = "`string` or `string=string`";
     pub const parse_treat_err_as_bug: &str = "either no value or a non-negative number";
-    pub const parse_trait_solver: &str =
-        "one of the supported solver modes (`classic`, `next`, or `next-coherence`)";
+    pub const parse_next_solver_config: &str = "a comma separated list of solver configurations: `globally` (default), `coherence`, `dump-tree`, `dump-tree-on-error";
     pub const parse_lto: &str =
         "either a boolean (`yes`, `no`, `on`, `off`, etc), `thin`, `fat`, or omitted";
     pub const parse_linker_plugin_lto: &str =
@@ -429,7 +428,6 @@ mod desc {
         "a `,` separated combination of `bti`, `b-key`, `pac-ret`, or `leaf`";
     pub const parse_proc_macro_execution_strategy: &str =
         "one of supported execution strategies (`same-thread`, or `cross-thread`)";
-    pub const parse_dump_solver_proof_tree: &str = "one of: `always`, `on-request`, `on-error`";
     pub const parse_remap_path_scope: &str = "comma separated list of scopes: `macro`, `diagnostics`, `unsplit-debuginfo`, `split-debuginfo`, `split-debuginfo-path`, `object`, `all`";
     pub const parse_inlining_threshold: &str =
         "either a boolean (`yes`, `no`, `on`, `off`, etc), or a non-negative number";
@@ -1032,15 +1030,48 @@ mod parse {
         }
     }
 
-    pub(crate) fn parse_trait_solver(slot: &mut TraitSolver, v: Option<&str>) -> bool {
-        match v {
-            Some("classic") => *slot = TraitSolver::Classic,
-            Some("next") => *slot = TraitSolver::Next,
-            Some("next-coherence") => *slot = TraitSolver::NextCoherence,
-            // default trait solver is subject to change..
-            Some("default") => *slot = TraitSolver::Classic,
-            _ => return false,
+    pub(crate) fn parse_next_solver_config(
+        slot: &mut Option<NextSolverConfig>,
+        v: Option<&str>,
+    ) -> bool {
+        if let Some(config) = v {
+            let mut coherence = false;
+            let mut globally = true;
+            let mut dump_tree = None;
+            for c in config.split(',') {
+                match c {
+                    "globally" => globally = true,
+                    "coherence" => {
+                        globally = false;
+                        coherence = true;
+                    }
+                    "dump-tree" => {
+                        if dump_tree.replace(DumpSolverProofTree::Always).is_some() {
+                            return false;
+                        }
+                    }
+                    "dump-tree-on-error" => {
+                        if dump_tree.replace(DumpSolverProofTree::OnError).is_some() {
+                            return false;
+                        }
+                    }
+                    _ => return false,
+                }
+            }
+
+            *slot = Some(NextSolverConfig {
+                coherence: coherence || globally,
+                globally,
+                dump_tree: dump_tree.unwrap_or_default(),
+            });
+        } else {
+            *slot = Some(NextSolverConfig {
+                coherence: true,
+                globally: true,
+                dump_tree: Default::default(),
+            });
         }
+
         true
     }
 
@@ -1305,19 +1336,6 @@ mod parse {
         true
     }
 
-    pub(crate) fn parse_dump_solver_proof_tree(
-        slot: &mut DumpSolverProofTree,
-        v: Option<&str>,
-    ) -> bool {
-        match v {
-            None | Some("always") => *slot = DumpSolverProofTree::Always,
-            Some("never") => *slot = DumpSolverProofTree::Never,
-            Some("on-error") => *slot = DumpSolverProofTree::OnError,
-            _ => return false,
-        };
-        true
-    }
-
     pub(crate) fn parse_inlining_threshold(slot: &mut InliningThreshold, v: Option<&str>) -> bool {
         match v {
             Some("always" | "yes") => {
@@ -1591,9 +1609,6 @@ options! {
         "output statistics about monomorphization collection"),
     dump_mono_stats_format: DumpMonoStatsFormat = (DumpMonoStatsFormat::Markdown, parse_dump_mono_stats, [UNTRACKED],
         "the format to use for -Z dump-mono-stats (`markdown` (default) or `json`)"),
-    dump_solver_proof_tree: DumpSolverProofTree = (DumpSolverProofTree::Never, parse_dump_solver_proof_tree, [UNTRACKED],
-        "dump a proof tree for every goal evaluated by the new trait solver. If the flag is specified without any options after it
-        then it defaults to `always`. If the flag is not specified at all it defaults to `on-request`."),
     dwarf_version: Option<u32> = (None, parse_opt_number, [TRACKED],
         "version of DWARF debug information to emit (default: 2 or 4, depending on platform)"),
     dylib_lto: bool = (false, parse_bool, [UNTRACKED],
@@ -1722,6 +1737,8 @@ options! {
         "the size at which the `large_assignments` lint starts to be emitted"),
     mutable_noalias: bool = (true, parse_bool, [TRACKED],
         "emit noalias metadata for mutable references (default: yes)"),
+    next_solver: Option<NextSolverConfig> = (None, parse_next_solver_config, [TRACKED],
+        "enable and configure the next generation trait solver used by rustc"),
     nll_facts: bool = (false, parse_bool, [UNTRACKED],
         "dump facts from NLL analysis into side files (default: no)"),
     nll_facts_dir: String = ("nll-facts".to_string(), parse_string, [UNTRACKED],
@@ -1922,8 +1939,6 @@ written to standard error output)"),
         "for every macro invocation, print its name and arguments (default: no)"),
     track_diagnostics: bool = (false, parse_bool, [UNTRACKED],
         "tracks where in rustc a diagnostic was emitted"),
-    trait_solver: TraitSolver = (TraitSolver::Classic, parse_trait_solver, [TRACKED],
-        "specify the trait solver mode used by rustc (default: classic)"),
     // Diagnostics are considered side-effects of a query (see `QuerySideEffects`) and are saved
     // alongside query results and changes to translation options can affect diagnostics - so
     // translation options should be tracked.
diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
index b3e7a63c972..cafb858794a 100644
--- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
+++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
@@ -200,9 +200,10 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> {
         let result = f(&mut ecx);
 
         let tree = ecx.inspect.finalize();
-        if let (Some(tree), DumpSolverProofTree::Always) =
-            (&tree, infcx.tcx.sess.opts.unstable_opts.dump_solver_proof_tree)
-        {
+        if let (Some(tree), DumpSolverProofTree::Always) = (
+            &tree,
+            infcx.tcx.sess.opts.unstable_opts.next_solver.map(|c| c.dump_tree).unwrap_or_default(),
+        ) {
             let mut lock = std::io::stdout().lock();
             let _ = lock.write_fmt(format_args!("{tree:?}\n"));
             let _ = lock.flush();
@@ -377,7 +378,7 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> {
         //
         // This assert was removed as it did not hold for goals constraining
         // an inference variable to a recursive alias, e.g. in
-        // tests/ui/traits/new-solver/overflow/recursive-self-normalization.rs.
+        // tests/ui/traits/next-solver/overflow/recursive-self-normalization.rs.
         //
         // Once we have decided on how to handle trait-system-refactor-initiative#75,
         // we should re-add an assert here.
@@ -421,7 +422,7 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> {
                     self.compute_const_evaluatable_goal(Goal { param_env, predicate: ct })
                 }
                 ty::PredicateKind::ConstEquate(_, _) => {
-                    bug!("ConstEquate should not be emitted when `-Ztrait-solver=next` is active")
+                    bug!("ConstEquate should not be emitted when `-Znext-solver` is active")
                 }
                 ty::PredicateKind::NormalizesTo(predicate) => {
                     self.compute_normalizes_to_goal(Goal { param_env, predicate })
diff --git a/compiler/rustc_trait_selection/src/solve/inspect/build.rs b/compiler/rustc_trait_selection/src/solve/inspect/build.rs
index 0d46df44c91..c857aae572d 100644
--- a/compiler/rustc_trait_selection/src/solve/inspect/build.rs
+++ b/compiler/rustc_trait_selection/src/solve/inspect/build.rs
@@ -265,7 +265,7 @@ impl<'tcx> ProofTreeBuilder<'tcx> {
             GenerateProofTree::Never => ProofTreeBuilder::new_noop(),
             GenerateProofTree::IfEnabled => {
                 let opts = &tcx.sess.opts.unstable_opts;
-                match opts.dump_solver_proof_tree {
+                match opts.next_solver.map(|c| c.dump_tree).unwrap_or_default() {
                     DumpSolverProofTree::Always => ProofTreeBuilder::new_root(),
                     // `OnError` is handled by reevaluating goals in error
                     // reporting with `GenerateProofTree::Yes`.
diff --git a/compiler/rustc_trait_selection/src/solve/mod.rs b/compiler/rustc_trait_selection/src/solve/mod.rs
index f45473e06dc..1e58106e353 100644
--- a/compiler/rustc_trait_selection/src/solve/mod.rs
+++ b/compiler/rustc_trait_selection/src/solve/mod.rs
@@ -1,7 +1,6 @@
 //! The next-generation trait solver, currently still WIP.
 //!
-//! As a user of rust, you can use `-Ztrait-solver=next` or `next-coherence`
-//! to enable the new trait solver always, or just within coherence, respectively.
+//! As a user of rust, you can use `-Znext-solver` to enable the new trait solver.
 //!
 //! As a developer of rustc, you shouldn't be using the new trait
 //! solver without asking the trait-system-refactor-initiative, but it can
@@ -248,7 +247,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
             return None;
         }
 
-        // FIXME(-Ztrait-solver=next): We should instead try to find a `Certainty::Yes` response with
+        // FIXME(-Znext-solver): We should instead try to find a `Certainty::Yes` response with
         // a subset of the constraints that all the other responses have.
         let one = responses[0];
         if responses[1..].iter().all(|&resp| resp == one) {
diff --git a/compiler/rustc_trait_selection/src/solve/search_graph.rs b/compiler/rustc_trait_selection/src/solve/search_graph.rs
index 71adebffc15..2a08b80e02a 100644
--- a/compiler/rustc_trait_selection/src/solve/search_graph.rs
+++ b/compiler/rustc_trait_selection/src/solve/search_graph.rs
@@ -38,7 +38,7 @@ struct StackEntry<'tcx> {
     /// If we were to use that result when later trying to prove another cycle
     /// participant, we can end up with unstable query results.
     ///
-    /// See tests/ui/new-solver/coinduction/incompleteness-unstable-result.rs for
+    /// See tests/ui/next-solver/coinduction/incompleteness-unstable-result.rs for
     /// an example of where this is needed.
     cycle_participants: FxHashSet<CanonicalInput<'tcx>>,
 }
@@ -237,7 +237,7 @@ impl<'tcx> SearchGraph<'tcx> {
                     // in unstable results due to incompleteness.
                     //
                     // However, a test for this would be an even more complex version of
-                    // tests/ui/traits/new-solver/coinduction/incompleteness-unstable-result.rs.
+                    // tests/ui/traits/next-solver/coinduction/incompleteness-unstable-result.rs.
                     // I did not bother to write such a test and we have no regression test
                     // for this. It would be good to have such a test :)
                     #[allow(rustc::potential_query_instability)]
@@ -248,7 +248,7 @@ impl<'tcx> SearchGraph<'tcx> {
                 // until we reach a fixpoint. It is not enough to simply retry the
                 // `root` goal of this cycle.
                 //
-                // See tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.rs
+                // See tests/ui/traits/next-solver/cycles/fixpoint-rerun-all-cycle-heads.rs
                 // for an example.
                 self.stack[stack_depth].has_been_used = true;
                 return if let Some(result) = self.stack[stack_depth].provisional_result {
diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals.rs b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
index 5807f7c6153..9536fde7c93 100644
--- a/compiler/rustc_trait_selection/src/solve/trait_goals.rs
+++ b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
@@ -445,7 +445,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
             return Err(NoSolution);
         }
 
-        // FIXME(-Ztrait-solver=next): Implement this when we get const working in the new solver
+        // FIXME(-Znext-solver): Implement this when we get const working in the new solver
 
         // `Destruct` is automatically implemented for every type in
         // non-const environments.
diff --git a/compiler/rustc_trait_selection/src/traits/coherence.rs b/compiler/rustc_trait_selection/src/traits/coherence.rs
index db4d4a93e54..88ebea70021 100644
--- a/compiler/rustc_trait_selection/src/traits/coherence.rs
+++ b/compiler/rustc_trait_selection/src/traits/coherence.rs
@@ -855,7 +855,7 @@ where
     }
 
     fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
-        // Need to lazily normalize here in with `-Ztrait-solver=next-coherence`.
+        // Need to lazily normalize here in with `-Znext-solver=coherence`.
         let ty = match (self.lazily_normalize_ty)(ty) {
             Ok(ty) => ty,
             Err(err) => return ControlFlow::Break(OrphanCheckEarlyExit::NormalizationFailure(err)),
@@ -1069,7 +1069,7 @@ impl<'a, 'tcx> ProofTreeVisitor<'tcx> for AmbiguityCausesVisitor<'a, 'tcx> {
                 let lazily_normalize_ty = |ty: Ty<'tcx>| {
                     let mut fulfill_cx = <dyn TraitEngine<'tcx>>::new(infcx);
                     if matches!(ty.kind(), ty::Alias(..)) {
-                        // FIXME(-Ztrait-solver=next-coherence): we currently don't
+                        // FIXME(-Znext-solver=coherence): we currently don't
                         // normalize opaque types here, resulting in diverging behavior
                         // for TAITs.
                         match infcx
diff --git a/compiler/rustc_trait_selection/src/traits/engine.rs b/compiler/rustc_trait_selection/src/traits/engine.rs
index 67718d0a348..013a50f9fa1 100644
--- a/compiler/rustc_trait_selection/src/traits/engine.rs
+++ b/compiler/rustc_trait_selection/src/traits/engine.rs
@@ -25,7 +25,6 @@ use rustc_middle::ty::ToPredicate;
 use rustc_middle::ty::TypeFoldable;
 use rustc_middle::ty::Variance;
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_session::config::TraitSolver;
 
 pub trait TraitEngineExt<'tcx> {
     fn new(infcx: &InferCtxt<'tcx>) -> Box<Self>;
@@ -33,18 +32,16 @@ pub trait TraitEngineExt<'tcx> {
 
 impl<'tcx> TraitEngineExt<'tcx> for dyn TraitEngine<'tcx> {
     fn new(infcx: &InferCtxt<'tcx>) -> Box<Self> {
-        match (infcx.tcx.sess.opts.unstable_opts.trait_solver, infcx.next_trait_solver()) {
-            (TraitSolver::Classic, false) | (TraitSolver::NextCoherence, false) => {
-                Box::new(FulfillmentContext::new(infcx))
-            }
-            (TraitSolver::Classic | TraitSolver::Next | TraitSolver::NextCoherence, true) => {
-                Box::new(NextFulfillmentCtxt::new(infcx))
-            }
-            (TraitSolver::Next, false) => bug!(
-                "incompatible combination of -Ztrait-solver flag ({:?}) and InferCtxt::next_trait_solver ({:?})",
-                infcx.tcx.sess.opts.unstable_opts.trait_solver,
-                infcx.next_trait_solver()
-            ),
+        if infcx.next_trait_solver() {
+            Box::new(NextFulfillmentCtxt::new(infcx))
+        } else {
+            let new_solver_globally =
+                infcx.tcx.sess.opts.unstable_opts.next_solver.map_or(false, |c| c.globally);
+            assert!(
+                !new_solver_globally,
+                "using old solver even though new solver is enabled globally"
+            );
+            Box::new(FulfillmentContext::new(infcx))
         }
     }
 }
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
index 7f6e48f4464..b3bb0a9fcb7 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
@@ -37,7 +37,7 @@ use rustc_middle::ty::{
     self, SubtypePredicate, ToPolyTraitRef, ToPredicate, TraitRef, Ty, TyCtxt, TypeFoldable,
     TypeVisitable, TypeVisitableExt,
 };
-use rustc_session::config::{DumpSolverProofTree, TraitSolver};
+use rustc_session::config::DumpSolverProofTree;
 use rustc_session::Limit;
 use rustc_span::def_id::LOCAL_CRATE;
 use rustc_span::symbol::sym;
@@ -370,7 +370,9 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
     ) {
         let tcx = self.tcx;
 
-        if tcx.sess.opts.unstable_opts.dump_solver_proof_tree == DumpSolverProofTree::OnError {
+        if tcx.sess.opts.unstable_opts.next_solver.map(|c| c.dump_tree).unwrap_or_default()
+            == DumpSolverProofTree::OnError
+        {
             dump_proof_tree(root_obligation, self.infcx);
         }
 
@@ -812,23 +814,20 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
 
                     ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(ty)) => {
                         let ty = self.resolve_vars_if_possible(ty);
-                        match self.tcx.sess.opts.unstable_opts.trait_solver {
-                            TraitSolver::Classic => {
-                                // WF predicates cannot themselves make
-                                // errors. They can only block due to
-                                // ambiguity; otherwise, they always
-                                // degenerate into other obligations
-                                // (which may fail).
-                                span_bug!(span, "WF predicate not satisfied for {:?}", ty);
-                            }
-                            TraitSolver::Next | TraitSolver::NextCoherence => {
-                                // FIXME: we'll need a better message which takes into account
-                                // which bounds actually failed to hold.
-                                self.tcx.sess.struct_span_err(
-                                    span,
-                                    format!("the type `{ty}` is not well-formed"),
-                                )
-                            }
+                        if self.next_trait_solver() {
+                            // FIXME: we'll need a better message which takes into account
+                            // which bounds actually failed to hold.
+                            self.tcx.sess.struct_span_err(
+                                span,
+                                format!("the type `{ty}` is not well-formed"),
+                            )
+                        } else {
+                            // WF predicates cannot themselves make
+                            // errors. They can only block due to
+                            // ambiguity; otherwise, they always
+                            // degenerate into other obligations
+                            // (which may fail).
+                            span_bug!(span, "WF predicate not satisfied for {:?}", ty);
                         }
                     }
 
@@ -1562,7 +1561,9 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
 
     #[instrument(skip(self), level = "debug")]
     fn report_fulfillment_error(&self, error: &FulfillmentError<'tcx>) {
-        if self.tcx.sess.opts.unstable_opts.dump_solver_proof_tree == DumpSolverProofTree::OnError {
+        if self.tcx.sess.opts.unstable_opts.next_solver.map(|c| c.dump_tree).unwrap_or_default()
+            == DumpSolverProofTree::OnError
+        {
             dump_proof_tree(&error.root_obligation, self.infcx);
         }
 
@@ -1668,7 +1669,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     )
                     .into(),
                 };
-                // FIXME(-Ztrait-solver=next): For diagnostic purposes, it would be nice
+                // FIXME(-Znext-solver): For diagnostic purposes, it would be nice
                 // to deeply normalize this type.
                 let normalized_term =
                     ocx.normalize(&obligation.cause, obligation.param_env, unnormalized_term);
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index 64d2b5fc159..8c5f1e90715 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -315,7 +315,7 @@ pub fn normalize_param_env_or_error<'tcx>(
             // We do not normalize types here as there is no backwards compatibility requirement
             // for us to do so.
             //
-            // FIXME(-Ztrait-solver=next): remove this hack since we have deferred projection equality
+            // FIXME(-Znext-solver): remove this hack since we have deferred projection equality
             predicate.fold_with(&mut ConstNormalizer(tcx))
         }),
     )
@@ -386,7 +386,7 @@ pub fn normalize_param_env_or_error<'tcx>(
 
 /// Normalize a type and process all resulting obligations, returning any errors.
 ///
-/// FIXME(-Ztrait-solver=next): This should be replaced by `At::deeply_normalize`
+/// 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.
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index a08e35b566f..4c3eb05819f 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -67,7 +67,7 @@ pub trait NormalizeExt<'tcx> {
     /// same goals in both a temporary and the shared context which negatively impacts
     /// performance as these don't share caching.
     ///
-    /// FIXME(-Ztrait-solver=next): This has the same behavior as `traits::fully_normalize`
+    /// 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
diff --git a/compiler/rustc_trait_selection/src/traits/query/evaluate_obligation.rs b/compiler/rustc_trait_selection/src/traits/query/evaluate_obligation.rs
index 04b3119323f..d812d537d8c 100644
--- a/compiler/rustc_trait_selection/src/traits/query/evaluate_obligation.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/evaluate_obligation.rs
@@ -72,7 +72,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
                 let mut fulfill_cx = crate::solve::FulfillmentCtxt::new(self);
                 fulfill_cx.register_predicate_obligation(self, obligation.clone());
                 // True errors
-                // FIXME(-Ztrait-solver=next): Overflows are reported as ambig here, is that OK?
+                // FIXME(-Znext-solver): Overflows are reported as ambig here, is that OK?
                 if !fulfill_cx.select_where_possible(self).is_empty() {
                     Ok(EvaluationResult::EvaluatedToErr)
                 } else if !fulfill_cx.select_all_or_error(self).is_empty() {
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/ascribe_user_type.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/ascribe_user_type.rs
index 302b6016e5e..152ceeee869 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/ascribe_user_type.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/ascribe_user_type.rs
@@ -26,7 +26,7 @@ impl<'tcx> super::QueryTypeOp<'tcx> for AscribeUserType<'tcx> {
         tcx.type_op_ascribe_user_type(canonicalized)
     }
 
-    fn perform_locally_in_new_solver(
+    fn perform_locally_with_next_solver(
         ocx: &ObligationCtxt<'_, 'tcx>,
         key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution> {
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/eq.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/eq.rs
index f6589308806..57e649f3e43 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/eq.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/eq.rs
@@ -23,7 +23,7 @@ impl<'tcx> super::QueryTypeOp<'tcx> for Eq<'tcx> {
         tcx.type_op_eq(canonicalized)
     }
 
-    fn perform_locally_in_new_solver(
+    fn perform_locally_with_next_solver(
         ocx: &ObligationCtxt<'_, 'tcx>,
         key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution> {
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs
index f9b8ea32d89..10528696b2d 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs
@@ -50,7 +50,7 @@ impl<'tcx> super::QueryTypeOp<'tcx> for ImpliedOutlivesBounds<'tcx> {
         tcx.implied_outlives_bounds(canonicalized)
     }
 
-    fn perform_locally_in_new_solver(
+    fn perform_locally_with_next_solver(
         ocx: &ObligationCtxt<'_, 'tcx>,
         key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution> {
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
index cd09aaff2d9..272f1a54f81 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
@@ -89,7 +89,7 @@ pub trait QueryTypeOp<'tcx>: fmt::Debug + Copy + TypeFoldable<TyCtxt<'tcx>> + 't
     /// make sure to feed it predefined opaque types and the defining anchor
     /// and that would require duplicating all of the tcx queries. Instead,
     /// just perform these ops locally.
-    fn perform_locally_in_new_solver(
+    fn perform_locally_with_next_solver(
         ocx: &ObligationCtxt<'_, 'tcx>,
         key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution>;
@@ -149,7 +149,7 @@ where
         if infcx.next_trait_solver() {
             return Ok(scrape_region_constraints(
                 infcx,
-                |ocx| QueryTypeOp::perform_locally_in_new_solver(ocx, self),
+                |ocx| QueryTypeOp::perform_locally_with_next_solver(ocx, self),
                 "query type op",
                 span,
             )?
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/normalize.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/normalize.rs
index 9559f5002f6..3b33f6e6144 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/normalize.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/normalize.rs
@@ -25,11 +25,11 @@ where
         T::type_op_method(tcx, canonicalized)
     }
 
-    fn perform_locally_in_new_solver(
+    fn perform_locally_with_next_solver(
         ocx: &ObligationCtxt<'_, 'tcx>,
         key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution> {
-        // FIXME(-Ztrait-solver=next): shouldn't be using old normalizer
+        // FIXME(-Znext-solver): shouldn't be using old normalizer
         Ok(ocx.normalize(&ObligationCause::dummy(), key.param_env, key.value.value))
     }
 }
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/outlives.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/outlives.rs
index f2c1243f931..07587e37411 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/outlives.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/outlives.rs
@@ -42,7 +42,7 @@ impl<'tcx> super::QueryTypeOp<'tcx> for DropckOutlives<'tcx> {
         tcx.dropck_outlives(canonicalized)
     }
 
-    fn perform_locally_in_new_solver(
+    fn perform_locally_with_next_solver(
         ocx: &ObligationCtxt<'_, 'tcx>,
         key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution> {
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs
index 789ef647246..e21ede47f6d 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs
@@ -40,7 +40,7 @@ impl<'tcx> super::QueryTypeOp<'tcx> for ProvePredicate<'tcx> {
         tcx.type_op_prove_predicate(canonicalized)
     }
 
-    fn perform_locally_in_new_solver(
+    fn perform_locally_with_next_solver(
         ocx: &ObligationCtxt<'_, 'tcx>,
         key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution> {
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/subtype.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/subtype.rs
index 10976d5cd71..ae11b0825bd 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/subtype.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/subtype.rs
@@ -20,7 +20,7 @@ impl<'tcx> super::QueryTypeOp<'tcx> for Subtype<'tcx> {
         tcx.type_op_subtype(canonicalized)
     }
 
-    fn perform_locally_in_new_solver(
+    fn perform_locally_with_next_solver(
         ocx: &ObligationCtxt<'_, 'tcx>,
         key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution> {
diff --git a/compiler/rustc_trait_selection/src/traits/structural_normalize.rs b/compiler/rustc_trait_selection/src/traits/structural_normalize.rs
index 32de8feda81..b9ab26fe2fe 100644
--- a/compiler/rustc_trait_selection/src/traits/structural_normalize.rs
+++ b/compiler/rustc_trait_selection/src/traits/structural_normalize.rs
@@ -22,7 +22,7 @@ impl<'tcx> StructurallyNormalizeExt<'tcx> for At<'_, 'tcx> {
         assert!(!ty.is_ty_var(), "should have resolved vars before calling");
 
         if self.infcx.next_trait_solver() {
-            // FIXME(-Ztrait-solver=next): correctly handle
+            // FIXME(-Znext-solver): correctly handle
             // overflow here.
             for _ in 0..256 {
                 let ty::Alias(ty::Projection | ty::Inherent | ty::Weak, alias) = *ty.kind() else {
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 055671afd14..5d53a4d28f2 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -2543,10 +2543,10 @@ impl<'test> TestCx<'test> {
                 rustc.args(&["-Zpolonius"]);
             }
             Some(CompareMode::NextSolver) => {
-                rustc.args(&["-Ztrait-solver=next"]);
+                rustc.args(&["-Znext-solver"]);
             }
             Some(CompareMode::NextSolverCoherence) => {
-                rustc.args(&["-Ztrait-solver=next-coherence"]);
+                rustc.args(&["-Znext-solver=coherence"]);
             }
             Some(CompareMode::SplitDwarf) if self.config.target.contains("windows") => {
                 rustc.args(&["-Csplit-debuginfo=unpacked", "-Zunstable-options"]);
diff --git a/tests/ui/associated-inherent-types/inference.rs b/tests/ui/associated-inherent-types/inference.rs
index 66f879c5a71..054034b4c28 100644
--- a/tests/ui/associated-inherent-types/inference.rs
+++ b/tests/ui/associated-inherent-types/inference.rs
@@ -1,7 +1,7 @@
 // Testing inference capabilities.
 // check-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(inherent_associated_types)]
 #![allow(incomplete_features)]
diff --git a/tests/ui/async-await/normalize-output-in-signature-deduction.rs b/tests/ui/async-await/normalize-output-in-signature-deduction.rs
index 960065a83a4..e07fe9e98ec 100644
--- a/tests/ui/async-await/normalize-output-in-signature-deduction.rs
+++ b/tests/ui/async-await/normalize-output-in-signature-deduction.rs
@@ -1,6 +1,6 @@
 // edition:2021
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // check-pass
 
 #![feature(type_alias_impl_trait)]
diff --git a/tests/ui/async-await/return-type-notation/normalizing-self-auto-trait-issue-109924.rs b/tests/ui/async-await/return-type-notation/normalizing-self-auto-trait-issue-109924.rs
index e581e5ffda7..6097c7f1073 100644
--- a/tests/ui/async-await/return-type-notation/normalizing-self-auto-trait-issue-109924.rs
+++ b/tests/ui/async-await/return-type-notation/normalizing-self-auto-trait-issue-109924.rs
@@ -1,7 +1,7 @@
 // revisions: current next
 //[current] known-bug: #109924
 //[next] check-pass
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // edition:2021
 
 #![feature(return_type_notation)]
diff --git a/tests/ui/auto-traits/issue-23080-2.rs b/tests/ui/auto-traits/issue-23080-2.rs
index 882b8f39384..d63cd9d5dd6 100644
--- a/tests/ui/auto-traits/issue-23080-2.rs
+++ b/tests/ui/auto-traits/issue-23080-2.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(auto_traits)]
 #![feature(negative_impls)]
diff --git a/tests/ui/closures/infer-signature-from-impl.rs b/tests/ui/closures/infer-signature-from-impl.rs
index 6e8c94177bf..8b18e4ef9e7 100644
--- a/tests/ui/closures/infer-signature-from-impl.rs
+++ b/tests/ui/closures/infer-signature-from-impl.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 //[next] known-bug: trait-system-refactor-initiative#71
 //[current] check-pass
 
diff --git a/tests/ui/coherence/coherence-overlap-downstream-inherent.rs b/tests/ui/coherence/coherence-overlap-downstream-inherent.rs
index 2c3ef4fd3f7..94a7ecbe11f 100644
--- a/tests/ui/coherence/coherence-overlap-downstream-inherent.rs
+++ b/tests/ui/coherence/coherence-overlap-downstream-inherent.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 // Tests that we consider `T: Sugar + Fruit` to be ambiguous, even
 // though no impls are found.
diff --git a/tests/ui/coherence/coherence-overlap-downstream.rs b/tests/ui/coherence/coherence-overlap-downstream.rs
index a4e559604a0..171b2a32fc5 100644
--- a/tests/ui/coherence/coherence-overlap-downstream.rs
+++ b/tests/ui/coherence/coherence-overlap-downstream.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 // Tests that we consider `T: Sugar + Fruit` to be ambiguous, even
 // though no impls are found.
diff --git a/tests/ui/coherence/coherence-overlap-issue-23516-inherent.rs b/tests/ui/coherence/coherence-overlap-issue-23516-inherent.rs
index a7c90a6b8c8..6f5cc980491 100644
--- a/tests/ui/coherence/coherence-overlap-issue-23516-inherent.rs
+++ b/tests/ui/coherence/coherence-overlap-issue-23516-inherent.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 // Tests that we consider `Box<U>: !Sugar` to be ambiguous, even
 // though we see no impl of `Sugar` for `Box`. Therefore, an overlap
diff --git a/tests/ui/coherence/coherence-overlap-issue-23516.rs b/tests/ui/coherence/coherence-overlap-issue-23516.rs
index c846d39716b..4daaed4366f 100644
--- a/tests/ui/coherence/coherence-overlap-issue-23516.rs
+++ b/tests/ui/coherence/coherence-overlap-issue-23516.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 // Tests that we consider `Box<U>: !Sugar` to be ambiguous, even
 // though we see no impl of `Sugar` for `Box`. Therefore, an overlap
diff --git a/tests/ui/coherence/inter-crate-ambiguity-causes-notes.rs b/tests/ui/coherence/inter-crate-ambiguity-causes-notes.rs
index 743e80d3f18..0f785b4e5f6 100644
--- a/tests/ui/coherence/inter-crate-ambiguity-causes-notes.rs
+++ b/tests/ui/coherence/inter-crate-ambiguity-causes-notes.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 struct S;
 
diff --git a/tests/ui/coherence/normalize-for-errors.rs b/tests/ui/coherence/normalize-for-errors.rs
index 367d34251ae..30723518bce 100644
--- a/tests/ui/coherence/normalize-for-errors.rs
+++ b/tests/ui/coherence/normalize-for-errors.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 struct MyType;
 trait MyTrait<S> {}
diff --git a/tests/ui/coherence/occurs-check/associated-type.rs b/tests/ui/coherence/occurs-check/associated-type.rs
index 909551f65be..227b6684785 100644
--- a/tests/ui/coherence/occurs-check/associated-type.rs
+++ b/tests/ui/coherence/occurs-check/associated-type.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 // A regression test for #105787
 
diff --git a/tests/ui/coherence/occurs-check/opaques.rs b/tests/ui/coherence/occurs-check/opaques.rs
index 9d31a3dc82d..2fa9dcebfde 100644
--- a/tests/ui/coherence/occurs-check/opaques.rs
+++ b/tests/ui/coherence/occurs-check/opaques.rs
@@ -1,5 +1,5 @@
 //revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 // A regression test for #105787
 
diff --git a/tests/ui/coinduction/canonicalization-rerun.rs b/tests/ui/coinduction/canonicalization-rerun.rs
index c68895fc4e6..bbd8d802630 100644
--- a/tests/ui/coinduction/canonicalization-rerun.rs
+++ b/tests/ui/coinduction/canonicalization-rerun.rs
@@ -1,6 +1,6 @@
 // check-pass
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 // If we use canonical goals during trait solving we have to reevaluate
 // the root goal of a cycle until we hit a fixpoint.
diff --git a/tests/ui/const-generics/defaults/default-param-wf-concrete.rs b/tests/ui/const-generics/defaults/default-param-wf-concrete.rs
index 09a00dd8e70..aa3307b92e4 100644
--- a/tests/ui/const-generics/defaults/default-param-wf-concrete.rs
+++ b/tests/ui/const-generics/defaults/default-param-wf-concrete.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 struct Foo<const N: u8 = { 255 + 1 }>;
 //~^ ERROR evaluation of constant value failed
diff --git a/tests/ui/consts/const-len-underflow-separate-spans.rs b/tests/ui/consts/const-len-underflow-separate-spans.rs
index 55704b64154..bd37be21576 100644
--- a/tests/ui/consts/const-len-underflow-separate-spans.rs
+++ b/tests/ui/consts/const-len-underflow-separate-spans.rs
@@ -3,7 +3,7 @@
 // overall context for what caused the evaluation.
 
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 const ONE: usize = 1;
 const TWO: usize = 2;
diff --git a/tests/ui/coroutine/clone-rpit.rs b/tests/ui/coroutine/clone-rpit.rs
index e0061e1c6bb..cbd28f88fcb 100644
--- a/tests/ui/coroutine/clone-rpit.rs
+++ b/tests/ui/coroutine/clone-rpit.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // check-pass
 
 #![feature(coroutines, coroutine_trait, coroutine_clone)]
diff --git a/tests/ui/coroutine/gen_block_is_iter.rs b/tests/ui/coroutine/gen_block_is_iter.rs
index 92625cf7c28..d43eef4a18d 100644
--- a/tests/ui/coroutine/gen_block_is_iter.rs
+++ b/tests/ui/coroutine/gen_block_is_iter.rs
@@ -1,6 +1,6 @@
 // revisions: next old
 //compile-flags: --edition 2024 -Zunstable-options
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // check-pass
 #![feature(gen_blocks)]
 
diff --git a/tests/ui/coroutine/gen_block_iterate.rs b/tests/ui/coroutine/gen_block_iterate.rs
index 18e1bb88772..8e72b00d99d 100644
--- a/tests/ui/coroutine/gen_block_iterate.rs
+++ b/tests/ui/coroutine/gen_block_iterate.rs
@@ -1,6 +1,6 @@
 // revisions: next old
 //compile-flags: --edition 2024 -Zunstable-options
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // run-pass
 #![feature(gen_blocks)]
 
diff --git a/tests/ui/coroutine/non-static-is-unpin.rs b/tests/ui/coroutine/non-static-is-unpin.rs
index d77fe659f08..238e49bbfdf 100644
--- a/tests/ui/coroutine/non-static-is-unpin.rs
+++ b/tests/ui/coroutine/non-static-is-unpin.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // run-pass
 
 #![feature(coroutines, coroutine_trait)]
diff --git a/tests/ui/coroutine/static-not-unpin.rs b/tests/ui/coroutine/static-not-unpin.rs
index 6ce78046dcc..f27183d11db 100644
--- a/tests/ui/coroutine/static-not-unpin.rs
+++ b/tests/ui/coroutine/static-not-unpin.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(coroutines)]
 
diff --git a/tests/ui/dyn-star/box.rs b/tests/ui/dyn-star/box.rs
index 87c8356a174..8b2f46bd1b2 100644
--- a/tests/ui/dyn-star/box.rs
+++ b/tests/ui/dyn-star/box.rs
@@ -1,7 +1,7 @@
 // run-pass
 // revisions: current next
 //[current] compile-flags: -C opt-level=0
-//[next] compile-flags: -Ztrait-solver=next -C opt-level=0
+//[next] compile-flags: -Znext-solver -C opt-level=0
 
 #![feature(dyn_star)]
 #![allow(incomplete_features)]
diff --git a/tests/ui/dyn-star/check-size-at-cast-polymorphic-bad.rs b/tests/ui/dyn-star/check-size-at-cast-polymorphic-bad.rs
index 9846f871424..dffe6ae8a36 100644
--- a/tests/ui/dyn-star/check-size-at-cast-polymorphic-bad.rs
+++ b/tests/ui/dyn-star/check-size-at-cast-polymorphic-bad.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(dyn_star)]
 #![allow(incomplete_features)]
diff --git a/tests/ui/dyn-star/param-env-region-infer.rs b/tests/ui/dyn-star/param-env-region-infer.rs
index 50dec94d25b..1e331777765 100644
--- a/tests/ui/dyn-star/param-env-region-infer.rs
+++ b/tests/ui/dyn-star/param-env-region-infer.rs
@@ -1,7 +1,7 @@
 // revisions: current
 // incremental
 
-// FIXME(-Ztrait-solver=next): THis currently results in unstable query results:
+// FIXME(-Znext-solver): THis currently results in unstable query results:
 // `normalizes-to(opaque, opaque)` changes from `Maybe(Ambiguous)` to `Maybe(Overflow)`
 // once the hidden type of the opaque is already defined to be itself.
 
diff --git a/tests/ui/error-codes/E0476.rs b/tests/ui/error-codes/E0476.rs
index e9afc756726..d87916198c5 100644
--- a/tests/ui/error-codes/E0476.rs
+++ b/tests/ui/error-codes/E0476.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next-coherence
+//[next] compile-flags: -Znext-solver=coherence
 #![feature(coerce_unsized)]
 #![feature(unsize)]
 
diff --git a/tests/ui/for/issue-20605.rs b/tests/ui/for/issue-20605.rs
index 50d4c3fddb5..8ae9494faf8 100644
--- a/tests/ui/for/issue-20605.rs
+++ b/tests/ui/for/issue-20605.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 fn changer<'a>(mut things: Box<dyn Iterator<Item=&'a mut u8>>) {
     for item in *things { *item = 0 }
@@ -13,7 +13,7 @@ fn changer<'a>(mut things: Box<dyn Iterator<Item=&'a mut u8>>) {
     //[next]~| ERROR the type `Option<<<dyn Iterator<Item = &'a mut u8> as IntoIterator>::IntoIter as Iterator>::Item>` is not well-formed
     //[next]~| ERROR the size for values of type `<<dyn Iterator<Item = &'a mut u8> as IntoIterator>::IntoIter as Iterator>::Item` cannot be known at compilation time
     //[next]~| ERROR type `<<dyn Iterator<Item = &'a mut u8> as IntoIterator>::IntoIter as Iterator>::Item` cannot be dereferenced
-    // FIXME(-Ztrait-solver=next): these error messages are horrible and have to be
+    // FIXME(-Znext-solver): these error messages are horrible and have to be
     // improved before we stabilize the new solver.
 }
 
diff --git a/tests/ui/generic-associated-types/issue-102114.rs b/tests/ui/generic-associated-types/issue-102114.rs
index bb6622c0a5f..bb6369d7f8f 100644
--- a/tests/ui/generic-associated-types/issue-102114.rs
+++ b/tests/ui/generic-associated-types/issue-102114.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 trait A {
     type B<'b>;
diff --git a/tests/ui/higher-ranked/leak-check-in-selection.rs b/tests/ui/higher-ranked/leak-check-in-selection.rs
index e8d6cff856c..5b36902ffdf 100644
--- a/tests/ui/higher-ranked/leak-check-in-selection.rs
+++ b/tests/ui/higher-ranked/leak-check-in-selection.rs
@@ -1,6 +1,6 @@
 // run-pass
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 #![allow(coherence_leak_check)]
 
 trait Trait: Sized {
diff --git a/tests/ui/higher-ranked/trait-bounds/fn-ptr.rs b/tests/ui/higher-ranked/trait-bounds/fn-ptr.rs
index adb19c035bc..41f24dde01a 100644
--- a/tests/ui/higher-ranked/trait-bounds/fn-ptr.rs
+++ b/tests/ui/higher-ranked/trait-bounds/fn-ptr.rs
@@ -1,5 +1,5 @@
 // revisions: classic next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 //[next] check-pass
 
 fn ice()
diff --git a/tests/ui/higher-ranked/trait-bounds/future.rs b/tests/ui/higher-ranked/trait-bounds/future.rs
index 61d86a9cb23..baeb56e5d78 100644
--- a/tests/ui/higher-ranked/trait-bounds/future.rs
+++ b/tests/ui/higher-ranked/trait-bounds/future.rs
@@ -1,7 +1,7 @@
 // ignore-tidy-linelength
 // edition:2021
 // revisions: classic next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 //[next] check-pass
 //[classic] known-bug: #112347
 //[classic] build-fail
diff --git a/tests/ui/higher-ranked/trait-bounds/issue-95230.rs b/tests/ui/higher-ranked/trait-bounds/issue-95230.rs
index 49a1584d54e..027644a280b 100644
--- a/tests/ui/higher-ranked/trait-bounds/issue-95230.rs
+++ b/tests/ui/higher-ranked/trait-bounds/issue-95230.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 //[old] check-pass
 //[next] known-bug: #109764
 
diff --git a/tests/ui/impl-trait/auto-trait-coherence.rs b/tests/ui/impl-trait/auto-trait-coherence.rs
index a5cd01a87ff..e4226b20074 100644
--- a/tests/ui/impl-trait/auto-trait-coherence.rs
+++ b/tests/ui/impl-trait/auto-trait-coherence.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 // Tests that type alias impls traits do not leak auto-traits for
 // the purposes of coherence checking
diff --git a/tests/ui/impl-trait/autoderef.rs b/tests/ui/impl-trait/autoderef.rs
index cd2cdd9e3b3..48ff8be6549 100644
--- a/tests/ui/impl-trait/autoderef.rs
+++ b/tests/ui/impl-trait/autoderef.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // check-pass
 
 use std::path::Path;
diff --git a/tests/ui/impl-trait/erased-regions-in-hidden-ty.rs b/tests/ui/impl-trait/erased-regions-in-hidden-ty.rs
index 698123a932d..b1f36fc247f 100644
--- a/tests/ui/impl-trait/erased-regions-in-hidden-ty.rs
+++ b/tests/ui/impl-trait/erased-regions-in-hidden-ty.rs
@@ -1,6 +1,6 @@
 // revisions: current next
 // compile-flags: -Zverbose
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // normalize-stderr-test "DefId\([^\)]+\)" -> "DefId(..)"
 
 #![feature(rustc_attrs)]
diff --git a/tests/ui/impl-trait/in-trait/object-safety-sized.rs b/tests/ui/impl-trait/in-trait/object-safety-sized.rs
index 35afe80c97f..1a23493a94d 100644
--- a/tests/ui/impl-trait/in-trait/object-safety-sized.rs
+++ b/tests/ui/impl-trait/in-trait/object-safety-sized.rs
@@ -1,6 +1,6 @@
 // check-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 
 fn main() {
diff --git a/tests/ui/impl-trait/in-trait/opaque-variances.rs b/tests/ui/impl-trait/in-trait/opaque-variances.rs
index 60bfab0deb5..63e56051d1a 100644
--- a/tests/ui/impl-trait/in-trait/opaque-variances.rs
+++ b/tests/ui/impl-trait/in-trait/opaque-variances.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 fn foo<'a: 'a>(x: &'a Vec<i32>) -> impl Sized {
     ()
diff --git a/tests/ui/impl-trait/issue-103181-1.rs b/tests/ui/impl-trait/issue-103181-1.rs
index 5154abcd690..14c813cf00f 100644
--- a/tests/ui/impl-trait/issue-103181-1.rs
+++ b/tests/ui/impl-trait/issue-103181-1.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // edition:2021
 
 mod hyper {
diff --git a/tests/ui/impl-trait/recursive-coroutine.rs b/tests/ui/impl-trait/recursive-coroutine.rs
index f0bee4f120f..b82fe134a40 100644
--- a/tests/ui/impl-trait/recursive-coroutine.rs
+++ b/tests/ui/impl-trait/recursive-coroutine.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 #![feature(coroutines, coroutine_trait)]
 
 use std::ops::{Coroutine, CoroutineState};
diff --git a/tests/ui/impl-trait/reveal-during-codegen.rs b/tests/ui/impl-trait/reveal-during-codegen.rs
index 11463772eb3..7b2ca9c33f6 100644
--- a/tests/ui/impl-trait/reveal-during-codegen.rs
+++ b/tests/ui/impl-trait/reveal-during-codegen.rs
@@ -1,6 +1,6 @@
 // build-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 fn test() -> Option<impl Sized> {
     Some("")
diff --git a/tests/ui/impl-trait/two_tait_defining_each_other.rs b/tests/ui/impl-trait/two_tait_defining_each_other.rs
index b43a7cabd05..6a9e33500e5 100644
--- a/tests/ui/impl-trait/two_tait_defining_each_other.rs
+++ b/tests/ui/impl-trait/two_tait_defining_each_other.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 //[next] check-pass
 
 #![feature(type_alias_impl_trait)]
diff --git a/tests/ui/impl-trait/two_tait_defining_each_other2.rs b/tests/ui/impl-trait/two_tait_defining_each_other2.rs
index 817de109fbe..8a79af19776 100644
--- a/tests/ui/impl-trait/two_tait_defining_each_other2.rs
+++ b/tests/ui/impl-trait/two_tait_defining_each_other2.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 #![feature(type_alias_impl_trait)]
 
 type A = impl Foo; //[current]~ ERROR unconstrained opaque type
diff --git a/tests/ui/impl-trait/two_tait_defining_each_other3.rs b/tests/ui/impl-trait/two_tait_defining_each_other3.rs
index 6fb9e6e7188..55def937f48 100644
--- a/tests/ui/impl-trait/two_tait_defining_each_other3.rs
+++ b/tests/ui/impl-trait/two_tait_defining_each_other3.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 //[next] check-pass
 #![feature(type_alias_impl_trait)]
 
diff --git a/tests/ui/implied-bounds/hrlt-implied-trait-bounds-guard.rs b/tests/ui/implied-bounds/hrlt-implied-trait-bounds-guard.rs
index c177655c5ac..27c8f30ec32 100644
--- a/tests/ui/implied-bounds/hrlt-implied-trait-bounds-guard.rs
+++ b/tests/ui/implied-bounds/hrlt-implied-trait-bounds-guard.rs
@@ -1,5 +1,5 @@
 // A test exploiting the bug behind #25860 except with
-// implied trait bounds which currently don't exist without `-Ztrait-solver=chalk`.
+// implied trait bounds which currently don't exist.
 use std::marker::PhantomData;
 struct Foo<'a, 'b, T>(PhantomData<(&'a (), &'b (), T)>)
 where
diff --git a/tests/ui/inference/type-infer-generalize-ty-var.rs b/tests/ui/inference/type-infer-generalize-ty-var.rs
index 8b4a8c32bb2..6bf3c61ada8 100644
--- a/tests/ui/inference/type-infer-generalize-ty-var.rs
+++ b/tests/ui/inference/type-infer-generalize-ty-var.rs
@@ -1,6 +1,6 @@
 // check-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![allow(non_upper_case_globals)]
 #![allow(dead_code)]
diff --git a/tests/ui/issues/issue-13167.rs b/tests/ui/issues/issue-13167.rs
index 9a9f129ec3a..747f652d4af 100644
--- a/tests/ui/issues/issue-13167.rs
+++ b/tests/ui/issues/issue-13167.rs
@@ -1,7 +1,7 @@
 // check-pass
 // pretty-expanded FIXME #23616
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 use std::slice;
 
diff --git a/tests/ui/issues/issue-15734.rs b/tests/ui/issues/issue-15734.rs
index 27410d4c3b0..77517f61813 100644
--- a/tests/ui/issues/issue-15734.rs
+++ b/tests/ui/issues/issue-15734.rs
@@ -1,6 +1,6 @@
 // run-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 use std::ops::Index;
 
diff --git a/tests/ui/lazy-type-alias/coerce-behind-lazy.rs b/tests/ui/lazy-type-alias/coerce-behind-lazy.rs
index 745eadb9625..ec9a6739975 100644
--- a/tests/ui/lazy-type-alias/coerce-behind-lazy.rs
+++ b/tests/ui/lazy-type-alias/coerce-behind-lazy.rs
@@ -1,6 +1,6 @@
 // check-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(lazy_type_alias)]
 //~^ WARN the feature `lazy_type_alias` is incomplete
diff --git a/tests/ui/never_type/never-from-impl-is-reserved.rs b/tests/ui/never_type/never-from-impl-is-reserved.rs
index f358e045cf0..97fac59149b 100644
--- a/tests/ui/never_type/never-from-impl-is-reserved.rs
+++ b/tests/ui/never_type/never-from-impl-is-reserved.rs
@@ -1,7 +1,7 @@
 // check that the `for<T> T: From<!>` impl is reserved
 
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next-coherence
+//[next] compile-flags: -Znext-solver=coherence
 
 #![feature(never_type)]
 
diff --git a/tests/ui/nll/issue-53119.rs b/tests/ui/nll/issue-53119.rs
index 015b72367f1..d19a9a0327c 100644
--- a/tests/ui/nll/issue-53119.rs
+++ b/tests/ui/nll/issue-53119.rs
@@ -1,6 +1,6 @@
 // check-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 use std::ops::Deref;
 
diff --git a/tests/ui/object-safety/call-when-assoc-ty-is-sized.rs b/tests/ui/object-safety/call-when-assoc-ty-is-sized.rs
index 0b30a88fdd4..21dda7b8c9b 100644
--- a/tests/ui/object-safety/call-when-assoc-ty-is-sized.rs
+++ b/tests/ui/object-safety/call-when-assoc-ty-is-sized.rs
@@ -1,6 +1,6 @@
 // check-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 trait Foo {
     type Bar<'a>
diff --git a/tests/ui/panics/abort-on-panic.rs b/tests/ui/panics/abort-on-panic.rs
index 7fbee85ffd1..ff31fc24317 100644
--- a/tests/ui/panics/abort-on-panic.rs
+++ b/tests/ui/panics/abort-on-panic.rs
@@ -1,6 +1,6 @@
 // run-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![allow(unused_must_use)]
 #![feature(c_unwind)]
diff --git a/tests/ui/rfcs/rfc-2027-object-safe-for-dispatch/manual-self-impl-for-unsafe-obj.rs b/tests/ui/rfcs/rfc-2027-object-safe-for-dispatch/manual-self-impl-for-unsafe-obj.rs
index c27e8c4b019..c7665affb99 100644
--- a/tests/ui/rfcs/rfc-2027-object-safe-for-dispatch/manual-self-impl-for-unsafe-obj.rs
+++ b/tests/ui/rfcs/rfc-2027-object-safe-for-dispatch/manual-self-impl-for-unsafe-obj.rs
@@ -1,7 +1,7 @@
 // Check that we can manually implement an object-unsafe trait for its trait object.
 
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // run-pass
 
 #![feature(object_safe_for_dispatch)]
diff --git a/tests/ui/specialization/specialization-default-items-drop-coherence.rs b/tests/ui/specialization/specialization-default-items-drop-coherence.rs
index 44c598f19cb..37903c21071 100644
--- a/tests/ui/specialization/specialization-default-items-drop-coherence.rs
+++ b/tests/ui/specialization/specialization-default-items-drop-coherence.rs
@@ -1,6 +1,6 @@
 // revisions: classic coherence next
-//[next] compile-flags: -Ztrait-solver=next
-//[coherence] compile-flags: -Ztrait-solver=next-coherence
+//[next] compile-flags: -Znext-solver
+//[coherence] compile-flags: -Znext-solver=coherence
 //[classic] check-pass
 //[classic] known-bug: #105782
 
diff --git a/tests/ui/traits/deny-builtin-object-impl.rs b/tests/ui/traits/deny-builtin-object-impl.rs
index dce03a43b68..d0eb6382e41 100644
--- a/tests/ui/traits/deny-builtin-object-impl.rs
+++ b/tests/ui/traits/deny-builtin-object-impl.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(rustc_attrs)]
 
diff --git a/tests/ui/traits/issue-24010.rs b/tests/ui/traits/issue-24010.rs
index fd7d6751d5c..1eaa5bf0c67 100644
--- a/tests/ui/traits/issue-24010.rs
+++ b/tests/ui/traits/issue-24010.rs
@@ -1,6 +1,6 @@
 // run-pass
 // revisions: classic next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 trait Foo: Fn(i32) -> i32 + Send {}
 
diff --git a/tests/ui/traits/new-solver/projection/param-env-trait-candidate-1.rs b/tests/ui/traits/new-solver/projection/param-env-trait-candidate-1.rs
index e36d574efe2..b337c067374 100644
--- a/tests/ui/traits/new-solver/projection/param-env-trait-candidate-1.rs
+++ b/tests/ui/traits/new-solver/projection/param-env-trait-candidate-1.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // See https://github.com/rust-lang/trait-system-refactor-initiative/issues/1
 // a minimization of a pattern in core.
diff --git a/tests/ui/traits/new-solver/projection/param-env-trait-candidate-2.rs b/tests/ui/traits/new-solver/projection/param-env-trait-candidate-2.rs
index c8050997a1d..db8dc1eb9be 100644
--- a/tests/ui/traits/new-solver/projection/param-env-trait-candidate-2.rs
+++ b/tests/ui/traits/new-solver/projection/param-env-trait-candidate-2.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // See https://github.com/rust-lang/trait-system-refactor-initiative/issues/1,
 // a minimization of a pattern in core.
diff --git a/tests/ui/traits/new-solver/alias-bound-preference.rs b/tests/ui/traits/next-solver/alias-bound-preference.rs
index e4e0f634ef7..1c6e1209610 100644
--- a/tests/ui/traits/new-solver/alias-bound-preference.rs
+++ b/tests/ui/traits/next-solver/alias-bound-preference.rs
@@ -1,5 +1,5 @@
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // run-pass
 
 // A test for https://github.com/rust-lang/trait-system-refactor-initiative/issues/45.
diff --git a/tests/ui/traits/new-solver/alias-bound-unsound.rs b/tests/ui/traits/next-solver/alias-bound-unsound.rs
index ab84e3875e2..565bfe1186e 100644
--- a/tests/ui/traits/new-solver/alias-bound-unsound.rs
+++ b/tests/ui/traits/next-solver/alias-bound-unsound.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // Makes sure that alias bounds are not unsound!
 
diff --git a/tests/ui/traits/new-solver/alias-bound-unsound.stderr b/tests/ui/traits/next-solver/alias-bound-unsound.stderr
index b09c22f3f41..b09c22f3f41 100644
--- a/tests/ui/traits/new-solver/alias-bound-unsound.stderr
+++ b/tests/ui/traits/next-solver/alias-bound-unsound.stderr
diff --git a/tests/ui/traits/new-solver/alias-eq-in-canonical-response.rs b/tests/ui/traits/next-solver/alias-eq-in-canonical-response.rs
index 4bfb6323a53..aa7c94791a7 100644
--- a/tests/ui/traits/new-solver/alias-eq-in-canonical-response.rs
+++ b/tests/ui/traits/next-solver/alias-eq-in-canonical-response.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 trait Foo {
     type Gat<'a>
diff --git a/tests/ui/traits/new-solver/alias-relate/deeply-nested-no-hang.rs b/tests/ui/traits/next-solver/alias-relate/deeply-nested-no-hang.rs
index 4abce7b57d5..91cfda37adf 100644
--- a/tests/ui/traits/new-solver/alias-relate/deeply-nested-no-hang.rs
+++ b/tests/ui/traits/next-solver/alias-relate/deeply-nested-no-hang.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // regression test for trait-system-refactor-initiative#68
 trait Identity {
     type Assoc: ?Sized;
diff --git a/tests/ui/traits/new-solver/alias-relate/opaque-hidden-ty-is-rigid-alias.rs b/tests/ui/traits/next-solver/alias-relate/opaque-hidden-ty-is-rigid-alias.rs
index 29a73e1a967..88bbd13f9a2 100644
--- a/tests/ui/traits/new-solver/alias-relate/opaque-hidden-ty-is-rigid-alias.rs
+++ b/tests/ui/traits/next-solver/alias-relate/opaque-hidden-ty-is-rigid-alias.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 fn test<T: Iterator>(x: T::Item) -> impl Sized {
     x
diff --git a/tests/ui/traits/new-solver/alias-sub.rs b/tests/ui/traits/next-solver/alias-sub.rs
index 30c1981a92e..f7f23a024dd 100644
--- a/tests/ui/traits/new-solver/alias-sub.rs
+++ b/tests/ui/traits/next-solver/alias-sub.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Trait {
diff --git a/tests/ui/traits/new-solver/alias_eq_cant_be_furthur_normalized.rs b/tests/ui/traits/next-solver/alias_eq_cant_be_furthur_normalized.rs
index dc726ba51f9..04d1b949692 100644
--- a/tests/ui/traits/new-solver/alias_eq_cant_be_furthur_normalized.rs
+++ b/tests/ui/traits/next-solver/alias_eq_cant_be_furthur_normalized.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // check that a goal such as `alias-eq(<T as TraitB>::Assoc<bool>, <T as TraitB>::Assoc<?0>)`
 // succeeds with a constraint that `?0 = bool`
diff --git a/tests/ui/traits/new-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs b/tests/ui/traits/next-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs
index 3c7fc7403b1..48157192a10 100644
--- a/tests/ui/traits/new-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs
+++ b/tests/ui/traits/next-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // check-pass
 // (should not pass, should be turned into a coherence-only test)
diff --git a/tests/ui/traits/new-solver/alias_eq_simple.rs b/tests/ui/traits/next-solver/alias_eq_simple.rs
index 6792cf3ce35..21ad1a4fa3c 100644
--- a/tests/ui/traits/new-solver/alias_eq_simple.rs
+++ b/tests/ui/traits/next-solver/alias_eq_simple.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // test that the new solver can handle `alias-eq(<i32 as TraitB>::Assoc, u32)`
 
diff --git a/tests/ui/traits/new-solver/alias_eq_substs_eq_not_intercrate.rs b/tests/ui/traits/next-solver/alias_eq_substs_eq_not_intercrate.rs
index 204f6e8b071..4717aa80499 100644
--- a/tests/ui/traits/new-solver/alias_eq_substs_eq_not_intercrate.rs
+++ b/tests/ui/traits/next-solver/alias_eq_substs_eq_not_intercrate.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // check that a `alias-eq(<?a as TraitB>::Assoc, <?b as TraitB>::Assoc)` goal fails
 // during coherence. We must not incorrectly constrain `?a` and `?b` to be
diff --git a/tests/ui/traits/new-solver/alias_eq_substs_eq_not_intercrate.stderr b/tests/ui/traits/next-solver/alias_eq_substs_eq_not_intercrate.stderr
index 8c6840f72a7..8c6840f72a7 100644
--- a/tests/ui/traits/new-solver/alias_eq_substs_eq_not_intercrate.stderr
+++ b/tests/ui/traits/next-solver/alias_eq_substs_eq_not_intercrate.stderr
diff --git a/tests/ui/traits/new-solver/array-default.rs b/tests/ui/traits/next-solver/array-default.rs
index 5077137b09b..6bfbce7d433 100644
--- a/tests/ui/traits/new-solver/array-default.rs
+++ b/tests/ui/traits/next-solver/array-default.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 fn has_default<const N: usize>() where [(); N]: Default {}
diff --git a/tests/ui/traits/new-solver/assembly/assemble-normalizing-self-ty-impl-ambiguity.rs b/tests/ui/traits/next-solver/assembly/assemble-normalizing-self-ty-impl-ambiguity.rs
index 826e8c1e0b1..4401abd0783 100644
--- a/tests/ui/traits/new-solver/assembly/assemble-normalizing-self-ty-impl-ambiguity.rs
+++ b/tests/ui/traits/next-solver/assembly/assemble-normalizing-self-ty-impl-ambiguity.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 // Checks that we do not get ambiguity by considering an impl
diff --git a/tests/ui/traits/new-solver/assembly/runaway-impl-candidate-selection.rs b/tests/ui/traits/next-solver/assembly/runaway-impl-candidate-selection.rs
index 1dca86d3630..1edc1a8c58c 100644
--- a/tests/ui/traits/new-solver/assembly/runaway-impl-candidate-selection.rs
+++ b/tests/ui/traits/next-solver/assembly/runaway-impl-candidate-selection.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // In the new solver, we are trying to select `<?0 as Iterator>::Item: Debug`,
 // which, naively can be unified with every impl of `Debug` if we're not careful.
diff --git a/tests/ui/traits/new-solver/assembly/runaway-impl-candidate-selection.stderr b/tests/ui/traits/next-solver/assembly/runaway-impl-candidate-selection.stderr
index 4bd55ee80c6..4bd55ee80c6 100644
--- a/tests/ui/traits/new-solver/assembly/runaway-impl-candidate-selection.stderr
+++ b/tests/ui/traits/next-solver/assembly/runaway-impl-candidate-selection.stderr
diff --git a/tests/ui/traits/new-solver/async.fail.stderr b/tests/ui/traits/next-solver/async.fail.stderr
index ebd0ada2604..ebd0ada2604 100644
--- a/tests/ui/traits/new-solver/async.fail.stderr
+++ b/tests/ui/traits/next-solver/async.fail.stderr
diff --git a/tests/ui/traits/new-solver/async.rs b/tests/ui/traits/next-solver/async.rs
index 155b71eb749..5833c052234 100644
--- a/tests/ui/traits/new-solver/async.rs
+++ b/tests/ui/traits/next-solver/async.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // edition: 2021
 // revisions: pass fail
 //[pass] check-pass
diff --git a/tests/ui/traits/new-solver/auto-with-drop_tracking_mir.fail.stderr b/tests/ui/traits/next-solver/auto-with-drop_tracking_mir.fail.stderr
index ac05dfb2d46..ac05dfb2d46 100644
--- a/tests/ui/traits/new-solver/auto-with-drop_tracking_mir.fail.stderr
+++ b/tests/ui/traits/next-solver/auto-with-drop_tracking_mir.fail.stderr
diff --git a/tests/ui/traits/new-solver/auto-with-drop_tracking_mir.rs b/tests/ui/traits/next-solver/auto-with-drop_tracking_mir.rs
index 6b54718e35c..d4010a55244 100644
--- a/tests/ui/traits/new-solver/auto-with-drop_tracking_mir.rs
+++ b/tests/ui/traits/next-solver/auto-with-drop_tracking_mir.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // edition: 2021
 // revisions: pass fail
 //[pass] check-pass
diff --git a/tests/ui/traits/new-solver/borrowck-error.rs b/tests/ui/traits/next-solver/borrowck-error.rs
index 4787a2c7e11..25f1445941b 100644
--- a/tests/ui/traits/new-solver/borrowck-error.rs
+++ b/tests/ui/traits/next-solver/borrowck-error.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 use std::collections::HashMap;
 
diff --git a/tests/ui/traits/new-solver/borrowck-error.stderr b/tests/ui/traits/next-solver/borrowck-error.stderr
index 4cb41e7d597..4cb41e7d597 100644
--- a/tests/ui/traits/new-solver/borrowck-error.stderr
+++ b/tests/ui/traits/next-solver/borrowck-error.stderr
diff --git a/tests/ui/traits/new-solver/builtin-fn-must-return-sized.rs b/tests/ui/traits/next-solver/builtin-fn-must-return-sized.rs
index ba473653ecf..eab25214d63 100644
--- a/tests/ui/traits/new-solver/builtin-fn-must-return-sized.rs
+++ b/tests/ui/traits/next-solver/builtin-fn-must-return-sized.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 #![feature(fn_traits)]
 #![feature(unboxed_closures)]
diff --git a/tests/ui/traits/new-solver/builtin-fn-must-return-sized.stderr b/tests/ui/traits/next-solver/builtin-fn-must-return-sized.stderr
index 08047852f20..08047852f20 100644
--- a/tests/ui/traits/new-solver/builtin-fn-must-return-sized.stderr
+++ b/tests/ui/traits/next-solver/builtin-fn-must-return-sized.stderr
diff --git a/tests/ui/traits/new-solver/canonical-int-var-eq-in-response.rs b/tests/ui/traits/next-solver/canonical-int-var-eq-in-response.rs
index 4b013983a4a..ea2740523c9 100644
--- a/tests/ui/traits/new-solver/canonical-int-var-eq-in-response.rs
+++ b/tests/ui/traits/next-solver/canonical-int-var-eq-in-response.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Mirror {
diff --git a/tests/ui/traits/new-solver/canonical-ty-var-eq-in-response.rs b/tests/ui/traits/next-solver/canonical-ty-var-eq-in-response.rs
index d1c6b1077e8..b1e4a9e58cf 100644
--- a/tests/ui/traits/new-solver/canonical-ty-var-eq-in-response.rs
+++ b/tests/ui/traits/next-solver/canonical-ty-var-eq-in-response.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 trait Mirror {
     type Item;
diff --git a/tests/ui/traits/new-solver/canonicalize-effect-var.rs b/tests/ui/traits/next-solver/canonicalize-effect-var.rs
index 35b69ed1a6b..4a13ba37303 100644
--- a/tests/ui/traits/new-solver/canonicalize-effect-var.rs
+++ b/tests/ui/traits/next-solver/canonicalize-effect-var.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 #![feature(effects)]
diff --git a/tests/ui/traits/new-solver/cast-checks-handling-projections.rs b/tests/ui/traits/next-solver/cast-checks-handling-projections.rs
index 3b261062f78..406b4dc1211 100644
--- a/tests/ui/traits/new-solver/cast-checks-handling-projections.rs
+++ b/tests/ui/traits/next-solver/cast-checks-handling-projections.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 fn main() {
diff --git a/tests/ui/traits/new-solver/closure-inference-guidance.rs b/tests/ui/traits/next-solver/closure-inference-guidance.rs
index d2ad0cc0316..8175b92f882 100644
--- a/tests/ui/traits/new-solver/closure-inference-guidance.rs
+++ b/tests/ui/traits/next-solver/closure-inference-guidance.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 fn foo(i: isize) -> isize { i + 1 }
diff --git a/tests/ui/traits/new-solver/closure-substs-ambiguity.rs b/tests/ui/traits/next-solver/closure-substs-ambiguity.rs
index 48432f4020f..cc9ee58f27f 100644
--- a/tests/ui/traits/new-solver/closure-substs-ambiguity.rs
+++ b/tests/ui/traits/next-solver/closure-substs-ambiguity.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 fn main() {
diff --git a/tests/ui/traits/new-solver/coherence/issue-102048.rs b/tests/ui/traits/next-solver/coherence/issue-102048.rs
index 11636bfeb55..600e63d4d44 100644
--- a/tests/ui/traits/new-solver/coherence/issue-102048.rs
+++ b/tests/ui/traits/next-solver/coherence/issue-102048.rs
@@ -17,7 +17,7 @@
 // that to `i32`. We then try to unify `i32` from `impl1` with `u32` from `impl2` which fails,
 // causing coherence to consider these two impls distinct.
 
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 pub trait Trait<T> {}
 
 pub trait WithAssoc1<'a> {
diff --git a/tests/ui/traits/new-solver/coherence/issue-102048.stderr b/tests/ui/traits/next-solver/coherence/issue-102048.stderr
index 4e93ae28496..4e93ae28496 100644
--- a/tests/ui/traits/new-solver/coherence/issue-102048.stderr
+++ b/tests/ui/traits/next-solver/coherence/issue-102048.stderr
diff --git a/tests/ui/traits/new-solver/coherence/trait_ref_is_knowable-norm-overflow.rs b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-norm-overflow.rs
index b39ae0333ad..af471b5e193 100644
--- a/tests/ui/traits/new-solver/coherence/trait_ref_is_knowable-norm-overflow.rs
+++ b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-norm-overflow.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // Coherence should handle overflow while normalizing for
 // `trait_ref_is_knowable` correctly.
diff --git a/tests/ui/traits/new-solver/coherence/trait_ref_is_knowable-norm-overflow.stderr b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-norm-overflow.stderr
index e3c0dabf549..e3c0dabf549 100644
--- a/tests/ui/traits/new-solver/coherence/trait_ref_is_knowable-norm-overflow.stderr
+++ b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-norm-overflow.stderr
diff --git a/tests/ui/traits/new-solver/coherence/trait_ref_is_knowable-normalization-1.rs b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-normalization-1.rs
index c38e3baf5b4..e6ffb55b441 100644
--- a/tests/ui/traits/new-solver/coherence/trait_ref_is_knowable-normalization-1.rs
+++ b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-normalization-1.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Id {
diff --git a/tests/ui/traits/new-solver/coherence/trait_ref_is_knowable-normalization-2.rs b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-normalization-2.rs
index 2d53266db09..d16f9d22ce0 100644
--- a/tests/ui/traits/new-solver/coherence/trait_ref_is_knowable-normalization-2.rs
+++ b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-normalization-2.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 use std::future::{Future, IntoFuture};
diff --git a/tests/ui/traits/new-solver/coherence/trait_ref_is_knowable-normalization-3.rs b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-normalization-3.rs
index 2f27de4e4f4..90de6b847d0 100644
--- a/tests/ui/traits/new-solver/coherence/trait_ref_is_knowable-normalization-3.rs
+++ b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-normalization-3.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Id {
diff --git a/tests/ui/traits/new-solver/const-param-placeholder.fail.stderr b/tests/ui/traits/next-solver/const-param-placeholder.fail.stderr
index 163710706b0..163710706b0 100644
--- a/tests/ui/traits/new-solver/const-param-placeholder.fail.stderr
+++ b/tests/ui/traits/next-solver/const-param-placeholder.fail.stderr
diff --git a/tests/ui/traits/new-solver/const-param-placeholder.rs b/tests/ui/traits/next-solver/const-param-placeholder.rs
index a83102a4cdd..c22bc54cfca 100644
--- a/tests/ui/traits/new-solver/const-param-placeholder.rs
+++ b/tests/ui/traits/next-solver/const-param-placeholder.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // revisions: pass fail
 //[pass] check-pass
 
diff --git a/tests/ui/traits/new-solver/coroutine.fail.stderr b/tests/ui/traits/next-solver/coroutine.fail.stderr
index 14e67727d0b..14e67727d0b 100644
--- a/tests/ui/traits/new-solver/coroutine.fail.stderr
+++ b/tests/ui/traits/next-solver/coroutine.fail.stderr
diff --git a/tests/ui/traits/new-solver/coroutine.rs b/tests/ui/traits/next-solver/coroutine.rs
index af16f70fb56..727e2356859 100644
--- a/tests/ui/traits/new-solver/coroutine.rs
+++ b/tests/ui/traits/next-solver/coroutine.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // edition: 2021
 // revisions: pass fail
 //[pass] check-pass
diff --git a/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.rs b/tests/ui/traits/next-solver/cycles/coinduction/fixpoint-exponential-growth.rs
index 07c7d4fb29c..947b52da7c2 100644
--- a/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.rs
+++ b/tests/ui/traits/next-solver/cycles/coinduction/fixpoint-exponential-growth.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // Proving `W<?0>: Trait` instantiates `?0` with `(W<?1>, W<?2>)` and then
 // proves `W<?1>: Trait` and `W<?2>: Trait`, resulting in a coinductive cycle.
diff --git a/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.stderr b/tests/ui/traits/next-solver/cycles/coinduction/fixpoint-exponential-growth.stderr
index 150100f2c53..150100f2c53 100644
--- a/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.stderr
+++ b/tests/ui/traits/next-solver/cycles/coinduction/fixpoint-exponential-growth.stderr
diff --git a/tests/ui/traits/new-solver/cycles/coinduction/incompleteness-unstable-result.rs b/tests/ui/traits/next-solver/cycles/coinduction/incompleteness-unstable-result.rs
index 0cd14f05c8d..a3c07b98722 100644
--- a/tests/ui/traits/new-solver/cycles/coinduction/incompleteness-unstable-result.rs
+++ b/tests/ui/traits/next-solver/cycles/coinduction/incompleteness-unstable-result.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 #![feature(rustc_attrs)]
 
 // This test is incredibly subtle. At its core the goal is to get a coinductive cycle,
diff --git a/tests/ui/traits/new-solver/cycles/coinduction/incompleteness-unstable-result.stderr b/tests/ui/traits/next-solver/cycles/coinduction/incompleteness-unstable-result.stderr
index d4932191791..d4932191791 100644
--- a/tests/ui/traits/new-solver/cycles/coinduction/incompleteness-unstable-result.stderr
+++ b/tests/ui/traits/next-solver/cycles/coinduction/incompleteness-unstable-result.stderr
diff --git a/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.rs b/tests/ui/traits/next-solver/cycles/double-cycle-inductive-coinductive.rs
index 5617e45adf6..0f19bc2c592 100644
--- a/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.rs
+++ b/tests/ui/traits/next-solver/cycles/double-cycle-inductive-coinductive.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 #![feature(rustc_attrs)]
 
 // Test that having both an inductive and a coinductive cycle
diff --git a/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.stderr b/tests/ui/traits/next-solver/cycles/double-cycle-inductive-coinductive.stderr
index a3404da51f0..a3404da51f0 100644
--- a/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.stderr
+++ b/tests/ui/traits/next-solver/cycles/double-cycle-inductive-coinductive.stderr
diff --git a/tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.rs b/tests/ui/traits/next-solver/cycles/fixpoint-rerun-all-cycle-heads.rs
index 27906392340..c7e2e2d5e04 100644
--- a/tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.rs
+++ b/tests/ui/traits/next-solver/cycles/fixpoint-rerun-all-cycle-heads.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 #![feature(rustc_attrs)]
 
 // Check that we correctly rerun the trait solver for heads of cycles,
diff --git a/tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.stderr b/tests/ui/traits/next-solver/cycles/fixpoint-rerun-all-cycle-heads.stderr
index 7b3075f4ff3..7b3075f4ff3 100644
--- a/tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.stderr
+++ b/tests/ui/traits/next-solver/cycles/fixpoint-rerun-all-cycle-heads.stderr
diff --git a/tests/ui/traits/new-solver/cycles/inductive-cycle-but-err.rs b/tests/ui/traits/next-solver/cycles/inductive-cycle-but-err.rs
index cda98789886..fdc7afea378 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-cycle-but-err.rs
+++ b/tests/ui/traits/next-solver/cycles/inductive-cycle-but-err.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 #![feature(trivial_bounds, marker_trait_attr)]
 #![allow(trivial_bounds)]
 // This previously triggered a bug in the provisional cache.
diff --git a/tests/ui/traits/new-solver/cycles/inductive-cycle-but-err.stderr b/tests/ui/traits/next-solver/cycles/inductive-cycle-but-err.stderr
index acacaf6a331..acacaf6a331 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-cycle-but-err.stderr
+++ b/tests/ui/traits/next-solver/cycles/inductive-cycle-but-err.stderr
diff --git a/tests/ui/traits/new-solver/cycles/inductive-cycle-but-ok.rs b/tests/ui/traits/next-solver/cycles/inductive-cycle-but-ok.rs
index d4851eb694b..d6d9762bb73 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-cycle-but-ok.rs
+++ b/tests/ui/traits/next-solver/cycles/inductive-cycle-but-ok.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 #![feature(trivial_bounds, marker_trait_attr)]
 #![allow(trivial_bounds)]
diff --git a/tests/ui/traits/new-solver/cycles/inductive-cycle-discarded-coinductive-constraints.rs b/tests/ui/traits/next-solver/cycles/inductive-cycle-discarded-coinductive-constraints.rs
index 530e6d0ecf3..a32f7a13a03 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-cycle-discarded-coinductive-constraints.rs
+++ b/tests/ui/traits/next-solver/cycles/inductive-cycle-discarded-coinductive-constraints.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 #![feature(rustc_attrs, marker_trait_attr)]
 #[rustc_coinductive]
 trait Trait {}
diff --git a/tests/ui/traits/new-solver/cycles/inductive-fixpoint-hang.rs b/tests/ui/traits/next-solver/cycles/inductive-fixpoint-hang.rs
index 062c6ae98d5..efeb8d0231e 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-fixpoint-hang.rs
+++ b/tests/ui/traits/next-solver/cycles/inductive-fixpoint-hang.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // This currently hangs if we do not erase constraints from
 // overflow.
diff --git a/tests/ui/traits/new-solver/cycles/inductive-fixpoint-hang.stderr b/tests/ui/traits/next-solver/cycles/inductive-fixpoint-hang.stderr
index 42451920744..42451920744 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-fixpoint-hang.stderr
+++ b/tests/ui/traits/next-solver/cycles/inductive-fixpoint-hang.stderr
diff --git a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs b/tests/ui/traits/next-solver/cycles/inductive-not-on-stack.rs
index f06b98a79cf..f2f6e009d54 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs
+++ b/tests/ui/traits/next-solver/cycles/inductive-not-on-stack.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 #![feature(rustc_attrs, trivial_bounds)]
 
 // We have to be careful here:
diff --git a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.stderr b/tests/ui/traits/next-solver/cycles/inductive-not-on-stack.stderr
index 859b3f3f1c7..859b3f3f1c7 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.stderr
+++ b/tests/ui/traits/next-solver/cycles/inductive-not-on-stack.stderr
diff --git a/tests/ui/traits/new-solver/cycles/leak-check-coinductive-cycle.rs b/tests/ui/traits/next-solver/cycles/leak-check-coinductive-cycle.rs
index a6d31872673..9ff362ec882 100644
--- a/tests/ui/traits/new-solver/cycles/leak-check-coinductive-cycle.rs
+++ b/tests/ui/traits/next-solver/cycles/leak-check-coinductive-cycle.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 #![feature(rustc_attrs)]
 
diff --git a/tests/ui/traits/new-solver/cycles/provisional-result-done.rs b/tests/ui/traits/next-solver/cycles/provisional-result-done.rs
index 589d34dd7ab..0f3b84ce520 100644
--- a/tests/ui/traits/new-solver/cycles/provisional-result-done.rs
+++ b/tests/ui/traits/next-solver/cycles/provisional-result-done.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 // This tests checks that we update results in the provisional cache when
diff --git a/tests/ui/traits/new-solver/deduce-closure-signature-after-normalization.rs b/tests/ui/traits/next-solver/deduce-closure-signature-after-normalization.rs
index 51f62bc2312..08f26686b2f 100644
--- a/tests/ui/traits/new-solver/deduce-closure-signature-after-normalization.rs
+++ b/tests/ui/traits/next-solver/deduce-closure-signature-after-normalization.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Foo {
diff --git a/tests/ui/traits/new-solver/deduce-ty-from-object.rs b/tests/ui/traits/next-solver/deduce-ty-from-object.rs
index 7398bce7b61..b627fd720e3 100644
--- a/tests/ui/traits/new-solver/deduce-ty-from-object.rs
+++ b/tests/ui/traits/next-solver/deduce-ty-from-object.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 fn main() {
     let x: Box<dyn Iterator<Item = ()>> = Box::new(std::iter::empty());
diff --git a/tests/ui/traits/new-solver/dedup-regions.rs b/tests/ui/traits/next-solver/dedup-regions.rs
index f376f39a5a6..dd406333f27 100644
--- a/tests/ui/traits/new-solver/dedup-regions.rs
+++ b/tests/ui/traits/next-solver/dedup-regions.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 struct A(*mut ());
diff --git a/tests/ui/traits/new-solver/destruct.rs b/tests/ui/traits/next-solver/destruct.rs
index 30d7777b78a..5093344e4b6 100644
--- a/tests/ui/traits/new-solver/destruct.rs
+++ b/tests/ui/traits/next-solver/destruct.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 #![feature(const_trait_impl)]
diff --git a/tests/ui/traits/new-solver/dont-coerce-infer-to-dyn.rs b/tests/ui/traits/next-solver/dont-coerce-infer-to-dyn.rs
index c2ac80459ca..da07869f3b6 100644
--- a/tests/ui/traits/new-solver/dont-coerce-infer-to-dyn.rs
+++ b/tests/ui/traits/next-solver/dont-coerce-infer-to-dyn.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 use std::fmt::Display;
diff --git a/tests/ui/traits/new-solver/dont-elaborate-for-projections.rs b/tests/ui/traits/next-solver/dont-elaborate-for-projections.rs
index e608250063c..9123871db97 100644
--- a/tests/ui/traits/new-solver/dont-elaborate-for-projections.rs
+++ b/tests/ui/traits/next-solver/dont-elaborate-for-projections.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Iter<'a, I: 'a>: Iterator<Item = &'a I> {}
diff --git a/tests/ui/traits/new-solver/dont-ice-on-assoc-projection.rs b/tests/ui/traits/next-solver/dont-ice-on-assoc-projection.rs
index b9798c79d5e..1e1ef8c23a2 100644
--- a/tests/ui/traits/new-solver/dont-ice-on-assoc-projection.rs
+++ b/tests/ui/traits/next-solver/dont-ice-on-assoc-projection.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next-coherence
+// compile-flags: -Znext-solver=coherence
 
 // Makes sure we don't ICE on associated const projection when the feature gate
 // is not enabled, since we should avoid encountering ICEs on stable if possible.
diff --git a/tests/ui/traits/new-solver/dont-ice-on-assoc-projection.stderr b/tests/ui/traits/next-solver/dont-ice-on-assoc-projection.stderr
index 368f5cd0c3b..368f5cd0c3b 100644
--- a/tests/ui/traits/new-solver/dont-ice-on-assoc-projection.stderr
+++ b/tests/ui/traits/next-solver/dont-ice-on-assoc-projection.stderr
diff --git a/tests/ui/traits/new-solver/dont-loop-fulfill-on-region-constraints.rs b/tests/ui/traits/next-solver/dont-loop-fulfill-on-region-constraints.rs
index b241e3bf865..a85098a95ad 100644
--- a/tests/ui/traits/new-solver/dont-loop-fulfill-on-region-constraints.rs
+++ b/tests/ui/traits/next-solver/dont-loop-fulfill-on-region-constraints.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Eq<'a, 'b, T> {}
diff --git a/tests/ui/traits/new-solver/dont-normalize-proj-with-error.rs b/tests/ui/traits/next-solver/dont-normalize-proj-with-error.rs
index 19a6fa990ff..fd1682cd61a 100644
--- a/tests/ui/traits/new-solver/dont-normalize-proj-with-error.rs
+++ b/tests/ui/traits/next-solver/dont-normalize-proj-with-error.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // Test that we don't incorrectly leak unconstrained inference variables
 // if the projection contained an error. This caused an ICE in writeback.
diff --git a/tests/ui/traits/new-solver/dont-normalize-proj-with-error.stderr b/tests/ui/traits/next-solver/dont-normalize-proj-with-error.stderr
index 576ede52aff..576ede52aff 100644
--- a/tests/ui/traits/new-solver/dont-normalize-proj-with-error.stderr
+++ b/tests/ui/traits/next-solver/dont-normalize-proj-with-error.stderr
diff --git a/tests/ui/traits/new-solver/dont-remap-tait-substs.rs b/tests/ui/traits/next-solver/dont-remap-tait-substs.rs
index 309bee8aa8c..b089f0df3c7 100644
--- a/tests/ui/traits/new-solver/dont-remap-tait-substs.rs
+++ b/tests/ui/traits/next-solver/dont-remap-tait-substs.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 // Makes sure we don't prepopulate the MIR typeck of `define`
diff --git a/tests/ui/traits/new-solver/dont-type_of-tait-in-defining-scope.not_send.stderr b/tests/ui/traits/next-solver/dont-type_of-tait-in-defining-scope.not_send.stderr
index 076dab29d89..076dab29d89 100644
--- a/tests/ui/traits/new-solver/dont-type_of-tait-in-defining-scope.not_send.stderr
+++ b/tests/ui/traits/next-solver/dont-type_of-tait-in-defining-scope.not_send.stderr
diff --git a/tests/ui/traits/new-solver/dont-type_of-tait-in-defining-scope.rs b/tests/ui/traits/next-solver/dont-type_of-tait-in-defining-scope.rs
index 08f14d7494d..a1f38e69e53 100644
--- a/tests/ui/traits/new-solver/dont-type_of-tait-in-defining-scope.rs
+++ b/tests/ui/traits/next-solver/dont-type_of-tait-in-defining-scope.rs
@@ -1,5 +1,5 @@
 // revisions: is_send not_send
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 //[is_send] check-pass
 
 #![feature(type_alias_impl_trait)]
diff --git a/tests/ui/traits/new-solver/dyn-any-dont-prefer-impl.rs b/tests/ui/traits/next-solver/dyn-any-dont-prefer-impl.rs
index af35a6195e0..bb1c24a001f 100644
--- a/tests/ui/traits/new-solver/dyn-any-dont-prefer-impl.rs
+++ b/tests/ui/traits/next-solver/dyn-any-dont-prefer-impl.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 // Test that selection prefers the builtin trait object impl for `Any`
diff --git a/tests/ui/traits/new-solver/elaborate-item-bounds.rs b/tests/ui/traits/next-solver/elaborate-item-bounds.rs
index 076aefcf8fc..0f1f6c0445c 100644
--- a/tests/ui/traits/new-solver/elaborate-item-bounds.rs
+++ b/tests/ui/traits/next-solver/elaborate-item-bounds.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Foo {
diff --git a/tests/ui/traits/new-solver/equating-projection-cyclically.rs b/tests/ui/traits/next-solver/equating-projection-cyclically.rs
index 845597e9ce1..e7c80cfd797 100644
--- a/tests/ui/traits/new-solver/equating-projection-cyclically.rs
+++ b/tests/ui/traits/next-solver/equating-projection-cyclically.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 trait Test {
     type Assoc;
diff --git a/tests/ui/traits/new-solver/escaping-bound-vars-in-writeback-normalization.rs b/tests/ui/traits/next-solver/escaping-bound-vars-in-writeback-normalization.rs
index 29784c32a1b..77bedc351e7 100644
--- a/tests/ui/traits/new-solver/escaping-bound-vars-in-writeback-normalization.rs
+++ b/tests/ui/traits/next-solver/escaping-bound-vars-in-writeback-normalization.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Trivial {
diff --git a/tests/ui/traits/new-solver/float-canonical.rs b/tests/ui/traits/next-solver/float-canonical.rs
index b8748cd433b..90d75bacbf4 100644
--- a/tests/ui/traits/new-solver/float-canonical.rs
+++ b/tests/ui/traits/next-solver/float-canonical.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 fn foo(x: f64) {
diff --git a/tests/ui/traits/new-solver/fn-trait-closure.rs b/tests/ui/traits/next-solver/fn-trait-closure.rs
index bd65737ee39..cd2ae1f6fb2 100644
--- a/tests/ui/traits/new-solver/fn-trait-closure.rs
+++ b/tests/ui/traits/next-solver/fn-trait-closure.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 fn require_fn(_: impl Fn() -> i32) {}
diff --git a/tests/ui/traits/new-solver/fn-trait.rs b/tests/ui/traits/next-solver/fn-trait.rs
index 0a19e626553..1e3d8a21c7c 100644
--- a/tests/ui/traits/new-solver/fn-trait.rs
+++ b/tests/ui/traits/next-solver/fn-trait.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 fn require_fn(_: impl Fn() -> i32) {}
 
diff --git a/tests/ui/traits/new-solver/fn-trait.stderr b/tests/ui/traits/next-solver/fn-trait.stderr
index e33487235e6..e33487235e6 100644
--- a/tests/ui/traits/new-solver/fn-trait.stderr
+++ b/tests/ui/traits/next-solver/fn-trait.stderr
diff --git a/tests/ui/traits/new-solver/generalize/generalize-proj-new-universe-index-1.rs b/tests/ui/traits/next-solver/generalize/generalize-proj-new-universe-index-1.rs
index b0b9b6bbd20..4a70bd5f815 100644
--- a/tests/ui/traits/new-solver/generalize/generalize-proj-new-universe-index-1.rs
+++ b/tests/ui/traits/next-solver/generalize/generalize-proj-new-universe-index-1.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 // A minimization of an ambiguity when using typenum. See
diff --git a/tests/ui/traits/new-solver/generalize/generalize-proj-new-universe-index-2.rs b/tests/ui/traits/next-solver/generalize/generalize-proj-new-universe-index-2.rs
index 94d645a9859..70758e7deaa 100644
--- a/tests/ui/traits/new-solver/generalize/generalize-proj-new-universe-index-2.rs
+++ b/tests/ui/traits/next-solver/generalize/generalize-proj-new-universe-index-2.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // known-bug: trait-system-refactor-initiative#60
 
 // Generalizing a projection containing an inference variable
diff --git a/tests/ui/traits/new-solver/generalize/generalize-proj-new-universe-index-2.stderr b/tests/ui/traits/next-solver/generalize/generalize-proj-new-universe-index-2.stderr
index e4922b0c3e9..e4922b0c3e9 100644
--- a/tests/ui/traits/new-solver/generalize/generalize-proj-new-universe-index-2.stderr
+++ b/tests/ui/traits/next-solver/generalize/generalize-proj-new-universe-index-2.stderr
diff --git a/tests/ui/traits/new-solver/generalize/occurs-check-nested-alias.next.stderr b/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.next.stderr
index ad8b24a39c7..ad8b24a39c7 100644
--- a/tests/ui/traits/new-solver/generalize/occurs-check-nested-alias.next.stderr
+++ b/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.next.stderr
diff --git a/tests/ui/traits/new-solver/generalize/occurs-check-nested-alias.rs b/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.rs
index 02ac091c0a8..e51508d684f 100644
--- a/tests/ui/traits/new-solver/generalize/occurs-check-nested-alias.rs
+++ b/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.rs
@@ -3,7 +3,7 @@
 
 // Currently always fails to generalize the outer alias, even if it
 // is treated as rigid by `alias-relate`.
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 //[next] known-bug: trait-system-refactor-initiative#8
 #![crate_type = "lib"]
 #![allow(unused)]
diff --git a/tests/ui/traits/new-solver/higher-ranked-dyn-bounds.rs b/tests/ui/traits/next-solver/higher-ranked-dyn-bounds.rs
index c886aeeda3e..b87210d7fb3 100644
--- a/tests/ui/traits/new-solver/higher-ranked-dyn-bounds.rs
+++ b/tests/ui/traits/next-solver/higher-ranked-dyn-bounds.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Trait<'a> {
diff --git a/tests/ui/traits/new-solver/int-var-alias-eq.rs b/tests/ui/traits/next-solver/int-var-alias-eq.rs
index 790197e2d97..26ba7f8e511 100644
--- a/tests/ui/traits/new-solver/int-var-alias-eq.rs
+++ b/tests/ui/traits/next-solver/int-var-alias-eq.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // HIR typeck ends up equating `<?0i as Add>::Output == ?0i`.
 // Want to make sure that we emit an alias-eq goal for this,
diff --git a/tests/ui/traits/new-solver/int-var-is-send.rs b/tests/ui/traits/next-solver/int-var-is-send.rs
index 083aa90e1f6..d8b963f2008 100644
--- a/tests/ui/traits/new-solver/int-var-is-send.rs
+++ b/tests/ui/traits/next-solver/int-var-is-send.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 fn needs_send(_: impl Send) {}
diff --git a/tests/ui/traits/new-solver/iter-filter-projection.rs b/tests/ui/traits/next-solver/iter-filter-projection.rs
index 8fb62323aa5..f948831ad52 100644
--- a/tests/ui/traits/new-solver/iter-filter-projection.rs
+++ b/tests/ui/traits/next-solver/iter-filter-projection.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 use std::{iter, slice};
diff --git a/tests/ui/traits/new-solver/lazy-nested-obligations-1.rs b/tests/ui/traits/next-solver/lazy-nested-obligations-1.rs
index af00cbb3ba8..f9e73a93c27 100644
--- a/tests/ui/traits/new-solver/lazy-nested-obligations-1.rs
+++ b/tests/ui/traits/next-solver/lazy-nested-obligations-1.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // Issue 94358
 
 fn foo<C>(_: C)
diff --git a/tests/ui/traits/new-solver/lazy-nested-obligations-2.rs b/tests/ui/traits/next-solver/lazy-nested-obligations-2.rs
index 20f504928c7..b85f9d9736c 100644
--- a/tests/ui/traits/new-solver/lazy-nested-obligations-2.rs
+++ b/tests/ui/traits/next-solver/lazy-nested-obligations-2.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 pub trait With {
diff --git a/tests/ui/traits/new-solver/lazy-nested-obligations-3.rs b/tests/ui/traits/next-solver/lazy-nested-obligations-3.rs
index baf39957240..5fb4832dd08 100644
--- a/tests/ui/traits/new-solver/lazy-nested-obligations-3.rs
+++ b/tests/ui/traits/next-solver/lazy-nested-obligations-3.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // Issue 96750
 
 use std::marker::PhantomData;
diff --git a/tests/ui/traits/new-solver/member-constraints-in-root-universe.rs b/tests/ui/traits/next-solver/member-constraints-in-root-universe.rs
index 97c44305864..16e95e94ce5 100644
--- a/tests/ui/traits/new-solver/member-constraints-in-root-universe.rs
+++ b/tests/ui/traits/next-solver/member-constraints-in-root-universe.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Trait {
diff --git a/tests/ui/traits/new-solver/more-object-bound.rs b/tests/ui/traits/next-solver/more-object-bound.rs
index bb730b18ef7..8522f034d87 100644
--- a/tests/ui/traits/new-solver/more-object-bound.rs
+++ b/tests/ui/traits/next-solver/more-object-bound.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // From #80800
 
 trait SuperTrait {
diff --git a/tests/ui/traits/new-solver/more-object-bound.stderr b/tests/ui/traits/next-solver/more-object-bound.stderr
index e3be2931e12..e3be2931e12 100644
--- a/tests/ui/traits/new-solver/more-object-bound.stderr
+++ b/tests/ui/traits/next-solver/more-object-bound.stderr
diff --git a/tests/ui/traits/new-solver/negative-coherence-bounds.rs b/tests/ui/traits/next-solver/negative-coherence-bounds.rs
index 5436b02c3de..5436b02c3de 100644
--- a/tests/ui/traits/new-solver/negative-coherence-bounds.rs
+++ b/tests/ui/traits/next-solver/negative-coherence-bounds.rs
diff --git a/tests/ui/traits/new-solver/negative-coherence-bounds.stderr b/tests/ui/traits/next-solver/negative-coherence-bounds.stderr
index 4127f51f56d..4127f51f56d 100644
--- a/tests/ui/traits/new-solver/negative-coherence-bounds.stderr
+++ b/tests/ui/traits/next-solver/negative-coherence-bounds.stderr
diff --git a/tests/ui/traits/new-solver/nested-alias-bound.rs b/tests/ui/traits/next-solver/nested-alias-bound.rs
index c365902dbe5..2e3de0ac66d 100644
--- a/tests/ui/traits/new-solver/nested-alias-bound.rs
+++ b/tests/ui/traits/next-solver/nested-alias-bound.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait A {
diff --git a/tests/ui/traits/new-solver/nested-obligations-with-bound-vars-gat.rs b/tests/ui/traits/next-solver/nested-obligations-with-bound-vars-gat.rs
index 92bad959095..94c6c285680 100644
--- a/tests/ui/traits/new-solver/nested-obligations-with-bound-vars-gat.rs
+++ b/tests/ui/traits/next-solver/nested-obligations-with-bound-vars-gat.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // Issue 96230
 
 use std::fmt::Debug;
diff --git a/tests/ui/traits/new-solver/normalize-async-closure-in-trait.rs b/tests/ui/traits/next-solver/normalize-async-closure-in-trait.rs
index cc16cc87169..b58db2be841 100644
--- a/tests/ui/traits/new-solver/normalize-async-closure-in-trait.rs
+++ b/tests/ui/traits/next-solver/normalize-async-closure-in-trait.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 // edition:2021
 
diff --git a/tests/ui/traits/new-solver/normalize-param-env-1.rs b/tests/ui/traits/next-solver/normalize-param-env-1.rs
index b02a5d62330..92d4051378b 100644
--- a/tests/ui/traits/new-solver/normalize-param-env-1.rs
+++ b/tests/ui/traits/next-solver/normalize-param-env-1.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // Issue 108933
 
 trait Add<Rhs> {
diff --git a/tests/ui/traits/new-solver/normalize-param-env-2.rs b/tests/ui/traits/next-solver/normalize-param-env-2.rs
index 7c2cebdd200..ce084651bfb 100644
--- a/tests/ui/traits/new-solver/normalize-param-env-2.rs
+++ b/tests/ui/traits/next-solver/normalize-param-env-2.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // Issue 92505
 
 trait A<T> {
diff --git a/tests/ui/traits/new-solver/normalize-param-env-3.rs b/tests/ui/traits/next-solver/normalize-param-env-3.rs
index ce2974b2a16..e15e1155a1a 100644
--- a/tests/ui/traits/new-solver/normalize-param-env-3.rs
+++ b/tests/ui/traits/next-solver/normalize-param-env-3.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // Issue 100177
 
 trait GenericTrait<T> {}
diff --git a/tests/ui/traits/new-solver/normalize-rcvr-for-inherent.rs b/tests/ui/traits/next-solver/normalize-rcvr-for-inherent.rs
index d70534feb07..d308b1695f5 100644
--- a/tests/ui/traits/new-solver/normalize-rcvr-for-inherent.rs
+++ b/tests/ui/traits/next-solver/normalize-rcvr-for-inherent.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 // Verify that we can assemble inherent impl candidates on a possibly
diff --git a/tests/ui/traits/new-solver/normalize-unsize-rhs.rs b/tests/ui/traits/next-solver/normalize-unsize-rhs.rs
index 1bb5c9b4111..6ca82d1b872 100644
--- a/tests/ui/traits/new-solver/normalize-unsize-rhs.rs
+++ b/tests/ui/traits/next-solver/normalize-unsize-rhs.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait A {}
diff --git a/tests/ui/traits/new-solver/normalized-const-built-in-op.rs b/tests/ui/traits/next-solver/normalized-const-built-in-op.rs
index 2443e517813..0fffe7b4369 100644
--- a/tests/ui/traits/new-solver/normalized-const-built-in-op.rs
+++ b/tests/ui/traits/next-solver/normalized-const-built-in-op.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 const fn foo() {
diff --git a/tests/ui/traits/new-solver/normalizes_to_ignores_unnormalizable_candidate.rs b/tests/ui/traits/next-solver/normalizes_to_ignores_unnormalizable_candidate.rs
index 46343241b45..7dc87daccd9 100644
--- a/tests/ui/traits/new-solver/normalizes_to_ignores_unnormalizable_candidate.rs
+++ b/tests/ui/traits/next-solver/normalizes_to_ignores_unnormalizable_candidate.rs
@@ -1,5 +1,5 @@
 // [no_self_infer] check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // revisions: self_infer no_self_infer
 
 // checks that the new solver is smart enough to infer `?0 = U` when solving:
@@ -7,7 +7,7 @@
 // with `normalizes-to(<Vec<U> as Trait>::Assoc, u8)` in the paramenv even when
 // there is a separate `Vec<T>: Trait` bound  in the paramenv.
 //
-// FIXME(-Ztrait-solver=next)
+// FIXME(-Znext-solver)
 // This could also compile for `normalizes-to(<?0 as Trait>::Assoc, u8)` but
 // we currently immediately consider a goal ambiguous if the self type is an
 // inference variable.
diff --git a/tests/ui/traits/new-solver/normalizes_to_ignores_unnormalizable_candidate.self_infer.stderr b/tests/ui/traits/next-solver/normalizes_to_ignores_unnormalizable_candidate.self_infer.stderr
index c1a8b74df08..c1a8b74df08 100644
--- a/tests/ui/traits/new-solver/normalizes_to_ignores_unnormalizable_candidate.self_infer.stderr
+++ b/tests/ui/traits/next-solver/normalizes_to_ignores_unnormalizable_candidate.self_infer.stderr
diff --git a/tests/ui/traits/new-solver/object-soundness-requires-generalization.rs b/tests/ui/traits/next-solver/object-soundness-requires-generalization.rs
index d02dada72c9..6e709d9ae8e 100644
--- a/tests/ui/traits/new-solver/object-soundness-requires-generalization.rs
+++ b/tests/ui/traits/next-solver/object-soundness-requires-generalization.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // ignore-test
 
 trait Trait {
diff --git a/tests/ui/traits/new-solver/object-unsafety.rs b/tests/ui/traits/next-solver/object-unsafety.rs
index da843c91478..8aae7217398 100644
--- a/tests/ui/traits/new-solver/object-unsafety.rs
+++ b/tests/ui/traits/next-solver/object-unsafety.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 trait Setup {
     type From: Copy;
@@ -17,7 +17,7 @@ pub fn copy_any<T>(t: &T) -> T {
     //~| ERROR the type `<dyn Setup<From = T> as Setup>::From` is not well-formed
     //~| ERROR the size for values of type `<dyn Setup<From = T> as Setup>::From` cannot be known at compilation time
 
-    // FIXME(-Ztrait-solver=next): These error messages are horrible and some of them
+    // FIXME(-Znext-solver): These error messages are horrible and some of them
     // are even simple fallout from previous error.
 }
 
diff --git a/tests/ui/traits/new-solver/object-unsafety.stderr b/tests/ui/traits/next-solver/object-unsafety.stderr
index 914a8f9d4c5..914a8f9d4c5 100644
--- a/tests/ui/traits/new-solver/object-unsafety.stderr
+++ b/tests/ui/traits/next-solver/object-unsafety.stderr
diff --git a/tests/ui/traits/new-solver/opportunistic-region-resolve.rs b/tests/ui/traits/next-solver/opportunistic-region-resolve.rs
index 2610789cd48..d852332d0e5 100644
--- a/tests/ui/traits/new-solver/opportunistic-region-resolve.rs
+++ b/tests/ui/traits/next-solver/opportunistic-region-resolve.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 #![feature(rustc_attrs)]
diff --git a/tests/ui/traits/new-solver/overflow/exponential-trait-goals.rs b/tests/ui/traits/next-solver/overflow/exponential-trait-goals.rs
index 3d2e70a639f..a465bcecfe0 100644
--- a/tests/ui/traits/new-solver/overflow/exponential-trait-goals.rs
+++ b/tests/ui/traits/next-solver/overflow/exponential-trait-goals.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 trait Trait {}
 
diff --git a/tests/ui/traits/new-solver/overflow/exponential-trait-goals.stderr b/tests/ui/traits/next-solver/overflow/exponential-trait-goals.stderr
index 90b54b1e789..90b54b1e789 100644
--- a/tests/ui/traits/new-solver/overflow/exponential-trait-goals.stderr
+++ b/tests/ui/traits/next-solver/overflow/exponential-trait-goals.stderr
diff --git a/tests/ui/traits/new-solver/overflow/global-cache.rs b/tests/ui/traits/next-solver/overflow/global-cache.rs
index adc03da04a8..fe4032ca62e 100644
--- a/tests/ui/traits/new-solver/overflow/global-cache.rs
+++ b/tests/ui/traits/next-solver/overflow/global-cache.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // Check that we consider the reached depth of global cache
 // entries when detecting overflow. We would otherwise be unstable
diff --git a/tests/ui/traits/new-solver/overflow/global-cache.stderr b/tests/ui/traits/next-solver/overflow/global-cache.stderr
index 67616619384..67616619384 100644
--- a/tests/ui/traits/new-solver/overflow/global-cache.stderr
+++ b/tests/ui/traits/next-solver/overflow/global-cache.stderr
diff --git a/tests/ui/traits/new-solver/overflow/recursion-limit-zero-issue-115351.rs b/tests/ui/traits/next-solver/overflow/recursion-limit-zero-issue-115351.rs
index 539c9614e82..52a17a14281 100644
--- a/tests/ui/traits/new-solver/overflow/recursion-limit-zero-issue-115351.rs
+++ b/tests/ui/traits/next-solver/overflow/recursion-limit-zero-issue-115351.rs
@@ -2,7 +2,7 @@
 //~| ERROR overflow evaluating the requirement `Self: Trait`
 
 // This is a non-regression test for issue #115351, where a recursion limit of 0 caused an ICE.
-// compile-flags: -Ztrait-solver=next --crate-type=lib
+// compile-flags: -Znext-solver --crate-type=lib
 // check-fail
 
 #![recursion_limit = "0"]
diff --git a/tests/ui/traits/new-solver/overflow/recursion-limit-zero-issue-115351.stderr b/tests/ui/traits/next-solver/overflow/recursion-limit-zero-issue-115351.stderr
index 16b25d90ace..16b25d90ace 100644
--- a/tests/ui/traits/new-solver/overflow/recursion-limit-zero-issue-115351.stderr
+++ b/tests/ui/traits/next-solver/overflow/recursion-limit-zero-issue-115351.stderr
diff --git a/tests/ui/traits/new-solver/overflow/recursive-self-normalization-2.rs b/tests/ui/traits/next-solver/overflow/recursive-self-normalization-2.rs
index 3e10b2b595e..327ef865de9 100644
--- a/tests/ui/traits/new-solver/overflow/recursive-self-normalization-2.rs
+++ b/tests/ui/traits/next-solver/overflow/recursive-self-normalization-2.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 trait Foo1 {
     type Assoc1;
diff --git a/tests/ui/traits/new-solver/overflow/recursive-self-normalization-2.stderr b/tests/ui/traits/next-solver/overflow/recursive-self-normalization-2.stderr
index eda62b99c44..eda62b99c44 100644
--- a/tests/ui/traits/new-solver/overflow/recursive-self-normalization-2.stderr
+++ b/tests/ui/traits/next-solver/overflow/recursive-self-normalization-2.stderr
diff --git a/tests/ui/traits/new-solver/overflow/recursive-self-normalization.rs b/tests/ui/traits/next-solver/overflow/recursive-self-normalization.rs
index 36ef856a466..f45d208e666 100644
--- a/tests/ui/traits/new-solver/overflow/recursive-self-normalization.rs
+++ b/tests/ui/traits/next-solver/overflow/recursive-self-normalization.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 trait Foo {
     type Assoc;
diff --git a/tests/ui/traits/new-solver/overflow/recursive-self-normalization.stderr b/tests/ui/traits/next-solver/overflow/recursive-self-normalization.stderr
index b0a0a69761a..b0a0a69761a 100644
--- a/tests/ui/traits/new-solver/overflow/recursive-self-normalization.stderr
+++ b/tests/ui/traits/next-solver/overflow/recursive-self-normalization.stderr
diff --git a/tests/ui/traits/new-solver/param-candidate-doesnt-shadow-project.rs b/tests/ui/traits/next-solver/param-candidate-doesnt-shadow-project.rs
index bdf999ec5dd..f67b073c53c 100644
--- a/tests/ui/traits/new-solver/param-candidate-doesnt-shadow-project.rs
+++ b/tests/ui/traits/next-solver/param-candidate-doesnt-shadow-project.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Foo {
diff --git a/tests/ui/traits/new-solver/param-discr-kind.rs b/tests/ui/traits/next-solver/param-discr-kind.rs
index e319ddea106..c66b0b9f45f 100644
--- a/tests/ui/traits/new-solver/param-discr-kind.rs
+++ b/tests/ui/traits/next-solver/param-discr-kind.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 fn foo<T>(x: T) {
diff --git a/tests/ui/traits/new-solver/pointee.rs b/tests/ui/traits/next-solver/pointee.rs
index 93c0542ace4..a56df549a8d 100644
--- a/tests/ui/traits/new-solver/pointee.rs
+++ b/tests/ui/traits/next-solver/pointee.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 #![feature(ptr_metadata)]
 
diff --git a/tests/ui/traits/new-solver/pointer-like.rs b/tests/ui/traits/next-solver/pointer-like.rs
index 98630176976..f6cc718c6e2 100644
--- a/tests/ui/traits/new-solver/pointer-like.rs
+++ b/tests/ui/traits/next-solver/pointer-like.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 #![feature(pointer_like_trait)]
 
diff --git a/tests/ui/traits/new-solver/pointer-like.stderr b/tests/ui/traits/next-solver/pointer-like.stderr
index 4b624fd0d35..4b624fd0d35 100644
--- a/tests/ui/traits/new-solver/pointer-like.stderr
+++ b/tests/ui/traits/next-solver/pointer-like.stderr
diff --git a/tests/ui/traits/new-solver/prefer-candidate-no-constraints.rs b/tests/ui/traits/next-solver/prefer-candidate-no-constraints.rs
index 6f8164f3a40..a47f819f192 100644
--- a/tests/ui/traits/new-solver/prefer-candidate-no-constraints.rs
+++ b/tests/ui/traits/next-solver/prefer-candidate-no-constraints.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Foo {}
diff --git a/tests/ui/traits/new-solver/prefer-param-env-on-ambiguity.rs b/tests/ui/traits/next-solver/prefer-param-env-on-ambiguity.rs
index 909b33ec3d5..f8c0223e187 100644
--- a/tests/ui/traits/new-solver/prefer-param-env-on-ambiguity.rs
+++ b/tests/ui/traits/next-solver/prefer-param-env-on-ambiguity.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Foo<'a> {}
diff --git a/tests/ui/traits/new-solver/projection-discr-kind.rs b/tests/ui/traits/next-solver/projection-discr-kind.rs
index 20296b287b1..bf557f8633a 100644
--- a/tests/ui/traits/new-solver/projection-discr-kind.rs
+++ b/tests/ui/traits/next-solver/projection-discr-kind.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // Check that `<T::Assoc as DiscriminantKind>::Discriminant` doesn't normalize
 // to itself and cause overflow/ambiguity.
diff --git a/tests/ui/traits/new-solver/projection-discr-kind.stderr b/tests/ui/traits/next-solver/projection-discr-kind.stderr
index 69999c75522..69999c75522 100644
--- a/tests/ui/traits/new-solver/projection-discr-kind.stderr
+++ b/tests/ui/traits/next-solver/projection-discr-kind.stderr
diff --git a/tests/ui/traits/new-solver/slice-match-byte-lit.rs b/tests/ui/traits/next-solver/slice-match-byte-lit.rs
index 4f848062595..1edc9f1e8e9 100644
--- a/tests/ui/traits/new-solver/slice-match-byte-lit.rs
+++ b/tests/ui/traits/next-solver/slice-match-byte-lit.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 fn test(s: &[u8]) {
diff --git a/tests/ui/traits/new-solver/specialization-transmute.rs b/tests/ui/traits/next-solver/specialization-transmute.rs
index fac7d76f8cf..58b62f52dfd 100644
--- a/tests/ui/traits/new-solver/specialization-transmute.rs
+++ b/tests/ui/traits/next-solver/specialization-transmute.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 #![feature(specialization)]
 //~^ WARN the feature `specialization` is incomplete
diff --git a/tests/ui/traits/new-solver/specialization-transmute.stderr b/tests/ui/traits/next-solver/specialization-transmute.stderr
index eaf32a475ac..eaf32a475ac 100644
--- a/tests/ui/traits/new-solver/specialization-transmute.stderr
+++ b/tests/ui/traits/next-solver/specialization-transmute.stderr
diff --git a/tests/ui/traits/new-solver/specialization-unconstrained.rs b/tests/ui/traits/next-solver/specialization-unconstrained.rs
index 7fd753109be..950fb1512bc 100644
--- a/tests/ui/traits/new-solver/specialization-unconstrained.rs
+++ b/tests/ui/traits/next-solver/specialization-unconstrained.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 #![feature(specialization)]
 //~^ WARN the feature `specialization` is incomplete
diff --git a/tests/ui/traits/new-solver/specialization-unconstrained.stderr b/tests/ui/traits/next-solver/specialization-unconstrained.stderr
index ed4dafa1484..ed4dafa1484 100644
--- a/tests/ui/traits/new-solver/specialization-unconstrained.stderr
+++ b/tests/ui/traits/next-solver/specialization-unconstrained.stderr
diff --git a/tests/ui/traits/new-solver/stall-num-var-auto-trait.fallback.stderr b/tests/ui/traits/next-solver/stall-num-var-auto-trait.fallback.stderr
index 2e3c22c8d38..2e3c22c8d38 100644
--- a/tests/ui/traits/new-solver/stall-num-var-auto-trait.fallback.stderr
+++ b/tests/ui/traits/next-solver/stall-num-var-auto-trait.fallback.stderr
diff --git a/tests/ui/traits/new-solver/stall-num-var-auto-trait.rs b/tests/ui/traits/next-solver/stall-num-var-auto-trait.rs
index 0539c3a4292..f5bf985cdb2 100644
--- a/tests/ui/traits/new-solver/stall-num-var-auto-trait.rs
+++ b/tests/ui/traits/next-solver/stall-num-var-auto-trait.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // revisions: fallback constrain
 //[constrain] check-pass
 
diff --git a/tests/ui/traits/new-solver/structural-resolve-field.rs b/tests/ui/traits/next-solver/structural-resolve-field.rs
index 01899c9ad64..b247e237534 100644
--- a/tests/ui/traits/new-solver/structural-resolve-field.rs
+++ b/tests/ui/traits/next-solver/structural-resolve-field.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 #[derive(Default)]
diff --git a/tests/ui/traits/new-solver/tait-eq-proj-2.rs b/tests/ui/traits/next-solver/tait-eq-proj-2.rs
index 77ea8bc246e..a3df053dd83 100644
--- a/tests/ui/traits/new-solver/tait-eq-proj-2.rs
+++ b/tests/ui/traits/next-solver/tait-eq-proj-2.rs
@@ -1,9 +1,9 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 #![feature(type_alias_impl_trait)]
 
-// Similar to tests/ui/traits/new-solver/tait-eq-proj.rs
+// Similar to tests/ui/traits/next-solver/tait-eq-proj.rs
 // but check the alias-sub relation in the other direction.
 
 type Tait = impl Iterator<Item = impl Sized>;
diff --git a/tests/ui/traits/new-solver/tait-eq-proj.rs b/tests/ui/traits/next-solver/tait-eq-proj.rs
index 01ef2ec953a..871e8e1e9fc 100644
--- a/tests/ui/traits/new-solver/tait-eq-proj.rs
+++ b/tests/ui/traits/next-solver/tait-eq-proj.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 #![feature(type_alias_impl_trait)]
diff --git a/tests/ui/traits/new-solver/tait-eq-tait.rs b/tests/ui/traits/next-solver/tait-eq-tait.rs
index 70d9dc0eaa8..2629a124c3a 100644
--- a/tests/ui/traits/new-solver/tait-eq-tait.rs
+++ b/tests/ui/traits/next-solver/tait-eq-tait.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 // Not exactly sure if this is the inference behavior we *want*,
diff --git a/tests/ui/traits/new-solver/temporary-ambiguity.rs b/tests/ui/traits/next-solver/temporary-ambiguity.rs
index c6c11a1a1de..6102de7e446 100644
--- a/tests/ui/traits/new-solver/temporary-ambiguity.rs
+++ b/tests/ui/traits/next-solver/temporary-ambiguity.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 // Checks that we don't explode when we assemble >1 candidate for a goal.
diff --git a/tests/ui/traits/new-solver/trait-upcast-lhs-needs-normalization.rs b/tests/ui/traits/next-solver/trait-upcast-lhs-needs-normalization.rs
index 79114b93b78..2a482f74668 100644
--- a/tests/ui/traits/new-solver/trait-upcast-lhs-needs-normalization.rs
+++ b/tests/ui/traits/next-solver/trait-upcast-lhs-needs-normalization.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 pub trait A {}
 pub trait B: A {}
diff --git a/tests/ui/traits/new-solver/try-example.rs b/tests/ui/traits/next-solver/try-example.rs
index e826f3a0059..92b0b597881 100644
--- a/tests/ui/traits/new-solver/try-example.rs
+++ b/tests/ui/traits/next-solver/try-example.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 use std::error::Error;
 
diff --git a/tests/ui/traits/new-solver/two-projection-param-candidates-are-ambiguous.rs b/tests/ui/traits/next-solver/two-projection-param-candidates-are-ambiguous.rs
index 3c7fc0d813d..d25e372b5d8 100644
--- a/tests/ui/traits/new-solver/two-projection-param-candidates-are-ambiguous.rs
+++ b/tests/ui/traits/next-solver/two-projection-param-candidates-are-ambiguous.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // When we're solving `<T as Foo>::Assoc = i32`, we actually first solve
 // `<T as Foo>::Assoc = ?1t`, then unify `?1t` with `i32`. That goal
diff --git a/tests/ui/traits/new-solver/two-projection-param-candidates-are-ambiguous.stderr b/tests/ui/traits/next-solver/two-projection-param-candidates-are-ambiguous.stderr
index dfff9f11b87..dfff9f11b87 100644
--- a/tests/ui/traits/new-solver/two-projection-param-candidates-are-ambiguous.stderr
+++ b/tests/ui/traits/next-solver/two-projection-param-candidates-are-ambiguous.stderr
diff --git a/tests/ui/traits/new-solver/unevaluated-const-impl-trait-ref.fails.stderr b/tests/ui/traits/next-solver/unevaluated-const-impl-trait-ref.fails.stderr
index 4be90c702a0..4be90c702a0 100644
--- a/tests/ui/traits/new-solver/unevaluated-const-impl-trait-ref.fails.stderr
+++ b/tests/ui/traits/next-solver/unevaluated-const-impl-trait-ref.fails.stderr
diff --git a/tests/ui/traits/new-solver/unevaluated-const-impl-trait-ref.rs b/tests/ui/traits/next-solver/unevaluated-const-impl-trait-ref.rs
index 26c595bc974..77a169d48de 100644
--- a/tests/ui/traits/new-solver/unevaluated-const-impl-trait-ref.rs
+++ b/tests/ui/traits/next-solver/unevaluated-const-impl-trait-ref.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // revisions: works fails
 //[works] check-pass
 
diff --git a/tests/ui/traits/new-solver/unsafe-auto-trait-impl.rs b/tests/ui/traits/next-solver/unsafe-auto-trait-impl.rs
index bcfc747ebb1..f66bf0b87ec 100644
--- a/tests/ui/traits/new-solver/unsafe-auto-trait-impl.rs
+++ b/tests/ui/traits/next-solver/unsafe-auto-trait-impl.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 struct Foo(*mut ());
diff --git a/tests/ui/traits/new-solver/unsize-although-ambiguous.rs b/tests/ui/traits/next-solver/unsize-although-ambiguous.rs
index 431988a5fff..8217701b9f8 100644
--- a/tests/ui/traits/new-solver/unsize-although-ambiguous.rs
+++ b/tests/ui/traits/next-solver/unsize-although-ambiguous.rs
@@ -1,5 +1,5 @@
 // check-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 use std::fmt::Display;
 
diff --git a/tests/ui/traits/new-solver/unsize-good.rs b/tests/ui/traits/next-solver/unsize-good.rs
index 87ed9cfd10a..04ebe66f21c 100644
--- a/tests/ui/traits/new-solver/unsize-good.rs
+++ b/tests/ui/traits/next-solver/unsize-good.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 #![feature(unsized_tuple_coercion)]
diff --git a/tests/ui/traits/new-solver/upcast-right-substs.rs b/tests/ui/traits/next-solver/upcast-right-substs.rs
index 97eb189d5c7..5e4d958c895 100644
--- a/tests/ui/traits/new-solver/upcast-right-substs.rs
+++ b/tests/ui/traits/next-solver/upcast-right-substs.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 // check-pass
 
 trait Foo: Bar<i32> + Bar<u32> {}
diff --git a/tests/ui/traits/new-solver/upcast-wrong-substs.rs b/tests/ui/traits/next-solver/upcast-wrong-substs.rs
index 3376f9787d3..0cd253007fc 100644
--- a/tests/ui/traits/new-solver/upcast-wrong-substs.rs
+++ b/tests/ui/traits/next-solver/upcast-wrong-substs.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 trait Foo: Bar<i32> + Bar<u32> {}
 
diff --git a/tests/ui/traits/new-solver/upcast-wrong-substs.stderr b/tests/ui/traits/next-solver/upcast-wrong-substs.stderr
index 00ba1ef678f..00ba1ef678f 100644
--- a/tests/ui/traits/new-solver/upcast-wrong-substs.stderr
+++ b/tests/ui/traits/next-solver/upcast-wrong-substs.stderr
diff --git a/tests/ui/traits/new-solver/winnow-specializing-impls.rs b/tests/ui/traits/next-solver/winnow-specializing-impls.rs
index 06f64de7403..d70a9159611 100644
--- a/tests/ui/traits/new-solver/winnow-specializing-impls.rs
+++ b/tests/ui/traits/next-solver/winnow-specializing-impls.rs
@@ -1,5 +1,5 @@
 // build-pass
-// compile-flags: -Ztrait-solver=next
+// compile-flags: -Znext-solver
 
 // Tests that the specializing impl `<() as Foo>` holds during codegen.
 
diff --git a/tests/ui/traits/non-lifetime-via-dyn-builtin.rs b/tests/ui/traits/non-lifetime-via-dyn-builtin.rs
index 9a8a5ced2e2..996cd295dc4 100644
--- a/tests/ui/traits/non-lifetime-via-dyn-builtin.rs
+++ b/tests/ui/traits/non-lifetime-via-dyn-builtin.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // check-pass
 
 #![feature(non_lifetime_binders)]
diff --git a/tests/ui/traits/reservation-impl/coherence-conflict.rs b/tests/ui/traits/reservation-impl/coherence-conflict.rs
index 6bbd90f94dc..cdea162d64a 100644
--- a/tests/ui/traits/reservation-impl/coherence-conflict.rs
+++ b/tests/ui/traits/reservation-impl/coherence-conflict.rs
@@ -1,6 +1,6 @@
 // check that reservation impls are accounted for in negative reasoning.
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 #![feature(rustc_attrs)]
 
 trait MyTrait {}
diff --git a/tests/ui/traits/reservation-impl/no-use.rs b/tests/ui/traits/reservation-impl/no-use.rs
index 864f1791fd0..10aad3605ea 100644
--- a/tests/ui/traits/reservation-impl/no-use.rs
+++ b/tests/ui/traits/reservation-impl/no-use.rs
@@ -1,6 +1,6 @@
 // check that reservation impls can't be used as normal impls in positive reasoning.
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 #![feature(rustc_attrs)]
 
 trait MyTrait { fn foo(&self); }
diff --git a/tests/ui/traits/reservation-impl/non-lattice-ok.rs b/tests/ui/traits/reservation-impl/non-lattice-ok.rs
index 7787904d9b2..9a3c2b4f991 100644
--- a/tests/ui/traits/reservation-impl/non-lattice-ok.rs
+++ b/tests/ui/traits/reservation-impl/non-lattice-ok.rs
@@ -34,7 +34,7 @@
 // check that reservation impls can't be used as normal impls in positive reasoning.
 
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(rustc_attrs, never_type)]
 
diff --git a/tests/ui/traits/reservation-impl/ok.rs b/tests/ui/traits/reservation-impl/ok.rs
index 8ff6645a2b3..2d945f6adeb 100644
--- a/tests/ui/traits/reservation-impl/ok.rs
+++ b/tests/ui/traits/reservation-impl/ok.rs
@@ -4,7 +4,7 @@
 // but still.
 
 // revisions: old next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(rustc_attrs)]
 
diff --git a/tests/ui/traits/trait-upcasting/fewer-associated.rs b/tests/ui/traits/trait-upcasting/fewer-associated.rs
index 937818aac58..e7ca6fa5208 100644
--- a/tests/ui/traits/trait-upcasting/fewer-associated.rs
+++ b/tests/ui/traits/trait-upcasting/fewer-associated.rs
@@ -1,7 +1,7 @@
 // check-pass
 // issue: 114035
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 trait A: B {
     type Assoc;
diff --git a/tests/ui/traits/trait-upcasting/illegal-upcast-from-impl.rs b/tests/ui/traits/trait-upcasting/illegal-upcast-from-impl.rs
index 4b730dab7cc..5a493fd48b3 100644
--- a/tests/ui/traits/trait-upcasting/illegal-upcast-from-impl.rs
+++ b/tests/ui/traits/trait-upcasting/illegal-upcast-from-impl.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 trait Super {
     type Assoc;
diff --git a/tests/ui/traits/trait-upcasting/issue-11515.rs b/tests/ui/traits/trait-upcasting/issue-11515.rs
index 66ab1ce260a..a1edb53ec37 100644
--- a/tests/ui/traits/trait-upcasting/issue-11515.rs
+++ b/tests/ui/traits/trait-upcasting/issue-11515.rs
@@ -1,6 +1,6 @@
 // check-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 struct Test {
     func: Box<dyn FnMut() + 'static>,
diff --git a/tests/ui/traits/trait-upcasting/normalization.rs b/tests/ui/traits/trait-upcasting/normalization.rs
index c57640e7e34..b594969483a 100644
--- a/tests/ui/traits/trait-upcasting/normalization.rs
+++ b/tests/ui/traits/trait-upcasting/normalization.rs
@@ -1,7 +1,7 @@
 // check-pass
 // issue: 114113
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 trait Mirror {
     type Assoc;
diff --git a/tests/ui/traits/trait-upcasting/type-checking-test-1.rs b/tests/ui/traits/trait-upcasting/type-checking-test-1.rs
index 3b6ec3b65e7..7d3deeeaa61 100644
--- a/tests/ui/traits/trait-upcasting/type-checking-test-1.rs
+++ b/tests/ui/traits/trait-upcasting/type-checking-test-1.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 trait Foo: Bar<i32> + Bar<u32> {}
 trait Bar<T> {
diff --git a/tests/ui/traits/trait-upcasting/upcast-through-struct-tail.rs b/tests/ui/traits/trait-upcasting/upcast-through-struct-tail.rs
index 9981d436062..f8cf793e4a4 100644
--- a/tests/ui/traits/trait-upcasting/upcast-through-struct-tail.rs
+++ b/tests/ui/traits/trait-upcasting/upcast-through-struct-tail.rs
@@ -1,6 +1,6 @@
 // check-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 struct Wrapper<T: ?Sized>(T);
 
diff --git a/tests/ui/transmutability/primitives/bool-mut.rs b/tests/ui/transmutability/primitives/bool-mut.rs
index 49dbe90e4b8..6ee168d1a71 100644
--- a/tests/ui/transmutability/primitives/bool-mut.rs
+++ b/tests/ui/transmutability/primitives/bool-mut.rs
@@ -1,5 +1,5 @@
 // check-fail
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(transmutability)]
 mod assert {
diff --git a/tests/ui/transmutability/primitives/bool.rs b/tests/ui/transmutability/primitives/bool.rs
index 654e7b47ede..ac4024b7f33 100644
--- a/tests/ui/transmutability/primitives/bool.rs
+++ b/tests/ui/transmutability/primitives/bool.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(transmutability)]
 mod assert {
diff --git a/tests/ui/transmutability/primitives/numbers.rs b/tests/ui/transmutability/primitives/numbers.rs
index e980e91ed06..1afc7d677ee 100644
--- a/tests/ui/transmutability/primitives/numbers.rs
+++ b/tests/ui/transmutability/primitives/numbers.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![crate_type = "lib"]
 #![feature(transmutability)]
diff --git a/tests/ui/transmutability/primitives/unit.rs b/tests/ui/transmutability/primitives/unit.rs
index 12eac175106..5ea96cf8ba7 100644
--- a/tests/ui/transmutability/primitives/unit.rs
+++ b/tests/ui/transmutability/primitives/unit.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 //! The unit type, `()`, should be one byte.
 
diff --git a/tests/ui/type-alias-impl-trait/assoc-type-const.rs b/tests/ui/type-alias-impl-trait/assoc-type-const.rs
index 6632a3450e5..e385fe045fc 100644
--- a/tests/ui/type-alias-impl-trait/assoc-type-const.rs
+++ b/tests/ui/type-alias-impl-trait/assoc-type-const.rs
@@ -3,7 +3,7 @@
 
 // check-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 #![feature(impl_trait_in_assoc_type)]
 
 trait UnwrapItemsExt<'a, const C: usize> {
diff --git a/tests/ui/type-alias-impl-trait/cross_inference.rs b/tests/ui/type-alias-impl-trait/cross_inference.rs
index 5eaf0ddda99..c5ef75fee61 100644
--- a/tests/ui/type-alias-impl-trait/cross_inference.rs
+++ b/tests/ui/type-alias-impl-trait/cross_inference.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // check-pass
 
 #![feature(type_alias_impl_trait)]
diff --git a/tests/ui/type-alias-impl-trait/issue-76202-trait-impl-for-tait.rs b/tests/ui/type-alias-impl-trait/issue-76202-trait-impl-for-tait.rs
index 386b77d4d16..af1c18bbb59 100644
--- a/tests/ui/type-alias-impl-trait/issue-76202-trait-impl-for-tait.rs
+++ b/tests/ui/type-alias-impl-trait/issue-76202-trait-impl-for-tait.rs
@@ -2,7 +2,7 @@
 // Tests that we don't ICE when we have a trait impl on a TAIT.
 
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // check-pass
 
 #![feature(type_alias_impl_trait)]
diff --git a/tests/ui/type-alias-impl-trait/issue-78450.rs b/tests/ui/type-alias-impl-trait/issue-78450.rs
index 236e9f4e88c..c51dfb6782b 100644
--- a/tests/ui/type-alias-impl-trait/issue-78450.rs
+++ b/tests/ui/type-alias-impl-trait/issue-78450.rs
@@ -1,6 +1,6 @@
 // check-pass
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(impl_trait_in_assoc_type)]
 
diff --git a/tests/ui/type-alias-impl-trait/normalize-hidden-types.rs b/tests/ui/type-alias-impl-trait/normalize-hidden-types.rs
index 8d80546444a..371cac6da7c 100644
--- a/tests/ui/type-alias-impl-trait/normalize-hidden-types.rs
+++ b/tests/ui/type-alias-impl-trait/normalize-hidden-types.rs
@@ -1,7 +1,7 @@
 // Regression test for #112691
 //
 // revisions: current next
-// [next] compile-flags: -Ztrait-solver=next
+// [next] compile-flags: -Znext-solver
 // [next] check-pass
 // [current]: known-bug: #112691
 
diff --git a/tests/ui/type-alias-impl-trait/rpit_tait_equality_in_canonical_query.rs b/tests/ui/type-alias-impl-trait/rpit_tait_equality_in_canonical_query.rs
index 0f0002f7797..222841f3467 100644
--- a/tests/ui/type-alias-impl-trait/rpit_tait_equality_in_canonical_query.rs
+++ b/tests/ui/type-alias-impl-trait/rpit_tait_equality_in_canonical_query.rs
@@ -6,7 +6,7 @@
 //! have a situation where the RPIT gets constrained outside its anchor.
 
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 //[next] check-pass
 
 //[current] known-bug: #108498
diff --git a/tests/ui/type-alias-impl-trait/wf-in-associated-type.rs b/tests/ui/type-alias-impl-trait/wf-in-associated-type.rs
index b966ca4bff0..22e2b0efd1f 100644
--- a/tests/ui/type-alias-impl-trait/wf-in-associated-type.rs
+++ b/tests/ui/type-alias-impl-trait/wf-in-associated-type.rs
@@ -2,7 +2,7 @@
 //
 // revisions: pass pass_next fail
 // [pass] check-pass
-// [pass_next] compile-flags: -Ztrait-solver=next
+// [pass_next] compile-flags: -Znext-solver
 // [pass_next] check-pass
 // [fail] check-fail
 
diff --git a/tests/ui/unsized/issue-71659.rs b/tests/ui/unsized/issue-71659.rs
index db5c2e205aa..65a867caf8f 100644
--- a/tests/ui/unsized/issue-71659.rs
+++ b/tests/ui/unsized/issue-71659.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 
 #![feature(unsize)]
 
diff --git a/tests/ui/unsized/issue-75899.rs b/tests/ui/unsized/issue-75899.rs
index 71943103291..56c8a72bfcc 100644
--- a/tests/ui/unsized/issue-75899.rs
+++ b/tests/ui/unsized/issue-75899.rs
@@ -1,5 +1,5 @@
 // revisions: current next
-//[next] compile-flags: -Ztrait-solver=next
+//[next] compile-flags: -Znext-solver
 // check-pass
 
 trait Trait {}