Rollup of 4 pull requests

Cargo.lock

@@ -2760,7 +2760,7 @@ dependencies = [
  "tabled",
  "tar",
  "tempfile",
- "xz",
+ "xz2",
  "zip",
 ]
 
@@ -6586,15 +6586,6 @@ dependencies = [
  "rustix",
 ]
 
-[[package]]
-name = "xz"
-version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c887690ff2a2e233e8e49633461521f98ec57fbff9d59a884c9a4f04ec1da34"
-dependencies = [
- "xz2",
-]
-
 [[package]]
 name = "xz2"
 version = "0.1.7"

compiler/rustc_hir_typeck/src/method/mod.rs

@@ -315,7 +315,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         trait_def_id: DefId,
         self_ty: Ty<'tcx>,
         opt_input_types: Option<&[Ty<'tcx>]>,
-    ) -> (traits::PredicateObligation<'tcx>, &'tcx ty::List<ty::GenericArg<'tcx>>) {
+    ) -> (traits::PredicateObligation<'tcx>, ty::GenericArgsRef<'tcx>) {
         // Construct a trait-reference `self_ty : Trait<input_tys>`
         let args = GenericArgs::for_item(self.tcx, trait_def_id, |param, _| {
             match param.kind {
@@ -365,7 +365,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         m_name: Ident,
         trait_def_id: DefId,
         obligation: traits::PredicateObligation<'tcx>,
-        args: &'tcx ty::List<ty::GenericArg<'tcx>>,
+        args: ty::GenericArgsRef<'tcx>,
     ) -> Option<InferOk<'tcx, MethodCallee<'tcx>>> {
         debug!(?obligation);
 

compiler/rustc_hir_typeck/src/pat.rs

@@ -1676,7 +1676,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         unmentioned_fields: &mut Vec<(&'tcx ty::FieldDef, Ident)>,
         pat: &'tcx Pat<'tcx>,
         variant: &ty::VariantDef,
-        args: &'tcx ty::List<ty::GenericArg<'tcx>>,
+        args: ty::GenericArgsRef<'tcx>,
     ) -> Diag<'tcx> {
         let tcx = self.tcx;
         let (field_names, t, plural) = if let [field] = inexistent_fields {

compiler/rustc_lint/src/for_loops_over_fallibles.rs

@@ -9,7 +9,7 @@ use crate::{
 use hir::{Expr, Pat};
 use rustc_hir as hir;
 use rustc_infer::{infer::TyCtxtInferExt, traits::ObligationCause};
-use rustc_middle::ty::{self, List};
+use rustc_middle::ty;
 use rustc_session::{declare_lint, declare_lint_pass};
 use rustc_span::{sym, Span};
 use rustc_trait_selection::traits::ObligationCtxt;
@@ -123,7 +123,7 @@ fn extract_iterator_next_call<'tcx>(
 fn suggest_question_mark<'tcx>(
     cx: &LateContext<'tcx>,
     adt: ty::AdtDef<'tcx>,
-    args: &List<ty::GenericArg<'tcx>>,
+    args: ty::GenericArgsRef<'tcx>,
     span: Span,
 ) -> bool {
     let Some(body_id) = cx.enclosing_body else { return false };

compiler/rustc_middle/src/ty/context.rs

@@ -2331,7 +2331,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn mk_args_from_iter<I, T>(self, iter: I) -> T::Output
     where
         I: Iterator<Item = T>,
-        T: CollectAndApply<GenericArg<'tcx>, &'tcx List<GenericArg<'tcx>>>,
+        T: CollectAndApply<GenericArg<'tcx>, ty::GenericArgsRef<'tcx>>,
     {
         T::collect_and_apply(iter, |xs| self.mk_args(xs))
     }

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -977,7 +977,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
     fn pretty_print_opaque_impl_type(
         &mut self,
         def_id: DefId,
-        args: &'tcx ty::List<ty::GenericArg<'tcx>>,
+        args: ty::GenericArgsRef<'tcx>,
     ) -> Result<(), PrintError> {
         let tcx = self.tcx();
 

compiler/rustc_target/src/lib.rs

@@ -7,16 +7,17 @@
 //! more 'stuff' here in the future. It does not have a dependency on
 //! LLVM.
 
+// tidy-alphabetical-start
+#![allow(internal_features)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
-#![feature(min_exhaustive_patterns)]
-#![feature(rustdoc_internals)]
 #![feature(assert_matches)]
 #![feature(iter_intersperse)]
 #![feature(let_chains)]
+#![feature(min_exhaustive_patterns)]
 #![feature(rustc_attrs)]
-#![feature(step_trait)]
-#![allow(internal_features)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 use std::path::{Path, PathBuf};
 

compiler/rustc_target/src/spec/mod.rs

@@ -603,19 +603,6 @@ impl LinkSelfContainedDefault {
         self == LinkSelfContainedDefault::False
     }
 
-    /// Returns whether the target spec explicitly requests self-contained linking, i.e. not via
-    /// inference.
-    pub fn is_linker_enabled(self) -> bool {
-        match self {
-            LinkSelfContainedDefault::True => true,
-            LinkSelfContainedDefault::False => false,
-            LinkSelfContainedDefault::WithComponents(c) => {
-                c.contains(LinkSelfContainedComponents::LINKER)
-            }
-            _ => false,
-        }
-    }
-
     /// Returns the key to use when serializing the setting to json:
     /// - individual components in a `link-self-contained` object value
     /// - the other variants as a backwards-compatible `crt-objects-fallback` string

compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs

@@ -409,6 +409,7 @@ pub(in crate::solve) fn make_canonical_state<'tcx, T: TypeFoldable<TyCtxt<'tcx>>
 /// This currently assumes that unifying the var values trivially succeeds.
 /// Adding any inference constraints which weren't present when originally
 /// computing the canonical query can result in bugs.
+#[instrument(level = "debug", skip(infcx, span, param_env))]
 pub(in crate::solve) fn instantiate_canonical_state<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>(
     infcx: &InferCtxt<'tcx>,
     span: Span,

compiler/rustc_trait_selection/src/solve/inspect/analyse.rs

@@ -146,6 +146,11 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
     /// inference constraints, and optionally the args of an impl if this candidate
     /// came from a `CandidateSource::Impl`. This function modifies the state of the
     /// `infcx`.
+    #[instrument(
+        level = "debug",
+        skip_all,
+        fields(goal = ?self.goal.goal, nested_goals = ?self.nested_goals)
+    )]
     pub fn instantiate_nested_goals_and_opt_impl_args(
         &self,
         span: Span,
@@ -213,10 +218,23 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
                     };
                     let goal =
                         goal.with(infcx.tcx, ty::NormalizesTo { alias, term: unconstrained_term });
-                    let proof_tree = EvalCtxt::enter_root(infcx, GenerateProofTree::Yes, |ecx| {
-                        ecx.evaluate_goal_raw(GoalEvaluationKind::Root, GoalSource::Misc, goal)
-                    })
-                    .1;
+                    // We have to use a `probe` here as evaluating a `NormalizesTo` can constrain the
+                    // expected term. This means that candidates which only fail due to nested goals
+                    // and which normalize to a different term then the final result could ICE: when
+                    // building their proof tree, the expected term was unconstrained, but when
+                    // instantiating the candidate it is already constrained to the result of another
+                    // candidate.
+                    let proof_tree = infcx
+                        .probe(|_| {
+                            EvalCtxt::enter_root(infcx, GenerateProofTree::Yes, |ecx| {
+                                ecx.evaluate_goal_raw(
+                                    GoalEvaluationKind::Root,
+                                    GoalSource::Misc,
+                                    goal,
+                                )
+                            })
+                        })
+                        .1;
                     InspectGoal::new(
                         infcx,
                         self.goal.depth + 1,
@@ -225,13 +243,17 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
                         source,
                     )
                 }
-                _ => InspectGoal::new(
-                    infcx,
-                    self.goal.depth + 1,
-                    infcx.evaluate_root_goal(goal, GenerateProofTree::Yes).1.unwrap(),
-                    None,
-                    source,
-                ),
+                _ => {
+                    // We're using a probe here as evaluating a goal could constrain
+                    // inference variables by choosing one candidate. If we then recurse
+                    // into another candidate who ends up with different inference
+                    // constraints, we get an ICE if we already applied the constraints
+                    // from the chosen candidate.
+                    let proof_tree = infcx
+                        .probe(|_| infcx.evaluate_root_goal(goal, GenerateProofTree::Yes).1)
+                        .unwrap();
+                    InspectGoal::new(infcx, self.goal.depth + 1, proof_tree, None, source)
+                }
             })
             .collect();
 

compiler/rustc_trait_selection/src/traits/misc.rs

@@ -10,7 +10,7 @@ use rustc_infer::infer::canonical::Canonical;
 use rustc_infer::infer::{RegionResolutionError, TyCtxtInferExt};
 use rustc_infer::traits::query::NoSolution;
 use rustc_infer::{infer::outlives::env::OutlivesEnvironment, traits::FulfillmentError};
-use rustc_middle::ty::{self, AdtDef, GenericArg, List, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::DUMMY_SP;
 
 use super::outlives_bounds::InferCtxtExt;
@@ -129,7 +129,7 @@ pub fn all_fields_implement_trait<'tcx>(
     param_env: ty::ParamEnv<'tcx>,
     self_type: Ty<'tcx>,
     adt: AdtDef<'tcx>,
-    args: &'tcx List<GenericArg<'tcx>>,
+    args: ty::GenericArgsRef<'tcx>,
     parent_cause: ObligationCause<'tcx>,
     lang_item: LangItem,
 ) -> Result<(), Vec<(&'tcx ty::FieldDef, Ty<'tcx>, InfringingFieldsReason<'tcx>)>> {

src/tools/clippy/clippy_lints/src/default_union_representation.rs

@@ -2,7 +2,7 @@ use clippy_utils::diagnostics::span_lint_and_help;
 use rustc_hir::{HirId, Item, ItemKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::layout::LayoutOf;
-use rustc_middle::ty::{self, FieldDef, GenericArg, List};
+use rustc_middle::ty::{self, FieldDef};
 use rustc_session::declare_lint_pass;
 use rustc_span::sym;
 
@@ -85,7 +85,7 @@ fn is_union_with_two_non_zst_fields<'tcx>(cx: &LateContext<'tcx>, item: &Item<'t
     }
 }
 
-fn is_zst<'tcx>(cx: &LateContext<'tcx>, field: &FieldDef, args: &'tcx List<GenericArg<'tcx>>) -> bool {
+fn is_zst<'tcx>(cx: &LateContext<'tcx>, field: &FieldDef, args: ty::GenericArgsRef<'tcx>) -> bool {
     let ty = field.ty(cx.tcx, args);
     if let Ok(layout) = cx.layout_of(ty) {
         layout.is_zst()

src/tools/clippy/clippy_lints/src/needless_borrows_for_generic_args.rs

@@ -13,7 +13,7 @@ use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::mir::{Rvalue, StatementKind};
 use rustc_middle::ty::{
-    self, ClauseKind, EarlyBinder, FnSig, GenericArg, GenericArgKind, List, ParamTy, ProjectionPredicate, Ty,
+    self, ClauseKind, EarlyBinder, FnSig, GenericArg, GenericArgKind, ParamTy, ProjectionPredicate, Ty,
 };
 use rustc_session::impl_lint_pass;
 use rustc_span::symbol::sym;
@@ -161,7 +161,7 @@ fn needless_borrow_count<'tcx>(
     cx: &LateContext<'tcx>,
     possible_borrowers: &mut Vec<(LocalDefId, PossibleBorrowerMap<'tcx, 'tcx>)>,
     fn_id: DefId,
-    callee_args: &'tcx List<GenericArg<'tcx>>,
+    callee_args: ty::GenericArgsRef<'tcx>,
     arg_index: usize,
     param_ty: ParamTy,
     mut expr: &Expr<'tcx>,

src/tools/clippy/clippy_utils/src/ty.rs

@@ -19,7 +19,7 @@ use rustc_middle::traits::EvaluationResult;
 use rustc_middle::ty::layout::ValidityRequirement;
 use rustc_middle::ty::{
     self, AdtDef, AliasTy, AssocKind, Binder, BoundRegion, FnSig, GenericArg, GenericArgKind, GenericArgsRef,
-    GenericParamDefKind, IntTy, List, ParamEnv, Region, RegionKind, ToPredicate, TraitRef, Ty, TyCtxt,
+    GenericParamDefKind, IntTy, ParamEnv, Region, RegionKind, ToPredicate, TraitRef, Ty, TyCtxt,
     TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor, UintTy, VariantDef, VariantDiscr,
 };
 use rustc_span::symbol::Ident;
@@ -961,7 +961,11 @@ pub struct AdtVariantInfo {
 
 impl AdtVariantInfo {
     /// Returns ADT variants ordered by size
-    pub fn new<'tcx>(cx: &LateContext<'tcx>, adt: AdtDef<'tcx>, subst: &'tcx List<GenericArg<'tcx>>) -> Vec<Self> {
+    pub fn new<'tcx>(
+        cx: &LateContext<'tcx>,
+        adt: AdtDef<'tcx>,
+        subst: GenericArgsRef<'tcx>
+    ) -> Vec<Self> {
         let mut variants_size = adt
             .variants()
             .iter()

src/tools/opt-dist/Cargo.toml

@@ -16,7 +16,7 @@ camino = "1"
 reqwest = { version = "0.11", features = ["blocking"] }
 zip = { version = "0.6", default-features = false, features = ["deflate"] }
 tar = "0.4"
-xz = "0.1"
+xz = { version = "0.1", package = "xz2" }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 glob = "0.3"

tests/ui/traits/next-solver/coherence/ambiguity-causes-canonical-state-ice-1.rs

@@ -0,0 +1,43 @@
+//@ compile-flags: -Znext-solver=coherence
+//@ check-pass
+
+// A regression test for #124791. Computing ambiguity causes
+// for the overlap of the `ToString` impls caused an ICE.
+#![crate_type = "lib"]
+#![feature(min_specialization)]
+trait Display {}
+
+trait ToOwned {
+    type Owned;
+}
+
+impl<T> ToOwned for T {
+    type Owned = T;
+}
+
+struct Cow<B: ?Sized>(B);
+
+impl<B: ?Sized> Display for Cow<B>
+where
+    B: ToOwned,
+    B::Owned: Display,
+{
+}
+
+impl Display for () {}
+
+trait ToString {
+    fn to_string();
+}
+
+impl<T: Display + ?Sized> ToString for T {
+    default fn to_string() {}
+}
+
+impl ToString for Cow<str> {
+    fn to_string() {}
+}
+
+impl ToOwned for str {
+    type Owned = ();
+}

tests/ui/traits/next-solver/coherence/ambiguity-causes-canonical-state-ice-2.rs

@@ -0,0 +1,19 @@
+//@ compile-flags: -Znext-solver=coherence
+
+// A regression test for #124791. Computing ambiguity causes
+// for the overlap of the `ToString` impls caused an ICE.
+#![crate_type = "lib"]
+trait ToOwned {
+    type Owned;
+}
+impl<T> ToOwned for T {
+    type Owned = u8;
+}
+impl ToOwned for str {
+    type Owned = i8;
+}
+
+trait Overlap {}
+impl<T: ToOwned<Owned = i8> + ?Sized> Overlap for T {}
+impl Overlap for str {}
+//~^ ERROR conflicting implementations of trait `Overlap`

tests/ui/traits/next-solver/coherence/ambiguity-causes-canonical-state-ice-2.stderr

@@ -0,0 +1,11 @@
+error[E0119]: conflicting implementations of trait `Overlap` for type `str`
+  --> $DIR/ambiguity-causes-canonical-state-ice-2.rs:18:1
+   |
+LL | impl<T: ToOwned<Owned = i8> + ?Sized> Overlap for T {}
+   | --------------------------------------------------- first implementation here
+LL | impl Overlap for str {}
+   | ^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `str`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0119`.

tests/ui/traits/next-solver/cycles/coinduction/incompleteness-unstable-result.rs

@@ -61,7 +61,7 @@ where
     // entering the cycle from `A` fails, but would work if we were to use the cache
     // result of `B<X>`.
     impls_trait::<A<X>, _, _, _>();
-    //~^ ERROR the trait bound `A<X>: Trait<i32, u8, u8>` is not satisfied
+    //~^ ERROR the trait bound `A<X>: Trait<_, _, _>` is not satisfied
 }
 
 fn main() {