Rollup of 7 pull requests

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

@@ -11,9 +11,9 @@ use rustc_errors::MultiSpan;
 use rustc_errors::{
     codes::*, pluralize, struct_span_code_err, Applicability, Diag, ErrorGuaranteed,
 };
-use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::{self as hir, Node};
 use rustc_middle::bug;
 use rustc_middle::query::Key;
 use rustc_middle::ty::print::{PrintPolyTraitRefExt as _, PrintTraitRefExt as _};
@@ -740,7 +740,15 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         if object_safety_violations {
             return;
         }
+
+        // related to issue #91997, turbofishes added only when in an expr or pat
+        let mut in_expr_or_pat = false;
         if let ([], [bound]) = (&potential_assoc_types[..], &trait_bounds) {
+            let grandparent = tcx.parent_hir_node(tcx.parent_hir_id(bound.trait_ref.hir_ref_id));
+            in_expr_or_pat = match grandparent {
+                Node::Expr(_) | Node::Pat(_) => true,
+                _ => false,
+            };
             match bound.trait_ref.path.segments {
                 // FIXME: `trait_ref.path.span` can point to a full path with multiple
                 // segments, even though `trait_ref.path.segments` is of length `1`. Work
@@ -896,6 +904,10 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     // `Trait<'a, Item = Type>` while accounting for the `<'a>` in the
                     // suggestion.
                     format!("{}, {}>", &snippet[..snippet.len() - 1], types.join(", "))
+                } else if in_expr_or_pat {
+                    // The user wrote `Iterator`, so we don't have a type we can suggest, but at
+                    // least we can clue them to the correct syntax `Iterator::<Item = Type>`.
+                    format!("{}::<{}>", snippet, types.join(", "))
                 } else {
                     // The user wrote `Iterator`, so we don't have a type we can suggest, but at
                     // least we can clue them to the correct syntax `Iterator<Item = Type>`.

compiler/rustc_trait_selection/src/traits/normalize.rs

@@ -109,16 +109,13 @@ pub(super) fn needs_normalization<'tcx, T: TypeVisitable<TyCtxt<'tcx>>>(
     value: &T,
     reveal: Reveal,
 ) -> bool {
-    // This mirrors `ty::TypeFlags::HAS_ALIASES` except that we take `Reveal` into account.
-
-    let mut flags = ty::TypeFlags::HAS_TY_PROJECTION
-        | ty::TypeFlags::HAS_TY_WEAK
-        | ty::TypeFlags::HAS_TY_INHERENT
-        | ty::TypeFlags::HAS_CT_PROJECTION;
+    let mut flags = ty::TypeFlags::HAS_ALIAS;
 
+    // Opaques are treated as rigid with `Reveal::UserFacing`,
+    // so we can ignore those.
     match reveal {
-        Reveal::UserFacing => {}
-        Reveal::All => flags |= ty::TypeFlags::HAS_TY_OPAQUE,
+        Reveal::UserFacing => flags.remove(ty::TypeFlags::HAS_TY_OPAQUE),
+        Reveal::All => {}
     }
 
     value.has_type_flags(flags)

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

@@ -64,20 +64,6 @@ mod _match;
 mod candidate_assembly;
 mod confirmation;
 
-/// Whether to consider the binder of higher ranked goals for the `leak_check` when
-/// evaluating higher-ranked goals. See #119820 for more info.
-///
-/// While this is a bit hacky, it is necessary to match the behavior of the new solver:
-/// We eagerly instantiate binders in the new solver, outside of candidate selection, so
-/// the leak check inside of candidates does not consider any bound vars from the higher
-/// ranked goal. However, we do exit the binder once we're completely finished with a goal,
-/// so the leak-check can be used in evaluate by causing nested higher-ranked goals to fail.
-#[derive(Debug, Copy, Clone)]
-enum LeakCheckHigherRankedGoal {
-    No,
-    Yes,
-}
-
 #[derive(Clone, Debug, Eq, PartialEq, Hash)]
 pub enum IntercrateAmbiguityCause<'tcx> {
     DownstreamCrate { trait_ref: ty::TraitRef<'tcx>, self_ty: Option<Ty<'tcx>> },
@@ -402,10 +388,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     let mut no_candidates_apply = true;
 
                     for c in candidate_set.vec.iter() {
-                        if self
-                            .evaluate_candidate(stack, c, LeakCheckHigherRankedGoal::No)?
-                            .may_apply()
-                        {
+                        if self.evaluate_candidate(stack, c)?.may_apply() {
                             no_candidates_apply = false;
                             break;
                         }
@@ -476,7 +459,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         // is needed for specialization. Propagate overflow if it occurs.
         let mut candidates = candidates
             .into_iter()
-            .map(|c| match self.evaluate_candidate(stack, &c, LeakCheckHigherRankedGoal::No) {
+            .map(|c| match self.evaluate_candidate(stack, &c) {
                 Ok(eval) if eval.may_apply() => {
                     Ok(Some(EvaluatedCandidate { candidate: c, evaluation: eval }))
                 }
@@ -566,7 +549,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         obligation: &PredicateObligation<'tcx>,
     ) -> Result<EvaluationResult, OverflowError> {
         debug_assert!(!self.infcx.next_trait_solver());
-        self.evaluation_probe(|this, _outer_universe| {
+        self.evaluation_probe(|this| {
             let goal =
                 this.infcx.resolve_vars_if_possible((obligation.predicate, obligation.param_env));
             let mut result = this.evaluate_predicate_recursively(
@@ -589,11 +572,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// `op`, but this can be overwritten if necessary.
     fn evaluation_probe(
         &mut self,
-        op: impl FnOnce(&mut Self, &mut ty::UniverseIndex) -> Result<EvaluationResult, OverflowError>,
+        op: impl FnOnce(&mut Self) -> Result<EvaluationResult, OverflowError>,
     ) -> Result<EvaluationResult, OverflowError> {
         self.infcx.probe(|snapshot| -> Result<EvaluationResult, OverflowError> {
-            let mut outer_universe = self.infcx.universe();
-            let result = op(self, &mut outer_universe)?;
+            let outer_universe = self.infcx.universe();
+            let result = op(self)?;
 
             match self.infcx.leak_check(outer_universe, Some(snapshot)) {
                 Ok(()) => {}
@@ -1254,7 +1237,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         }
 
         match self.candidate_from_obligation(stack) {
-            Ok(Some(c)) => self.evaluate_candidate(stack, &c, LeakCheckHigherRankedGoal::Yes),
+            Ok(Some(c)) => self.evaluate_candidate(stack, &c),
             Ok(None) => Ok(EvaluatedToAmbig),
             Err(Overflow(OverflowError::Canonical)) => Err(OverflowError::Canonical),
             Err(..) => Ok(EvaluatedToErr),
@@ -1279,10 +1262,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// Further evaluates `candidate` to decide whether all type parameters match and whether nested
     /// obligations are met. Returns whether `candidate` remains viable after this further
     /// scrutiny.
-    ///
-    /// Depending on the value of [LeakCheckHigherRankedGoal], we may ignore the binder of the goal
-    /// when eagerly detecting higher ranked region errors via the `leak_check`. See that enum for
-    /// more info.
     #[instrument(
         level = "debug",
         skip(self, stack),
@@ -1293,25 +1272,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         &mut self,
         stack: &TraitObligationStack<'o, 'tcx>,
         candidate: &SelectionCandidate<'tcx>,
-        leak_check_higher_ranked_goal: LeakCheckHigherRankedGoal,
     ) -> Result<EvaluationResult, OverflowError> {
-        let mut result = self.evaluation_probe(|this, outer_universe| {
-            // We eagerly instantiate higher ranked goals to prevent universe errors
-            // from impacting candidate selection. This matches the behavior of the new
-            // solver. This slightly weakens type inference.
-            //
-            // In case there are no unresolved type or const variables this
-            // should still not be necessary to select a unique impl as any overlap
-            // relying on a universe error from higher ranked goals should have resulted
-            // in an overlap error in coherence.
-            let p = self.infcx.enter_forall_and_leak_universe(stack.obligation.predicate);
-            let obligation = stack.obligation.with(this.tcx(), ty::Binder::dummy(p));
-            match leak_check_higher_ranked_goal {
-                LeakCheckHigherRankedGoal::No => *outer_universe = self.infcx.universe(),
-                LeakCheckHigherRankedGoal::Yes => {}
-            }
-
-            match this.confirm_candidate(&obligation, candidate.clone()) {
+        let mut result = self.evaluation_probe(|this| {
+            match this.confirm_candidate(stack.obligation, candidate.clone()) {
                 Ok(selection) => {
                     debug!(?selection);
                     this.evaluate_predicates_recursively(
@@ -1731,19 +1694,14 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             })
             .map_err(|_| ())
     }
+
     fn where_clause_may_apply<'o>(
         &mut self,
         stack: &TraitObligationStack<'o, 'tcx>,
         where_clause_trait_ref: ty::PolyTraitRef<'tcx>,
     ) -> Result<EvaluationResult, OverflowError> {
-        self.evaluation_probe(|this, outer_universe| {
-            // Eagerly instantiate higher ranked goals.
-            //
-            // See the comment in `evaluate_candidate` to see why.
-            let p = self.infcx.enter_forall_and_leak_universe(stack.obligation.predicate);
-            let obligation = stack.obligation.with(this.tcx(), ty::Binder::dummy(p));
-            *outer_universe = self.infcx.universe();
-            match this.match_where_clause_trait_ref(&obligation, where_clause_trait_ref) {
+        self.evaluation_probe(|this| {
+            match this.match_where_clause_trait_ref(stack.obligation, where_clause_trait_ref) {
                 Ok(obligations) => this.evaluate_predicates_recursively(stack.list(), obligations),
                 Err(()) => Ok(EvaluatedToErr),
             }

compiler/rustc_type_ir/src/flags.rs

@@ -14,7 +14,7 @@ bitflags::bitflags! {
         /// Does this have `ConstKind::Param`?
         const HAS_CT_PARAM                = 1 << 2;
 
-        const HAS_PARAM                 = TypeFlags::HAS_TY_PARAM.bits()
+        const HAS_PARAM                   = TypeFlags::HAS_TY_PARAM.bits()
                                           | TypeFlags::HAS_RE_PARAM.bits()
                                           | TypeFlags::HAS_CT_PARAM.bits();
 
@@ -27,7 +27,7 @@ bitflags::bitflags! {
 
         /// Does this have inference variables? Used to determine whether
         /// inference is required.
-        const HAS_INFER                 = TypeFlags::HAS_TY_INFER.bits()
+        const HAS_INFER                   = TypeFlags::HAS_TY_INFER.bits()
                                           | TypeFlags::HAS_RE_INFER.bits()
                                           | TypeFlags::HAS_CT_INFER.bits();
 
@@ -39,7 +39,7 @@ bitflags::bitflags! {
         const HAS_CT_PLACEHOLDER          = 1 << 8;
 
         /// Does this have placeholders?
-        const HAS_PLACEHOLDER           = TypeFlags::HAS_TY_PLACEHOLDER.bits()
+        const HAS_PLACEHOLDER             = TypeFlags::HAS_TY_PLACEHOLDER.bits()
                                           | TypeFlags::HAS_RE_PLACEHOLDER.bits()
                                           | TypeFlags::HAS_CT_PLACEHOLDER.bits();
 
@@ -81,7 +81,7 @@ bitflags::bitflags! {
         /// Does this have `Alias` or `ConstKind::Unevaluated`?
         ///
         /// Rephrased, could this term be normalized further?
-        const HAS_ALIASES              = TypeFlags::HAS_TY_PROJECTION.bits()
+        const HAS_ALIAS                   = TypeFlags::HAS_TY_PROJECTION.bits()
                                           | TypeFlags::HAS_TY_WEAK.bits()
                                           | TypeFlags::HAS_TY_OPAQUE.bits()
                                           | TypeFlags::HAS_TY_INHERENT.bits()

compiler/rustc_type_ir/src/visit.rs

@@ -230,7 +230,7 @@ pub trait TypeVisitableExt<I: Interner>: TypeVisitable<I> {
     }
 
     fn has_aliases(&self) -> bool {
-        self.has_type_flags(TypeFlags::HAS_ALIASES)
+        self.has_type_flags(TypeFlags::HAS_ALIAS)
     }
 
     fn has_inherent_projections(&self) -> bool {

library/alloc/src/slice/tests.rs

@@ -240,6 +240,7 @@ fn panic_safe() {
 
 #[test]
 #[cfg_attr(miri, ignore)] // Miri is too slow
+#[cfg_attr(not(panic = "unwind"), ignore = "test requires unwinding support")]
 fn test_sort() {
     let mut rng = test_rng();
 

src/bootstrap/bootstrap_test.py

@@ -138,6 +138,25 @@ def build_args(self, configure_args=None, args=None, env=None):
         if env is None:
             env = {}
 
+        # This test ends up invoking build_bootstrap_cmd, which searches for
+        # the Cargo binary and errors out if it cannot be found. This is not a
+        # problem in most cases, but there is a scenario where it would cause
+        # the test to fail.
+        #
+        # When a custom local Cargo is configured in config.toml (with the
+        # build.cargo setting), no Cargo is downloaded to any location known by
+        # bootstrap, and bootstrap relies on that setting to find it.
+        #
+        # In this test though we are not using the config.toml of the caller:
+        # we are generating a blank one instead. If we don't set build.cargo in
+        # it, the test will have no way to find Cargo, failing the test.
+        cargo_bin = os.environ.get("BOOTSTRAP_TEST_CARGO_BIN")
+        if cargo_bin is not None:
+            configure_args += ["--set", "build.cargo=" + cargo_bin]
+        rustc_bin = os.environ.get("BOOTSTRAP_TEST_RUSTC_BIN")
+        if rustc_bin is not None:
+            configure_args += ["--set", "build.rustc=" + rustc_bin]
+
         env = env.copy()
         env["PATH"] = os.environ["PATH"]
 

src/bootstrap/src/core/build_steps/test.rs

@@ -2979,6 +2979,8 @@ impl Step for Bootstrap {
             .args(["-m", "unittest", "bootstrap_test.py"])
             .env("BUILD_DIR", &builder.out)
             .env("BUILD_PLATFORM", builder.build.build.triple)
+            .env("BOOTSTRAP_TEST_RUSTC_BIN", &builder.initial_rustc)
+            .env("BOOTSTRAP_TEST_CARGO_BIN", &builder.initial_cargo)
             .current_dir(builder.src.join("src/bootstrap/"));
         // NOTE: we intentionally don't pass test_args here because the args for unittest and cargo test are mutually incompatible.
         // Use `python -m unittest` manually if you want to pass arguments.

src/bootstrap/src/core/config/config.rs

@@ -1330,6 +1330,17 @@ impl Config {
             TomlConfig::default()
         };
 
+        if cfg!(test) {
+            // When configuring bootstrap for tests, make sure to set the rustc and Cargo to the
+            // same ones used to call the tests (if custom ones are not defined in the toml). If we
+            // don't do that, bootstrap will use its own detection logic to find a suitable rustc
+            // and Cargo, which doesn't work when the caller is specìfying a custom local rustc or
+            // Cargo in their config.toml.
+            let build = toml.build.get_or_insert_with(Default::default);
+            build.rustc = build.rustc.take().or(std::env::var_os("RUSTC").map(|p| p.into()));
+            build.cargo = build.cargo.take().or(std::env::var_os("CARGO").map(|p| p.into()));
+        }
+
         if let Some(include) = &toml.profile {
             // Allows creating alias for profile names, allowing
             // profiles to be renamed while maintaining back compatibility
@@ -1448,7 +1459,12 @@ impl Config {
             rustc
         } else {
             config.download_beta_toolchain();
-            config.out.join(config.build.triple).join("stage0/bin/rustc")
+            config
+                .out
+                .join(config.build.triple)
+                .join("stage0")
+                .join("bin")
+                .join(exe("rustc", config.build))
         };
 
         config.initial_cargo = if let Some(cargo) = cargo {
@@ -1458,7 +1474,12 @@ impl Config {
             cargo
         } else {
             config.download_beta_toolchain();
-            config.out.join(config.build.triple).join("stage0/bin/cargo")
+            config
+                .out
+                .join(config.build.triple)
+                .join("stage0")
+                .join("bin")
+                .join(exe("cargo", config.build))
         };
 
         // NOTE: it's important this comes *after* we set `initial_rustc` just above.

src/ci/docker/run.sh

@@ -93,7 +93,7 @@ if [ -f "$docker_dir/$image/Dockerfile" ]; then
     docker --version
 
     REGISTRY=ghcr.io
-    REGISTRY_USERNAME=${GITHUB_REPOSITORY_OWNER}
+    REGISTRY_USERNAME=${GITHUB_REPOSITORY_OWNER:-rust-lang-ci}
     # Tag used to push the final Docker image, so that it can be pulled by e.g. rustup
     IMAGE_TAG=${REGISTRY}/${REGISTRY_USERNAME}/rust-ci:${cksum}
     # Tag used to cache the Docker build

tests/ui/errors/dynless-turbofish-e0191-issue-91997.rs

@@ -0,0 +1,8 @@
+trait MyIterator : Iterator {}
+
+fn main() {
+    let _ = MyIterator::next;
+}
+//~^^ ERROR the value of the associated type `Item` in `Iterator` must be specified [E0191]
+//~| WARN trait objects without an explicit `dyn` are deprecated [bare_trait_objects]
+//~| WARN this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!

tests/ui/errors/dynless-turbofish-e0191-issue-91997.stderr

@@ -0,0 +1,23 @@
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/dynless-turbofish-e0191-issue-91997.rs:4:13
+   |
+LL |     let _ = MyIterator::next;
+   |             ^^^^^^^^^^
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
+   = note: `#[warn(bare_trait_objects)]` on by default
+help: if this is an object-safe trait, use `dyn`
+   |
+LL |     let _ = <dyn MyIterator>::next;
+   |             ++++           +
+
+error[E0191]: the value of the associated type `Item` in `Iterator` must be specified
+  --> $DIR/dynless-turbofish-e0191-issue-91997.rs:4:13
+   |
+LL |     let _ = MyIterator::next;
+   |             ^^^^^^^^^^ help: specify the associated type: `MyIterator::<Item = Type>`
+
+error: aborting due to 1 previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0191`.

tests/ui/higher-ranked/leak-check/candidate-from-env-universe-err-1.next.stderr

@@ -0,0 +1,23 @@
+error[E0277]: the trait bound `for<'a> &'a &T: Trait` is not satisfied
+  --> $DIR/candidate-from-env-universe-err-1.rs:27:16
+   |
+LL |     hr_bound::<&T>();
+   |                ^^ the trait `for<'a> Trait` is not implemented for `&'a &T`
+   |
+note: required by a bound in `hr_bound`
+  --> $DIR/candidate-from-env-universe-err-1.rs:14:20
+   |
+LL | fn hr_bound<T>()
+   |    -------- required by a bound in this function
+LL | where
+LL |     for<'a> &'a T: Trait,
+   |                    ^^^^^ required by this bound in `hr_bound`
+help: consider removing the leading `&`-reference
+   |
+LL -     hr_bound::<&T>();
+LL +     hr_bound::<T>();
+   |
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.