Auto merge of rust-lang#125393 - matthiaskrgr:rollup-vy2yf8v, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#124227 (Make sure that the method resolution matches in `note_source_of_type_mismatch_constraint`)
 - rust-lang#124896 (miri: rename intrinsic_fallback_checks_ub to intrinsic_fallback_is_spec)
 - rust-lang#125015 (Pattern types: Prohibit generic args on const params)
 - rust-lang#125043 (reference type safety invariant docs: clarification)
 - rust-lang#125259 (An async closure may implement `FnMut`/`Fn` if it has no self-borrows)
 - rust-lang#125306 (Force the inner coroutine of an async closure to `move` if the outer closure is `move` and `FnOnce`)
 - rust-lang#125378 (remove tracing tree indent lines)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_hir_analysis/messages.ftl

@@ -371,9 +371,9 @@ hir_analysis_pass_to_variadic_function = can't pass `{$ty}` to variadic function
     .suggestion = cast the value to `{$cast_ty}`
     .help = cast the value to `{$cast_ty}`
 
-hir_analysis_pattern_type_non_const_range = "range patterns must have constant range start and end"
-hir_analysis_pattern_type_wild_pat = "wildcard patterns are not permitted for pattern types"
-    .label = "this type is the same as the inner type without a pattern"
+hir_analysis_pattern_type_non_const_range = range patterns must have constant range start and end
+hir_analysis_pattern_type_wild_pat = wildcard patterns are not permitted for pattern types
+    .label = this type is the same as the inner type without a pattern
 hir_analysis_placeholder_not_allowed_item_signatures = the placeholder `_` is not allowed within types on item signatures for {$kind}
     .label = not allowed in type signatures
 

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

@@ -1382,7 +1382,7 @@ pub enum GenericsArgsErrExtend<'tcx> {
         span: Span,
     },
     SelfTyParam(Span),
-    TyParam(DefId),
+    Param(DefId),
     DefVariant,
     None,
 }
@@ -1498,11 +1498,11 @@ fn generics_args_err_extend<'a>(
         GenericsArgsErrExtend::DefVariant => {
             err.note("enum variants can't have type parameters");
         }
-        GenericsArgsErrExtend::TyParam(def_id) => {
-            if let Some(span) = tcx.def_ident_span(def_id) {
-                let name = tcx.item_name(def_id);
-                err.span_note(span, format!("type parameter `{name}` defined here"));
-            }
+        GenericsArgsErrExtend::Param(def_id) => {
+            let span = tcx.def_ident_span(def_id).unwrap();
+            let kind = tcx.def_descr(def_id);
+            let name = tcx.item_name(def_id);
+            err.span_note(span, format!("{kind} `{name}` defined here"));
         }
         GenericsArgsErrExtend::SelfTyParam(span) => {
             err.span_suggestion_verbose(

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -1757,7 +1757,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 assert_eq!(opt_self_ty, None);
                 let _ = self.prohibit_generic_args(
                     path.segments.iter(),
-                    GenericsArgsErrExtend::TyParam(def_id),
+                    GenericsArgsErrExtend::Param(def_id),
                 );
                 self.lower_ty_param(hir_id)
             }
@@ -2190,10 +2190,15 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
                                 hir::ExprKind::Path(hir::QPath::Resolved(
                                     _,
-                                    &hir::Path {
-                                        res: Res::Def(DefKind::ConstParam, def_id), ..
+                                    path @ &hir::Path {
+                                        res: Res::Def(DefKind::ConstParam, def_id),
+                                        ..
                                     },
                                 )) => {
+                                    let _ = self.prohibit_generic_args(
+                                        path.segments.iter(),
+                                        GenericsArgsErrExtend::Param(def_id),
+                                    );
                                     let ty = tcx
                                         .type_of(def_id)
                                         .no_bound_vars()

compiler/rustc_hir_typeck/src/demand.rs

@@ -373,8 +373,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 let Some(arg_ty) = self.node_ty_opt(args[idx].hir_id) else {
                     return false;
                 };
-                let possible_rcvr_ty = expr_finder.uses.iter().find_map(|binding| {
+                let possible_rcvr_ty = expr_finder.uses.iter().rev().find_map(|binding| {
                     let possible_rcvr_ty = self.node_ty_opt(binding.hir_id)?;
+                    if possible_rcvr_ty.is_ty_var() {
+                        return None;
+                    }
                     // Fudge the receiver, so we can do new inference on it.
                     let possible_rcvr_ty = possible_rcvr_ty.fold_with(&mut fudger);
                     let method = self
@@ -386,6 +389,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             binding,
                         )
                         .ok()?;
+                    // Make sure we select the same method that we started with...
+                    if Some(method.def_id)
+                        != self.typeck_results.borrow().type_dependent_def_id(call_expr.hir_id)
+                    {
+                        return None;
+                    }
                     // Unify the method signature with our incompatible arg, to
                     // do inference in the *opposite* direction and to find out
                     // what our ideal rcvr ty would look like.
@@ -456,6 +465,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 ) else {
                     continue;
                 };
+                // Make sure we select the same method that we started with...
+                if Some(method.def_id)
+                    != self.typeck_results.borrow().type_dependent_def_id(parent_expr.hir_id)
+                {
+                    continue;
+                }
 
                 let ideal_rcvr_ty = rcvr_ty.fold_with(&mut fudger);
                 let ideal_method = self
@@ -505,13 +520,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     // blame arg, if possible. Don't do this if we're coming from
                     // arg mismatch code, because we'll possibly suggest a mutually
                     // incompatible fix at the original mismatch site.
+                    // HACK(compiler-errors): We don't actually consider the implications
+                    // of our inference guesses in `emit_type_mismatch_suggestions`, so
+                    // only suggest things when we know our type error is precisely due to
+                    // a type mismatch, and not via some projection or something. See #116155.
                     if matches!(source, TypeMismatchSource::Ty(_))
                         && let Some(ideal_method) = ideal_method
-                        && let ideal_arg_ty = self.resolve_vars_if_possible(ideal_method.sig.inputs()[idx + 1])
-                        // HACK(compiler-errors): We don't actually consider the implications
-                        // of our inference guesses in `emit_type_mismatch_suggestions`, so
-                        // only suggest things when we know our type error is precisely due to
-                        // a type mismatch, and not via some projection or something. See #116155.
+                        && Some(ideal_method.def_id)
+                            == self
+                                .typeck_results
+                                .borrow()
+                                .type_dependent_def_id(parent_expr.hir_id)
+                        && let ideal_arg_ty =
+                            self.resolve_vars_if_possible(ideal_method.sig.inputs()[idx + 1])
                         && !ideal_arg_ty.has_non_region_infer()
                     {
                         self.emit_type_mismatch_suggestions(

compiler/rustc_hir_typeck/src/upvar.rs

@@ -204,6 +204,60 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             fake_reads: Default::default(),
         };
 
+        let _ = euv::ExprUseVisitor::new(
+            &FnCtxt::new(self, self.tcx.param_env(closure_def_id), closure_def_id),
+            &mut delegate,
+        )
+        .consume_body(body);
+
+        // There are several curious situations with coroutine-closures where
+        // analysis is too aggressive with borrows when the coroutine-closure is
+        // marked `move`. Specifically:
+        //
+        // 1. If the coroutine-closure was inferred to be `FnOnce` during signature
+        // inference, then it's still possible that we try to borrow upvars from
+        // the coroutine-closure because they are not used by the coroutine body
+        // in a way that forces a move. See the test:
+        // `async-await/async-closures/force-move-due-to-inferred-kind.rs`.
+        //
+        // 2. If the coroutine-closure is forced to be `FnOnce` due to the way it
+        // uses its upvars, but not *all* upvars would force the closure to `FnOnce`.
+        // See the test: `async-await/async-closures/force-move-due-to-actually-fnonce.rs`.
+        //
+        // This would lead to an impossible to satisfy situation, since `AsyncFnOnce`
+        // coroutine bodies can't borrow from their parent closure. To fix this,
+        // we force the inner coroutine to also be `move`. This only matters for
+        // coroutine-closures that are `move` since otherwise they themselves will
+        // be borrowing from the outer environment, so there's no self-borrows occuring.
+        //
+        // One *important* note is that we do a call to `process_collected_capture_information`
+        // to eagerly test whether the coroutine would end up `FnOnce`, but we do this
+        // *before* capturing all the closure args by-value below, since that would always
+        // cause the analysis to return `FnOnce`.
+        if let UpvarArgs::Coroutine(..) = args
+            && let hir::CoroutineKind::Desugared(_, hir::CoroutineSource::Closure) =
+                self.tcx.coroutine_kind(closure_def_id).expect("coroutine should have kind")
+            && let parent_hir_id =
+                self.tcx.local_def_id_to_hir_id(self.tcx.local_parent(closure_def_id))
+            && let parent_ty = self.node_ty(parent_hir_id)
+            && let hir::CaptureBy::Value { move_kw } =
+                self.tcx.hir_node(parent_hir_id).expect_closure().capture_clause
+        {
+            // (1.) Closure signature inference forced this closure to `FnOnce`.
+            if let Some(ty::ClosureKind::FnOnce) = self.closure_kind(parent_ty) {
+                capture_clause = hir::CaptureBy::Value { move_kw };
+            }
+            // (2.) The way that the closure uses its upvars means it's `FnOnce`.
+            else if let (_, ty::ClosureKind::FnOnce, _) = self
+                .process_collected_capture_information(
+                    capture_clause,
+                    &delegate.capture_information,
+                )
+            {
+                capture_clause = hir::CaptureBy::Value { move_kw };
+            }
+        }
+
         // As noted in `lower_coroutine_body_with_moved_arguments`, we default the capture mode
         // to `ByRef` for the `async {}` block internal to async fns/closure. This means
         // that we would *not* be moving all of the parameters into the async block by default.
@@ -253,34 +307,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
         }
 
-        let _ = euv::ExprUseVisitor::new(
-            &FnCtxt::new(self, self.tcx.param_env(closure_def_id), closure_def_id),
-            &mut delegate,
-        )
-        .consume_body(body);
-
-        // If a coroutine is comes from a coroutine-closure that is `move`, but
-        // the coroutine-closure was inferred to be `FnOnce` during signature
-        // inference, then it's still possible that we try to borrow upvars from
-        // the coroutine-closure because they are not used by the coroutine body
-        // in a way that forces a move.
-        //
-        // This would lead to an impossible to satisfy situation, since `AsyncFnOnce`
-        // coroutine bodies can't borrow from their parent closure. To fix this,
-        // we force the inner coroutine to also be `move`. This only matters for
-        // coroutine-closures that are `move` since otherwise they themselves will
-        // be borrowing from the outer environment, so there's no self-borrows occuring.
-        if let UpvarArgs::Coroutine(..) = args
-            && let hir::CoroutineKind::Desugared(_, hir::CoroutineSource::Closure) =
-                self.tcx.coroutine_kind(closure_def_id).expect("coroutine should have kind")
-            && let parent_hir_id =
-                self.tcx.local_def_id_to_hir_id(self.tcx.local_parent(closure_def_id))
-            && let parent_ty = self.node_ty(parent_hir_id)
-            && let Some(ty::ClosureKind::FnOnce) = self.closure_kind(parent_ty)
-        {
-            capture_clause = self.tcx.hir_node(parent_hir_id).expect_closure().capture_clause;
-        }
-
         debug!(
             "For closure={:?}, capture_information={:#?}",
             closure_def_id, delegate.capture_information
@@ -289,7 +315,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         self.log_capture_analysis_first_pass(closure_def_id, &delegate.capture_information, span);
 
         let (capture_information, closure_kind, origin) = self
-            .process_collected_capture_information(capture_clause, delegate.capture_information);
+            .process_collected_capture_information(capture_clause, &delegate.capture_information);
 
         self.compute_min_captures(closure_def_id, capture_information, span);
 
@@ -545,13 +571,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     fn process_collected_capture_information(
         &self,
         capture_clause: hir::CaptureBy,
-        capture_information: InferredCaptureInformation<'tcx>,
+        capture_information: &InferredCaptureInformation<'tcx>,
     ) -> (InferredCaptureInformation<'tcx>, ty::ClosureKind, Option<(Span, Place<'tcx>)>) {
         let mut closure_kind = ty::ClosureKind::LATTICE_BOTTOM;
         let mut origin: Option<(Span, Place<'tcx>)> = None;
 
         let processed = capture_information
-            .into_iter()
+            .iter()
+            .cloned()
             .map(|(place, mut capture_info)| {
                 // Apply rules for safety before inferring closure kind
                 let (place, capture_kind) =

compiler/rustc_log/src/lib.rs

@@ -103,7 +103,6 @@ pub fn init_logger(cfg: LoggerConfig) -> Result<(), Error> {
 
     let mut layer = tracing_tree::HierarchicalLayer::default()
         .with_writer(io::stderr)
-        .with_indent_lines(true)
         .with_ansi(color_logs)
         .with_targets(true)
         .with_verbose_exit(verbose_entry_exit)

compiler/rustc_middle/src/ty/sty.rs

@@ -401,6 +401,45 @@ impl<'tcx> CoroutineClosureArgs<'tcx> {
     pub fn coroutine_witness_ty(self) -> Ty<'tcx> {
         self.split().coroutine_witness_ty
     }
+
+    pub fn has_self_borrows(&self) -> bool {
+        match self.coroutine_captures_by_ref_ty().kind() {
+            ty::FnPtr(sig) => sig
+                .skip_binder()
+                .visit_with(&mut HasRegionsBoundAt { binder: ty::INNERMOST })
+                .is_break(),
+            ty::Error(_) => true,
+            _ => bug!(),
+        }
+    }
+}
+/// Unlike `has_escaping_bound_vars` or `outermost_exclusive_binder`, this will
+/// detect only regions bound *at* the debruijn index.
+struct HasRegionsBoundAt {
+    binder: ty::DebruijnIndex,
+}
+// FIXME: Could be optimized to not walk into components with no escaping bound vars.
+impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for HasRegionsBoundAt {
+    type Result = ControlFlow<()>;
+    fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
+        &mut self,
+        t: &ty::Binder<'tcx, T>,
+    ) -> Self::Result {
+        self.binder.shift_in(1);
+        t.super_visit_with(self)?;
+        self.binder.shift_out(1);
+        ControlFlow::Continue(())
+    }
+
+    fn visit_region(&mut self, r: ty::Region<'tcx>) -> Self::Result {
+        if let ty::ReBound(binder, _) = *r
+            && self.binder == binder
+        {
+            ControlFlow::Break(())
+        } else {
+            ControlFlow::Continue(())
+        }
+    }
 }
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable)]

compiler/rustc_pattern_analysis/tests/common/mod.rs

@@ -13,7 +13,6 @@ pub fn init_tracing() {
     use tracing_subscriber::Layer;
     let _ = tracing_tree::HierarchicalLayer::default()
         .with_writer(std::io::stderr)
-        .with_indent_lines(true)
         .with_ansi(true)
         .with_targets(true)
         .with_indent_amount(2)

compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs

@@ -300,14 +300,11 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_callable<'tcx>(
                     return Err(NoSolution);
                 }
 
-                // If `Fn`/`FnMut`, we only implement this goal if we
-                // have no captures.
-                let no_borrows = match args.tupled_upvars_ty().kind() {
-                    ty::Tuple(tys) => tys.is_empty(),
-                    ty::Error(_) => false,
-                    _ => bug!("tuple_fields called on non-tuple"),
-                };
-                if closure_kind != ty::ClosureKind::FnOnce && !no_borrows {
+                // A coroutine-closure implements `FnOnce` *always*, since it may
+                // always be called once. It additionally implements `Fn`/`FnMut`
+                // only if it has no upvars referencing the closure-env lifetime,
+                // and if the closure kind permits it.
+                if closure_kind != ty::ClosureKind::FnOnce && args.has_self_borrows() {
                     return Err(NoSolution);
                 }
 

compiler/rustc_trait_selection/src/solve/search_graph.rs

@@ -279,6 +279,7 @@ impl<'tcx> SearchGraph<TyCtxt<'tcx>> {
         };
 
         if let Some(result) = self.lookup_global_cache(tcx, input, available_depth, inspect) {
+            debug!("global cache hit");
             return result;
         }
 
@@ -360,7 +361,7 @@ impl<'tcx> SearchGraph<TyCtxt<'tcx>> {
                 for _ in 0..FIXPOINT_STEP_LIMIT {
                     match self.fixpoint_step_in_task(tcx, input, inspect, &mut prove_goal) {
                         StepResult::Done(final_entry, result) => return (final_entry, result),
-                        StepResult::HasChanged => {}
+                        StepResult::HasChanged => debug!("fixpoint changed provisional results"),
                     }
                 }
 

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

@@ -418,20 +418,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     // Ambiguity if upvars haven't been constrained yet
                     && !args.tupled_upvars_ty().is_ty_var()
                 {
-                    let no_borrows = match args.tupled_upvars_ty().kind() {
-                        ty::Tuple(tys) => tys.is_empty(),
-                        ty::Error(_) => false,
-                        _ => bug!("tuple_fields called on non-tuple"),
-                    };
                     // A coroutine-closure implements `FnOnce` *always*, since it may
                     // always be called once. It additionally implements `Fn`/`FnMut`
-                    // only if it has no upvars (therefore no borrows from the closure
-                    // that would need to be represented with a lifetime) and if the
-                    // closure kind permits it.
-                    // FIXME(async_closures): Actually, it could also implement `Fn`/`FnMut`
-                    // if it takes all of its upvars by copy, and none by ref. This would
-                    // require us to record a bit more information during upvar analysis.
-                    if no_borrows && closure_kind.extends(kind) {
+                    // only if it has no upvars referencing the closure-env lifetime,
+                    // and if the closure kind permits it.
+                    if closure_kind.extends(kind) && !args.has_self_borrows() {
                         candidates.vec.push(ClosureCandidate { is_const });
                     } else if kind == ty::ClosureKind::FnOnce {
                         candidates.vec.push(ClosureCandidate { is_const });