Rollup of 8 pull requests

compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs

@@ -62,7 +62,8 @@ impl OutlivesSuggestionBuilder {
             | RegionNameSource::AnonRegionFromUpvar(..)
             | RegionNameSource::AnonRegionFromOutput(..)
             | RegionNameSource::AnonRegionFromYieldTy(..)
-            | RegionNameSource::AnonRegionFromAsyncFn(..) => {
+            | RegionNameSource::AnonRegionFromAsyncFn(..)
+            | RegionNameSource::AnonRegionFromImplSignature(..) => {
                 debug!("Region {:?} is NOT suggestable", name);
                 false
             }

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -6,7 +6,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_middle::ty::print::RegionHighlightMode;
 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
-use rustc_middle::ty::{self, RegionVid, Ty};
+use rustc_middle::ty::{self, DefIdTree, RegionVid, Ty};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
 
@@ -45,6 +45,8 @@ pub(crate) enum RegionNameSource {
     AnonRegionFromYieldTy(Span, String),
     /// An anonymous region from an async fn.
     AnonRegionFromAsyncFn(Span),
+    /// An anonymous region from an impl self type or trait
+    AnonRegionFromImplSignature(Span, &'static str),
 }
 
 /// Describes what to highlight to explain to the user that we're giving an anonymous region a
@@ -75,7 +77,8 @@ impl RegionName {
             | RegionNameSource::AnonRegionFromUpvar(..)
             | RegionNameSource::AnonRegionFromOutput(..)
             | RegionNameSource::AnonRegionFromYieldTy(..)
-            | RegionNameSource::AnonRegionFromAsyncFn(..) => false,
+            | RegionNameSource::AnonRegionFromAsyncFn(..)
+            | RegionNameSource::AnonRegionFromImplSignature(..) => false,
         }
     }
 
@@ -87,7 +90,8 @@ impl RegionName {
             | RegionNameSource::SynthesizedFreeEnvRegion(span, _)
             | RegionNameSource::AnonRegionFromUpvar(span, _)
             | RegionNameSource::AnonRegionFromYieldTy(span, _)
-            | RegionNameSource::AnonRegionFromAsyncFn(span) => Some(span),
+            | RegionNameSource::AnonRegionFromAsyncFn(span)
+            | RegionNameSource::AnonRegionFromImplSignature(span, _) => Some(span),
             RegionNameSource::AnonRegionFromArgument(ref highlight)
             | RegionNameSource::AnonRegionFromOutput(ref highlight, _) => match *highlight {
                 RegionNameHighlight::MatchedHirTy(span)
@@ -166,6 +170,12 @@ impl RegionName {
             RegionNameSource::AnonRegionFromYieldTy(span, type_name) => {
                 diag.span_label(*span, format!("yield type is {type_name}"));
             }
+            RegionNameSource::AnonRegionFromImplSignature(span, location) => {
+                diag.span_label(
+                    *span,
+                    format!("lifetime `{self}` appears in the `impl`'s {location}"),
+                );
+            }
             RegionNameSource::Static => {}
         }
     }
@@ -240,7 +250,8 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
             .or_else(|| self.give_name_if_anonymous_region_appears_in_arguments(fr))
             .or_else(|| self.give_name_if_anonymous_region_appears_in_upvars(fr))
             .or_else(|| self.give_name_if_anonymous_region_appears_in_output(fr))
-            .or_else(|| self.give_name_if_anonymous_region_appears_in_yield_ty(fr));
+            .or_else(|| self.give_name_if_anonymous_region_appears_in_yield_ty(fr))
+            .or_else(|| self.give_name_if_anonymous_region_appears_in_impl_signature(fr));
 
         if let Some(ref value) = value {
             self.region_names.try_borrow_mut().unwrap().insert(fr, value.clone());
@@ -840,4 +851,43 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
             source: RegionNameSource::AnonRegionFromYieldTy(yield_span, type_name),
         })
     }
+
+    fn give_name_if_anonymous_region_appears_in_impl_signature(
+        &self,
+        fr: RegionVid,
+    ) -> Option<RegionName> {
+        let ty::ReEarlyBound(region) = *self.to_error_region(fr)? else {
+            return None;
+        };
+        if region.has_name() {
+            return None;
+        };
+
+        let tcx = self.infcx.tcx;
+        let body_parent_did = tcx.opt_parent(self.mir_def_id().to_def_id())?;
+        if tcx.parent(region.def_id) != body_parent_did
+            || tcx.def_kind(body_parent_did) != DefKind::Impl
+        {
+            return None;
+        }
+
+        let mut found = false;
+        tcx.fold_regions(tcx.type_of(body_parent_did), &mut true, |r: ty::Region<'tcx>, _| {
+            if *r == ty::ReEarlyBound(region) {
+                found = true;
+            }
+            r
+        });
+
+        Some(RegionName {
+            name: self.synthesize_region_name(),
+            source: RegionNameSource::AnonRegionFromImplSignature(
+                tcx.def_span(region.def_id),
+                // FIXME(compiler-errors): Does this ever actually show up
+                // anywhere other than the self type? I couldn't create an
+                // example of a `'_` in the impl's trait being referenceable.
+                if found { "self type" } else { "header" },
+            ),
+        })
+    }
 }

compiler/rustc_builtin_macros/src/assert/context.rs

@@ -1,11 +1,10 @@
-use crate::assert::expr_if_not;
 use rustc_ast::{
     attr,
     ptr::P,
     token,
     tokenstream::{DelimSpan, TokenStream, TokenTree},
-    BorrowKind, Expr, ExprKind, ItemKind, MacArgs, MacCall, MacDelimiter, Mutability, Path,
-    PathSegment, Stmt, StructRest, UseTree, UseTreeKind, DUMMY_NODE_ID,
+    BinOpKind, BorrowKind, Expr, ExprKind, ItemKind, MacArgs, MacCall, MacDelimiter, Mutability,
+    Path, PathSegment, Stmt, StructRest, UnOp, UseTree, UseTreeKind, DUMMY_NODE_ID,
 };
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
@@ -16,11 +15,19 @@ use rustc_span::{
 };
 
 pub(super) struct Context<'cx, 'a> {
+    // An optimization.
+    //
+    // Elements that aren't consumed (PartialEq, PartialOrd, ...) can be copied **after** the
+    // `assert!` expression fails rather than copied on-the-fly.
+    best_case_captures: Vec<Stmt>,
     // Top-level `let captureN = Capture::new()` statements
     capture_decls: Vec<Capture>,
     cx: &'cx ExtCtxt<'a>,
     // Formatting string used for debugging
     fmt_string: String,
+    // If the current expression being visited consumes itself. Used to construct
+    // `best_case_captures`.
+    is_consumed: bool,
     // Top-level `let __local_bindN = &expr` statements
     local_bind_decls: Vec<Stmt>,
     // Used to avoid capturing duplicated paths
@@ -36,9 +43,11 @@ pub(super) struct Context<'cx, 'a> {
 impl<'cx, 'a> Context<'cx, 'a> {
     pub(super) fn new(cx: &'cx ExtCtxt<'a>, span: Span) -> Self {
         Self {
+            best_case_captures: <_>::default(),
             capture_decls: <_>::default(),
             cx,
             fmt_string: <_>::default(),
+            is_consumed: true,
             local_bind_decls: <_>::default(),
             paths: <_>::default(),
             span,
@@ -69,14 +78,22 @@ impl<'cx, 'a> Context<'cx, 'a> {
         self.manage_cond_expr(&mut cond_expr);
         let initial_imports = self.build_initial_imports();
         let panic = self.build_panic(&expr_str, panic_path);
+        let cond_expr_with_unlikely = self.build_unlikely(cond_expr);
+
+        let Self { best_case_captures, capture_decls, cx, local_bind_decls, span, .. } = self;
 
-        let Self { capture_decls, cx, local_bind_decls, span, .. } = self;
+        let mut assert_then_stmts = Vec::with_capacity(2);
+        assert_then_stmts.extend(best_case_captures);
+        assert_then_stmts.push(self.cx.stmt_expr(panic));
+        let assert_then = self.cx.block(span, assert_then_stmts);
 
         let mut stmts = Vec::with_capacity(4);
         stmts.push(initial_imports);
         stmts.extend(capture_decls.into_iter().map(|c| c.decl));
         stmts.extend(local_bind_decls);
-        stmts.push(cx.stmt_expr(expr_if_not(cx, span, cond_expr, panic, None)));
+        stmts.push(
+            cx.stmt_expr(cx.expr(span, ExprKind::If(cond_expr_with_unlikely, assert_then, None))),
+        );
         cx.expr_block(cx.block(span, stmts))
     }
 
@@ -115,6 +132,16 @@ impl<'cx, 'a> Context<'cx, 'a> {
         )
     }
 
+    /// Takes the conditional expression of `assert!` and then wraps it inside `unlikely`
+    fn build_unlikely(&self, cond_expr: P<Expr>) -> P<Expr> {
+        let unlikely_path = self.cx.std_path(&[sym::intrinsics, sym::unlikely]);
+        self.cx.expr_call(
+            self.span,
+            self.cx.expr_path(self.cx.path(self.span, unlikely_path)),
+            vec![self.cx.expr(self.span, ExprKind::Unary(UnOp::Not, cond_expr))],
+        )
+    }
+
     /// The necessary custom `panic!(...)` expression.
     ///
     /// panic!(
@@ -167,17 +194,39 @@ impl<'cx, 'a> Context<'cx, 'a> {
     /// See [Self::manage_initial_capture] and [Self::manage_try_capture]
     fn manage_cond_expr(&mut self, expr: &mut P<Expr>) {
         match (*expr).kind {
-            ExprKind::AddrOf(_, _, ref mut local_expr) => {
-                self.manage_cond_expr(local_expr);
+            ExprKind::AddrOf(_, mutability, ref mut local_expr) => {
+                self.with_is_consumed_management(
+                    matches!(mutability, Mutability::Mut),
+                    |this| this.manage_cond_expr(local_expr)
+                );
             }
             ExprKind::Array(ref mut local_exprs) => {
                 for local_expr in local_exprs {
                     self.manage_cond_expr(local_expr);
                 }
             }
-            ExprKind::Binary(_, ref mut lhs, ref mut rhs) => {
-                self.manage_cond_expr(lhs);
-                self.manage_cond_expr(rhs);
+            ExprKind::Binary(ref op, ref mut lhs, ref mut rhs) => {
+                self.with_is_consumed_management(
+                    matches!(
+                        op.node,
+                        BinOpKind::Add
+                            | BinOpKind::And
+                            | BinOpKind::BitAnd
+                            | BinOpKind::BitOr
+                            | BinOpKind::BitXor
+                            | BinOpKind::Div
+                            | BinOpKind::Mul
+                            | BinOpKind::Or
+                            | BinOpKind::Rem
+                            | BinOpKind::Shl
+                            | BinOpKind::Shr
+                            | BinOpKind::Sub
+                    ),
+                    |this| {
+                        this.manage_cond_expr(lhs);
+                        this.manage_cond_expr(rhs);
+                    }
+                );
             }
             ExprKind::Call(_, ref mut local_exprs) => {
                 for local_expr in local_exprs {
@@ -228,8 +277,11 @@ impl<'cx, 'a> Context<'cx, 'a> {
                     self.manage_cond_expr(local_expr);
                 }
             }
-            ExprKind::Unary(_, ref mut local_expr) => {
-                self.manage_cond_expr(local_expr);
+            ExprKind::Unary(un_op, ref mut local_expr) => {
+                self.with_is_consumed_management(
+                    matches!(un_op, UnOp::Neg | UnOp::Not),
+                    |this| this.manage_cond_expr(local_expr)
+                );
             }
             // Expressions that are not worth or can not be captured.
             //
@@ -337,9 +389,23 @@ impl<'cx, 'a> Context<'cx, 'a> {
             ))
             .add_trailing_semicolon();
         let local_bind_path = self.cx.expr_path(Path::from_ident(local_bind));
-        let ret = self.cx.stmt_expr(local_bind_path);
-        let block = self.cx.expr_block(self.cx.block(self.span, vec![try_capture_call, ret]));
-        *expr = self.cx.expr_deref(self.span, block);
+        let rslt = if self.is_consumed {
+            let ret = self.cx.stmt_expr(local_bind_path);
+            self.cx.expr_block(self.cx.block(self.span, vec![try_capture_call, ret]))
+        } else {
+            self.best_case_captures.push(try_capture_call);
+            local_bind_path
+        };
+        *expr = self.cx.expr_deref(self.span, rslt);
+    }
+
+    // Calls `f` with the internal `is_consumed` set to `curr_is_consumed` and then
+    // sets the internal `is_consumed` back to its original value.
+    fn with_is_consumed_management(&mut self, curr_is_consumed: bool, f: impl FnOnce(&mut Self)) {
+        let prev_is_consumed = self.is_consumed;
+        self.is_consumed = curr_is_consumed;
+        f(self);
+        self.is_consumed = prev_is_consumed;
     }
 }
 

compiler/rustc_lint_defs/src/lib.rs

@@ -26,6 +26,9 @@ macro_rules! pluralize {
     ("is", $x:expr) => {
         if $x == 1 { "is" } else { "are" }
     };
+    ("was", $x:expr) => {
+        if $x == 1 { "was" } else { "were" }
+    };
     ("this", $x:expr) => {
         if $x == 1 { "this" } else { "these" }
     };

compiler/rustc_metadata/src/creader.rs

@@ -133,6 +133,10 @@ impl CStore {
         CrateNum::new(self.metas.len() - 1)
     }
 
+    pub fn has_crate_data(&self, cnum: CrateNum) -> bool {
+        self.metas[cnum].is_some()
+    }
+
     pub(crate) fn get_crate_data(&self, cnum: CrateNum) -> CrateMetadataRef<'_> {
         let cdata = self.metas[cnum]
             .as_ref()

compiler/rustc_middle/src/traits/mod.rs

@@ -253,7 +253,7 @@ pub enum ObligationCauseCode<'tcx> {
     ObjectTypeBound(Ty<'tcx>, ty::Region<'tcx>),
 
     /// Obligation incurred due to an object cast.
-    ObjectCastObligation(/* Object type */ Ty<'tcx>),
+    ObjectCastObligation(/* Concrete type */ Ty<'tcx>, /* Object type */ Ty<'tcx>),
 
     /// Obligation incurred due to a coercion.
     Coercion {

compiler/rustc_resolve/src/ident.rs

@@ -1502,6 +1502,7 @@ impl<'a> Resolver<'a> {
                         return PathResult::NonModule(PartialRes::new(Res::Err));
                     } else if opt_ns.is_some() && (is_last || maybe_assoc) {
                         self.lint_if_path_starts_with_module(finalize, path, second_binding);
+                        record_segment_res(self, res);
                         return PathResult::NonModule(PartialRes::with_unresolved_segments(
                             res,
                             path.len() - i - 1,

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

@@ -484,10 +484,9 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                             err.span_label(span, explanation);
                         }
 
-                        if let ObligationCauseCode::ObjectCastObligation(obj_ty) = obligation.cause.code().peel_derives() &&
-                           let Some(self_ty) = trait_predicate.self_ty().no_bound_vars() &&
+                        if let ObligationCauseCode::ObjectCastObligation(concrete_ty, obj_ty) = obligation.cause.code().peel_derives() &&
                            Some(trait_ref.def_id()) == self.tcx.lang_items().sized_trait() {
-                            self.suggest_borrowing_for_object_cast(&mut err, &obligation, self_ty, *obj_ty);
+                            self.suggest_borrowing_for_object_cast(&mut err, &root_obligation, *concrete_ty, *obj_ty);
                         }
 
                         if trait_predicate.is_const_if_const() && obligation.param_env.is_const() {
@@ -1560,7 +1559,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
                     obligation.cause.code().peel_derives(),
                     ObligationCauseCode::ItemObligation(_)
                         | ObligationCauseCode::BindingObligation(_, _)
-                        | ObligationCauseCode::ObjectCastObligation(_)
+                        | ObligationCauseCode::ObjectCastObligation(..)
                         | ObligationCauseCode::OpaqueType
                 );
                 if let Err(error) = self.at(&obligation.cause, obligation.param_env).eq_exp(

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -2217,9 +2217,10 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                     err.span_note(tcx.def_span(item_def_id), &descr);
                 }
             }
-            ObligationCauseCode::ObjectCastObligation(object_ty) => {
+            ObligationCauseCode::ObjectCastObligation(concrete_ty, object_ty) => {
                 err.note(&format!(
-                    "required for the cast to the object type `{}`",
+                    "required for the cast from `{}` to the object type `{}`",
+                    self.ty_to_string(concrete_ty),
                     self.ty_to_string(object_ty)
                 ));
             }

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

@@ -813,7 +813,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 let cause = ObligationCause::new(
                     obligation.cause.span,
                     obligation.cause.body_id,
-                    ObjectCastObligation(target),
+                    ObjectCastObligation(source, target),
                 );
                 let outlives = ty::OutlivesPredicate(r_a, r_b);
                 nested.push(Obligation::with_depth(
@@ -910,7 +910,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 let cause = ObligationCause::new(
                     obligation.cause.span,
                     obligation.cause.body_id,
-                    ObjectCastObligation(target),
+                    ObjectCastObligation(source, target),
                 );
                 let outlives = ty::OutlivesPredicate(r_a, r_b);
                 nested.push(Obligation::with_depth(
@@ -931,7 +931,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 let cause = ObligationCause::new(
                     obligation.cause.span,
                     obligation.cause.body_id,
-                    ObjectCastObligation(target),
+                    ObjectCastObligation(source, target),
                 );
 
                 let predicate_to_obligation = |predicate| {