Rollup of 6 pull requests

compiler/rustc_ast_lowering/src/delegation.rs

@@ -38,7 +38,7 @@
 
 use crate::{ImplTraitPosition, ResolverAstLoweringExt};
 
-use super::{ImplTraitContext, LoweringContext, ParamMode};
+use super::{ImplTraitContext, LoweringContext, ParamMode, ParenthesizedGenericArgs};
 
 use ast::visit::Visitor;
 use hir::def::{DefKind, PartialRes, Res};
@@ -259,8 +259,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         self_param_id: pat_node_id,
                     };
                     self_resolver.visit_block(block);
-                    let block = this.lower_block(block, false);
-                    this.mk_expr(hir::ExprKind::Block(block, None), block.span)
+                    this.lower_target_expr(&block)
                 } else {
                     let pat_hir_id = this.lower_node_id(pat_node_id);
                     this.generate_arg(pat_hir_id, span)
@@ -273,26 +272,74 @@ impl<'hir> LoweringContext<'_, 'hir> {
         })
     }
 
-    // Generates fully qualified call for the resulting body.
+    // FIXME(fn_delegation): Alternatives for target expression lowering:
+    // https://github.com/rust-lang/rfcs/pull/3530#issuecomment-2197170600.
+    fn lower_target_expr(&mut self, block: &Block) -> hir::Expr<'hir> {
+        if block.stmts.len() == 1
+            && let StmtKind::Expr(expr) = &block.stmts[0].kind
+        {
+            return self.lower_expr_mut(expr);
+        }
+
+        let block = self.lower_block(block, false);
+        self.mk_expr(hir::ExprKind::Block(block, None), block.span)
+    }
+
+    // Generates expression for the resulting body. If possible, `MethodCall` is used
+    // instead of fully qualified call for the self type coercion.
     fn finalize_body_lowering(
         &mut self,
         delegation: &Delegation,
         args: Vec<hir::Expr<'hir>>,
         span: Span,
     ) -> hir::Expr<'hir> {
-        let path = self.lower_qpath(
-            delegation.id,
-            &delegation.qself,
-            &delegation.path,
-            ParamMode::Optional,
-            ImplTraitContext::Disallowed(ImplTraitPosition::Path),
-            None,
-        );
-
         let args = self.arena.alloc_from_iter(args);
-        let path_expr = self.arena.alloc(self.mk_expr(hir::ExprKind::Path(path), span));
-        let call = self.arena.alloc(self.mk_expr(hir::ExprKind::Call(path_expr, args), span));
 
+        let has_generic_args =
+            delegation.path.segments.iter().rev().skip(1).any(|segment| segment.args.is_some());
+
+        let call = if self
+            .get_resolution_id(delegation.id, span)
+            .and_then(|def_id| Ok(self.has_self(def_id, span)))
+            .unwrap_or_default()
+            && delegation.qself.is_none()
+            && !has_generic_args
+        {
+            let ast_segment = delegation.path.segments.last().unwrap();
+            let segment = self.lower_path_segment(
+                delegation.path.span,
+                ast_segment,
+                ParamMode::Optional,
+                ParenthesizedGenericArgs::Err,
+                ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                None,
+                None,
+            );
+            let segment = self.arena.alloc(segment);
+
+            let method_call_id = self.next_id();
+            if let Some(traits) = self.resolver.trait_map.remove(&delegation.id) {
+                self.trait_map.insert(method_call_id.local_id, traits.into_boxed_slice());
+            }
+
+            self.arena.alloc(hir::Expr {
+                hir_id: method_call_id,
+                kind: hir::ExprKind::MethodCall(segment, &args[0], &args[1..], span),
+                span,
+            })
+        } else {
+            let path = self.lower_qpath(
+                delegation.id,
+                &delegation.qself,
+                &delegation.path,
+                ParamMode::Optional,
+                ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                None,
+            );
+
+            let callee_path = self.arena.alloc(self.mk_expr(hir::ExprKind::Path(path), span));
+            self.arena.alloc(self.mk_expr(hir::ExprKind::Call(callee_path, args), span))
+        };
         let block = self.arena.alloc(hir::Block {
             stmts: &[],
             expr: Some(call),

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -4,7 +4,7 @@
 #![allow(rustc::untranslatable_diagnostic)]
 
 use either::Either;
-use hir::ClosureKind;
+use hir::{ClosureKind, Path};
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_errors::{codes::*, struct_span_code_err, Applicability, Diag, MultiSpan};
@@ -16,6 +16,7 @@ use rustc_hir::{CoroutineKind, CoroutineSource, LangItem};
 use rustc_middle::bug;
 use rustc_middle::hir::nested_filter::OnlyBodies;
 use rustc_middle::mir::tcx::PlaceTy;
+use rustc_middle::mir::VarDebugInfoContents;
 use rustc_middle::mir::{
     self, AggregateKind, BindingForm, BorrowKind, CallSource, ClearCrossCrate, ConstraintCategory,
     FakeBorrowKind, FakeReadCause, LocalDecl, LocalInfo, LocalKind, Location, MutBorrowKind,
@@ -546,7 +547,14 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
                     self.suggest_cloning(err, ty, expr, None, Some(move_spans));
                 }
             }
-            if let Some(pat) = finder.pat {
+
+            self.suggest_ref_for_dbg_args(expr, place, move_span, err);
+
+            // it's useless to suggest inserting `ref` when the span don't comes from local code
+            if let Some(pat) = finder.pat
+                && !move_span.is_dummy()
+                && !self.infcx.tcx.sess.source_map().is_imported(move_span)
+            {
                 *in_pattern = true;
                 let mut sugg = vec![(pat.span.shrink_to_lo(), "ref ".to_string())];
                 if let Some(pat) = finder.parent_pat {
@@ -561,6 +569,59 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
         }
     }
 
+    // for dbg!(x) which may take ownership, suggest dbg!(&x) instead
+    // but here we actually do not check whether the macro name is `dbg!`
+    // so that we may extend the scope a bit larger to cover more cases
+    fn suggest_ref_for_dbg_args(
+        &self,
+        body: &hir::Expr<'_>,
+        place: &Place<'tcx>,
+        move_span: Span,
+        err: &mut Diag<'infcx>,
+    ) {
+        let var_info = self.body.var_debug_info.iter().find(|info| match info.value {
+            VarDebugInfoContents::Place(ref p) => p == place,
+            _ => false,
+        });
+        let arg_name = if let Some(var_info) = var_info {
+            var_info.name
+        } else {
+            return;
+        };
+        struct MatchArgFinder {
+            expr_span: Span,
+            match_arg_span: Option<Span>,
+            arg_name: Symbol,
+        }
+        impl Visitor<'_> for MatchArgFinder {
+            fn visit_expr(&mut self, e: &hir::Expr<'_>) {
+                // dbg! is expanded into a match pattern, we need to find the right argument span
+                if let hir::ExprKind::Match(expr, ..) = &e.kind
+                    && let hir::ExprKind::Path(hir::QPath::Resolved(
+                        _,
+                        path @ Path { segments: [seg], .. },
+                    )) = &expr.kind
+                    && seg.ident.name == self.arg_name
+                    && self.expr_span.source_callsite().contains(expr.span)
+                {
+                    self.match_arg_span = Some(path.span);
+                }
+                hir::intravisit::walk_expr(self, e);
+            }
+        }
+
+        let mut finder = MatchArgFinder { expr_span: move_span, match_arg_span: None, arg_name };
+        finder.visit_expr(body);
+        if let Some(macro_arg_span) = finder.match_arg_span {
+            err.span_suggestion_verbose(
+                macro_arg_span.shrink_to_lo(),
+                "consider borrowing instead of transferring ownership",
+                "&",
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+
     fn report_use_of_uninitialized(
         &self,
         mpi: MovePathIndex,

compiler/rustc_const_eval/src/interpret/place.rs

@@ -995,13 +995,25 @@ where
     }
 
     /// Returns a wide MPlace of type `str` to a new 1-aligned allocation.
+    /// Immutable strings are deduplicated and stored in global memory.
     pub fn allocate_str(
         &mut self,
         str: &str,
         kind: MemoryKind<M::MemoryKind>,
         mutbl: Mutability,
     ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
-        let ptr = self.allocate_bytes_ptr(str.as_bytes(), Align::ONE, kind, mutbl)?;
+        let tcx = self.tcx.tcx;
+
+        // Use cache for immutable strings.
+        let ptr = if mutbl.is_not() {
+            // Use dedup'd allocation function.
+            let id = tcx.allocate_bytes_dedup(str.as_bytes());
+
+            // Turn untagged "global" pointers (obtained via `tcx`) into the machine pointer to the allocation.
+            M::adjust_alloc_root_pointer(&self, Pointer::from(id), Some(kind))?
+        } else {
+            self.allocate_bytes_ptr(str.as_bytes(), Align::ONE, kind, mutbl)?
+        };
         let meta = Scalar::from_target_usize(u64::try_from(str.len()).unwrap(), self);
         let layout = self.layout_of(self.tcx.types.str_).unwrap();
         Ok(self.ptr_with_meta_to_mplace(ptr.into(), MemPlaceMeta::Meta(meta), layout))

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -583,6 +583,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     IsSuggestion(true),
                     callee_ty.peel_refs(),
                     callee_expr.unwrap().hir_id,
+                    None,
                     TraitsInScope,
                     |mut ctxt| ctxt.probe_for_similar_candidate(),
                 )
@@ -948,6 +949,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 &mut err,
             );
 
+            self.suggest_deref_unwrap_or(
+                &mut err,
+                error_span,
+                callee_ty,
+                call_ident,
+                expected_ty,
+                provided_ty,
+                provided_args[*provided_idx],
+                is_method,
+            );
+
             // Call out where the function is defined
             self.label_fn_like(
                 &mut err,

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -1429,6 +1429,74 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         true
     }
 
+    // Suggest to change `Option<&Vec<T>>::unwrap_or(&[])` to `Option::map_or(&[], |v| v)`.
+    #[instrument(level = "trace", skip(self, err, provided_expr))]
+    pub(crate) fn suggest_deref_unwrap_or(
+        &self,
+        err: &mut Diag<'_>,
+        error_span: Span,
+        callee_ty: Option<Ty<'tcx>>,
+        call_ident: Option<Ident>,
+        expected_ty: Ty<'tcx>,
+        provided_ty: Ty<'tcx>,
+        provided_expr: &Expr<'tcx>,
+        is_method: bool,
+    ) {
+        if !is_method {
+            return;
+        }
+        let Some(callee_ty) = callee_ty else {
+            return;
+        };
+        let ty::Adt(callee_adt, _) = callee_ty.peel_refs().kind() else {
+            return;
+        };
+        let adt_name = if self.tcx.is_diagnostic_item(sym::Option, callee_adt.did()) {
+            "Option"
+        } else if self.tcx.is_diagnostic_item(sym::Result, callee_adt.did()) {
+            "Result"
+        } else {
+            return;
+        };
+
+        let Some(call_ident) = call_ident else {
+            return;
+        };
+        if call_ident.name != sym::unwrap_or {
+            return;
+        }
+
+        let ty::Ref(_, peeled, _mutability) = provided_ty.kind() else {
+            return;
+        };
+
+        // NOTE: Can we reuse `suggest_deref_or_ref`?
+
+        // Create an dummy type `&[_]` so that both &[] and `&Vec<T>` can coerce to it.
+        let dummy_ty = if let ty::Array(elem_ty, size) = peeled.kind()
+            && let ty::Infer(_) = elem_ty.kind()
+            && size.try_eval_target_usize(self.tcx, self.param_env) == Some(0)
+        {
+            let slice = Ty::new_slice(self.tcx, *elem_ty);
+            Ty::new_imm_ref(self.tcx, self.tcx.lifetimes.re_static, slice)
+        } else {
+            provided_ty
+        };
+
+        if !self.can_coerce(expected_ty, dummy_ty) {
+            return;
+        }
+        let msg = format!("use `{adt_name}::map_or` to deref inner value of `{adt_name}`");
+        err.multipart_suggestion_verbose(
+            msg,
+            vec![
+                (call_ident.span, "map_or".to_owned()),
+                (provided_expr.span.shrink_to_hi(), ", |v| v".to_owned()),
+            ],
+            Applicability::MachineApplicable,
+        );
+    }
+
     /// Suggest wrapping the block in square brackets instead of curly braces
     /// in case the block was mistaken array syntax, e.g. `{ 1 }` -> `[ 1 ]`.
     pub(crate) fn suggest_block_to_brackets(
@@ -1610,6 +1678,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         IsSuggestion(true),
                         self_ty,
                         expr.hir_id,
+                        None,
                         ProbeScope::TraitsInScope,
                     )
                 {

compiler/rustc_hir_typeck/src/method/mod.rs

@@ -104,6 +104,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             IsSuggestion(true),
             self_ty,
             call_expr_id,
+            None,
             ProbeScope::TraitsInScope,
         ) {
             Ok(pick) => {
@@ -182,8 +183,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         self_expr: &'tcx hir::Expr<'tcx>,
         args: &'tcx [hir::Expr<'tcx>],
     ) -> Result<MethodCallee<'tcx>, MethodError<'tcx>> {
-        let pick =
-            self.lookup_probe(segment.ident, self_ty, call_expr, ProbeScope::TraitsInScope)?;
+        let pick = self.lookup_probe(
+            segment.ident,
+            self_ty,
+            call_expr,
+            segment.res.opt_def_id(),
+            ProbeScope::TraitsInScope,
+        )?;
 
         self.lint_edition_dependent_dot_call(
             self_ty, segment, span, call_expr, self_expr, &pick, args,
@@ -208,6 +214,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     segment.ident,
                     trait_type,
                     call_expr,
+                    None,
                     ProbeScope::TraitsInScope,
                 ) {
                     Ok(ref new_pick) if pick.differs_from(new_pick) => {
@@ -276,6 +283,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         method_name: Ident,
         self_ty: Ty<'tcx>,
         call_expr: &hir::Expr<'_>,
+        expected_def_id: Option<DefId>,
         scope: ProbeScope,
     ) -> probe::PickResult<'tcx> {
         let pick = self.probe_for_name(
@@ -285,6 +293,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             IsSuggestion(false),
             self_ty,
             call_expr.hir_id,
+            expected_def_id,
             scope,
         )?;
         pick.maybe_emit_unstable_name_collision_hint(self.tcx, method_name.span, call_expr.hir_id);
@@ -306,6 +315,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             IsSuggestion(true),
             self_ty,
             call_expr.hir_id,
+            None,
             scope,
         )?;
         Ok(pick)
@@ -529,6 +539,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             IsSuggestion(false),
             self_ty,
             expr_id,
+            None,
             ProbeScope::TraitsInScope,
         );
         let pick = match (pick, struct_variant) {