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Suggest borrowing arguments in generic positions when trait bounds are satisfied
This subsumes the suggestions to borrow arguments with `AsRef`/`Borrow` bounds and those to borrow arguments with `Fn` and `FnMut` bounds. It works for other traits implemented on references as well, such as `std::io::Read`, `std::io::Write`, and `core::fmt::Write`. Incidentally, by making the logic for suggesting borrowing closures general, this removes some spurious suggestions to mutably borrow `FnMut` closures in assignments, as well as an unhelpful suggestion to add a `Clone` constraint to an `impl Fn` argument.
This commit is contained in:
dianne
parent
ea37000b56
commit
2ab8480605
@ -27,7 +27,7 @@ use rustc_middle::mir::{
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};
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use rustc_middle::ty::print::PrintTraitRefExt as _;
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use rustc_middle::ty::{
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self, PredicateKind, Ty, TyCtxt, TypeSuperVisitable, TypeVisitor, Upcast,
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self, ClauseKind, PredicateKind, Ty, TyCtxt, TypeSuperVisitable, TypeVisitor, Upcast,
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suggest_constraining_type_params,
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};
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use rustc_middle::util::CallKind;
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@ -39,6 +39,7 @@ use rustc_span::{BytePos, Span, Symbol};
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use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
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use rustc_trait_selection::error_reporting::traits::FindExprBySpan;
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use rustc_trait_selection::infer::InferCtxtExt;
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use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
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use rustc_trait_selection::traits::{Obligation, ObligationCause, ObligationCtxt};
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use tracing::{debug, instrument};
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@ -201,16 +202,15 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
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let mut has_suggest_reborrow = false;
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if !seen_spans.contains(&move_span) {
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if !closure {
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self.suggest_ref_or_clone(
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mpi,
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&mut err,
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&mut in_pattern,
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move_spans,
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moved_place.as_ref(),
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&mut has_suggest_reborrow,
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);
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}
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self.suggest_ref_or_clone(
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mpi,
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&mut err,
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&mut in_pattern,
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move_spans,
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moved_place.as_ref(),
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&mut has_suggest_reborrow,
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closure,
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);
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let msg_opt = CapturedMessageOpt {
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is_partial_move,
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@ -266,27 +266,11 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
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}
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}
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let opt_name = self.describe_place_with_options(place.as_ref(), DescribePlaceOpt {
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including_downcast: true,
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including_tuple_field: true,
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});
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let note_msg = match opt_name {
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Some(name) => format!("`{name}`"),
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None => "value".to_owned(),
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};
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if self.suggest_borrow_fn_like(&mut err, ty, &move_site_vec, ¬e_msg)
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|| if let UseSpans::FnSelfUse { kind, .. } = use_spans
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&& let CallKind::FnCall { fn_trait_id, self_ty } = kind
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&& let ty::Param(_) = self_ty.kind()
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&& ty == self_ty
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&& self.infcx.tcx.is_lang_item(fn_trait_id, LangItem::FnOnce)
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{
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// this is a type parameter `T: FnOnce()`, don't suggest `T: FnOnce() + Clone`.
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true
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} else {
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false
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}
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{
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if self.param_env.caller_bounds().iter().any(|c| {
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c.as_trait_clause().is_some_and(|pred| {
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pred.skip_binder().self_ty() == ty && self.infcx.tcx.is_fn_trait(pred.def_id())
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})
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}) {
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// Suppress the next suggestion since we don't want to put more bounds onto
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// something that already has `Fn`-like bounds (or is a closure), so we can't
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// restrict anyways.
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@ -295,6 +279,14 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
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self.suggest_adding_bounds(&mut err, ty, copy_did, span);
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}
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let opt_name = self.describe_place_with_options(place.as_ref(), DescribePlaceOpt {
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including_downcast: true,
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including_tuple_field: true,
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});
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let note_msg = match opt_name {
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Some(name) => format!("`{name}`"),
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None => "value".to_owned(),
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};
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if needs_note {
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if let Some(local) = place.as_local() {
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let span = self.body.local_decls[local].source_info.span;
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@ -341,6 +333,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
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move_spans: UseSpans<'tcx>,
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moved_place: PlaceRef<'tcx>,
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has_suggest_reborrow: &mut bool,
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moved_or_invoked_closure: bool,
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) {
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let move_span = match move_spans {
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UseSpans::ClosureUse { capture_kind_span, .. } => capture_kind_span,
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@ -428,17 +421,18 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
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}
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let typeck = self.infcx.tcx.typeck(self.mir_def_id());
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let parent = self.infcx.tcx.parent_hir_node(expr.hir_id);
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let (def_id, args, offset) = if let hir::Node::Expr(parent_expr) = parent
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let (def_id, call_id, args, offset) = if let hir::Node::Expr(parent_expr) = parent
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&& let hir::ExprKind::MethodCall(_, _, args, _) = parent_expr.kind
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{
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(typeck.type_dependent_def_id(parent_expr.hir_id), args, 1)
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let def_id = typeck.type_dependent_def_id(parent_expr.hir_id);
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(def_id, Some(parent_expr.hir_id), args, 1)
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} else if let hir::Node::Expr(parent_expr) = parent
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&& let hir::ExprKind::Call(call, args) = parent_expr.kind
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&& let ty::FnDef(def_id, _) = typeck.node_type(call.hir_id).kind()
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{
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(Some(*def_id), args, 0)
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(Some(*def_id), Some(call.hir_id), args, 0)
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} else {
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(None, &[][..], 0)
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(None, None, &[][..], 0)
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};
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let ty = place.ty(self.body, self.infcx.tcx).ty;
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@ -449,14 +443,9 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
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// The move occurred as one of the arguments to a function call. Is that
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// argument generic? `def_id` can't be a closure here, so using `fn_sig` is fine
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let arg_param = if self.infcx.tcx.def_kind(def_id).is_fn_like()
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&& let Some(arg_ty) = self
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.infcx
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.tcx
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.fn_sig(def_id)
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.instantiate_identity()
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.skip_binder()
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.inputs()
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.get(pos + offset)
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&& let sig =
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self.infcx.tcx.fn_sig(def_id).instantiate_identity().skip_binder()
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&& let Some(arg_ty) = sig.inputs().get(pos + offset)
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&& let ty::Param(arg_param) = arg_ty.kind()
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{
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Some(arg_param)
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@ -478,54 +467,22 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
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return;
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}
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let mut mutbl = ty::Mutability::Not;
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if let Some(param) = arg_param
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&& self
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.infcx
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.tcx
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.predicates_of(def_id)
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.instantiate_identity(self.infcx.tcx)
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.predicates
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.into_iter()
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.any(|pred| {
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if let ty::ClauseKind::Trait(predicate) = pred.kind().skip_binder()
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&& [
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self.infcx.tcx.get_diagnostic_item(sym::AsRef),
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self.infcx.tcx.get_diagnostic_item(sym::AsMut),
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self.infcx.tcx.get_diagnostic_item(sym::Borrow),
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self.infcx.tcx.get_diagnostic_item(sym::BorrowMut),
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]
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.contains(&Some(predicate.def_id()))
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&& *predicate.self_ty().kind() == ty::Param(*param)
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{
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if [
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self.infcx.tcx.get_diagnostic_item(sym::AsMut),
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self.infcx.tcx.get_diagnostic_item(sym::BorrowMut),
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]
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.contains(&Some(predicate.def_id()))
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{
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mutbl = ty::Mutability::Mut;
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}
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true
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} else {
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false
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}
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})
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// If the moved place is used generically by the callee and a reference to it
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// would still satisfy any bounds on its type, suggest borrowing.
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if let Some(¶m) = arg_param
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&& let Some(generic_args) = call_id.and_then(|id| typeck.node_args_opt(id))
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&& let Some(ref_mutability) = self.suggest_borrow_generic_arg(
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err,
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def_id,
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generic_args,
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param,
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moved_place,
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pos + offset,
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ty,
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expr.span,
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)
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{
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// The type of the argument corresponding to the expression that got moved
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// is a type parameter `T`, which is has a `T: AsRef` obligation.
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let place_desc = if let Some(desc) = self.describe_place(moved_place) {
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format!("`{desc}`")
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} else {
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"here".to_owned()
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};
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err.span_suggestion_verbose(
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expr.span.shrink_to_lo(),
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format!("consider {}borrowing {place_desc}", mutbl.mutably_str()),
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mutbl.ref_prefix_str(),
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Applicability::MaybeIncorrect,
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);
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can_suggest_clone = mutbl.is_mut();
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can_suggest_clone = ref_mutability.is_mut();
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} else if let Some(local_def_id) = def_id.as_local()
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&& let node = self.infcx.tcx.hir_node_by_def_id(local_def_id)
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&& let Some(fn_decl) = node.fn_decl()
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@ -563,6 +520,8 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
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} else if let UseSpans::FnSelfUse { kind: CallKind::Normal { .. }, .. } = move_spans
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{
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// We already suggest cloning for these cases in `explain_captures`.
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} else if moved_or_invoked_closure {
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// Do not suggest `closure.clone()()`.
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} else if let UseSpans::ClosureUse {
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closure_kind:
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ClosureKind::Coroutine(CoroutineKind::Desugared(_, CoroutineSource::Block)),
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@ -671,6 +630,113 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
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);
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}
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/// If a place is used after being moved as an argument to a function, the function is generic
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/// in that argument, and a reference to the argument's type would still satisfy the function's
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/// bounds, suggest borrowing. This covers, e.g., borrowing an `impl Fn()` argument being passed
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/// in an `impl FnOnce()` position.
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/// Returns `Some(mutability)` when suggesting to borrow with mutability `mutability`, or `None`
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/// if no suggestion is made.
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fn suggest_borrow_generic_arg(
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&self,
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err: &mut Diag<'_>,
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callee_did: DefId,
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generic_args: ty::GenericArgsRef<'tcx>,
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param: ty::ParamTy,
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moved_place: PlaceRef<'tcx>,
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moved_arg_pos: usize,
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moved_arg_ty: Ty<'tcx>,
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place_span: Span,
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) -> Option<ty::Mutability> {
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let tcx = self.infcx.tcx;
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let sig = tcx.fn_sig(callee_did).instantiate_identity().skip_binder();
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let clauses = tcx.predicates_of(callee_did).instantiate_identity(self.infcx.tcx).predicates;
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// First, is there at least one method on one of `param`'s trait bounds?
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// This keeps us from suggesting borrowing the argument to `mem::drop`, e.g.
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if !clauses.iter().any(|clause| {
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clause.as_trait_clause().is_some_and(|tc| {
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tc.self_ty().skip_binder().is_param(param.index)
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&& tc.polarity() == ty::PredicatePolarity::Positive
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&& tcx
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.supertrait_def_ids(tc.def_id())
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.flat_map(|trait_did| tcx.associated_items(trait_did).in_definition_order())
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.any(|item| item.fn_has_self_parameter)
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})
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}) {
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return None;
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}
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// Try borrowing a shared reference first, then mutably.
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if let Some(mutbl) = [ty::Mutability::Not, ty::Mutability::Mut].into_iter().find(|&mutbl| {
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let re = self.infcx.tcx.lifetimes.re_erased;
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let ref_ty = Ty::new_ref(self.infcx.tcx, re, moved_arg_ty, mutbl);
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// Ensure that substituting `ref_ty` in the callee's signature doesn't break
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// other inputs or the return type.
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let new_args = tcx.mk_args_from_iter(generic_args.iter().enumerate().map(
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|(i, arg)| {
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if i == param.index as usize { ref_ty.into() } else { arg }
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},
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));
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let can_subst = |ty: Ty<'tcx>| {
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// Normalize before comparing to see through type aliases and projections.
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let old_ty = ty::EarlyBinder::bind(ty).instantiate(tcx, generic_args);
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let new_ty = ty::EarlyBinder::bind(ty).instantiate(tcx, new_args);
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if let Ok(old_ty) = tcx.try_normalize_erasing_regions(self.param_env, old_ty)
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&& let Ok(new_ty) = tcx.try_normalize_erasing_regions(self.param_env, new_ty)
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{
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old_ty == new_ty
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} else {
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false
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}
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};
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if !can_subst(sig.output())
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|| sig
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.inputs()
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.iter()
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.enumerate()
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.any(|(i, &input_ty)| i != moved_arg_pos && !can_subst(input_ty))
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{
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return false;
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}
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// Test the callee's predicates, substituting a reference in for the self ty
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// in bounds on `param`.
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clauses.iter().all(|&clause| {
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let clause_for_ref = clause.kind().map_bound(|kind| match kind {
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ClauseKind::Trait(c) if c.self_ty().is_param(param.index) => {
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ClauseKind::Trait(c.with_self_ty(tcx, ref_ty))
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}
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ClauseKind::Projection(c) if c.self_ty().is_param(param.index) => {
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ClauseKind::Projection(c.with_self_ty(tcx, ref_ty))
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}
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_ => kind,
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});
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self.infcx.predicate_must_hold_modulo_regions(&Obligation::new(
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tcx,
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ObligationCause::dummy(),
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self.param_env,
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ty::EarlyBinder::bind(clause_for_ref).instantiate(tcx, generic_args),
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))
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})
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}) {
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let place_desc = if let Some(desc) = self.describe_place(moved_place) {
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format!("`{desc}`")
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} else {
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"here".to_owned()
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};
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err.span_suggestion_verbose(
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place_span.shrink_to_lo(),
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format!("consider {}borrowing {place_desc}", mutbl.mutably_str()),
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mutbl.ref_prefix_str(),
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Applicability::MaybeIncorrect,
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);
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Some(mutbl)
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} else {
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None
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}
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}
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fn report_use_of_uninitialized(
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&self,
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mpi: MovePathIndex,
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@ -851,74 +917,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
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);
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}
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fn suggest_borrow_fn_like(
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&self,
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err: &mut Diag<'_>,
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ty: Ty<'tcx>,
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move_sites: &[MoveSite],
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value_name: &str,
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) -> bool {
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let tcx = self.infcx.tcx;
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// Find out if the predicates show that the type is a Fn or FnMut
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let find_fn_kind_from_did = |(pred, _): (ty::Clause<'tcx>, _)| {
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if let ty::ClauseKind::Trait(pred) = pred.kind().skip_binder()
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&& pred.self_ty() == ty
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{
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if tcx.is_lang_item(pred.def_id(), LangItem::Fn) {
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return Some(hir::Mutability::Not);
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} else if tcx.is_lang_item(pred.def_id(), LangItem::FnMut) {
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return Some(hir::Mutability::Mut);
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}
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}
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None
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};
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// If the type is opaque/param/closure, and it is Fn or FnMut, let's suggest (mutably)
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// borrowing the type, since `&mut F: FnMut` iff `F: FnMut` and similarly for `Fn`.
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// These types seem reasonably opaque enough that they could be instantiated with their
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// borrowed variants in a function body when we see a move error.
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let borrow_level = match *ty.kind() {
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ty::Param(_) => tcx
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.explicit_predicates_of(self.mir_def_id().to_def_id())
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.predicates
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.iter()
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.copied()
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.find_map(find_fn_kind_from_did),
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ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => tcx
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.explicit_item_super_predicates(def_id)
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.iter_instantiated_copied(tcx, args)
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.find_map(|(clause, span)| find_fn_kind_from_did((clause, span))),
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ty::Closure(_, args) => match args.as_closure().kind() {
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ty::ClosureKind::Fn => Some(hir::Mutability::Not),
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ty::ClosureKind::FnMut => Some(hir::Mutability::Mut),
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_ => None,
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},
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_ => None,
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};
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let Some(borrow_level) = borrow_level else {
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return false;
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};
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let sugg = move_sites
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.iter()
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.map(|move_site| {
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let move_out = self.move_data.moves[(*move_site).moi];
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let moved_place = &self.move_data.move_paths[move_out.path].place;
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let move_spans = self.move_spans(moved_place.as_ref(), move_out.source);
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||||
let move_span = move_spans.args_or_use();
|
||||
let suggestion = borrow_level.ref_prefix_str().to_owned();
|
||||
(move_span.shrink_to_lo(), suggestion)
|
||||
})
|
||||
.collect();
|
||||
err.multipart_suggestion_verbose(
|
||||
format!("consider {}borrowing {value_name}", borrow_level.mutably_str()),
|
||||
sugg,
|
||||
Applicability::MaybeIncorrect,
|
||||
);
|
||||
true
|
||||
}
|
||||
|
||||
/// In a move error that occurs on a call within a loop, we try to identify cases where cloning
|
||||
/// the value would lead to a logic error. We infer these cases by seeing if the moved value is
|
||||
/// part of the logic to break the loop, either through an explicit `break` or if the expression
|
||||
|
||||
@ -11,10 +11,6 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
|
||||
|
|
||||
LL | if let MultiVariant::Point(ref mut x, _) = point {
|
||||
| ^^^^^
|
||||
help: consider mutably borrowing `c`
|
||||
|
|
||||
LL | let a = &mut c;
|
||||
| ++++
|
||||
|
||||
error: aborting due to 1 previous error
|
||||
|
||||
|
||||
@ -11,10 +11,6 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
|
||||
|
|
||||
LL | let SingleVariant::Point(ref mut x, _) = point;
|
||||
| ^^^^^
|
||||
help: consider mutably borrowing `c`
|
||||
|
|
||||
LL | let b = &mut c;
|
||||
| ++++
|
||||
|
||||
error: aborting due to 1 previous error
|
||||
|
||||
|
||||
@ -11,10 +11,6 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
|
||||
|
|
||||
LL | x.y.a += 1;
|
||||
| ^^^^^
|
||||
help: consider mutably borrowing `hello`
|
||||
|
|
||||
LL | let b = &mut hello;
|
||||
| ++++
|
||||
|
||||
error: aborting due to 1 previous error
|
||||
|
||||
|
||||
@ -11,10 +11,6 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
|
||||
|
|
||||
LL | x.0 += 1;
|
||||
| ^^^
|
||||
help: consider mutably borrowing `hello`
|
||||
|
|
||||
LL | let b = &mut hello;
|
||||
| ++++
|
||||
|
||||
error: aborting due to 1 previous error
|
||||
|
||||
|
||||
@ -1,23 +1,20 @@
|
||||
//! auxiliary definitons for suggest-borrow-for-generic-arg.rs, to ensure the suggestion works on
|
||||
//! functions defined in other crates.
|
||||
|
||||
use std::borrow::{Borrow, BorrowMut};
|
||||
use std::convert::{AsMut, AsRef};
|
||||
pub struct Bar;
|
||||
use std::io::{self, Read, Write};
|
||||
use std::iter::Sum;
|
||||
|
||||
impl AsRef<Bar> for Bar {
|
||||
fn as_ref(&self) -> &Bar {
|
||||
self
|
||||
}
|
||||
pub fn write_stuff<W: Write>(mut writer: W) -> io::Result<()> {
|
||||
writeln!(writer, "stuff")
|
||||
}
|
||||
|
||||
impl AsMut<Bar> for Bar {
|
||||
fn as_mut(&mut self) -> &mut Bar {
|
||||
self
|
||||
}
|
||||
pub fn read_and_discard<R: Read>(mut reader: R) -> io::Result<()> {
|
||||
let mut buf = Vec::new();
|
||||
reader.read_to_end(&mut buf).map(|_| ())
|
||||
}
|
||||
|
||||
pub fn foo<T: AsRef<Bar>>(_: T) {}
|
||||
pub fn qux<T: AsMut<Bar>>(_: T) {}
|
||||
pub fn bat<T: Borrow<T>>(_: T) {}
|
||||
pub fn baz<T: BorrowMut<T>>(_: T) {}
|
||||
pub fn sum_three<I: IntoIterator>(iter: I) -> <I as IntoIterator>::Item
|
||||
where <I as IntoIterator>::Item: Sum
|
||||
{
|
||||
iter.into_iter().take(3).sum()
|
||||
}
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
fn takes_fn(f: impl Fn()) { //~ HELP if `impl Fn()` implemented `Clone`
|
||||
fn takes_fn(f: impl Fn()) {
|
||||
loop {
|
||||
takes_fnonce(f);
|
||||
//~^ ERROR use of moved value
|
||||
|
||||
@ -8,21 +8,6 @@ LL | loop {
|
||||
LL | takes_fnonce(f);
|
||||
| ^ value moved here, in previous iteration of loop
|
||||
|
|
||||
note: consider changing this parameter type in function `takes_fnonce` to borrow instead if owning the value isn't necessary
|
||||
--> $DIR/borrow-closures-instead-of-move.rs:34:20
|
||||
|
|
||||
LL | fn takes_fnonce(_: impl FnOnce()) {}
|
||||
| ------------ ^^^^^^^^^^^^^ this parameter takes ownership of the value
|
||||
| |
|
||||
| in this function
|
||||
help: if `impl Fn()` implemented `Clone`, you could clone the value
|
||||
--> $DIR/borrow-closures-instead-of-move.rs:1:16
|
||||
|
|
||||
LL | fn takes_fn(f: impl Fn()) {
|
||||
| ^^^^^^^^^ consider constraining this type parameter with `Clone`
|
||||
LL | loop {
|
||||
LL | takes_fnonce(f);
|
||||
| - you could clone this value
|
||||
help: consider borrowing `f`
|
||||
|
|
||||
LL | takes_fnonce(&f);
|
||||
@ -40,13 +25,6 @@ LL | takes_fnonce(m);
|
||||
LL | takes_fnonce(m);
|
||||
| ^ value used here after move
|
||||
|
|
||||
note: consider changing this parameter type in function `takes_fnonce` to borrow instead if owning the value isn't necessary
|
||||
--> $DIR/borrow-closures-instead-of-move.rs:34:20
|
||||
|
|
||||
LL | fn takes_fnonce(_: impl FnOnce()) {}
|
||||
| ------------ ^^^^^^^^^^^^^ this parameter takes ownership of the value
|
||||
| |
|
||||
| in this function
|
||||
help: if `impl FnMut()` implemented `Clone`, you could clone the value
|
||||
--> $DIR/borrow-closures-instead-of-move.rs:9:20
|
||||
|
|
||||
|
||||
@ -24,10 +24,6 @@ LL | fn conspirator<F>(mut f: F) where F: FnMut(&mut R, bool) {
|
||||
| ^ consider constraining this type parameter with `Clone`
|
||||
LL | let mut r = R {c: Box::new(f)};
|
||||
| - you could clone this value
|
||||
help: consider mutably borrowing `f`
|
||||
|
|
||||
LL | let mut r = R {c: Box::new(&mut f)};
|
||||
| ++++
|
||||
|
||||
error: aborting due to 2 previous errors
|
||||
|
||||
|
||||
@ -1,22 +1,46 @@
|
||||
//! Test suggetions to borrow generic arguments instead of moving when all predicates hold after
|
||||
//! substituting in the reference type.
|
||||
//! Test suggetions to borrow generic arguments instead of moving. Tests for other instances of this
|
||||
//! can be found in `moved-value-on-as-ref-arg.rs` and `borrow-closures-instead-of-move.rs`
|
||||
//@ run-rustfix
|
||||
//@ aux-build:suggest-borrow-for-generic-arg-aux.rs
|
||||
//@ aux-crate:aux=suggest-borrow-for-generic-arg-aux.rs
|
||||
//@ edition: 2021
|
||||
|
||||
#![allow(unused_mut)]
|
||||
extern crate suggest_borrow_for_generic_arg_aux as aux;
|
||||
use std::io::{self, Write};
|
||||
|
||||
pub fn main() {
|
||||
let bar = aux::Bar;
|
||||
aux::foo(&bar); //~ HELP consider borrowing `bar`
|
||||
let _baa = bar; //~ ERROR use of moved value
|
||||
let mut bar = aux::Bar;
|
||||
aux::qux(&mut bar); //~ HELP consider mutably borrowing `bar`
|
||||
let _baa = bar; //~ ERROR use of moved value
|
||||
let bar = aux::Bar;
|
||||
aux::bat(&bar); //~ HELP consider borrowing `bar`
|
||||
let _baa = bar; //~ ERROR use of moved value
|
||||
let mut bar = aux::Bar;
|
||||
aux::baz(&mut bar); //~ HELP consider mutably borrowing `bar`
|
||||
let _baa = bar; //~ ERROR use of moved value
|
||||
// test for `std::io::Write` (#131413)
|
||||
fn test_write() -> io::Result<()> {
|
||||
let mut stdout = io::stdout();
|
||||
aux::write_stuff(&stdout)?; //~ HELP consider borrowing `stdout`
|
||||
writeln!(stdout, "second line")?; //~ ERROR borrow of moved value: `stdout`
|
||||
|
||||
let mut buf = Vec::new();
|
||||
aux::write_stuff(&mut buf.clone())?; //~ HELP consider mutably borrowing `buf`
|
||||
//~^ HELP consider cloning the value
|
||||
writeln!(buf, "second_line") //~ ERROR borrow of moved value: `buf`
|
||||
}
|
||||
|
||||
/// test for `std::io::Read` (#131413)
|
||||
fn test_read() -> io::Result<()> {
|
||||
let stdin = io::stdin();
|
||||
aux::read_and_discard(&stdin)?; //~ HELP consider borrowing `stdin`
|
||||
aux::read_and_discard(stdin)?; //~ ERROR use of moved value: `stdin`
|
||||
|
||||
let mut bytes = std::collections::VecDeque::from([1, 2, 3, 4, 5, 6]);
|
||||
aux::read_and_discard(&mut bytes.clone())?; //~ HELP consider mutably borrowing `bytes`
|
||||
//~^ HELP consider cloning the value
|
||||
aux::read_and_discard(bytes) //~ ERROR use of moved value: `bytes`
|
||||
}
|
||||
|
||||
/// test that suggestions work with projection types in the callee's signature
|
||||
fn test_projections() {
|
||||
let mut iter = [1, 2, 3, 4, 5, 6].into_iter();
|
||||
let _six: usize = aux::sum_three(&mut iter.clone()); //~ HELP consider mutably borrowing `iter`
|
||||
//~^ HELP consider cloning the value
|
||||
let _fifteen: usize = aux::sum_three(iter); //~ ERROR use of moved value: `iter`
|
||||
}
|
||||
|
||||
fn main() {
|
||||
test_write().unwrap();
|
||||
test_read().unwrap();
|
||||
test_projections();
|
||||
}
|
||||
|
||||
@ -1,22 +1,46 @@
|
||||
//! Test suggetions to borrow generic arguments instead of moving when all predicates hold after
|
||||
//! substituting in the reference type.
|
||||
//! Test suggetions to borrow generic arguments instead of moving. Tests for other instances of this
|
||||
//! can be found in `moved-value-on-as-ref-arg.rs` and `borrow-closures-instead-of-move.rs`
|
||||
//@ run-rustfix
|
||||
//@ aux-build:suggest-borrow-for-generic-arg-aux.rs
|
||||
//@ aux-crate:aux=suggest-borrow-for-generic-arg-aux.rs
|
||||
//@ edition: 2021
|
||||
|
||||
#![allow(unused_mut)]
|
||||
extern crate suggest_borrow_for_generic_arg_aux as aux;
|
||||
use std::io::{self, Write};
|
||||
|
||||
pub fn main() {
|
||||
let bar = aux::Bar;
|
||||
aux::foo(bar); //~ HELP consider borrowing `bar`
|
||||
let _baa = bar; //~ ERROR use of moved value
|
||||
let mut bar = aux::Bar;
|
||||
aux::qux(bar); //~ HELP consider mutably borrowing `bar`
|
||||
let _baa = bar; //~ ERROR use of moved value
|
||||
let bar = aux::Bar;
|
||||
aux::bat(bar); //~ HELP consider borrowing `bar`
|
||||
let _baa = bar; //~ ERROR use of moved value
|
||||
let mut bar = aux::Bar;
|
||||
aux::baz(bar); //~ HELP consider mutably borrowing `bar`
|
||||
let _baa = bar; //~ ERROR use of moved value
|
||||
// test for `std::io::Write` (#131413)
|
||||
fn test_write() -> io::Result<()> {
|
||||
let mut stdout = io::stdout();
|
||||
aux::write_stuff(stdout)?; //~ HELP consider borrowing `stdout`
|
||||
writeln!(stdout, "second line")?; //~ ERROR borrow of moved value: `stdout`
|
||||
|
||||
let mut buf = Vec::new();
|
||||
aux::write_stuff(buf)?; //~ HELP consider mutably borrowing `buf`
|
||||
//~^ HELP consider cloning the value
|
||||
writeln!(buf, "second_line") //~ ERROR borrow of moved value: `buf`
|
||||
}
|
||||
|
||||
/// test for `std::io::Read` (#131413)
|
||||
fn test_read() -> io::Result<()> {
|
||||
let stdin = io::stdin();
|
||||
aux::read_and_discard(stdin)?; //~ HELP consider borrowing `stdin`
|
||||
aux::read_and_discard(stdin)?; //~ ERROR use of moved value: `stdin`
|
||||
|
||||
let mut bytes = std::collections::VecDeque::from([1, 2, 3, 4, 5, 6]);
|
||||
aux::read_and_discard(bytes)?; //~ HELP consider mutably borrowing `bytes`
|
||||
//~^ HELP consider cloning the value
|
||||
aux::read_and_discard(bytes) //~ ERROR use of moved value: `bytes`
|
||||
}
|
||||
|
||||
/// test that suggestions work with projection types in the callee's signature
|
||||
fn test_projections() {
|
||||
let mut iter = [1, 2, 3, 4, 5, 6].into_iter();
|
||||
let _six: usize = aux::sum_three(iter); //~ HELP consider mutably borrowing `iter`
|
||||
//~^ HELP consider cloning the value
|
||||
let _fifteen: usize = aux::sum_three(iter); //~ ERROR use of moved value: `iter`
|
||||
}
|
||||
|
||||
fn main() {
|
||||
test_write().unwrap();
|
||||
test_read().unwrap();
|
||||
test_projections();
|
||||
}
|
||||
|
||||
@ -1,63 +1,93 @@
|
||||
error[E0382]: use of moved value: `bar`
|
||||
--> $DIR/suggest-borrow-for-generic-arg.rs:12:16
|
||||
error[E0382]: borrow of moved value: `stdout`
|
||||
--> $DIR/suggest-borrow-for-generic-arg.rs:14:14
|
||||
|
|
||||
LL | let bar = aux::Bar;
|
||||
| --- move occurs because `bar` has type `Bar`, which does not implement the `Copy` trait
|
||||
LL | aux::foo(bar);
|
||||
| --- value moved here
|
||||
LL | let _baa = bar;
|
||||
| ^^^ value used here after move
|
||||
LL | let mut stdout = io::stdout();
|
||||
| ---------- move occurs because `stdout` has type `Stdout`, which does not implement the `Copy` trait
|
||||
LL | aux::write_stuff(stdout)?;
|
||||
| ------ value moved here
|
||||
LL | writeln!(stdout, "second line")?;
|
||||
| ^^^^^^ value borrowed here after move
|
||||
|
|
||||
help: consider borrowing `bar`
|
||||
help: consider borrowing `stdout`
|
||||
|
|
||||
LL | aux::foo(&bar);
|
||||
| +
|
||||
LL | aux::write_stuff(&stdout)?;
|
||||
| +
|
||||
|
||||
error[E0382]: use of moved value: `bar`
|
||||
--> $DIR/suggest-borrow-for-generic-arg.rs:15:16
|
||||
error[E0382]: borrow of moved value: `buf`
|
||||
--> $DIR/suggest-borrow-for-generic-arg.rs:19:14
|
||||
|
|
||||
LL | let mut bar = aux::Bar;
|
||||
| ------- move occurs because `bar` has type `Bar`, which does not implement the `Copy` trait
|
||||
LL | aux::qux(bar);
|
||||
| --- value moved here
|
||||
LL | let _baa = bar;
|
||||
| ^^^ value used here after move
|
||||
LL | let mut buf = Vec::new();
|
||||
| ------- move occurs because `buf` has type `Vec<u8>`, which does not implement the `Copy` trait
|
||||
LL | aux::write_stuff(buf)?;
|
||||
| --- value moved here
|
||||
LL |
|
||||
LL | writeln!(buf, "second_line")
|
||||
| ^^^ value borrowed here after move
|
||||
|
|
||||
help: consider mutably borrowing `bar`
|
||||
help: consider mutably borrowing `buf`
|
||||
|
|
||||
LL | aux::qux(&mut bar);
|
||||
| ++++
|
||||
LL | aux::write_stuff(&mut buf)?;
|
||||
| ++++
|
||||
help: consider cloning the value if the performance cost is acceptable
|
||||
|
|
||||
LL | aux::write_stuff(buf.clone())?;
|
||||
| ++++++++
|
||||
|
||||
error[E0382]: use of moved value: `bar`
|
||||
--> $DIR/suggest-borrow-for-generic-arg.rs:18:16
|
||||
error[E0382]: use of moved value: `stdin`
|
||||
--> $DIR/suggest-borrow-for-generic-arg.rs:26:27
|
||||
|
|
||||
LL | let bar = aux::Bar;
|
||||
| --- move occurs because `bar` has type `Bar`, which does not implement the `Copy` trait
|
||||
LL | aux::bat(bar);
|
||||
| --- value moved here
|
||||
LL | let _baa = bar;
|
||||
| ^^^ value used here after move
|
||||
LL | let stdin = io::stdin();
|
||||
| ----- move occurs because `stdin` has type `Stdin`, which does not implement the `Copy` trait
|
||||
LL | aux::read_and_discard(stdin)?;
|
||||
| ----- value moved here
|
||||
LL | aux::read_and_discard(stdin)?;
|
||||
| ^^^^^ value used here after move
|
||||
|
|
||||
help: consider borrowing `bar`
|
||||
help: consider borrowing `stdin`
|
||||
|
|
||||
LL | aux::bat(&bar);
|
||||
| +
|
||||
LL | aux::read_and_discard(&stdin)?;
|
||||
| +
|
||||
|
||||
error[E0382]: use of moved value: `bar`
|
||||
--> $DIR/suggest-borrow-for-generic-arg.rs:21:16
|
||||
error[E0382]: use of moved value: `bytes`
|
||||
--> $DIR/suggest-borrow-for-generic-arg.rs:31:27
|
||||
|
|
||||
LL | let mut bar = aux::Bar;
|
||||
| ------- move occurs because `bar` has type `Bar`, which does not implement the `Copy` trait
|
||||
LL | aux::baz(bar);
|
||||
| --- value moved here
|
||||
LL | let _baa = bar;
|
||||
| ^^^ value used here after move
|
||||
LL | let mut bytes = std::collections::VecDeque::from([1, 2, 3, 4, 5, 6]);
|
||||
| --------- move occurs because `bytes` has type `VecDeque<u8>`, which does not implement the `Copy` trait
|
||||
LL | aux::read_and_discard(bytes)?;
|
||||
| ----- value moved here
|
||||
LL |
|
||||
LL | aux::read_and_discard(bytes)
|
||||
| ^^^^^ value used here after move
|
||||
|
|
||||
help: consider mutably borrowing `bar`
|
||||
help: consider mutably borrowing `bytes`
|
||||
|
|
||||
LL | aux::baz(&mut bar);
|
||||
| ++++
|
||||
LL | aux::read_and_discard(&mut bytes)?;
|
||||
| ++++
|
||||
help: consider cloning the value if the performance cost is acceptable
|
||||
|
|
||||
LL | aux::read_and_discard(bytes.clone())?;
|
||||
| ++++++++
|
||||
|
||||
error: aborting due to 4 previous errors
|
||||
error[E0382]: use of moved value: `iter`
|
||||
--> $DIR/suggest-borrow-for-generic-arg.rs:39:42
|
||||
|
|
||||
LL | let mut iter = [1, 2, 3, 4, 5, 6].into_iter();
|
||||
| -------- move occurs because `iter` has type `std::array::IntoIter<usize, 6>`, which does not implement the `Copy` trait
|
||||
LL | let _six: usize = aux::sum_three(iter);
|
||||
| ---- value moved here
|
||||
LL |
|
||||
LL | let _fifteen: usize = aux::sum_three(iter);
|
||||
| ^^^^ value used here after move
|
||||
|
|
||||
help: consider mutably borrowing `iter`
|
||||
|
|
||||
LL | let _six: usize = aux::sum_three(&mut iter);
|
||||
| ++++
|
||||
help: consider cloning the value if the performance cost is acceptable
|
||||
|
|
||||
LL | let _six: usize = aux::sum_three(iter.clone());
|
||||
| ++++++++
|
||||
|
||||
error: aborting due to 5 previous errors
|
||||
|
||||
For more information about this error, try `rustc --explain E0382`.
|
||||
|
||||
@ -11,10 +11,6 @@ note: closure cannot be moved more than once as it is not `Copy` due to moving t
|
||||
|
|
||||
LL | a += 1;
|
||||
| ^
|
||||
help: consider mutably borrowing `hello`
|
||||
|
|
||||
LL | let b = &mut hello;
|
||||
| ++++
|
||||
|
||||
error: aborting due to 1 previous error
|
||||
|
||||
|
||||
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Reference in New Issue
Block a user