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https://github.com/rust-lang/rust.git
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Better account for FnOnce in move errors
```
error[E0382]: use of moved value: `blk`
--> $DIR/once-cant-call-twice-on-heap.rs:8:5
|
LL | fn foo<F:FnOnce()>(blk: F) {
| --- move occurs because `blk` has type `F`, which does not implement the `Copy` trait
LL | blk();
| ----- `blk` moved due to this call
LL | blk();
| ^^^ value used here after move
|
note: `FnOnce` closures can only be called once
--> $DIR/once-cant-call-twice-on-heap.rs:6:10
|
LL | fn foo<F:FnOnce()>(blk: F) {
| ^^^^^^^^ `F` is made to be an `FnOnce` closure here
LL | blk();
| ----- this value implements `FnOnce`, which causes it to be moved when called
```
This commit is contained in:
Esteban Küber
parent
dfe28debb9
commit
4ca876b7a4
@ -87,6 +87,12 @@ borrowck_move_unsized =
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borrowck_moved_a_fn_once_in_call =
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this value implements `FnOnce`, which causes it to be moved when called
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borrowck_moved_a_fn_once_in_call_call =
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`FnOnce` closures can only be called once
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borrowck_moved_a_fn_once_in_call_def =
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`{$ty}` is made to be an `FnOnce` closure here
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borrowck_moved_due_to_await =
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{$place_name} {$is_partial ->
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[true] partially moved
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@ -283,7 +283,19 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
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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 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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&& Some(fn_trait_id) == self.infcx.tcx.lang_items().fn_once_trait()
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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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// 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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@ -1016,7 +1028,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
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None
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}
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})
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&& { true }
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&& parent_binop == other_parent_binop
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{
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// Explicitly look for `expr += other_expr;` and avoid suggesting
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@ -5,6 +5,7 @@ use crate::session_diagnostics::{
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CaptureVarKind, CaptureVarPathUseCause, OnClosureNote,
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};
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use rustc_errors::{Applicability, Diag};
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use rustc_errors::{DiagCtxt, MultiSpan};
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use rustc_hir as hir;
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use rustc_hir::def::{CtorKind, Namespace};
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use rustc_hir::CoroutineKind;
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@ -29,6 +30,8 @@ use rustc_trait_selection::infer::InferCtxtExt;
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use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt as _;
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use rustc_trait_selection::traits::type_known_to_meet_bound_modulo_regions;
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use crate::fluent_generated as fluent;
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use super::borrow_set::BorrowData;
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use super::MirBorrowckCtxt;
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@ -587,7 +590,7 @@ impl UseSpans<'_> {
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#[allow(rustc::diagnostic_outside_of_impl)]
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pub(super) fn args_subdiag(
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self,
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dcx: &rustc_errors::DiagCtxt,
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dcx: &DiagCtxt,
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err: &mut Diag<'_>,
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f: impl FnOnce(Span) -> CaptureArgLabel,
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) {
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@ -601,7 +604,7 @@ impl UseSpans<'_> {
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#[allow(rustc::diagnostic_outside_of_impl)]
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pub(super) fn var_path_only_subdiag(
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self,
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dcx: &rustc_errors::DiagCtxt,
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dcx: &DiagCtxt,
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err: &mut Diag<'_>,
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action: crate::InitializationRequiringAction,
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) {
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@ -639,7 +642,7 @@ impl UseSpans<'_> {
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#[allow(rustc::diagnostic_outside_of_impl)]
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pub(super) fn var_subdiag(
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self,
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dcx: &rustc_errors::DiagCtxt,
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dcx: &DiagCtxt,
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err: &mut Diag<'_>,
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kind: Option<rustc_middle::mir::BorrowKind>,
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f: impl FnOnce(hir::ClosureKind, Span) -> CaptureVarCause,
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@ -1034,7 +1037,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
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.map(|n| format!("`{n}`"))
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.unwrap_or_else(|| "value".to_owned());
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match kind {
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CallKind::FnCall { fn_trait_id, .. }
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CallKind::FnCall { fn_trait_id, self_ty }
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if Some(fn_trait_id) == self.infcx.tcx.lang_items().fn_once_trait() =>
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{
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err.subdiagnostic(
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@ -1046,7 +1049,58 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
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is_loop_message,
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},
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);
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err.subdiagnostic(self.dcx(), CaptureReasonNote::FnOnceMoveInCall { var_span });
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if let ty::Param(param_ty) = self_ty.kind()
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&& let generics = self.infcx.tcx.generics_of(self.mir_def_id())
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&& let param = generics.type_param(param_ty, self.infcx.tcx)
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&& let Some(hir_generics) = self
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.infcx
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.tcx
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.typeck_root_def_id(self.mir_def_id().to_def_id())
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.as_local()
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.and_then(|def_id| self.infcx.tcx.hir().get_generics(def_id))
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&& let spans = hir_generics
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.predicates
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.iter()
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.filter_map(|pred| match pred {
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hir::WherePredicate::BoundPredicate(pred) => Some(pred),
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_ => None,
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})
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.filter(|pred| {
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if let Some((id, _)) = pred.bounded_ty.as_generic_param() {
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id == param.def_id
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} else {
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false
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}
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})
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.flat_map(|pred| pred.bounds)
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.filter_map(|bound| {
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if let Some(trait_ref) = bound.trait_ref()
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&& let Some(trait_def_id) = trait_ref.trait_def_id()
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&& trait_def_id == fn_trait_id
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{
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Some(bound.span())
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} else {
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None
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}
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})
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.collect::<Vec<Span>>()
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&& !spans.is_empty()
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{
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let mut span: MultiSpan = spans.clone().into();
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for sp in spans {
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span.push_span_label(sp, fluent::borrowck_moved_a_fn_once_in_call_def);
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}
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span.push_span_label(
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fn_call_span,
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fluent::borrowck_moved_a_fn_once_in_call,
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);
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err.span_note(span, fluent::borrowck_moved_a_fn_once_in_call_call);
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} else {
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err.subdiagnostic(
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self.dcx(),
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CaptureReasonNote::FnOnceMoveInCall { var_span },
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);
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}
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}
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CallKind::Operator { self_arg, trait_id, .. } => {
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let self_arg = self_arg.unwrap();
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@ -29,15 +29,13 @@ LL | f(1, 2);
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LL | f(1, 2);
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| ^ value used here after move
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|
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note: this value implements `FnOnce`, which causes it to be moved when called
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--> $DIR/borrowck-unboxed-closures.rs:11:5
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note: `FnOnce` closures can only be called once
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--> $DIR/borrowck-unboxed-closures.rs:10:8
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|
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LL | fn c<F:FnOnce(isize, isize) -> isize>(f: F) {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `F` is made to be an `FnOnce` closure here
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LL | f(1, 2);
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| ^
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help: consider further restricting this bound
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LL | fn c<F:FnOnce(isize, isize) -> isize + Copy>(f: F) {
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| ++++++
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| ------- this value implements `FnOnce`, which causes it to be moved when called
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error: aborting due to 3 previous errors
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@ -8,15 +8,13 @@ LL | blk();
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LL | blk();
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| ^^^ value used here after move
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|
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note: this value implements `FnOnce`, which causes it to be moved when called
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--> $DIR/once-cant-call-twice-on-heap.rs:7:5
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note: `FnOnce` closures can only be called once
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--> $DIR/once-cant-call-twice-on-heap.rs:6:10
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|
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LL | fn foo<F:FnOnce()>(blk: F) {
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| ^^^^^^^^ `F` is made to be an `FnOnce` closure here
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LL | blk();
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| ^^^
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help: consider further restricting this bound
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LL | fn foo<F:FnOnce() + Copy>(blk: F) {
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| ++++++
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| ----- this value implements `FnOnce`, which causes it to be moved when called
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error: aborting due to 1 previous error
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