Explain method-call move errors in loops
PR #73708 added a more detailed explanation of move errors that occur due to a call to a method that takes `self`. This PR extends that logic to work when a move error occurs due to a method call in the previous iteration of a loop.
This commit is contained in:
Aaron Hill
parent
ddf2cc7f8e
commit
de90afc72e
@ -151,95 +151,88 @@ pub(in crate::borrow_check) fn report_use_of_moved_or_uninitialized(
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let move_msg = if move_spans.for_closure() { " into closure" } else { "" };
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let loop_message = if location == move_out.source || move_site.traversed_back_edge {
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", in previous iteration of loop"
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} else {
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""
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};
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if location == move_out.source {
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err.span_label(
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span,
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format!(
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"value {}moved{} here, in previous iteration of loop",
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partially_str, move_msg
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),
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);
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is_loop_move = true;
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} else if move_site.traversed_back_edge {
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}
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if let UseSpans::FnSelfUse { var_span, fn_call_span, fn_span, kind } = move_spans {
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let place_name = self
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.describe_place(moved_place.as_ref())
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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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FnSelfUseKind::FnOnceCall => {
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err.span_label(
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fn_call_span,
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&format!(
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"{} {}moved due to this call{}",
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place_name, partially_str, loop_message
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),
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);
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err.span_note(
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var_span,
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"this value implements `FnOnce`, which causes it to be moved when called",
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);
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}
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FnSelfUseKind::Operator { self_arg } => {
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err.span_label(
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fn_call_span,
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&format!(
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"{} {}moved due to usage in operator{}",
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place_name, partially_str, loop_message
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),
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);
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if self.fn_self_span_reported.insert(fn_span) {
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err.span_note(
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self_arg.span,
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"calling this operator moves the left-hand side",
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);
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}
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}
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FnSelfUseKind::Normal { self_arg, implicit_into_iter } => {
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if implicit_into_iter {
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err.span_label(
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fn_call_span,
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&format!(
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"{} {}moved due to this implicit call to `.into_iter()`{}",
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place_name, partially_str, loop_message
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),
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);
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} else {
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err.span_label(
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fn_call_span,
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&format!(
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"{} {}moved due to this method call{}",
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place_name, partially_str, loop_message
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),
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);
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}
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// Avoid pointing to the same function in multiple different
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// error messages
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if self.fn_self_span_reported.insert(self_arg.span) {
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err.span_note(
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self_arg.span,
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&format!("this function consumes the receiver `self` by taking ownership of it, which moves {}", place_name)
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);
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}
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}
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// Deref::deref takes &self, which cannot cause a move
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FnSelfUseKind::DerefCoercion { .. } => unreachable!(),
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}
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} else {
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err.span_label(
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move_span,
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format!(
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"value {}moved{} here, in previous iteration of loop",
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partially_str, move_msg
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),
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format!("value {}moved{} here{}", partially_str, move_msg, loop_message),
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);
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} else {
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if let UseSpans::FnSelfUse { var_span, fn_call_span, fn_span, kind } =
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move_spans
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{
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let place_name = self
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.describe_place(moved_place.as_ref())
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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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FnSelfUseKind::FnOnceCall => {
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err.span_label(
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fn_call_span,
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&format!(
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"{} {}moved due to this call",
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place_name, partially_str
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),
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);
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err.span_note(
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var_span,
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"this value implements `FnOnce`, which causes it to be moved when called",
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);
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}
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FnSelfUseKind::Operator { self_arg } => {
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err.span_label(
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fn_call_span,
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&format!(
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"{} {}moved due to usage in operator",
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place_name, partially_str
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),
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);
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if self.fn_self_span_reported.insert(fn_span) {
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err.span_note(
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self_arg.span,
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"calling this operator moves the left-hand side",
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);
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}
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}
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FnSelfUseKind::Normal { self_arg, implicit_into_iter } => {
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if implicit_into_iter {
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err.span_label(
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fn_call_span,
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&format!(
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"{} {}moved due to this implicit call to `.into_iter()`",
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place_name, partially_str
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),
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);
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} else {
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err.span_label(
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fn_call_span,
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&format!(
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"{} {}moved due to this method call",
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place_name, partially_str
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),
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);
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}
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// Avoid pointing to the same function in multiple different
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// error messages
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if self.fn_self_span_reported.insert(self_arg.span) {
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err.span_note(
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self_arg.span,
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&format!("this function consumes the receiver `self` by taking ownership of it, which moves {}", place_name)
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);
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}
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}
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// Deref::deref takes &self, which cannot cause a move
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FnSelfUseKind::DerefCoercion { .. } => unreachable!(),
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}
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} else {
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err.span_label(
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move_span,
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format!("value {}moved{} here", partially_str, move_msg),
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);
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// If the move error occurs due to a loop, don't show
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// another message for the same span
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if loop_message.is_empty() {
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move_spans.var_span_label(
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&mut err,
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format!(
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@ -250,6 +243,7 @@ pub(in crate::borrow_check) fn report_use_of_moved_or_uninitialized(
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);
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}
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}
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if let UseSpans::PatUse(span) = move_spans {
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err.span_suggestion_verbose(
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span.shrink_to_lo(),
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@ -69,6 +69,11 @@ fn move_out(val: Container) {
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let container = Container(vec![]);
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for _val in container.custom_into_iter() {}
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container; //~ ERROR use of moved
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let foo2 = Foo;
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loop {
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foo2.use_self(); //~ ERROR use of moved
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}
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}
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fn main() {}
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@ -152,7 +152,16 @@ note: this function consumes the receiver `self` by taking ownership of it, whic
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LL | fn custom_into_iter(self) -> impl Iterator<Item = bool> {
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| ^^^^
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error: aborting due to 11 previous errors
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error[E0382]: use of moved value: `foo2`
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--> $DIR/move-fn-self-receiver.rs:75:9
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LL | let foo2 = Foo;
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| ---- move occurs because `foo2` has type `Foo`, which does not implement the `Copy` trait
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LL | loop {
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LL | foo2.use_self();
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| ^^^^ ---------- `foo2` moved due to this method call, in previous iteration of loop
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error: aborting due to 12 previous errors
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Some errors have detailed explanations: E0382, E0505.
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For more information about an error, try `rustc --explain E0382`.
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@ -15,8 +15,14 @@ LL | for i in &a {
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LL | for j in a {
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| ^
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| |
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| value moved here, in previous iteration of loop
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| `a` moved due to this implicit call to `.into_iter()`, in previous iteration of loop
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| help: consider borrowing to avoid moving into the for loop: `&a`
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note: this function consumes the receiver `self` by taking ownership of it, which moves `a`
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--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
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LL | fn into_iter(self) -> Self::IntoIter;
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| ^^^^
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error: aborting due to 2 previous errors
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