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Rollup merge of #80324 - Aaron1011:loop-move-fn-self, r=oli-obk

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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:
Yuki Okushi 2021-01-12 07:59:10 +09:00 committed by GitHub
commit 8e6472fe32
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GPG Key ID: 4AEE18F83AFDEB23
15 changed files with 118 additions and 104 deletions
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162
compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs
View File

@ -151,95 +151,88 @@ pub(in crate::borrow_check) fn report_use_of_moved_or_uninitialized(
let move_msg = if move_spans.for_closure() { " into closure" } else { "" };
let loop_message = if location == move_out.source || move_site.traversed_back_edge {
", in previous iteration of loop"
} else {
""
};
if location == move_out.source {
err.span_label(
span,
format!(
"value {}moved{} here, in previous iteration of loop",
partially_str, move_msg
),
);
is_loop_move = true;
} else if move_site.traversed_back_edge {
}
if let UseSpans::FnSelfUse { var_span, fn_call_span, fn_span, kind } = move_spans {
let place_name = self
.describe_place(moved_place.as_ref())
.map(|n| format!("`{}`", n))
.unwrap_or_else(|| "value".to_owned());
match kind {
FnSelfUseKind::FnOnceCall => {
err.span_label(
fn_call_span,
&format!(
"{} {}moved due to this call{}",
place_name, partially_str, loop_message
),
);
err.span_note(
var_span,
"this value implements `FnOnce`, which causes it to be moved when called",
);
}
FnSelfUseKind::Operator { self_arg } => {
err.span_label(
fn_call_span,
&format!(
"{} {}moved due to usage in operator{}",
place_name, partially_str, loop_message
),
);
if self.fn_self_span_reported.insert(fn_span) {
err.span_note(
self_arg.span,
"calling this operator moves the left-hand side",
);
}
}
FnSelfUseKind::Normal { self_arg, implicit_into_iter } => {
if implicit_into_iter {
err.span_label(
fn_call_span,
&format!(
"{} {}moved due to this implicit call to `.into_iter()`{}",
place_name, partially_str, loop_message
),
);
} else {
err.span_label(
fn_call_span,
&format!(
"{} {}moved due to this method call{}",
place_name, partially_str, loop_message
),
);
}
// Avoid pointing to the same function in multiple different
// error messages
if self.fn_self_span_reported.insert(self_arg.span) {
err.span_note(
self_arg.span,
&format!("this function takes ownership of the receiver `self`, which moves {}", place_name)
);
}
}
// Deref::deref takes &self, which cannot cause a move
FnSelfUseKind::DerefCoercion { .. } => unreachable!(),
}
} else {
err.span_label(
move_span,
format!(
"value {}moved{} here, in previous iteration of loop",
partially_str, move_msg
),
format!("value {}moved{} here{}", partially_str, move_msg, loop_message),
);
} else {
if let UseSpans::FnSelfUse { var_span, fn_call_span, fn_span, kind } =
move_spans
{
let place_name = self
.describe_place(moved_place.as_ref())
.map(|n| format!("`{}`", n))
.unwrap_or_else(|| "value".to_owned());
match kind {
FnSelfUseKind::FnOnceCall => {
err.span_label(
fn_call_span,
&format!(
"{} {}moved due to this call",
place_name, partially_str
),
);
err.span_note(
var_span,
"this value implements `FnOnce`, which causes it to be moved when called",
);
}
FnSelfUseKind::Operator { self_arg } => {
err.span_label(
fn_call_span,
&format!(
"{} {}moved due to usage in operator",
place_name, partially_str
),
);
if self.fn_self_span_reported.insert(fn_span) {
err.span_note(
self_arg.span,
"calling this operator moves the left-hand side",
);
}
}
FnSelfUseKind::Normal { self_arg, implicit_into_iter } => {
if implicit_into_iter {
err.span_label(
fn_call_span,
&format!(
"{} {}moved due to this implicit call to `.into_iter()`",
place_name, partially_str
),
);
} else {
err.span_label(
fn_call_span,
&format!(
"{} {}moved due to this method call",
place_name, partially_str
),
);
}
// Avoid pointing to the same function in multiple different
// error messages
if self.fn_self_span_reported.insert(self_arg.span) {
err.span_note(
self_arg.span,
&format!("this function consumes the receiver `self` by taking ownership of it, which moves {}", place_name)
);
}
}
// Deref::deref takes &self, which cannot cause a move
FnSelfUseKind::DerefCoercion { .. } => unreachable!(),
}
} else {
err.span_label(
move_span,
format!("value {}moved{} here", partially_str, move_msg),
);
// If the move error occurs due to a loop, don't show
// another message for the same span
if loop_message.is_empty() {
move_spans.var_span_label(
&mut err,
format!(
@ -250,6 +243,7 @@ pub(in crate::borrow_check) fn report_use_of_moved_or_uninitialized(
);
}
}
if let UseSpans::PatUse(span) = move_spans {
err.span_suggestion_verbose(
span.shrink_to_lo(),

2
src/test/ui/codemap_tests/tab_3.stderr
View File

@ -9,7 +9,7 @@ LL | {
LL | println!("{:?}", some_vec);
| ^^^^^^^^ value borrowed here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `some_vec`
note: this function takes ownership of the receiver `self`, which moves `some_vec`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;

2
src/test/ui/issues/issue-34721.stderr
View File

@ -13,7 +13,7 @@ LL | };
LL | x.zero()
| ^ value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `x`
note: this function takes ownership of the receiver `self`, which moves `x`
--> $DIR/issue-34721.rs:4:13
|
LL | fn zero(self) -> Self;

2
src/test/ui/issues/issue-61108.stderr
View File

@ -12,7 +12,7 @@ LL | for l in bad_letters {
LL | bad_letters.push('s');
| ^^^^^^^^^^^ value borrowed here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `bad_letters`
note: this function takes ownership of the receiver `self`, which moves `bad_letters`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;

2
src/test/ui/issues/issue-64559.stderr
View File

@ -13,7 +13,7 @@ LL | let _closure = || orig;
| |
| value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `orig`
note: this function takes ownership of the receiver `self`, which moves `orig`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;

5
src/test/ui/moves/move-fn-self-receiver.rs
View File

@ -69,6 +69,11 @@ fn move_out(val: Container) {
let container = Container(vec![]);
for _val in container.custom_into_iter() {}
container; //~ ERROR use of moved
let foo2 = Foo;
loop {
foo2.use_self(); //~ ERROR use of moved
}
}
fn main() {}

23
src/test/ui/moves/move-fn-self-receiver.stderr
View File

@ -6,7 +6,7 @@ LL | val.0.into_iter().next();
LL | val.0;
| ^^^^^ value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `val.0`
note: this function takes ownership of the receiver `self`, which moves `val.0`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;
@ -23,7 +23,7 @@ LL | foo.use_self();
LL | foo;
| ^^^ value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `foo`
note: this function takes ownership of the receiver `self`, which moves `foo`
--> $DIR/move-fn-self-receiver.rs:13:17
|
LL | fn use_self(self) {}
@ -49,7 +49,7 @@ LL | boxed_foo.use_box_self();
LL | boxed_foo;
| ^^^^^^^^^ value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `boxed_foo`
note: this function takes ownership of the receiver `self`, which moves `boxed_foo`
--> $DIR/move-fn-self-receiver.rs:14:21
|
LL | fn use_box_self(self: Box<Self>) {}
@ -65,7 +65,7 @@ LL | pin_box_foo.use_pin_box_self();
LL | pin_box_foo;
| ^^^^^^^^^^^ value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `pin_box_foo`
note: this function takes ownership of the receiver `self`, which moves `pin_box_foo`
--> $DIR/move-fn-self-receiver.rs:15:25
|
LL | fn use_pin_box_self(self: Pin<Box<Self>>) {}
@ -91,7 +91,7 @@ LL | rc_foo.use_rc_self();
LL | rc_foo;
| ^^^^^^ value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `rc_foo`
note: this function takes ownership of the receiver `self`, which moves `rc_foo`
--> $DIR/move-fn-self-receiver.rs:16:20
|
LL | fn use_rc_self(self: Rc<Self>) {}
@ -146,13 +146,22 @@ LL | for _val in container.custom_into_iter() {}
LL | container;
| ^^^^^^^^^ value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `container`
note: this function takes ownership of the receiver `self`, which moves `container`
--> $DIR/move-fn-self-receiver.rs:23:25
|
LL | fn custom_into_iter(self) -> impl Iterator<Item = bool> {
| ^^^^
error: aborting due to 11 previous errors
error[E0382]: use of moved value: `foo2`
--> $DIR/move-fn-self-receiver.rs:75:9
|
LL | let foo2 = Foo;
| ---- move occurs because `foo2` has type `Foo`, which does not implement the `Copy` trait
LL | loop {
LL | foo2.use_self();
| ^^^^ ---------- `foo2` moved due to this method call, in previous iteration of loop
error: aborting due to 12 previous errors
Some errors have detailed explanations: E0382, E0505.
For more information about an error, try `rustc --explain E0382`.

2
src/test/ui/moves/moves-based-on-type-access-to-field.stderr
View File

@ -8,7 +8,7 @@ LL | consume(x.into_iter().next().unwrap());
LL | touch(&x[0]);
| ^ value borrowed here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `x`
note: this function takes ownership of the receiver `self`, which moves `x`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;

4
src/test/ui/moves/moves-based-on-type-exprs.stderr
View File

@ -108,7 +108,7 @@ LL | let _y = x.into_iter().next().unwrap();
LL | touch(&x);
| ^^ value borrowed here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `x`
note: this function takes ownership of the receiver `self`, which moves `x`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;
@ -124,7 +124,7 @@ LL | let _y = [x.into_iter().next().unwrap(); 1];
LL | touch(&x);
| ^^ value borrowed here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `x`
note: this function takes ownership of the receiver `self`, which moves `x`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;

8
src/test/ui/suggestions/borrow-for-loop-head.stderr
View File

@ -15,8 +15,14 @@ LL | for i in &a {
LL | for j in a {
| ^
| |
| value moved here, in previous iteration of loop
| `a` moved due to this implicit call to `.into_iter()`, in previous iteration of loop
| help: consider borrowing to avoid moving into the for loop: `&a`
|
note: this function takes ownership of the receiver `self`, which moves `a`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;
| ^^^^
error: aborting due to 2 previous errors

2
src/test/ui/unsized-locals/borrow-after-move.stderr
View File

@ -51,7 +51,7 @@ LL | y.foo();
LL | println!("{}", &y);
| ^^ value borrowed here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `y`
note: this function takes ownership of the receiver `self`, which moves `y`
--> $DIR/borrow-after-move.rs:5:12
|
LL | fn foo(self) -> String;

2
src/test/ui/unsized-locals/double-move.stderr
View File

@ -47,7 +47,7 @@ LL | y.foo();
LL | y.foo();
| ^ value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `y`
note: this function takes ownership of the receiver `self`, which moves `y`
--> $DIR/double-move.rs:5:12
|
LL | fn foo(self) -> String;

2
src/test/ui/use/use-after-move-self-based-on-type.stderr
View File

@ -8,7 +8,7 @@ LL | self.bar();
LL | return self.x;
| ^^^^^^ value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `self`
note: this function takes ownership of the receiver `self`, which moves `self`
--> $DIR/use-after-move-self-based-on-type.rs:15:16
|
LL | pub fn bar(self) {}

2
src/test/ui/use/use-after-move-self.stderr
View File

@ -8,7 +8,7 @@ LL | self.bar();
LL | return *self.x;
| ^^^^^^^ value used here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `self`
note: this function takes ownership of the receiver `self`, which moves `self`
--> $DIR/use-after-move-self.rs:13:16
|
LL | pub fn bar(self) {}

2
src/test/ui/walk-struct-literal-with.stderr
View File

@ -8,7 +8,7 @@ LL | let end = Mine{other_val:1, ..start.make_string_bar()};
LL | println!("{}", start.test);
| ^^^^^^^^^^ value borrowed here after move
|
note: this function consumes the receiver `self` by taking ownership of it, which moves `start`
note: this function takes ownership of the receiver `self`, which moves `start`
--> $DIR/walk-struct-literal-with.rs:7:28
|
LL | fn make_string_bar(mut self) -> Mine{