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Rollup merge of #124595 - estebank:issue-104232, r=davidtwco

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Suggest cloning `Arc` moved into closure

```
error[E0382]: borrow of moved value: `x`
  --> $DIR/moves-based-on-type-capture-clause-bad.rs:9:20
   |
LL |     let x = "Hello world!".to_string();
   |         - move occurs because `x` has type `String`, which does not implement the `Copy` trait
LL |     thread::spawn(move || {
   |                   ------- value moved into closure here
LL |         println!("{}", x);
   |                        - variable moved due to use in closure
LL |     });
LL |     println!("{}", x);
   |                    ^ value borrowed here after move
   |
   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider cloning the value before moving it into the closure
   |
LL ~     let value = x.clone();
LL ~     thread::spawn(move || {
LL ~         println!("{}", value);
   |
```

Fix rust-lang/rust#104232.
This commit is contained in:
Matthias Krüger
2025-06-26 15:47:16 +02:00
committed by GitHub
parent 8f21a5c92e 904652b2d0
commit aa8ba54caf
13 changed files with 85 additions and 33 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
View File

@@ -518,11 +518,11 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
} = move_spans
&& can_suggest_clone
{
self.suggest_cloning(err, ty, expr, Some(move_spans));
self.suggest_cloning(err, place.as_ref(), ty, expr, Some(move_spans));
} else if self.suggest_hoisting_call_outside_loop(err, expr) && can_suggest_clone {
// The place where the type moves would be misleading to suggest clone.
// #121466
self.suggest_cloning(err, ty, expr, Some(move_spans));
self.suggest_cloning(err, place.as_ref(), ty, expr, Some(move_spans));
}
}
@@ -1224,6 +1224,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
pub(crate) fn suggest_cloning(
&self,
err: &mut Diag<'_>,
place: PlaceRef<'tcx>,
ty: Ty<'tcx>,
expr: &'tcx hir::Expr<'tcx>,
use_spans: Option<UseSpans<'tcx>>,
@@ -1238,7 +1239,13 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
}
if self.implements_clone(ty) {
self.suggest_cloning_inner(err, ty, expr);
if self.in_move_closure(expr) {
if let Some(name) = self.describe_place(place) {
self.suggest_clone_of_captured_var_in_move_closure(err, &name, use_spans);
}
} else {
self.suggest_cloning_inner(err, ty, expr);
}
} else if let ty::Adt(def, args) = ty.kind()
&& def.did().as_local().is_some()
&& def.variants().iter().all(|variant| {
@@ -1505,7 +1512,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
if let hir::ExprKind::AddrOf(_, _, borrowed_expr) = expr.kind
&& let Some(ty) = typeck_results.expr_ty_opt(borrowed_expr)
{
self.suggest_cloning(&mut err, ty, borrowed_expr, Some(move_spans));
self.suggest_cloning(&mut err, place.as_ref(), ty, borrowed_expr, Some(move_spans));
} else if typeck_results.expr_adjustments(expr).first().is_some_and(|adj| {
matches!(
adj.kind,
@@ -1518,7 +1525,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
)
}) && let Some(ty) = typeck_results.expr_ty_opt(expr)
{
self.suggest_cloning(&mut err, ty, expr, Some(move_spans));
self.suggest_cloning(&mut err, place.as_ref(), ty, expr, Some(move_spans));
}
}
self.buffer_error(err);

39
compiler/rustc_borrowck/src/diagnostics/move_errors.rs
View File

@@ -325,25 +325,17 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
self.cannot_move_out_of(span, &description)
}
fn suggest_clone_of_captured_var_in_move_closure(
pub(in crate::diagnostics) fn suggest_clone_of_captured_var_in_move_closure(
&self,
err: &mut Diag<'_>,
upvar_hir_id: HirId,
upvar_name: &str,
use_spans: Option<UseSpans<'tcx>>,
) {
let tcx = self.infcx.tcx;
let typeck_results = tcx.typeck(self.mir_def_id());
let Some(use_spans) = use_spans else { return };
// We only care about the case where a closure captured a binding.
let UseSpans::ClosureUse { args_span, .. } = use_spans else { return };
let Some(body_id) = tcx.hir_node(self.mir_hir_id()).body_id() else { return };
// Fetch the type of the expression corresponding to the closure-captured binding.
let Some(captured_ty) = typeck_results.node_type_opt(upvar_hir_id) else { return };
if !self.implements_clone(captured_ty) {
// We only suggest cloning the captured binding if the type can actually be cloned.
return;
};
// Find the closure that captured the binding.
let mut expr_finder = FindExprBySpan::new(args_span, tcx);
expr_finder.include_closures = true;
@@ -396,7 +388,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
.indentation_before(stmt.span)
.unwrap_or_else(|| " ".to_string());
err.multipart_suggestion_verbose(
"clone the value before moving it into the closure",
"consider cloning the value before moving it into the closure",
vec![
(
stmt.span.shrink_to_lo(),
@@ -426,7 +418,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
.indentation_before(closure_expr.span)
.unwrap_or_else(|| " ".to_string());
err.multipart_suggestion_verbose(
"clone the value before moving it into the closure",
"consider cloning the value before moving it into the closure",
vec![
(
closure_expr.span.shrink_to_lo(),
@@ -523,20 +515,12 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
);
let closure_span = tcx.def_span(def_id);
let mut err = self
.cannot_move_out_of(span, &place_description)
self.cannot_move_out_of(span, &place_description)
.with_span_label(upvar_span, "captured outer variable")
.with_span_label(
closure_span,
format!("captured by this `{closure_kind}` closure"),
);
self.suggest_clone_of_captured_var_in_move_closure(
&mut err,
upvar_hir_id,
&upvar_name,
use_spans,
);
err
)
}
_ => {
let source = self.borrowed_content_source(deref_base);
@@ -597,7 +581,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
};
if let Some(expr) = self.find_expr(span) {
self.suggest_cloning(err, place_ty, expr, None);
self.suggest_cloning(err, move_from.as_ref(), place_ty, expr, None);
}
err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label {
@@ -629,7 +613,13 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
};
if let Some(expr) = self.find_expr(use_span) {
self.suggest_cloning(err, place_ty, expr, Some(use_spans));
self.suggest_cloning(
err,
original_path.as_ref(),
place_ty,
expr,
Some(use_spans),
);
}
err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label {
@@ -832,7 +822,8 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
let place_desc = self.local_name(*local).map(|sym| format!("`{sym}`"));
if let Some(expr) = self.find_expr(binding_span) {
self.suggest_cloning(err, bind_to.ty, expr, None);
let local_place: PlaceRef<'tcx> = (*local).into();
self.suggest_cloning(err, local_place, bind_to.ty, expr, None);
}
err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label {

2
tests/ui/borrowck/borrowck-move-by-capture.stderr
View File

@@ -12,7 +12,7 @@ LL | let _h = to_fn_once(move || -> isize { *bar });
| | move occurs because `bar` has type `Box<isize>`, which does not implement the `Copy` trait
| `bar` is moved here
|
help: clone the value before moving it into the closure
help: consider cloning the value before moving it into the closure
|
LL ~ let value = bar.clone();
LL ~ let _h = to_fn_once(move || -> isize { value });

6
tests/ui/borrowck/borrowck-move-moved-value-into-closure.stderr
View File

@@ -12,6 +12,12 @@ LL | call_f(move|| { *t + 1 });
| ^^^^^^ -- use occurs due to use in closure
| |
| value used here after move
|
help: consider cloning the value before moving it into the closure
|
LL ~ let value = t.clone();
LL ~ call_f(move|| { value + 1 });
|
error: aborting due to 1 previous error

11
tests/ui/moves/moves-based-on-type-capture-clause-bad.fixed Normal file
View File

@@ -0,0 +1,11 @@
//@ run-rustfix
use std::thread;
fn main() {
let x = "Hello world!".to_string();
let value = x.clone();
thread::spawn(move || {
println!("{}", value);
});
println!("{}", x); //~ ERROR borrow of moved value
}

1
tests/ui/moves/moves-based-on-type-capture-clause-bad.rs
View File

@@ -1,3 +1,4 @@
//@ run-rustfix
use std::thread;
fn main() {

8
tests/ui/moves/moves-based-on-type-capture-clause-bad.stderr
View File

@@ -1,5 +1,5 @@
error[E0382]: borrow of moved value: `x`
--> $DIR/moves-based-on-type-capture-clause-bad.rs:8:20
--> $DIR/moves-based-on-type-capture-clause-bad.rs:9:20
|
LL | let x = "Hello world!".to_string();
| - move occurs because `x` has type `String`, which does not implement the `Copy` trait
@@ -12,6 +12,12 @@ LL | println!("{}", x);
| ^ value borrowed here after move
|
= note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider cloning the value before moving it into the closure
|
LL ~ let value = x.clone();
LL ~ thread::spawn(move || {
LL ~ println!("{}", value);
|
error: aborting due to 1 previous error

0
tests/ui/no-capture-arc.rs → tests/ui/moves/no-capture-arc.rs
View File

6
tests/ui/no-capture-arc.stderr → tests/ui/moves/no-capture-arc.stderr
View File

@@ -13,6 +13,12 @@ LL | assert_eq!((*arc_v)[2], 3);
| ^^^^^ value borrowed here after move
|
= note: borrow occurs due to deref coercion to `Vec<i32>`
help: consider cloning the value before moving it into the closure
|
LL ~ let value = arc_v.clone();
LL ~ thread::spawn(move|| {
LL ~ assert_eq!((*value)[3], 4);
|
error: aborting due to 1 previous error

17
tests/ui/moves/no-reuse-move-arc.fixed Normal file
View File

@@ -0,0 +1,17 @@
//@ run-rustfix
use std::sync::Arc;
use std::thread;
fn main() {
let v = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
let arc_v = Arc::new(v);
let value = arc_v.clone();
thread::spawn(move|| {
assert_eq!((*value)[3], 4);
});
assert_eq!((*arc_v)[2], 3); //~ ERROR borrow of moved value: `arc_v`
println!("{:?}", *arc_v);
}

1
tests/ui/no-reuse-move-arc.rs → tests/ui/moves/no-reuse-move-arc.rs
View File

@@ -1,3 +1,4 @@
//@ run-rustfix
use std::sync::Arc;
use std::thread;

8
tests/ui/no-reuse-move-arc.stderr → tests/ui/moves/no-reuse-move-arc.stderr
View File

@@ -1,5 +1,5 @@
error[E0382]: borrow of moved value: `arc_v`
--> $DIR/no-reuse-move-arc.rs:12:18
--> $DIR/no-reuse-move-arc.rs:13:18
|
LL | let arc_v = Arc::new(v);
| ----- move occurs because `arc_v` has type `Arc<Vec<i32>>`, which does not implement the `Copy` trait
@@ -13,6 +13,12 @@ LL | assert_eq!((*arc_v)[2], 3);
| ^^^^^ value borrowed here after move
|
= note: borrow occurs due to deref coercion to `Vec<i32>`
help: consider cloning the value before moving it into the closure
|
LL ~ let value = arc_v.clone();
LL ~ thread::spawn(move|| {
LL ~ assert_eq!((*value)[3], 4);
|
error: aborting due to 1 previous error

2
tests/ui/suggestions/option-content-move3.stderr
View File

@@ -79,7 +79,7 @@ LL | let x = var;
| variable moved due to use in closure
| move occurs because `var` has type `NotCopyableButCloneable`, which does not implement the `Copy` trait
|
help: clone the value before moving it into the closure
help: consider cloning the value before moving it into the closure
|
LL ~ {
LL + let value = var.clone();