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Rollup merge of #101285 - TaKO8Ki:do-not-suggest-adding-move-when-closure-is-already-marked-as-move, r=oli-obk

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Do not suggest adding `move` to closure when `move` is already used

Fixes #101227
This commit is contained in:
Matthias Krüger 2022-09-01 21:37:21 +02:00 • committed by GitHub
commit 1bafe0b020
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3 changed files with 37 additions and 3 deletions
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14
compiler/rustc_borrowck/src/diagnostics/region_errors.rs
View file

@ -902,7 +902,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
hir::ExprKind::MethodCall(.., args, _) => {
// only the first closre parameter of the method. args[0] is MethodCall PathSegment
for i in 1..args.len() {
if let hir::ExprKind::Closure(..) = args[i].kind {
if let hir::ExprKind::Closure(hir::Closure {
capture_clause: hir::CaptureBy::Ref,
..
}) = args[i].kind
{
closure_span = Some(args[i].span.shrink_to_lo());
break;
}
@ -911,7 +915,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
hir::ExprKind::Block(blk, _) => {
if let Some(ref expr) = blk.expr {
// only when the block is a closure
if let hir::ExprKind::Closure(..) = expr.kind {
if let hir::ExprKind::Closure(hir::Closure {
capture_clause: hir::CaptureBy::Ref,
..
}) = expr.kind
{
closure_span = Some(expr.span.shrink_to_lo());
}
}
@ -921,7 +929,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
if let Some(closure_span) = closure_span {
diag.span_suggestion_verbose(
closure_span,
format!("consider adding 'move' keyword before the nested closure"),
"consider adding 'move' keyword before the nested closure",
"move ",
Applicability::MaybeIncorrect,
);

8
src/test/ui/borrowck/do-not-suggest-adding-move-when-closure-is-already-marked-as-move.rs Normal file
View file

@ -0,0 +1,8 @@
fn main() {
let mut vec: Vec<i32> = Vec::new();
let closure = move || {
vec.clear();
let mut iter = vec.iter();
move || { iter.next() } //~ ERROR captured variable cannot escape `FnMut` closure bod
};
}

18
src/test/ui/borrowck/do-not-suggest-adding-move-when-closure-is-already-marked-as-move.stderr Normal file
View file

@ -0,0 +1,18 @@
error: captured variable cannot escape `FnMut` closure body
--> $DIR/do-not-suggest-adding-move-when-closure-is-already-marked-as-move.rs:6:9
|
LL | let mut vec: Vec<i32> = Vec::new();
| ------- variable defined here
LL | let closure = move || {
| - inferred to be a `FnMut` closure
LL | vec.clear();
| --- variable captured here
LL | let mut iter = vec.iter();
LL | move || { iter.next() }
| ^^^^^^^^^^^^^^^^^^^^^^^ returns a closure that contains a reference to a captured variable, which then escapes the closure body
|
= note: `FnMut` closures only have access to their captured variables while they are executing...
= note: ...therefore, they cannot allow references to captured variables to escape
error: aborting due to previous error