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NLL: Add closure cannot be moved note. #57099

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merged 1 commit into from
Jan 5, 2019
Merged

NLL: Add closure cannot be moved note. #57099

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82 changes: 43 additions & 39 deletions src/librustc_mir/borrow_check/error_reporting.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -123,7 +123,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
Origin::Mir,
);

self.add_closure_invoked_twice_with_moved_variable_suggestion(
self.add_moved_or_invoked_closure_note(
context.loc,
used_place,
&mut err,
Expand Down Expand Up @@ -1331,7 +1331,8 @@ enum StorageDeadOrDrop<'tcx> {

impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {

/// Adds a suggestion when a closure is invoked twice with a moved variable.
/// Adds a suggestion when a closure is invoked twice with a moved variable or when a closure
/// is moved after being invoked.
///
/// ```text
/// note: closure cannot be invoked more than once because it moves the variable `dict` out of
Expand All @@ -1341,30 +1342,18 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
/// LL | for (key, value) in dict {
/// | ^^^^
/// ```
pub(super) fn add_closure_invoked_twice_with_moved_variable_suggestion(
pub(super) fn add_moved_or_invoked_closure_note(
&self,
location: Location,
place: &Place<'tcx>,
diag: &mut DiagnosticBuilder<'_>,
) {
debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place);
let mut target = place.local();
debug!(
"add_closure_invoked_twice_with_moved_variable_suggestion: location={:?} place={:?} \
target={:?}",
location, place, target,
);
for stmt in &self.mir[location.block].statements[location.statement_index..] {
debug!(
"add_closure_invoked_twice_with_moved_variable_suggestion: stmt={:?} \
target={:?}",
stmt, target,
);
debug!("add_moved_or_invoked_closure_note: stmt={:?} target={:?}", stmt, target);
if let StatementKind::Assign(into, box Rvalue::Use(from)) = &stmt.kind {
debug!(
"add_closure_invoked_twice_with_moved_variable_suggestion: into={:?} \
from={:?}",
into, from,
);
debug!("add_fnonce_closure_note: into={:?} from={:?}", into, from);
match from {
Operand::Copy(ref place) |
Operand::Move(ref place) if target == place.local() =>
Expand All @@ -1374,12 +1363,9 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
}
}


// Check if we are attempting to call a closure after it has been invoked.
let terminator = self.mir[location.block].terminator();
debug!(
"add_closure_invoked_twice_with_moved_variable_suggestion: terminator={:?}",
terminator,
);
debug!("add_moved_or_invoked_closure_note: terminator={:?}", terminator);
if let TerminatorKind::Call {
func: Operand::Constant(box Constant {
literal: ty::Const { ty: &ty::TyS { sty: ty::TyKind::FnDef(id, _), .. }, .. },
Expand All @@ -1388,41 +1374,59 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
args,
..
} = &terminator.kind {
debug!("add_closure_invoked_twice_with_moved_variable_suggestion: id={:?}", id);
debug!("add_moved_or_invoked_closure_note: id={:?}", id);
if self.infcx.tcx.parent(id) == self.infcx.tcx.lang_items().fn_once_trait() {
let closure = match args.first() {
Some(Operand::Copy(ref place)) |
Some(Operand::Move(ref place)) if target == place.local() =>
place.local().unwrap(),
_ => return,
};
debug!(
"add_closure_invoked_twice_with_moved_variable_suggestion: closure={:?}",
closure,
);

if let ty::TyKind::Closure(did, _substs) = self.mir.local_decls[closure].ty.sty {
let node_id = match self.infcx.tcx.hir().as_local_node_id(did) {
Some(node_id) => node_id,
_ => return,
};
debug!("add_moved_or_invoked_closure_note: closure={:?}", closure);
if let ty::TyKind::Closure(did, _) = self.mir.local_decls[closure].ty.sty {
let node_id = self.infcx.tcx.hir().as_local_node_id(did).unwrap();
let hir_id = self.infcx.tcx.hir().node_to_hir_id(node_id);

if let Some((
span, name
)) = self.infcx.tcx.typeck_tables_of(did).closure_kind_origins().get(hir_id) {
if let Some((span, name)) = self.infcx.tcx.typeck_tables_of(did)
.closure_kind_origins()
.get(hir_id)
{
diag.span_note(
*span,
&format!(
"closure cannot be invoked more than once because it \
moves the variable `{}` out of its environment",
name,
"closure cannot be invoked more than once because it moves the \
variable `{}` out of its environment",
name,
),
);
return;
}
}
}
}

// Check if we are just moving a closure after it has been invoked.
if let Some(target) = target {
if let ty::TyKind::Closure(did, _) = self.mir.local_decls[target].ty.sty {
let node_id = self.infcx.tcx.hir().as_local_node_id(did).unwrap();
let hir_id = self.infcx.tcx.hir().node_to_hir_id(node_id);

if let Some((span, name)) = self.infcx.tcx.typeck_tables_of(did)
.closure_kind_origins()
.get(hir_id)
{
diag.span_note(
*span,
&format!(
"closure cannot be moved more than once as it is not `Copy` due to \
moving the variable `{}` out of its environment",
name
),
);
}
}
}
}

/// End-user visible description of `place` if one can be found. If the
Expand Down
6 changes: 6 additions & 0 deletions src/test/ui/not-copy-closure.nll.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,12 @@ LL | let b = hello;
| ----- value moved here
LL | let c = hello; //~ ERROR use of moved value: `hello` [E0382]
| ^^^^^ value used here after move
|
note: closure cannot be moved more than once as it is not `Copy` due to moving the variable `a` out of its environment
--> $DIR/not-copy-closure.rs:6:9
|
LL | a += 1;
| ^

error: aborting due to previous error

Expand Down