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Rollup merge of #87460 - FabianWolff:issue-87456, r=Aaron1011

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Point to closure when emitting 'cannot move out' for captured variable

Attempts to fix #87456. The error message now points to the capturing closure, but I was not able to explain _why_ the closure implements `Fn` or `FnMut` (`TypeckResults::closure_kind_origins` did not contain anything for the closure in question).

cc `@Aaron1011`
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Guillaume Gomez 2021-09-17 17:41:13 +02:00 • committed by GitHub
commit aed7f00097
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13 changed files with 503 additions and 215 deletions
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12
compiler/rustc_borrowck/src/diagnostics/move_errors.rs
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@ -336,15 +336,15 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
if def_id.as_local() == Some(self.mir_def_id()) && upvar_field.is_some() =>
{
let closure_kind_ty = closure_substs.as_closure().kind_ty();
let closure_kind = closure_kind_ty.to_opt_closure_kind();
let capture_description = match closure_kind {
Some(ty::ClosureKind::Fn) => "captured variable in an `Fn` closure",
Some(ty::ClosureKind::FnMut) => "captured variable in an `FnMut` closure",
let closure_kind = match closure_kind_ty.to_opt_closure_kind() {
Some(kind @ (ty::ClosureKind::Fn | ty::ClosureKind::FnMut)) => kind,
Some(ty::ClosureKind::FnOnce) => {
bug!("closure kind does not match first argument type")
}
None => bug!("closure kind not inferred by borrowck"),
};
let capture_description =
format!("captured variable in an `{}` closure", closure_kind);
let upvar = &self.upvars[upvar_field.unwrap().index()];
let upvar_hir_id = upvar.place.get_root_variable();
@ -368,6 +368,10 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
let mut diag = self.cannot_move_out_of(span, &place_description);
diag.span_label(upvar_span, "captured outer variable");
diag.span_label(
self.body.span,
format!("captured by this `{}` closure", closure_kind),
);
diag
}