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Stabilize move_ref_pattern

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This commit is contained in:
Amjad Alsharafi 2020-08-31 02:59:56 +08:00
parent 715e9340a1
commit da700cba08
49 changed files with 271 additions and 492 deletions
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70
compiler/rustc_mir_build/src/thir/pattern/check_match.rs
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@ -71,13 +71,13 @@ impl<'tcx> Visitor<'tcx> for MatchVisitor<'_, 'tcx> {
hir::LocalSource::AwaitDesugar => ("`await` future binding", None),
};
self.check_irrefutable(&loc.pat, msg, sp);
self.check_patterns(false, &loc.pat);
self.check_patterns(&loc.pat);
}
fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
intravisit::walk_param(self, param);
self.check_irrefutable(&param.pat, "function argument", None);
self.check_patterns(false, &param.pat);
self.check_patterns(&param.pat);
}
}
@ -119,10 +119,7 @@ impl PatCtxt<'_, '_> {
}
impl<'tcx> MatchVisitor<'_, 'tcx> {
fn check_patterns(&mut self, has_guard: bool, pat: &Pat<'_>) {
if !self.tcx.features().move_ref_pattern {
check_legality_of_move_bindings(self, has_guard, pat);
}
fn check_patterns(&mut self, pat: &Pat<'_>) {
pat.walk_always(|pat| check_borrow_conflicts_in_at_patterns(self, pat));
if !self.tcx.features().bindings_after_at {
check_legality_of_bindings_in_at_patterns(self, pat);
@ -165,7 +162,7 @@ impl<'tcx> MatchVisitor<'_, 'tcx> {
) {
for arm in arms {
// Check the arm for some things unrelated to exhaustiveness.
self.check_patterns(arm.guard.is_some(), &arm.pat);
self.check_patterns(&arm.pat);
}
let mut cx = self.new_cx(scrut.hir_id);
@ -601,65 +598,6 @@ fn is_binding_by_move(cx: &MatchVisitor<'_, '_>, hir_id: HirId, span: Span) -> b
!cx.typeck_results.node_type(hir_id).is_copy_modulo_regions(cx.tcx.at(span), cx.param_env)
}
/// Check the legality of legality of by-move bindings.
fn check_legality_of_move_bindings(cx: &mut MatchVisitor<'_, '_>, has_guard: bool, pat: &Pat<'_>) {
let sess = cx.tcx.sess;
let typeck_results = cx.typeck_results;
// Find all by-ref spans.
let mut by_ref_spans = Vec::new();
pat.each_binding(|_, hir_id, span, _| {
if let Some(ty::BindByReference(_)) =
typeck_results.extract_binding_mode(sess, hir_id, span)
{
by_ref_spans.push(span);
}
});
// Find bad by-move spans:
let by_move_spans = &mut Vec::new();
let mut check_move = |p: &Pat<'_>, sub: Option<&Pat<'_>>| {
// Check legality of moving out of the enum.
//
// `x @ Foo(..)` is legal, but `x @ Foo(y)` isn't.
if sub.map_or(false, |p| p.contains_bindings()) {
struct_span_err!(sess, p.span, E0007, "cannot bind by-move with sub-bindings")
.span_label(p.span, "binds an already bound by-move value by moving it")
.emit();
} else if !has_guard && !by_ref_spans.is_empty() {
by_move_spans.push(p.span);
}
};
pat.walk_always(|p| {
if let hir::PatKind::Binding(.., sub) = &p.kind {
if let Some(ty::BindByValue(_)) =
typeck_results.extract_binding_mode(sess, p.hir_id, p.span)
{
if is_binding_by_move(cx, p.hir_id, p.span) {
check_move(p, sub.as_deref());
}
}
}
});
// Found some bad by-move spans, error!
if !by_move_spans.is_empty() {
let mut err = feature_err(
&sess.parse_sess,
sym::move_ref_pattern,
by_move_spans.clone(),
"binding by-move and by-ref in the same pattern is unstable",
);
for span in by_ref_spans.iter() {
err.span_label(*span, "by-ref pattern here");
}
for span in by_move_spans.iter() {
err.span_label(*span, "by-move pattern here");
}
err.emit();
}
}
/// Check that there are no borrow or move conflicts in `binding @ subpat` patterns.
///
/// For example, this would reject: