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|
use Context::*;
use rustc_hir as hir;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::intravisit::{self, Visitor};
use rustc_hir::{Destination, Movability, Node};
use rustc_middle::hir::map::Map;
use rustc_middle::hir::nested_filter;
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::TyCtxt;
use rustc_session::Session;
use rustc_span::hygiene::DesugaringKind;
use rustc_span::Span;
use crate::errors::{
BreakInsideAsyncBlock, BreakInsideClosure, BreakNonLoop, ContinueLabeledBlock, OutsideLoop,
UnlabeledCfInWhileCondition, UnlabeledInLabeledBlock,
};
#[derive(Clone, Copy, Debug, PartialEq)]
enum Context {
Normal,
Loop(hir::LoopSource),
Closure(Span),
AsyncClosure(Span),
LabeledBlock,
AnonConst,
}
#[derive(Copy, Clone)]
struct CheckLoopVisitor<'a, 'hir> {
sess: &'a Session,
hir_map: Map<'hir>,
cx: Context,
}
fn check_mod_loops(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
tcx.hir().visit_item_likes_in_module(
module_def_id,
&mut CheckLoopVisitor { sess: &tcx.sess, hir_map: tcx.hir(), cx: Normal },
);
}
pub(crate) fn provide(providers: &mut Providers) {
*providers = Providers { check_mod_loops, ..*providers };
}
impl<'a, 'hir> Visitor<'hir> for CheckLoopVisitor<'a, 'hir> {
type NestedFilter = nested_filter::OnlyBodies;
fn nested_visit_map(&mut self) -> Self::Map {
self.hir_map
}
fn visit_anon_const(&mut self, c: &'hir hir::AnonConst) {
self.with_context(AnonConst, |v| intravisit::walk_anon_const(v, c));
}
fn visit_expr(&mut self, e: &'hir hir::Expr<'hir>) {
match e.kind {
hir::ExprKind::Loop(ref b, _, source, _) => {
self.with_context(Loop(source), |v| v.visit_block(&b));
}
hir::ExprKind::Closure(&hir::Closure {
ref fn_decl,
body,
fn_decl_span,
movability,
..
}) => {
let cx = if let Some(Movability::Static) = movability {
AsyncClosure(fn_decl_span)
} else {
Closure(fn_decl_span)
};
self.visit_fn_decl(&fn_decl);
self.with_context(cx, |v| v.visit_nested_body(body));
}
hir::ExprKind::Block(ref b, Some(_label)) => {
self.with_context(LabeledBlock, |v| v.visit_block(&b));
}
hir::ExprKind::Break(break_label, ref opt_expr) => {
if let Some(e) = opt_expr {
self.visit_expr(e);
}
if self.require_label_in_labeled_block(e.span, &break_label, "break") {
// If we emitted an error about an unlabeled break in a labeled
// block, we don't need any further checking for this break any more
return;
}
let loop_id = match break_label.target_id {
Ok(loop_id) => Some(loop_id),
Err(hir::LoopIdError::OutsideLoopScope) => None,
Err(hir::LoopIdError::UnlabeledCfInWhileCondition) => {
self.sess.emit_err(UnlabeledCfInWhileCondition {
span: e.span,
cf_type: "break",
});
None
}
Err(hir::LoopIdError::UnresolvedLabel) => None,
};
if let Some(Node::Block(_)) = loop_id.and_then(|id| self.hir_map.find(id)) {
return;
}
if let Some(break_expr) = opt_expr {
let (head, loop_label, loop_kind) = if let Some(loop_id) = loop_id {
match self.hir_map.expect_expr(loop_id).kind {
hir::ExprKind::Loop(_, label, source, sp) => {
(Some(sp), label, Some(source))
}
ref r => {
span_bug!(e.span, "break label resolved to a non-loop: {:?}", r)
}
}
} else {
(None, None, None)
};
match loop_kind {
None | Some(hir::LoopSource::Loop) => (),
Some(kind) => {
let suggestion = format!(
"break{}",
break_label
.label
.map_or_else(String::new, |l| format!(" {}", l.ident))
);
self.sess.emit_err(BreakNonLoop {
span: e.span,
head,
kind: kind.name(),
suggestion,
loop_label,
break_label: break_label.label,
break_expr_kind: &break_expr.kind,
break_expr_span: break_expr.span,
});
}
}
}
self.require_break_cx("break", e.span);
}
hir::ExprKind::Continue(destination) => {
self.require_label_in_labeled_block(e.span, &destination, "continue");
match destination.target_id {
Ok(loop_id) => {
if let Node::Block(block) = self.hir_map.find(loop_id).unwrap() {
self.sess.emit_err(ContinueLabeledBlock {
span: e.span,
block_span: block.span,
});
}
}
Err(hir::LoopIdError::UnlabeledCfInWhileCondition) => {
self.sess.emit_err(UnlabeledCfInWhileCondition {
span: e.span,
cf_type: "continue",
});
}
Err(_) => {}
}
self.require_break_cx("continue", e.span)
}
_ => intravisit::walk_expr(self, e),
}
}
}
impl<'a, 'hir> CheckLoopVisitor<'a, 'hir> {
fn with_context<F>(&mut self, cx: Context, f: F)
where
F: FnOnce(&mut CheckLoopVisitor<'a, 'hir>),
{
let old_cx = self.cx;
self.cx = cx;
f(self);
self.cx = old_cx;
}
fn require_break_cx(&self, name: &str, span: Span) {
match self.cx {
LabeledBlock | Loop(_) => {}
Closure(closure_span) => {
self.sess.emit_err(BreakInsideClosure { span, closure_span, name });
}
AsyncClosure(closure_span) => {
self.sess.emit_err(BreakInsideAsyncBlock { span, closure_span, name });
}
Normal | AnonConst => {
self.sess.emit_err(OutsideLoop { span, name });
}
}
}
fn require_label_in_labeled_block(
&mut self,
span: Span,
label: &Destination,
cf_type: &str,
) -> bool {
if !span.is_desugaring(DesugaringKind::QuestionMark)
&& self.cx == LabeledBlock
&& label.label.is_none()
{
self.sess.emit_err(UnlabeledInLabeledBlock { span, cf_type });
return true;
}
false
}
}
|
