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refactor the `pat_is_catchall` logic

This commit is contained in:
Ariel Ben-Yehuda 2016-09-24 18:23:46 +03:00
parent 732f22745d
commit 48387c8bd9
1 changed files with 20 additions and 20 deletions
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40
src/librustc_const_eval/check_match.rs
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@ -74,21 +74,6 @@ impl<'a, 'tcx> Pattern<'a, 'tcx> {
return pat;
}
/// Checks for common cases of "catchall" patterns that may not be intended as such.
fn is_catchall(self, dm: &DefMap) -> bool {
fn is_catchall(dm: &DefMap, pat: &Pat) -> bool {
match pat.node {
PatKind::Binding(.., None) => true,
PatKind::Binding(.., Some(ref s)) => is_catchall(dm, s),
PatKind::Ref(ref s, _) => is_catchall(dm, s),
PatKind::Tuple(ref v, _) => v.iter().all(|p|is_catchall(dm, &p)),
_ => false
}
}
is_catchall(dm, self.pat)
}
fn span(self) -> Span {
self.pat.span
}
@ -339,11 +324,25 @@ fn check_for_static_nan(cx: &MatchCheckCtxt, pat: &Pat) {
});
}
/// Checks for common cases of "catchall" patterns that may not be intended as such.
fn pat_is_catchall(dm: &DefMap, pat: &Pat) -> bool {
match pat.node {
PatKind::Binding(.., None) => true,
PatKind::Binding(.., Some(ref s)) => pat_is_catchall(dm, s),
PatKind::Ref(ref s, _) => pat_is_catchall(dm, s),
PatKind::Tuple(ref v, _) => v.iter().all(|p| {
pat_is_catchall(dm, &p)
}),
_ => false
}
}
// Check for unreachable patterns
fn check_arms(cx: &MatchCheckCtxt,
arms: &[(Vec<P<Pat>>, Option<&hir::Expr>)],
source: hir::MatchSource) {
let mut seen = Matrix(vec![]);
let mut catchall = None;
let mut printed_if_let_err = false;
for &(ref pats, guard) in arms {
for pat in pats {
@ -393,11 +392,8 @@ fn check_arms(cx: &MatchCheckCtxt,
"unreachable pattern");
err.span_label(pat.span, &format!("this is an unreachable pattern"));
// if we had a catchall pattern, hint at that
for row in &seen.0 {
if row[0].is_catchall(&cx.tcx.def_map.borrow()) {
span_note!(err, row[0].span(),
"this pattern matches any value");
}
if let Some(catchall) = catchall {
err.span_note(catchall, "this pattern matches any value");
}
err.emit();
},
@ -414,6 +410,10 @@ fn check_arms(cx: &MatchCheckCtxt,
let Matrix(mut rows) = seen;
rows.push(v);
seen = Matrix(rows);
if catchall.is_none() && pat_is_catchall(&cx.tcx.def_map.borrow(), pat) {
catchall = Some(pat.span);
}
}
}
}