Mirrors/rust-analyzer
2
0
Fork 0
mirror of https://github.com/rust-lang/rust-analyzer synced 2024-11-14 17:07:26 +00:00
Code Issues Projects Releases Packages Wiki Activity

Properly infer tuple patterns when encountering ellipsis

Browse source
This commit is contained in:
Lukas Wirth 2020-11-24 13:41:21 +01:00
parent 6294286fee
commit 35dd62e915
2 changed files with 64 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

25
crates/hir_ty/src/infer/pat.rs
View file

@ -111,20 +111,29 @@ impl<'a> InferenceContext<'a> {
let expected = expected;
let ty = match &body[pat] {
Pat::Tuple { ref args, .. } => {
Pat::Tuple { ref args, ellipsis } => {
let expectations = match expected.as_tuple() {
Some(parameters) => &*parameters.0,
_ => &[],
};
let expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown));
let inner_tys = args
.iter()
.zip(expectations_iter)
.map(|(&pat, ty)| self.infer_pat(pat, ty, default_bm))
.collect();
let (pre, post) = match ellipsis {
&Some(idx) => args.split_at(idx),
None => (&args[..], &[][..]),
};
let uncovered_range = pre.len()..expectations.len().saturating_sub(post.len());
let mut expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown));
let mut infer_pat = |(&pat, ty)| self.infer_pat(pat, ty, default_bm);
Ty::apply(TypeCtor::Tuple { cardinality: args.len() as u16 }, Substs(inner_tys))
let mut inner_tys = Vec::with_capacity(expectations.len());
inner_tys.extend(pre.iter().zip(expectations_iter.by_ref()).map(&mut infer_pat));
inner_tys.extend(expectations_iter.by_ref().take(uncovered_range.len()).cloned());
inner_tys.extend(post.iter().zip(expectations_iter).map(infer_pat));
Ty::apply(
TypeCtor::Tuple { cardinality: inner_tys.len() as u16 },
Substs(inner_tys.into()),
)
}
Pat::Or(ref pats) => {
if let Some((first_pat, rest)) = pats.split_first() {

47
crates/hir_ty/src/tests/patterns.rs
View file

@ -679,3 +679,50 @@ fn box_pattern() {
"#]],
);
}
#[test]
fn tuple_ellipsis_pattern() {
check_infer(
r#"
fn foo(tuple: (u8, i16, f32)) {
match tuple {
(.., b, c) => {},
(a, .., c) => {},
(a, b, ..) => {},
(a, b) => {/*too short*/}
(a, b, c, d) => {/*too long*/}
_ => {}
}
}"#,
expect![[r#"
7..12 'tuple': (u8, i16, f32)
30..224 '{ ... } }': ()
36..222 'match ... }': ()
42..47 'tuple': (u8, i16, f32)
58..68 '(.., b, c)': (u8, i16, f32)
63..64 'b': i16
66..67 'c': f32
72..74 '{}': ()
84..94 '(a, .., c)': (u8, i16, f32)
85..86 'a': u8
92..93 'c': f32
98..100 '{}': ()
110..120 '(a, b, ..)': (u8, i16, f32)
111..112 'a': u8
114..115 'b': i16
124..126 '{}': ()
136..142 '(a, b)': (u8, i16, f32)
137..138 'a': u8
140..141 'b': i16
146..161 '{/*too short*/}': ()
170..182 '(a, b, c, d)': (u8, i16, f32, {unknown})
171..172 'a': u8
174..175 'b': i16
177..178 'c': f32
180..181 'd': {unknown}
186..200 '{/*too long*/}': ()
209..210 '_': (u8, i16, f32)
214..216 '{}': ()
"#]],
);
}