1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
//! Type inference for patterns.
use std::iter::repeat;
use std::sync::Arc;
use test_utils::tested_by;
use super::{BindingMode, InferenceContext};
use crate::{
db::HirDatabase,
expr::{BindingAnnotation, Pat, PatId, RecordFieldPat},
ty::{Mutability, Substs, Ty, TypeCtor, TypeWalk},
Name, Path,
};
impl<'a, D: HirDatabase> InferenceContext<'a, D> {
fn infer_tuple_struct_pat(
&mut self,
path: Option<&Path>,
subpats: &[PatId],
expected: &Ty,
default_bm: BindingMode,
) -> Ty {
let (ty, def) = self.resolve_variant(path);
self.unify(&ty, expected);
let substs = ty.substs().unwrap_or_else(Substs::empty);
for (i, &subpat) in subpats.iter().enumerate() {
let expected_ty = def
.and_then(|d| d.field(self.db, &Name::new_tuple_field(i)))
.map_or(Ty::Unknown, |field| field.ty(self.db))
.subst(&substs);
let expected_ty = self.normalize_associated_types_in(expected_ty);
self.infer_pat(subpat, &expected_ty, default_bm);
}
ty
}
fn infer_record_pat(
&mut self,
path: Option<&Path>,
subpats: &[RecordFieldPat],
expected: &Ty,
default_bm: BindingMode,
id: PatId,
) -> Ty {
let (ty, def) = self.resolve_variant(path);
if let Some(variant) = def {
self.write_variant_resolution(id.into(), variant);
}
self.unify(&ty, expected);
let substs = ty.substs().unwrap_or_else(Substs::empty);
for subpat in subpats {
let matching_field = def.and_then(|it| it.field(self.db, &subpat.name));
let expected_ty =
matching_field.map_or(Ty::Unknown, |field| field.ty(self.db)).subst(&substs);
let expected_ty = self.normalize_associated_types_in(expected_ty);
self.infer_pat(subpat.pat, &expected_ty, default_bm);
}
ty
}
pub(super) fn infer_pat(
&mut self,
pat: PatId,
mut expected: &Ty,
mut default_bm: BindingMode,
) -> Ty {
let body = Arc::clone(&self.body); // avoid borrow checker problem
let is_non_ref_pat = match &body[pat] {
Pat::Tuple(..)
| Pat::TupleStruct { .. }
| Pat::Record { .. }
| Pat::Range { .. }
| Pat::Slice { .. } => true,
// FIXME: Path/Lit might actually evaluate to ref, but inference is unimplemented.
Pat::Path(..) | Pat::Lit(..) => true,
Pat::Wild | Pat::Bind { .. } | Pat::Ref { .. } | Pat::Missing => false,
};
if is_non_ref_pat {
while let Some((inner, mutability)) = expected.as_reference() {
expected = inner;
default_bm = match default_bm {
BindingMode::Move => BindingMode::Ref(mutability),
BindingMode::Ref(Mutability::Shared) => BindingMode::Ref(Mutability::Shared),
BindingMode::Ref(Mutability::Mut) => BindingMode::Ref(mutability),
}
}
} else if let Pat::Ref { .. } = &body[pat] {
tested_by!(match_ergonomics_ref);
// When you encounter a `&pat` pattern, reset to Move.
// This is so that `w` is by value: `let (_, &w) = &(1, &2);`
default_bm = BindingMode::Move;
}
// Lose mutability.
let default_bm = default_bm;
let expected = expected;
let ty = match &body[pat] {
Pat::Tuple(ref args) => {
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();
Ty::apply(TypeCtor::Tuple { cardinality: args.len() as u16 }, Substs(inner_tys))
}
Pat::Ref { pat, mutability } => {
let expectation = match expected.as_reference() {
Some((inner_ty, exp_mut)) => {
if *mutability != exp_mut {
// FIXME: emit type error?
}
inner_ty
}
_ => &Ty::Unknown,
};
let subty = self.infer_pat(*pat, expectation, default_bm);
Ty::apply_one(TypeCtor::Ref(*mutability), subty)
}
Pat::TupleStruct { path: p, args: subpats } => {
self.infer_tuple_struct_pat(p.as_ref(), subpats, expected, default_bm)
}
Pat::Record { path: p, args: fields } => {
self.infer_record_pat(p.as_ref(), fields, expected, default_bm, pat)
}
Pat::Path(path) => {
// FIXME use correct resolver for the surrounding expression
let resolver = self.resolver.clone();
self.infer_path(&resolver, &path, pat.into()).unwrap_or(Ty::Unknown)
}
Pat::Bind { mode, name: _, subpat } => {
let mode = if mode == &BindingAnnotation::Unannotated {
default_bm
} else {
BindingMode::convert(*mode)
};
let inner_ty = if let Some(subpat) = subpat {
self.infer_pat(*subpat, expected, default_bm)
} else {
expected.clone()
};
let inner_ty = self.insert_type_vars_shallow(inner_ty);
let bound_ty = match mode {
BindingMode::Ref(mutability) => {
Ty::apply_one(TypeCtor::Ref(mutability), inner_ty.clone())
}
BindingMode::Move => inner_ty.clone(),
};
let bound_ty = self.resolve_ty_as_possible(&mut vec![], bound_ty);
self.write_pat_ty(pat, bound_ty);
return inner_ty;
}
_ => Ty::Unknown,
};
// use a new type variable if we got Ty::Unknown here
let ty = self.insert_type_vars_shallow(ty);
self.unify(&ty, expected);
let ty = self.resolve_ty_as_possible(&mut vec![], ty);
self.write_pat_ty(pat, ty.clone());
ty
}
}
|
