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
|
//! This module provides the built-in trait implementations, e.g. to make
//! closures implement `Fn`.
use hir_def::{expr::Expr, lang_item::LangItemTarget, TraitId, TypeAliasId};
use hir_expand::name::name;
use ra_db::CrateId;
use super::{AssocTyValue, Impl};
use crate::{db::HirDatabase, ApplicationTy, Substs, TraitRef, Ty, TypeCtor};
pub(super) struct BuiltinImplData {
pub num_vars: usize,
pub trait_ref: TraitRef,
pub where_clauses: Vec<super::GenericPredicate>,
pub assoc_ty_values: Vec<AssocTyValue>,
}
pub(super) struct BuiltinImplAssocTyValueData {
pub impl_: Impl,
pub assoc_ty_id: TypeAliasId,
pub num_vars: usize,
pub value: Ty,
}
pub(super) fn get_builtin_impls(
db: &impl HirDatabase,
krate: CrateId,
ty: &Ty,
trait_: TraitId,
mut callback: impl FnMut(Impl),
) {
// Note: since impl_datum needs to be infallible, we need to make sure here
// that we have all prerequisites to build the respective impls.
if let Ty::Apply(ApplicationTy { ctor: TypeCtor::Closure { def, expr }, .. }) = ty {
for &fn_trait in [super::FnTrait::FnOnce, super::FnTrait::FnMut, super::FnTrait::Fn].iter()
{
if let Some(actual_trait) = get_fn_trait(db, krate, fn_trait) {
if trait_ == actual_trait {
let impl_ = super::ClosureFnTraitImplData { def: *def, expr: *expr, fn_trait };
if check_closure_fn_trait_impl_prerequisites(db, krate, impl_) {
callback(Impl::ClosureFnTraitImpl(impl_));
}
}
}
}
}
}
pub(super) fn impl_datum(db: &impl HirDatabase, krate: CrateId, impl_: Impl) -> BuiltinImplData {
match impl_ {
Impl::ImplBlock(_) => unreachable!(),
Impl::ClosureFnTraitImpl(data) => closure_fn_trait_impl_datum(db, krate, data),
}
}
pub(super) fn associated_ty_value(
db: &impl HirDatabase,
krate: CrateId,
data: AssocTyValue,
) -> BuiltinImplAssocTyValueData {
match data {
AssocTyValue::TypeAlias(_) => unreachable!(),
AssocTyValue::ClosureFnTraitImplOutput(data) => {
closure_fn_trait_output_assoc_ty_value(db, krate, data)
}
}
}
fn check_closure_fn_trait_impl_prerequisites(
db: &impl HirDatabase,
krate: CrateId,
data: super::ClosureFnTraitImplData,
) -> bool {
// the respective Fn/FnOnce/FnMut trait needs to exist
if get_fn_trait(db, krate, data.fn_trait).is_none() {
return false;
}
// FIXME: there are more assumptions that we should probably check here:
// the traits having no type params, FnOnce being a supertrait
// the FnOnce trait needs to exist and have an assoc type named Output
let fn_once_trait = match get_fn_trait(db, krate, super::FnTrait::FnOnce) {
Some(t) => t,
None => return false,
};
db.trait_data(fn_once_trait).associated_type_by_name(&name![Output]).is_some()
}
fn closure_fn_trait_impl_datum(
db: &impl HirDatabase,
krate: CrateId,
data: super::ClosureFnTraitImplData,
) -> BuiltinImplData {
// for some closure |X, Y| -> Z:
// impl<T, U, V> Fn<(T, U)> for closure<fn(T, U) -> V> { Output = V }
let trait_ = get_fn_trait(db, krate, data.fn_trait) // get corresponding fn trait
// the existence of the Fn trait has been checked before
.expect("fn trait for closure impl missing");
let num_args: u16 = match &db.body(data.def.into())[data.expr] {
Expr::Lambda { args, .. } => args.len() as u16,
_ => {
log::warn!("closure for closure type {:?} not found", data);
0
}
};
let arg_ty = Ty::apply(
TypeCtor::Tuple { cardinality: num_args },
Substs::builder(num_args as usize).fill_with_bound_vars(0).build(),
);
let sig_ty = Ty::apply(
TypeCtor::FnPtr { num_args },
Substs::builder(num_args as usize + 1).fill_with_bound_vars(0).build(),
);
let self_ty = Ty::apply_one(TypeCtor::Closure { def: data.def, expr: data.expr }, sig_ty);
let trait_ref = TraitRef {
trait_: trait_.into(),
substs: Substs::build_for_def(db, trait_).push(self_ty).push(arg_ty).build(),
};
let output_ty_id = AssocTyValue::ClosureFnTraitImplOutput(data.clone());
BuiltinImplData {
num_vars: num_args as usize + 1,
trait_ref,
where_clauses: Vec::new(),
assoc_ty_values: vec![output_ty_id],
}
}
fn closure_fn_trait_output_assoc_ty_value(
db: &impl HirDatabase,
krate: CrateId,
data: super::ClosureFnTraitImplData,
) -> BuiltinImplAssocTyValueData {
let impl_ = Impl::ClosureFnTraitImpl(data.clone());
let num_args: u16 = match &db.body(data.def.into())[data.expr] {
Expr::Lambda { args, .. } => args.len() as u16,
_ => {
log::warn!("closure for closure type {:?} not found", data);
0
}
};
let output_ty = Ty::Bound(num_args.into());
let fn_once_trait =
get_fn_trait(db, krate, super::FnTrait::FnOnce).expect("assoc ty value should not exist");
let output_ty_id = db
.trait_data(fn_once_trait)
.associated_type_by_name(&name![Output])
.expect("assoc ty value should not exist");
BuiltinImplAssocTyValueData {
impl_,
assoc_ty_id: output_ty_id,
num_vars: num_args as usize + 1,
value: output_ty,
}
}
fn get_fn_trait(
db: &impl HirDatabase,
krate: CrateId,
fn_trait: super::FnTrait,
) -> Option<TraitId> {
let target = db.lang_item(krate, fn_trait.lang_item_name().into())?;
match target {
LangItemTarget::TraitId(t) => Some(t),
_ => None,
}
}
|
