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
|
use crate::rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
use rustc_hir as hir;
use rustc_infer::infer::{InferOk, TyCtxtInferExt};
use rustc_infer::traits;
use rustc_middle::ty::subst::Subst;
use rustc_middle::ty::ToPredicate;
use rustc_span::DUMMY_SP;
use super::*;
pub(crate) struct BlanketImplFinder<'a, 'tcx> {
pub(crate) cx: &'a mut core::DocContext<'tcx>,
}
impl<'a, 'tcx> BlanketImplFinder<'a, 'tcx> {
pub(crate) fn get_blanket_impls(&mut self, item_def_id: DefId) -> Vec<Item> {
let param_env = self.cx.tcx.param_env(item_def_id);
let ty = self.cx.tcx.bound_type_of(item_def_id);
trace!("get_blanket_impls({:?})", ty);
let mut impls = Vec::new();
self.cx.with_all_traits(|cx, all_traits| {
for &trait_def_id in all_traits {
if !cx.cache.access_levels.is_public(trait_def_id)
|| cx.generated_synthetics.get(&(ty.0, trait_def_id)).is_some()
{
continue;
}
// NOTE: doesn't use `for_each_relevant_impl` to avoid looking at anything besides blanket impls
let trait_impls = cx.tcx.trait_impls_of(trait_def_id);
for &impl_def_id in trait_impls.blanket_impls() {
trace!(
"get_blanket_impls: Considering impl for trait '{:?}' {:?}",
trait_def_id,
impl_def_id
);
let trait_ref = cx.tcx.bound_impl_trait_ref(impl_def_id).unwrap();
let is_param = matches!(trait_ref.0.self_ty().kind(), ty::Param(_));
let may_apply = is_param && cx.tcx.infer_ctxt().enter(|infcx| {
let substs = infcx.fresh_substs_for_item(DUMMY_SP, item_def_id);
let ty = ty.subst(infcx.tcx, substs);
let param_env = EarlyBinder(param_env).subst(infcx.tcx, substs);
let impl_substs = infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
let trait_ref = trait_ref.subst(infcx.tcx, impl_substs);
// Require the type the impl is implemented on to match
// our type, and ignore the impl if there was a mismatch.
let cause = traits::ObligationCause::dummy();
let eq_result = infcx.at(&cause, param_env).eq(trait_ref.self_ty(), ty);
if let Ok(InferOk { value: (), obligations }) = eq_result {
// FIXME(eddyb) ignoring `obligations` might cause false positives.
drop(obligations);
trace!(
"invoking predicate_may_hold: param_env={:?}, trait_ref={:?}, ty={:?}",
param_env,
trait_ref,
ty
);
let predicates = cx
.tcx
.predicates_of(impl_def_id)
.instantiate(cx.tcx, impl_substs)
.predicates
.into_iter()
.chain(Some(
ty::Binder::dummy(trait_ref)
.to_poly_trait_predicate()
.map_bound(ty::PredicateKind::Trait)
.to_predicate(infcx.tcx),
));
for predicate in predicates {
debug!("testing predicate {:?}", predicate);
let obligation = traits::Obligation::new(
traits::ObligationCause::dummy(),
param_env,
predicate,
);
match infcx.evaluate_obligation(&obligation) {
Ok(eval_result) if eval_result.may_apply() => {}
Err(traits::OverflowError::Canonical) => {}
Err(traits::OverflowError::ErrorReporting) => {}
_ => {
return false;
}
}
}
true
} else {
false
}
});
debug!(
"get_blanket_impls: found applicable impl: {} for trait_ref={:?}, ty={:?}",
may_apply, trait_ref, ty
);
if !may_apply {
continue;
}
cx.generated_synthetics.insert((ty.0, trait_def_id));
impls.push(Item {
name: None,
attrs: Default::default(),
visibility: Inherited,
item_id: ItemId::Blanket { impl_id: impl_def_id, for_: item_def_id },
kind: Box::new(ImplItem(Box::new(Impl {
unsafety: hir::Unsafety::Normal,
generics: clean_ty_generics(
cx,
cx.tcx.generics_of(impl_def_id),
cx.tcx.explicit_predicates_of(impl_def_id),
),
// FIXME(eddyb) compute both `trait_` and `for_` from
// the post-inference `trait_ref`, as it's more accurate.
trait_: Some(clean_trait_ref_with_bindings(cx, trait_ref.0, &[])),
for_: clean_middle_ty(ty.0, cx, None),
items: cx.tcx
.associated_items(impl_def_id)
.in_definition_order()
.map(|x| x.clean(cx))
.collect::<Vec<_>>(),
polarity: ty::ImplPolarity::Positive,
kind: ImplKind::Blanket(Box::new(clean_middle_ty(trait_ref.0.self_ty(), cx, None))),
}))),
cfg: None,
});
}
}
});
impls
}
}
|
