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
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::{DefIdTree, TyCtxt};
use rustc_span::symbol::Symbol;
pub fn is_unstable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Symbol> {
if tcx.is_const_fn_raw(def_id) {
let const_stab = tcx.lookup_const_stability(def_id)?;
if const_stab.is_const_unstable() { Some(const_stab.feature) } else { None }
} else {
None
}
}
pub fn is_parent_const_impl_raw(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
let parent_id = tcx.local_parent(def_id);
tcx.def_kind(parent_id) == DefKind::Impl && tcx.constness(parent_id) == hir::Constness::Const
}
fn constness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Constness {
let def_id = def_id.expect_local();
let node = tcx.hir().get_by_def_id(def_id);
match node {
hir::Node::Ctor(_) => hir::Constness::Const,
hir::Node::Item(hir::Item { kind: hir::ItemKind::Impl(impl_), .. }) => impl_.constness,
hir::Node::ForeignItem(hir::ForeignItem { kind: hir::ForeignItemKind::Fn(..), .. }) => {
let is_const = if tcx.is_intrinsic(def_id) {
tcx.lookup_const_stability(def_id).is_some()
} else {
false
};
if is_const { hir::Constness::Const } else { hir::Constness::NotConst }
}
_ => {
if let Some(fn_kind) = node.fn_kind() {
if fn_kind.constness() == hir::Constness::Const {
return hir::Constness::Const;
}
let is_const = is_parent_const_impl_raw(tcx, def_id);
if is_const { hir::Constness::Const } else { hir::Constness::NotConst }
} else {
hir::Constness::NotConst
}
}
}
}
fn is_promotable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
tcx.is_const_fn(def_id)
&& match tcx.lookup_const_stability(def_id) {
Some(stab) => {
if cfg!(debug_assertions) && stab.promotable {
let sig = tcx.fn_sig(def_id);
assert_eq!(
sig.unsafety(),
hir::Unsafety::Normal,
"don't mark const unsafe fns as promotable",
);
}
stab.promotable
}
None => false,
}
}
pub fn provide(providers: &mut Providers) {
*providers = Providers { constness, is_promotable_const_fn, ..*providers };
}