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Commit c763ebc

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Dylan-DPCDylan-DPC
authored
Rollup merge of #102830 - compiler-errors:constness-parity, r=fee1-dead
Unify `tcx.constness` query and param env constness checks The checks that we do in the `constness` query seem inconsistent with the checks that we do to determine if an item's param-env is const, so I merged them into the `constness` query and call that from the `param_env` query. I'm not sure if this totally makes sense -- is there a case where `tcx.param_env()` would return a const param-env for an item whose `tcx.constness()` is `Constness::NotConst`? Because if not, it seems a bit dangerous that these two differ. Luckily, not many places actually use `tcx.constness()`, and the checks in `tcx.param_env()` seem stricter than the checks in `tcx.constness()` (at least for the types of items we type-check). Also, due to the way that `tcx.param_env()` is implemented, it _never_ used to return a const param-env for a item coming from a different crate, which also seems dangerous (though also probably not weaponizable currently, because we seldom actually compute the param-env for a non-local item).
2 parents 40deece + bef8681 commit c763ebc
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‎compiler/rustc_const_eval/src/const_eval/fn_queries.rs

Copy file name to clipboardExpand all lines: compiler/rustc_const_eval/src/const_eval/fn_queries.rs
+56-16Lines changed: 56 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -25,12 +25,10 @@ pub fn is_parent_const_impl_raw(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
2525
/// report whether said intrinsic has a `rustc_const_{un,}stable` attribute. Otherwise, return
2626
/// `Constness::NotConst`.
2727
fn constness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Constness {
28-
let def_id = def_id.expect_local();
29-
let node = tcx.hir().get_by_def_id(def_id);
30-
31-
match node {
28+
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
29+
match tcx.hir().get(hir_id) {
3230
hir::Node::Ctor(_) => hir::Constness::Const,
33-
hir::Node::Item(hir::Item { kind: hir::ItemKind::Impl(impl_), .. }) => impl_.constness,
31+
3432
hir::Node::ForeignItem(hir::ForeignItem { kind: hir::ForeignItemKind::Fn(..), .. }) => {
3533
// Intrinsics use `rustc_const_{un,}stable` attributes to indicate constness. All other
3634
// foreign items cannot be evaluated at compile-time.
@@ -41,20 +39,62 @@ fn constness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Constness {
4139
};
4240
if is_const { hir::Constness::Const } else { hir::Constness::NotConst }
4341
}
44-
_ => {
45-
if let Some(fn_kind) = node.fn_kind() {
46-
if fn_kind.constness() == hir::Constness::Const {
47-
return hir::Constness::Const;
48-
}
4942

50-
// If the function itself is not annotated with `const`, it may still be a `const fn`
51-
// if it resides in a const trait impl.
52-
let is_const = is_parent_const_impl_raw(tcx, def_id);
53-
if is_const { hir::Constness::Const } else { hir::Constness::NotConst }
54-
} else {
55-
hir::Constness::NotConst
43+
hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Fn(..), .. })
44+
if tcx.is_const_default_method(def_id) =>
45+
{
46+
hir::Constness::Const
47+
}
48+
49+
hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(..), .. })
50+
| hir::Node::Item(hir::Item { kind: hir::ItemKind::Static(..), .. })
51+
| hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Const(..), .. })
52+
| hir::Node::AnonConst(_)
53+
| hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
54+
| hir::Node::ImplItem(hir::ImplItem {
55+
kind:
56+
hir::ImplItemKind::Fn(
57+
hir::FnSig {
58+
header: hir::FnHeader { constness: hir::Constness::Const, .. },
59+
..
60+
},
61+
..,
62+
),
63+
..
64+
}) => hir::Constness::Const,
65+
66+
hir::Node::ImplItem(hir::ImplItem {
67+
kind: hir::ImplItemKind::Type(..) | hir::ImplItemKind::Fn(..),
68+
..
69+
}) => {
70+
let parent_hir_id = tcx.hir().get_parent_node(hir_id);
71+
match tcx.hir().get(parent_hir_id) {
72+
hir::Node::Item(hir::Item {
73+
kind: hir::ItemKind::Impl(hir::Impl { constness, .. }),
74+
..
75+
}) => *constness,
76+
_ => span_bug!(
77+
tcx.def_span(parent_hir_id.owner),
78+
"impl item's parent node is not an impl",
79+
),
5680
}
5781
}
82+
83+
hir::Node::Item(hir::Item {
84+
kind: hir::ItemKind::Fn(hir::FnSig { header: hir::FnHeader { constness, .. }, .. }, ..),
85+
..
86+
})
87+
| hir::Node::TraitItem(hir::TraitItem {
88+
kind:
89+
hir::TraitItemKind::Fn(hir::FnSig { header: hir::FnHeader { constness, .. }, .. }, ..),
90+
..
91+
})
92+
| hir::Node::Item(hir::Item {
93+
kind: hir::ItemKind::Impl(hir::Impl { constness, .. }),
94+
..
95+
}) => *constness,
96+
97+
_ => hir::Constness::NotConst,
5898
}
5999
}
60100

‎compiler/rustc_metadata/src/rmeta/encoder.rs

Copy file name to clipboardExpand all lines: compiler/rustc_metadata/src/rmeta/encoder.rs
+41-15Lines changed: 41 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -1059,6 +1059,43 @@ fn should_encode_const(def_kind: DefKind) -> bool {
10591059
}
10601060
}
10611061

1062+
fn should_encode_constness(def_kind: DefKind) -> bool {
1063+
match def_kind {
1064+
DefKind::Struct
1065+
| DefKind::Union
1066+
| DefKind::Enum
1067+
| DefKind::Trait
1068+
| DefKind::AssocTy
1069+
| DefKind::Fn
1070+
| DefKind::Const
1071+
| DefKind::Static(..)
1072+
| DefKind::Ctor(..)
1073+
| DefKind::AssocFn
1074+
| DefKind::AssocConst
1075+
| DefKind::AnonConst
1076+
| DefKind::InlineConst
1077+
| DefKind::OpaqueTy
1078+
| DefKind::ImplTraitPlaceholder
1079+
| DefKind::Impl
1080+
| DefKind::Closure
1081+
| DefKind::Generator
1082+
| DefKind::TyAlias => true,
1083+
DefKind::Variant
1084+
| DefKind::TraitAlias
1085+
| DefKind::ForeignTy
1086+
| DefKind::Field
1087+
| DefKind::TyParam
1088+
| DefKind::Mod
1089+
| DefKind::ForeignMod
1090+
| DefKind::ConstParam
1091+
| DefKind::Macro(..)
1092+
| DefKind::Use
1093+
| DefKind::LifetimeParam
1094+
| DefKind::GlobalAsm
1095+
| DefKind::ExternCrate => false,
1096+
}
1097+
}
1098+
10621099
fn should_encode_trait_impl_trait_tys<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool {
10631100
if tcx.def_kind(def_id) != DefKind::AssocFn {
10641101
return false;
@@ -1165,6 +1202,9 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
11651202
{
11661203
record!(self.tables.trait_impl_trait_tys[def_id] <- table);
11671204
}
1205+
if should_encode_constness(def_kind) {
1206+
self.tables.constness.set(def_id.index, tcx.constness(def_id));
1207+
}
11681208
}
11691209
let inherent_impls = tcx.crate_inherent_impls(());
11701210
for (def_id, implementations) in inherent_impls.inherent_impls.iter() {
@@ -1192,7 +1232,6 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
11921232
};
11931233

11941234
record!(self.tables.variant_data[def_id] <- data);
1195-
self.tables.constness.set(def_id.index, hir::Constness::Const);
11961235
record_array!(self.tables.children[def_id] <- variant.fields.iter().map(|f| {
11971236
assert!(f.did.is_local());
11981237
f.did.index
@@ -1220,7 +1259,6 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
12201259
};
12211260

12221261
record!(self.tables.variant_data[def_id] <- data);
1223-
self.tables.constness.set(def_id.index, hir::Constness::Const);
12241262
if variant.ctor_kind == CtorKind::Fn {
12251263
record!(self.tables.fn_sig[def_id] <- tcx.fn_sig(def_id));
12261264
}
@@ -1284,7 +1322,6 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
12841322

12851323
record!(self.tables.repr_options[def_id] <- adt_def.repr());
12861324
record!(self.tables.variant_data[def_id] <- data);
1287-
self.tables.constness.set(def_id.index, hir::Constness::Const);
12881325
if variant.ctor_kind == CtorKind::Fn {
12891326
record!(self.tables.fn_sig[def_id] <- tcx.fn_sig(def_id));
12901327
}
@@ -1320,7 +1357,6 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
13201357
}
13211358
};
13221359
self.tables.asyncness.set(def_id.index, m_sig.header.asyncness);
1323-
self.tables.constness.set(def_id.index, hir::Constness::NotConst);
13241360
}
13251361
ty::AssocKind::Type => {
13261362
self.encode_explicit_item_bounds(def_id);
@@ -1345,13 +1381,6 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
13451381
let hir::ImplItemKind::Fn(ref sig, body) = ast_item.kind else { bug!() };
13461382
self.tables.asyncness.set(def_id.index, sig.header.asyncness);
13471383
record_array!(self.tables.fn_arg_names[def_id] <- self.tcx.hir().body_param_names(body));
1348-
// Can be inside `impl const Trait`, so using sig.header.constness is not reliable
1349-
let constness = if self.tcx.is_const_fn_raw(def_id) {
1350-
hir::Constness::Const
1351-
} else {
1352-
hir::Constness::NotConst
1353-
};
1354-
self.tables.constness.set(def_id.index, constness);
13551384
}
13561385
ty::AssocKind::Const | ty::AssocKind::Type => {}
13571386
}
@@ -1474,7 +1503,6 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
14741503
hir::ItemKind::Fn(ref sig, .., body) => {
14751504
self.tables.asyncness.set(def_id.index, sig.header.asyncness);
14761505
record_array!(self.tables.fn_arg_names[def_id] <- self.tcx.hir().body_param_names(body));
1477-
self.tables.constness.set(def_id.index, sig.header.constness);
14781506
}
14791507
hir::ItemKind::Macro(ref macro_def, _) => {
14801508
if macro_def.macro_rules {
@@ -1495,7 +1523,6 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
14951523
hir::ItemKind::Struct(ref struct_def, _) => {
14961524
let adt_def = self.tcx.adt_def(def_id);
14971525
record!(self.tables.repr_options[def_id] <- adt_def.repr());
1498-
self.tables.constness.set(def_id.index, hir::Constness::Const);
14991526

15001527
// Encode def_ids for each field and method
15011528
// for methods, write all the stuff get_trait_method
@@ -1524,9 +1551,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
15241551
is_non_exhaustive: variant.is_field_list_non_exhaustive(),
15251552
});
15261553
}
1527-
hir::ItemKind::Impl(hir::Impl { defaultness, constness, .. }) => {
1554+
hir::ItemKind::Impl(hir::Impl { defaultness, .. }) => {
15281555
self.tables.impl_defaultness.set(def_id.index, *defaultness);
1529-
self.tables.constness.set(def_id.index, *constness);
15301556

15311557
let trait_ref = self.tcx.impl_trait_ref(def_id);
15321558
if let Some(trait_ref) = trait_ref {

‎compiler/rustc_ty_utils/src/ty.rs

Copy file name to clipboardExpand all lines: compiler/rustc_ty_utils/src/ty.rs
+1-68Lines changed: 1 addition & 68 deletions
Original file line numberDiff line numberDiff line change
@@ -137,77 +137,10 @@ fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> {
137137
let local_did = def_id.as_local();
138138
let hir_id = local_did.map(|def_id| tcx.hir().local_def_id_to_hir_id(def_id));
139139

140-
let constness = match hir_id {
141-
Some(hir_id) => match tcx.hir().get(hir_id) {
142-
hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Fn(..), .. })
143-
if tcx.is_const_default_method(def_id) =>
144-
{
145-
hir::Constness::Const
146-
}
147-
148-
hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(..), .. })
149-
| hir::Node::Item(hir::Item { kind: hir::ItemKind::Static(..), .. })
150-
| hir::Node::TraitItem(hir::TraitItem {
151-
kind: hir::TraitItemKind::Const(..), ..
152-
})
153-
| hir::Node::AnonConst(_)
154-
| hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
155-
| hir::Node::ImplItem(hir::ImplItem {
156-
kind:
157-
hir::ImplItemKind::Fn(
158-
hir::FnSig {
159-
header: hir::FnHeader { constness: hir::Constness::Const, .. },
160-
..
161-
},
162-
..,
163-
),
164-
..
165-
}) => hir::Constness::Const,
166-
167-
hir::Node::ImplItem(hir::ImplItem {
168-
kind: hir::ImplItemKind::Type(..) | hir::ImplItemKind::Fn(..),
169-
..
170-
}) => {
171-
let parent_hir_id = tcx.hir().get_parent_node(hir_id);
172-
match tcx.hir().get(parent_hir_id) {
173-
hir::Node::Item(hir::Item {
174-
kind: hir::ItemKind::Impl(hir::Impl { constness, .. }),
175-
..
176-
}) => *constness,
177-
_ => span_bug!(
178-
tcx.def_span(parent_hir_id.owner),
179-
"impl item's parent node is not an impl",
180-
),
181-
}
182-
}
183-
184-
hir::Node::Item(hir::Item {
185-
kind:
186-
hir::ItemKind::Fn(hir::FnSig { header: hir::FnHeader { constness, .. }, .. }, ..),
187-
..
188-
})
189-
| hir::Node::TraitItem(hir::TraitItem {
190-
kind:
191-
hir::TraitItemKind::Fn(
192-
hir::FnSig { header: hir::FnHeader { constness, .. }, .. },
193-
..,
194-
),
195-
..
196-
})
197-
| hir::Node::Item(hir::Item {
198-
kind: hir::ItemKind::Impl(hir::Impl { constness, .. }),
199-
..
200-
}) => *constness,
201-
202-
_ => hir::Constness::NotConst,
203-
},
204-
None => hir::Constness::NotConst,
205-
};
206-
207140
let unnormalized_env = ty::ParamEnv::new(
208141
tcx.intern_predicates(&predicates),
209142
traits::Reveal::UserFacing,
210-
constness,
143+
tcx.constness(def_id),
211144
);
212145

213146
let body_id =

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