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Unify tcx.constness and param env constness checks

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This commit is contained in:
Michael Goulet 2022-10-09 06:54:00 +00:00
parent db0597f561
commit c646c4d403
3 changed files with 98 additions and 99 deletions
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72
compiler/rustc_const_eval/src/const_eval/fn_queries.rs
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@ -25,12 +25,10 @@ pub fn is_parent_const_impl_raw(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
/// report whether said intrinsic has a `rustc_const_{un,}stable` attribute. Otherwise, return
/// `Constness::NotConst`.
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 {
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
match tcx.hir().get(hir_id) {
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(..), .. }) => {
// Intrinsics use `rustc_const_{un,}stable` attributes to indicate constness. All other
// foreign items cannot be evaluated at compile-time.
@ -41,20 +39,62 @@ fn constness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Constness {
};
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;
}
// If the function itself is not annotated with `const`, it may still be a `const fn`
// if it resides in a const trait impl.
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
hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Fn(..), .. })
if tcx.is_const_default_method(def_id) =>
{
hir::Constness::Const
}
hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(..), .. })
| hir::Node::Item(hir::Item { kind: hir::ItemKind::Static(..), .. })
| hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Const(..), .. })
| hir::Node::AnonConst(_)
| hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
| hir::Node::ImplItem(hir::ImplItem {
kind:
hir::ImplItemKind::Fn(
hir::FnSig {
header: hir::FnHeader { constness: hir::Constness::Const, .. },
..
},
..,
),
..
}) => hir::Constness::Const,
hir::Node::ImplItem(hir::ImplItem {
kind: hir::ImplItemKind::Type(..) | hir::ImplItemKind::Fn(..),
..
}) => {
let parent_hir_id = tcx.hir().get_parent_node(hir_id);
match tcx.hir().get(parent_hir_id) {
hir::Node::Item(hir::Item {
kind: hir::ItemKind::Impl(hir::Impl { constness, .. }),
..
}) => *constness,
_ => span_bug!(
tcx.def_span(parent_hir_id.owner),
"impl item's parent node is not an impl",
),
}
}
hir::Node::Item(hir::Item {
kind: hir::ItemKind::Fn(hir::FnSig { header: hir::FnHeader { constness, .. }, .. }, ..),
..
})
| hir::Node::TraitItem(hir::TraitItem {
kind:
hir::TraitItemKind::Fn(hir::FnSig { header: hir::FnHeader { constness, .. }, .. }, ..),
..
})
| hir::Node::Item(hir::Item {
kind: hir::ItemKind::Impl(hir::Impl { constness, .. }),
..
}) => *constness,
_ => hir::Constness::NotConst,
}
}