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Verify that only NeedsNonConstDrop expects promoteds

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This commit is contained in:
Tomasz Miąsko 2021-10-21 00:00:00 +00:00
parent 7581bae996
commit 74c6636d27
1 changed files with 10 additions and 4 deletions
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14
compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
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@ -46,6 +46,9 @@ pub trait Qualif {
/// Whether this `Qualif` is cleared when a local is moved from.
const IS_CLEARED_ON_MOVE: bool = false;
/// Whether this `Qualif` might be evaluated after the promotion and can encounter a promoted.
const ALLOW_PROMOTED: bool = false;
/// Extracts the field of `ConstQualifs` that corresponds to this `Qualif`.
fn in_qualifs(qualifs: &ConstQualifs) -> bool;
@ -129,6 +132,7 @@ pub struct NeedsNonConstDrop;
impl Qualif for NeedsNonConstDrop {
const ANALYSIS_NAME: &'static str = "flow_needs_nonconst_drop";
const IS_CLEARED_ON_MOVE: bool = true;
const ALLOW_PROMOTED: bool = true;
fn in_qualifs(qualifs: &ConstQualifs) -> bool {
qualifs.needs_non_const_drop
@ -309,11 +313,13 @@ where
// Check the qualifs of the value of `const` items.
if let Some(ct) = constant.literal.const_for_ty() {
if let ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs_: _, promoted: None }) =
ct.val
{
if let ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs_: _, promoted }) = ct.val {
// Use qualifs of the type for the promoted. Promoteds in MIR body should be possible
// only for `NeedsNonConstDrop` with precise drop checking. This is the only const
// check performed after the promotion. Verify that with an assertion.
assert!(promoted.is_none() || Q::ALLOW_PROMOTED);
// Don't peek inside trait associated constants.
if cx.tcx.trait_of_item(def.did).is_none() {
if promoted.is_none() && cx.tcx.trait_of_item(def.did).is_none() {
let qualifs = if let Some((did, param_did)) = def.as_const_arg() {
cx.tcx.at(constant.span).mir_const_qualif_const_arg((did, param_did))
} else {