Skip to content

prevent potential bug in encode_with_shorthand. #81100

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jan 18, 2021
Merged

prevent potential bug in encode_with_shorthand. #81100

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 3 additions & 3 deletions compiler/rustc_middle/src/ty/codec.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@ use rustc_data_structures::fx::FxHashMap;
use rustc_hir::def_id::{CrateNum, DefId};
use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
use rustc_span::Span;
use std::convert::{TryFrom, TryInto};
use std::hash::Hash;
use std::intrinsics;
use std::marker::DiscriminantKind;
Expand Down Expand Up @@ -95,7 +94,8 @@ where
E: TyEncoder<'tcx>,
M: for<'b> Fn(&'b mut E) -> &'b mut FxHashMap<T, usize>,
T: EncodableWithShorthand<'tcx, E>,
<T::Variant as DiscriminantKind>::Discriminant: Ord + TryFrom<usize>,
// The discriminant and shorthand must have the same size.
T::Variant: DiscriminantKind<Discriminant = isize>,
{
let existing_shorthand = cache(encoder).get(value).copied();
if let Some(shorthand) = existing_shorthand {
Expand All @@ -111,7 +111,7 @@ where
// The shorthand encoding uses the same usize as the
// discriminant, with an offset so they can't conflict.
let discriminant = intrinsics::discriminant_value(variant);
assert!(discriminant < SHORTHAND_OFFSET.try_into().ok().unwrap());
assert!(SHORTHAND_OFFSET > discriminant as usize);

let shorthand = start + SHORTHAND_OFFSET;

Expand Down