From 4375af53af48febdd3534d8d300b7769a4e0fb1c Mon Sep 17 00:00:00 2001 From: Maybe Waffle Date: Thu, 20 Apr 2023 18:46:29 +0000 Subject: [PATCH] Derive `HashStable` on `GenericArgKind` instead of implementing it by hand --- compiler/rustc_middle/src/ty/impls_ty.rs | 28 ------------------------ compiler/rustc_middle/src/ty/subst.rs | 2 +- 2 files changed, 1 insertion(+), 29 deletions(-) diff --git a/compiler/rustc_middle/src/ty/impls_ty.rs b/compiler/rustc_middle/src/ty/impls_ty.rs index 4c7822acdf785..02baa395c3c2f 100644 --- a/compiler/rustc_middle/src/ty/impls_ty.rs +++ b/compiler/rustc_middle/src/ty/impls_ty.rs @@ -73,34 +73,6 @@ impl<'a, 'tcx> HashStable> for ty::subst::GenericArg<'t } } -impl<'a, 'tcx> HashStable> for ty::subst::GenericArgKind<'tcx> { - fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { - match self { - // WARNING: We dedup cache the `HashStable` results for `List` - // while ignoring types and freely transmute - // between `List>` and `List>`. - // See `fn mk_type_list` for more details. - // - // We therefore hash types without adding a hash for their discriminant. - // - // In order to make it very unlikely for the sequence of bytes being hashed for - // a `GenericArgKind::Type` to be the same as the sequence of bytes being - // hashed for one of the other variants, we hash some very high number instead - // of their actual discriminant since `TyKind` should never start with anything - // that high. - ty::subst::GenericArgKind::Type(ty) => ty.hash_stable(hcx, hasher), - ty::subst::GenericArgKind::Const(ct) => { - 0xF3u8.hash_stable(hcx, hasher); - ct.hash_stable(hcx, hasher); - } - ty::subst::GenericArgKind::Lifetime(lt) => { - 0xF5u8.hash_stable(hcx, hasher); - lt.hash_stable(hcx, hasher); - } - } - } -} - // AllocIds get resolved to whatever they point to (to be stable) impl<'a> HashStable> for mir::interpret::AllocId { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { diff --git a/compiler/rustc_middle/src/ty/subst.rs b/compiler/rustc_middle/src/ty/subst.rs index 3e1b0706f6688..2b85eb971ce83 100644 --- a/compiler/rustc_middle/src/ty/subst.rs +++ b/compiler/rustc_middle/src/ty/subst.rs @@ -48,7 +48,7 @@ const TYPE_TAG: usize = 0b00; const REGION_TAG: usize = 0b01; const CONST_TAG: usize = 0b10; -#[derive(Debug, TyEncodable, TyDecodable, PartialEq, Eq, PartialOrd, Ord)] +#[derive(Debug, TyEncodable, TyDecodable, PartialEq, Eq, PartialOrd, Ord, HashStable)] pub enum GenericArgKind<'tcx> { Lifetime(ty::Region<'tcx>), Type(Ty<'tcx>),