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Remove HashStable impl for [hir::Attribute]. #154924

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Merged
rust-bors merged 1 commit into from
Apr 20, 2026
+0 −41
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Remove HashStable impl for [hir::Attribute]. #154924

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41 changes: 0 additions & 41 deletions compiler/rustc_middle/src/ich/impls_syntax.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,9 +3,6 @@

use rustc_ast as ast;
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_hir as hir;
use rustc_span::{Symbol, sym};
use smallvec::SmallVec;

use super::StableHashingContext;

Expand All @@ -16,44 +13,6 @@ impl<'a> HashStable<StableHashingContext<'a>> for ast::NodeId {
}
}

impl<'a> HashStable<StableHashingContext<'a>> for [hir::Attribute] {
fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
if self.is_empty() {
self.len().hash_stable(hcx, hasher);
return;
}

// Some attributes are always ignored during hashing.
let filtered: SmallVec<[&hir::Attribute; 8]> = self
.iter()
.filter(|attr| {
attr.is_doc_comment().is_none()
// FIXME(jdonszelmann) have a better way to handle ignored attrs
&& !attr.name().is_some_and(|ident| is_ignored_attr(ident))
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@JonathanBrouwer JonathanBrouwer Apr 7, 2026 •
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In fact attr.name() is not implemented for parsed attributes, so this check is always false.
Since other than cfg_trace all the attributes are only used for incremental tests, and the incremental tests still pass, I don't think this check is useful

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@JonathanBrouwer JonathanBrouwer Apr 7, 2026

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(attr.name() will be removed in the near future, as a follow-up of #154808)

})
.collect();

filtered.len().hash_stable(hcx, hasher);
for attr in filtered {
attr.hash_stable(hcx, hasher);
}
}
}

#[inline]
fn is_ignored_attr(name: Symbol) -> bool {
const IGNORED_ATTRIBUTES: &[Symbol] = &[
sym::cfg_trace, // FIXME(#138844) should this really be ignored?
sym::rustc_if_this_changed,
sym::rustc_then_this_would_need,
sym::rustc_clean,
sym::rustc_partition_reused,
sym::rustc_partition_codegened,
sym::rustc_expected_cgu_reuse,
];
IGNORED_ATTRIBUTES.contains(&name)
}

impl<'tcx> HashStable<StableHashingContext<'tcx>> for rustc_feature::Features {
fn hash_stable(&self, hcx: &mut StableHashingContext<'tcx>, hasher: &mut StableHasher) {
// Unfortunately we cannot exhaustively list fields here, since the
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