65 lines
2.7 KiB
Diff
65 lines
2.7 KiB
Diff
# UNDF: UNDF-2026-000000771
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diff --git a/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs b/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs
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index c935869..9218cd1 100644
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--- a/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs
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+++ b/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs
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@@ -1,9 +1,34 @@
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+use rustc_data_structures::fx::FxHashSet;
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use rustc_macros::HashStable;
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use smallvec::SmallVec;
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use tracing::instrument;
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use crate::ty::{self, DefId, OpaqueTypeKey, Ty, TyCtxt, TypingEnv};
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+/// Stack for cycle detection in `apply_inner`.
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+/// Wraps SmallVec (for push/pop LIFO order) with FxHashSet (for O(1) contains).
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+/// CWE-407 fix: SmallVec::contains is O(n); FxHashSet::contains is O(1).
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+#[derive(Default)]
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+struct EvalStack<'tcx> {
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+ vec: SmallVec<[Ty<'tcx>; 1]>,
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+ set: FxHashSet<Ty<'tcx>>,
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+}
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+
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+impl<'tcx> EvalStack<'tcx> {
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+ fn contains(&self, t: &Ty<'tcx>) -> bool {
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+ self.set.contains(t)
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+ }
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+ fn push(&mut self, t: Ty<'tcx>) {
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+ self.vec.push(t);
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+ self.set.insert(t);
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+ }
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+ fn pop(&mut self) {
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+ if let Some(t) = self.vec.pop() {
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+ self.set.remove(&t);
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+ }
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+ }
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+}
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+
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/// Represents whether some type is inhabited in a given context.
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/// Examples of uninhabited types are `!`, `enum Void {}`, or a struct
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/// containing either of those types.
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@@ -82,7 +107,7 @@ fn apply_inner<E: std::fmt::Debug>(
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self,
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tcx: TyCtxt<'tcx>,
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typing_env: TypingEnv<'tcx>,
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- eval_stack: &mut SmallVec<[Ty<'tcx>; 1]>, // for cycle detection
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+ eval_stack: &mut EvalStack<'tcx>, // for cycle detection; Set-backed for O(1) contains
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in_module: &impl Fn(DefId) -> Result<bool, E>,
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reveal_opaque: &impl Fn(OpaqueTypeKey<'tcx>) -> Option<Ty<'tcx>>,
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) -> Result<bool, E> {
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diff --git a/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs b/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs
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index 8462471..713fec3 100644
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--- a/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs
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+++ b/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs
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@@ -66,8 +66,10 @@ fn remove_existing(&mut self, tcx: TyCtxt<'tcx>, impl_def_id: DefId) {
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vec = &mut self.blanket_impls;
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}
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+ // CWE-407 partial fix: swap_remove is O(1) vs remove's O(n) shift.
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+ // position() scan is still O(n); full O(1) requires Children to use IndexSet<DefId>.
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let index = vec.iter().position(|d| *d == impl_def_id).unwrap();
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- vec.remove(index);
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+ vec.swap_remove(index);
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}
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/// Attempt to insert an impl into this set of children, while comparing for
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