diff options
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/select/mod.rs | 22 |
1 files changed, 0 insertions, 22 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs index 85016a701f3..8306090debc 100644 --- a/compiler/rustc_trait_selection/src/traits/select/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs @@ -2328,28 +2328,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { }); } - // We are performing deduplication here to avoid exponential blowups - // (#38528) from happening, but the real cause of the duplication is - // unknown. What we know is that the deduplication avoids exponential - // amount of predicates being propagated when processing deeply nested - // types. - // - // This code is hot enough that it's worth avoiding the allocation - // required for the FxHashSet when possible. Special-casing lengths 0, - // 1 and 2 covers roughly 75-80% of the cases. - if obligations.len() <= 1 { - // No possibility of duplicates. - } else if obligations.len() == 2 { - // Only two elements. Drop the second if they are equal. - if obligations[0] == obligations[1] { - obligations.truncate(1); - } - } else { - // Three or more elements. Use a general deduplication process. - let mut seen = FxHashSet::default(); - obligations.retain(|i| seen.insert(i.clone())); - } - obligations } } |