34 lines
849 B
Plaintext
34 lines
849 B
Plaintext
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== Why is this an issue?
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Having a manual `PartialEq` implementation for types with a derived `Hash` can lead to inconsistencies. The contract `k1 == k2 ⇒ hash(k1) == hash(k2)` must always hold. Inconsistencies can cause undefined behaviors, especially when these types are used in collections such as `HashMap`.
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=== Code examples
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==== Noncompliant code example
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[source,rust,diff-id=1,diff-type=noncompliant]
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----
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#[derive(Hash)]
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struct Foo;
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impl PartialEq for Foo {
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fn eq(&self, other: &Self) -> bool {
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// Some custom equality logic
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true // Noncompliant
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}
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}
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----
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==== Compliant solution
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[source,rust,diff-id=1,diff-type=compliant]
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----
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#[derive(Hash, PartialEq)]
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struct Foo;
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----
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== Resources
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=== Documentation
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* Clippy Lints - https://rust-lang.github.io/rust-clippy/master/index.html#derived_hash_with_manual_eq
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