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| -rw-r--r-- | src/tools/clippy/src/docs/derive_hash_xor_eq.txt | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/src/tools/clippy/src/docs/derive_hash_xor_eq.txt b/src/tools/clippy/src/docs/derive_hash_xor_eq.txt new file mode 100644 index 000000000..fbf623d5a --- /dev/null +++ b/src/tools/clippy/src/docs/derive_hash_xor_eq.txt @@ -0,0 +1,23 @@ +### What it does +Checks for deriving `Hash` but implementing `PartialEq` +explicitly or vice versa. + +### Why is this bad? +The implementation of these traits must agree (for +example for use with `HashMap`) so it’s probably a bad idea to use a +default-generated `Hash` implementation with an explicitly defined +`PartialEq`. In particular, the following must hold for any type: + +``` +k1 == k2 ⇒ hash(k1) == hash(k2) +``` + +### Example +``` +#[derive(Hash)] +struct Foo; + +impl PartialEq for Foo { + ... +} +```
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