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feat: derive Eq and Hash trait for messages where possible #1175

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merged 1 commit into from
Feb 12, 2025

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caspermeijn
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Integer and bytes types can be compared using trait Eq. Some generated Rust structs can also have this property by deriving the Eq trait.

Automatically derive Eq and Hash for:

  • messages that only have fields with integer or bytes types
  • messages where all field types also implement Eq and Hash
  • the Rust enum for one-of fields, where all fields implement Eq and Hash

Generated code for Protobuf enums already derives Eq and Hash.

BREAKING CHANGE: prost-build will automatically derive trait Eq and trait Hash for types where all field support those as well. If you manually impl Eq and/or impl Hash for generated types, then you need to remove the manual implementation. If you use type_attribute to derive(Eq) and/or derive(Hash), then you need to remove those.

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@LucioFranco LucioFranco left a comment

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LGTM, would it make sense to make these derives optional?

@caspermeijn
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LGTM, would it make sense to make these derives optional?

I think you mean something like skip_debug but for these traits. I feel like always implementing Eq is acceptable, as that is also the case for PartialEq.

The disadvantage of a skip function is that the complexity is raised in the code generator.

@LucioFranco
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Yeah, I was thinking it may help for those backward compat issues.

Integer and bytes types can be compared using trait Eq. Some generated Rust structs can also have this property by deriving the Eq trait.

Automatically derive Eq and Hash for:
- messages that only have fields with integer or bytes types
- messages where all field types also implement Eq and Hash
- the Rust enum for one-of fields, where all fields implement Eq and Hash

Generated code for Protobuf enums already derives Eq and Hash.

BREAKING CHANGE: `prost-build` will automatically derive `trait Eq` and `trait Hash` for types where all field support those as well. If you manually `impl Eq` and/or `impl Hash` for generated types, then you need to remove the manual implementation. If you use `type_attribute` to `derive(Eq)` and/or `derive(Hash)`, then you need to remove those.
@caspermeijn caspermeijn added this pull request to the merge queue Feb 12, 2025
Merged via the queue into tokio-rs:master with commit c7e9a00 Feb 12, 2025
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@caspermeijn caspermeijn deleted the trait_eq_and_hash branch February 12, 2025 08:04
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2 participants