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Avoid ambiguous associated item references#646

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djkoloski merged 4 commits intorkyv:mainfrom
woodruffw-forks:ww/ambiguous-associated-item
Jan 7, 2026
Merged

Avoid ambiguous associated item references#646
djkoloski merged 4 commits intorkyv:mainfrom
woodruffw-forks:ww/ambiguous-associated-item

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@woodruffw woodruffw commented Jan 7, 2026

Hello rkyv folks!

I noticed this while trying to derive rkyv::Archive on an enum that contains an Archived variant:

#[derive(
    Clone, Copy, Debug, Default, Eq, PartialEq, rkyv::Archive, rkyv::Deserialize, rkyv::Serialize,
)]
#[rkyv(derive(Debug))]
pub enum Status {
    #[default]
    Active,
    Archived,
    Quarantined,
    Deprecated,
}

yields the following error:

error: ambiguous associated item
   --> crates/uv-pypi-types/src/project_status.rs:14:49
    |
 14 |     Clone, Copy, Debug, Default, Eq, PartialEq, rkyv::Archive, rkyv::Deseriali...
    |                                                 ^^^^^^^^^^^^^
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #57644 <https://github.com/rust-lang/rust/issues/57644>
note: `Archived` could refer to the variant defined here
   --> crates/uv-pypi-types/src/project_status.rs:20:5
    |
 20 |     Archived,
    |     ^^^^^^^^
note: `Archived` could also refer to the associated type defined here
   --> /Users/william/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/rkyv-0.8.12/src/traits.rs:229:5
    |
229 |     type Archived: Portable;
    |     ^^^^^^^^^^^^^^^^^^^^^^^
    = note: `#[deny(ambiguous_associated_items)]` (part of `#[deny(future_incompatible)]`) on by default
    = note: this error originates in the derive macro `rkyv::Archive` (in Nightly builds, run with -Z macro-backtrace for more info)

error: could not compile `uv-pypi-types` (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...

This is happening because Archive (the trait) has an associated type Archived, so Self::Archive ambiguously refers to either Archive::Archived or to ProjectStatus::Archived.

The solution to this is for the first-party to disambiguate its access. In this case that's as simple as <Self as Archive>::Archived. This PR contains that change, plus its equivalent in the derive APIs.

Note: I haven't attempted to suss out other ambiguous associated items, this is only one I happened to hit! So there are potentially others lurking.

Rust tracker: rust-lang/rust#57644

@woodruffw
Avoid ambiguous associated item references
0e149f3 
Signed-off-by: William Woodruff <william@astral.sh>
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woodruffw commented Jan 7, 2026

(For some background context: this is for some changes to uv that involve a new piece of metadata, which in turn needs to be given the rkyv treatment like the rest of our cacheable/serializable metadata types.)

djkoloski
djkoloski requested changes Jan 7, 2026
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woodruffw and others added 2 commits January 7, 2026 18:26
@woodruffw @djkoloski
Update rkyv_derive/src/archive/enum.rs
f1c1e42 
Co-authored-by: David Koloski <djkoloski@gmail.com>
@woodruffw
Remove <Self as ...> forms
07c4669 
Signed-off-by: William Woodruff <william@astral.sh>
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woodruffw commented Jan 7, 2026

Oops, missed that formatting locally. Will fix.

@woodruffw
Fix cargo +nightly fmt --check
4053b4a 
Signed-off-by: William Woodruff <william@astral.sh>
woodruffw
woodruffw commented Jan 7, 2026
View reviewed changes
rkyv_derive/src/archive/enum.rs
out: #rkyv_path::Place<Self::Archived>,
resolver: <Self as #rkyv_path::Archive>::Resolver,
out: #rkyv_path::Place<
<Self as #rkyv_path::Archive>::Archived>,
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@woodruffw woodruffw Jan 7, 2026

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Not sure if this is the most ideal formatting 🙂

@djkoloski djkoloski merged commit 19e06e9 into rkyv:main Jan 7, 2026
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djkoloski commented Jan 7, 2026

Thanks for the PR! I try to wait at least a week between releases, so this will be in the next release in about four days.

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woodruffw commented Jan 7, 2026

Thanks for the PR! I try to wait at least a week between releases, so this will be in the next release in about four days.

Wonderful, thanks for the fast merge!

@woodruffw woodruffw deleted the ww/ambiguous-associated-item branch January 7, 2026 23:50
@woodruffw woodruffw mentioned this pull request Jan 7, 2026
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djkoloski commented Jan 13, 2026

A little late, but published now!

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woodruffw commented Jan 13, 2026

Much appreciated!

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