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Undocumented Attributes #532
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automatically_derivedis also an implementation detail, I don't know why it's not feature gated.automatically_derived— I vote "probably"? It has some use in the wild. I think the only reason to use it is for rustdoc. Are there other reasons to use it?What does the attribute do?
@petrochenkov Could you try a PR + crater to "destabilization"?
bench— I vote "no". It requires the unstableBencherto be used.👍
feature— I vote "maybe" 🤔? Although this is a nightly-oriented attribute, it is very widely used.👍 + note that it is unstable.
reexport_test_harness_main— I vote "no". Even though it is usable on stable, I think it is an internal implementation detail, and I do not see anyone using it.What... @petrochenkov I'd also attempt destabilization for this...
type_length_limit— I vote "yes". I think it is analogous torecursion_limit, and I suspect it just fell through the cracks.Sounds good.
These are just waiting to be finished:
@ehuss I think these PRs haven't received any attention for some time, if you would like to take over them that'd be nice.
What does the attribute do?
Hm, looking closer, I'm not sure. rustdoc used to use it to separate automatically derived traits, but it was removed in rust-lang/rust#34105. Just grepping through the code shows a few uses:
- Avoids unused warnings.
- Something about unsafety checks.
- Clippy uses it for some lints.
Here's a sampling of crates that use it in the wild:
- alga_derive
- aster
- bart_derive
- bit_manager_derive
- clippy_lints
- drop-take-derive
- enum-kinds
- enum-kinds-macros
- enum-map-derive
- enum_traits_macros
- eosio_macros
- gluon_codegen
- log4rs-rolling-file
- nue-codegen
- palette_derive
- runtime-fmt-derive
- serde_codegen
- serde_derive
- serde_derive_state
- serde_yaml_incomplete
if you would like to take over them that'd be nice.
Yea, I'll try to take a look. I think Jorge said he's busy with thesis work.
Something about unsafety checks.
That sounds concerning...
Here's a sampling of crates that use it in the wild:
Oh... wow; That seems quite unfortunate... Might be unfeasible to destabilize, maybe we should try to clarify semantics instead then...
That sounds concerning...
Here it is used to display a warning diagnostic if
#[derive]is used on something that uses#[repr(packed)]that doesn't implementCopy. Seems a bit presumptuous that all derives will do something unsafe, but I'm not going to read the long discussion where it was introduced (rust-lang/rust#44884).SAFE_PACKED_BORROWSsays it will become a hard error in the future.This can be closed, yes?
Yea. I seem to recall leaving it open for some reason, but now I can't remember.
There are a few attributes that are currently not documented. I wanted to get feedback if these should be documented. I've included my inclination, but I'd like to hear what others think.
automatically_derived— I vote "probably"? It has some use in the wild. I think the only reason to use it is for rustdoc. Are there other reasons to use it?feature— I vote "maybe" 🤔? Although this is a nightly-oriented attribute, it is very widely used.type_length_limit— I vote "yes". I think it is analogous torecursion_limit, and I suspect it just fell through the cracks.bench— I vote "no". It requires the unstableBencherto be used. (Now destabilized via Remove derivesEncodable/Decodableand unstabilize attribute#[bench]rust#62507)reexport_test_harness_main— I vote "no". Even though it is usable on stable, I think it is an internal implementation detail, and I do not see anyone using it.These are just waiting to be finished:
panic_handler(document #[panic_handler] #362)used(document #[used] #361)target_feature(target_feature (RFC 2045, RFC 2325) #286)