subscriber: make PartialOrd & Ord impls more correct
#995
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Currently, there are some minor issues with `Ord` and `PartialOrd` impls in `tracing_subscriber::filter::env`: - The `Directive` and `StaticDirective` types implement `PartialOrd` with an implementation that never returns `None`, and then have `Ord` implementations that call `partial_cmp` and `expect` that the returned value is `Some`. This isn't necessary. - `field::Match` implements `PartialOrd` manually but derives `Ord`. Since these traits must agree, using the derived implementation for one but manually implementing the other is potentially incorrect (see #991). This branch fixes these issues. I've moved actual comparison code from `PartialOrd` impls for `Directive` and `StaticDirective` to their `Ord` impls, and changed `PartialOrd::partial_cmp` for those types to call `Ord::cmp` and wrap it in a `Some`, rather than having `Ord::cmp` call `PartialOrd::partial_cmp` and unwrap it. This way, the fact that these comparison impls can never return `None` is encoded at the type level, rather than having an `expect` that will always succeed. Additionally, I've added a manual impl of `Ord` for `field::Match` and removed the derived impl. This should make Clippy happier. Signed-off-by: Eliza Weisman <eliza@buoyant.io>
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* upstream/master: subscriber: warn if trying to enable a statically disabled level (tokio-rs#990) subscriber: use macros for module declarations (tokio-rs#1009) chore: remove `stdlib.rs` (tokio-rs#1008) core: fix linked list tests reusing `Registration`s (tokio-rs#1016) subscriber: support dash in target names (tokio-rs#1012) docs: switch to intra-doc links in tracing-core (tokio-rs#1010) tracing-opentelemetry: implement additional record types (bool, i64, u64) (tokio-rs#1007) core: add intrusive linked list for callsite registry (tokio-rs#988) serde: allow tracing-serde to work on no_std. (tokio-rs#960) tracing: remove `Into<Option<Id>>` impl for `Span` (tokio-rs#1003) tracing: make `Entered` `!Send` (tokio-rs#1001) chore: fix nightly clippy warnings (tokio-rs#991) chore: bump all crate versions (tokio-rs#998) macros: fix the `tracing-macros` crate not compiling (tokio-rs#1000) tracing: prepare to release 0.1.21 (tokio-rs#997) core: prepare to release 0.1.17 (tokio-rs#996) subscriber: make `PartialOrd` & `Ord` impls more correct (tokio-rs#995) core, tracing: don't inline dispatcher::get_default (tokio-rs#994) core: make `Level` and `LevelFilter` `Copy` (tokio-rs#992)
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Motivation
Currently, there are some minor issues with
OrdandPartialOrdimplsin
tracing_subscriber::filter::env:DirectiveandStaticDirectivetypes implementPartialOrdwith an implementation that never returns
None, and then haveOrdimplementations that call
partial_cmpandexpectthat the returnedvalue is
Some. This isn't necessary.field::MatchimplementsPartialOrdmanually but derivesOrd.Since these traits must agree, using the derived implementation for
one but manually implementing the other is potentially incorrect (see
fix nightly clippy warnings #991).
Solution
This branch fixes these issues. I've moved actual comparison code from
PartialOrdimpls forDirectiveandStaticDirectiveto theirOrdimpls, and changed
PartialOrd::partial_cmpfor those types to callOrd::cmpand wrap it in aSome, rather than havingOrd::cmpcallPartialOrd::partial_cmpand unwrap it. This way, the fact that thesecomparison impls can never return
Noneis encoded at the type level,rather than having an
expectthat will always succeed.Additionally, I've added a manual impl of
Ordforfield::Matchandremoved the derived impl. This should make Clippy happier.
Signed-off-by: Eliza Weisman eliza@buoyant.io