feat(uri): derive equality for URI errors#850
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Allow InvalidUri and InvalidUriParts to implement PartialEq and Eq so library error types that wrap them can derive equality for tests. Keep ErrorKind private and leave broader error-type equality as a separate API question.
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Motivation
I opened #849 as the durable place for the API tradeoff. This PR is a small concrete version of the change so maintainers can evaluate the actual patch shape.
I have a library error type that wraps
http::uri::InvalidUri. I would like that error type to derivePartialEqandEqfor straightforward unit tests, butInvalidUricurrently prevents that.Change
This derives
PartialEqandEqforInvalidUriandInvalidUriParts.ErrorKindremains private.The test checks that both public error types implement
Eqand that repeatedInvalidUri/InvalidUriPartsfailures can be compared directly.Compatibility
I realize this is still a public contract. Prior discussions such as #128 and #204 were cautious about trait impls on error types because they can constrain future internals.
My take is that
PartialEq/Eqis a smaller commitment thanClone: it does not exposeErrorKind, and equality can remain a coarse comparison over the existing broad URI error category. That said, users could observe whether twoInvalidUrivalues compare equal, so I am opening this as a draft PR to get maintainer feedback on that tradeoff.Refs #849.
Validation