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arrow-kt
["Pitfall"] Inline functions lower coverage reports
What version are you currently using? 1.0.1
What would you like to see?
When using Validated#zip for my branch coverage not to drop.
We found this one semi-accidentally on our jacoco reports. Turns out that the deep inline of zip
https://github.com/arrow-kt/arrow/blob/main/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Validated.kt#L1026 https://github.com/arrow-kt/arrow/blob/main/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Validated.kt#L830-L848
ends in this single function
https://github.com/arrow-kt/arrow/blob/9928d163aaa225df3dc050da6914f603ff8c650e/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Validated.kt#L998-L1023
that once inlined introduces many branches that aren't executed...in every call!
My suggestion is to not inline those termination points.
My suggestion is to not inline those termination points.
We should still inline to allow suspension, so we need concrete implementations for all of them. Right?
Make the failure case (L1001-10021) a non-inline function and that should fix it. Either it's success or has some error, which calls a single non-inline function.
I don't think we want to optimise for coverage reports. I've noticed in some cases it still behaves weirdly, but I prefer to have the API more optimal than the coverage 😅. Closing this issue for now, feel free top open it again or re-ignite a discussion.
Doing some housekeeping. 😘