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Add UnsafeResultValueAccess annotation to Result class for safer value access #123

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Add UnsafeResultValueAccess annotation to Result class for safer value access #123

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1 change: 1 addition & 0 deletions buildSrc/src/main/kotlin/kotlin-conventions.gradle.kts
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Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,7 @@ kotlin {
all {
languageSettings.apply {
optIn("kotlin.contracts.ExperimentalContracts")
optIn("com.github.michaelbull.result.UnsafeResultValueAccess")
}
}

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18 changes: 18 additions & 0 deletions kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Result.kt
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Expand Up @@ -51,10 +51,12 @@ public value class Result<out V, out E> internal constructor(
private val inlineValue: Any?,
) {

@UnsafeResultValueAccess
@Suppress("UNCHECKED_CAST")
public val value: V
get() = inlineValue as V

@UnsafeResultValueAccess
@Suppress("UNCHECKED_CAST")
public val error: E
get() = (inlineValue as Failure<E>).error
Expand Down Expand Up @@ -102,3 +104,19 @@ private class Failure<out E>(
return "Failure($error)"
}
}

/**
* Marks access to [Result.value] or [Result.error] as potentially unsafe unless the [Result]
* is explicitly checked for [Result.isOk] or [Result.isErr] beforehand.
*
* Ensure that you verify the [Result] state using [Result.isOk] or [Result.isErr] before accessing its value.
* Alternatively, consider using the [Result.fold] function to safely handle the result.
*/
@RequiresOptIn(
level = RequiresOptIn.Level.ERROR,
message = "Accessing Result.value or Result.error without checking the Result state may lead to unsafe behavior.",
)
@MustBeDocumented
@Retention(AnnotationRetention.BINARY)
@Target(AnnotationTarget.PROPERTY)
public annotation class UnsafeResultValueAccess