Remove tailrec as this is not a tailrec function

[wmontwe]

Fixes a warning that: A function is marked as tail-recursive but no tail calls are found.

[cketti]

How/where are you getting this warning? The function is tail-recursive and "Show Kotlin Bytecode" in my IDE shows the compiler has converted the code to a loop as is expected when using tailrec.

[wmontwe]

How/where are you getting this warning? The function is tail-recursive and "Show Kotlin Bytecode" in my IDE shows the compiler has converted the code to a loop as is expected when using tailrec.

The build reports this and my IDE too. AS 2024.2.1 patch 3

Task :core:android:common:compileDebugKotlin
w: file:///Users/user/Code/mzla/thunderbird-android/core/android/common/src/main/kotlin/app/k9mail/core/android/common/activity/ContextExtensions.kt:10:1 A function is marked as tail-recursive but no tail calls are found.
w: file:///Users/user/Code/mzla/thunderbird-android/core/android/common/src/main/kotlin/app/k9mail/core/android/common/activity/ContextExtensions.kt:11:48 Recursive call is not a tail call.

[cketti]

Might be this bug: https://youtrack.jetbrains.com/issue/KT-73420

To avoid a StackOverflowException we shouldn't use recursion when the recursion depth is unknown.

The following code should be roughly equivalent to what the compiler generates when tailrec is working.

fun Context.findActivity(): Activity? {
    var context: Context? = this
    while (context != null && context !is Activity) {
        context = (context as? ContextWrapper)?.baseContext
    }

    return context as? Activity
}

Update:

Converting the code to not use the elvis operator seems to also fix the warning.

tailrec fun Context.findActivity(): Activity? {
    return if (this is Activity) {
        this
    } else {
        (this as? ContextWrapper)?.baseContext?.findActivity()
    }
}

[wmontwe]

I like the updated version and update the pull-request.