Consider the following code snippet in a custom View

class SlackToolbar(..., attrs: AttributeSet?) {
  var isThemeable = false
  init {
    if (attrs != null) {
      context.obtainStyledAttributes(attrs, R.styleable.SlackToolbar).use {
        isThemeable = it.getBoolean(R.styleable.SlackToolbar_isThemeable, true)
      }
    }
  }
}

This snippet, when targeting android SDK 31, reports no errors because TypedArray implements AutoCloseable and this uses Kotlin stdlib's top-level kotlin.use extension function on AutoCloseable. However, this seems to be a relatively new addition to the SDK. I actually can't find documentation that explicitly mentions when this was added, my best guess is that it was added in API 31 because that's when the corresponding close() method was added.

The above snippet will obviously then fail at runtime if running on SDK < 31, but thew NewApi lint gives no warnings or errors about it. I'm not entirely sure where it falls over as it's going through both an an inline extension function + a superinterface, but I figure that's a simple enough repro case.

Android Studio Dolphin | 2021.3.1 Canary 6
Build #AI-213.6777.52.2113.8265607, built on March 7, 2022
Runtime version: 11.0.13+0-b1751.21-8125866 x86_64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
macOS 12.2.1
GC: G1 Young Generation, G1 Old Generation
Memory: 5120M
Cores: 8
Registry:
    external.system.auto.import.disabled=true
    ide.text.editor.with.preview.show.floating.toolbar=false

Non-Bundled Plugins:
    Key Promoter X (2021.3)

Version of Gradle Plugin: 7.1.2
Version of Gradle: 7.4.1
Version of Java: openjdk version "17.0.2" 2022-01-18 LTS (zulu)
OS: macOS monterey 12.2.1

Issue 224572537

Links (2)

Issue metadata