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DESCRIBE THE ISSUE IN DETAIL:

Lint's NewAPI check fails to detect "illegal" usages of Matcher.group(String) (https://developer.android.com/reference/java/util/regex/Matcher#group(java.lang.String)) when used via Kotlin stlib APIs (https://github.com/JetBrains/kotlin/blob/b76452e15f37f616a0393747b3c624eb61535fb7/libraries/stdlib/src/kotlin/text/regex/MatchResult.kt#L42) in API levels < 26.

I don't know about the internals of the NewApi check, so I'm not sure this is something that's expected to be flagged as is, or whether Kotlin stdlib's should be doing something else for that to happen - opening the issue to get to the bottom of this.

STEPS TO REPRODUCE:

  1. Create an Android project with minSdk version < 26.
  2. Write some code that uses Kotlin stdlib's Regex and named groups. For example:
val myRegex = Regex("title=(?<title>.*)")

fun getTitle(from: String): String? {
    val titleMatch = myRegex.find(from) ?: return null
    val titleGroup = titleMatch.groups["title"] ?: return null
    return titleGroup.value
}

getTitle("title=Is this an Android Lint bug?")

✅ EXPECTED: Lint flags the usage of named groups groups["title"] as "requires API level 26"

❌ ACTUAL: Lint does not flag this, but app throws an exception at runtime in API levels < 26 when using this API.

ADDITIONAL INFORMATION

  • API levels < 26 exception stacktrace:
FATAL EXCEPTION: main

Process: com.vicgarci.newapiinvalidusagerepro, PID: 10015
java.lang.NoSuchMethodError: No virtual method start(Ljava/lang/String;)I in class Ljava/util/regex/Matcher; or its super classes (declaration of 'java.util.regex.Matcher' appears in /system/framework/core-oj.jar)
at kotlin.internal.jdk8.JDK8PlatformImplementations.getMatchResultNamedGroup(JDK8PlatformImplementations.kt:45)
at kotlin.text.MatcherMatchResult$groups$1.get(Regex.kt:370)
at kotlin.text.jdk8.RegexExtensionsJDK8Kt.get(RegexExtensions.kt:23)