.use extension checking

[Ruslan Magzyumov]

I need to check that use extension is used for Closable interface.

private val file = File("path")
val fileOutputStream = file.outputStream().write(999) //WARNING

private val file = File("path")
val fileOutputStream = file.outputStream().use { //NORMAL
// Some methods
}

I started off by looking for a method that returned type is inherits from Closable (in the example above is outputStream()) . How do I find the method that references on outputStream(), then to find its name?

[Tor Norbye]

The best way to do this would be to use the data flow analyzer, since you want to not just hardcode this to work with the exact above pattern -- e.g. what if somebody wrote it as

val stream = file.outputStream()

Log.i(something)

stream.write(...)

Here you want to track the output stream across the variable assignment.

See https://googlesamples.github.io/android-custom-lint-rules/api-guide/dataflow-analyzer.md.html .

-- Tor