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import scala.tools.partest.BytecodeTest
import scala.tools.asm
import scala.tools.asm.util._
import scala.tools.nsc.util.stringFromWriter
import scala.collection.JavaConverters._
object Test extends BytecodeTest {
val nullChecks = Set(asm.Opcodes.IFNONNULL, asm.Opcodes.IFNULL)
def show: Unit = {
def test(methodName: String, expected: Int) {
val classNode = loadClassNode("Lean")
val methodNode = getMethod(classNode, methodName)
val got = countNullChecks(methodNode.instructions)
assert(got == expected, s"$methodName: expected $expected but got $got comparisons")
}
test("string", expected = 0)
test("module", expected = 0)
test("moduleIndirect", expected = 2)
}
def countNullChecks(insnList: asm.tree.InsnList): Int =
insnList.iterator.asScala.map(_.getOpcode).count(nullChecks)
}
class Lean {
def string {
"" == toString
}
def module {
Nil == (toString: Any)
}
def moduleIndirect {
val n: Nil.type = null
n == (toString: Any) // still need null checks here.
}
}
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