How to detekt the type of a KtReferenceExpression?

Support
1

I’m creating a Detekt rule which suggests replacing map.getOrDefault(key, defaultExpression) with map.getOrElse(key) { defaultExpression } but I’m having difficulty checking the type of the receiver since I only want this rule to apply when `getOrDefault(key, defaultExpression) is called on an instance of a map.

This is the new rule:

import io.gitlab.arturbosch.detekt.api.Debt.Companion.FIVE_MINS
import io.gitlab.arturbosch.detekt.api.Issue
import io.gitlab.arturbosch.detekt.api.Rule
import io.gitlab.arturbosch.detekt.api.Severity.Warning
import org.jetbrains.kotlin.psi.KtDotQualifiedExpression
import org.jetbrains.kotlin.psi.KtReferenceExpression
import org.jetbrains.kotlin.psi.KtSimpleNameExpression

class GetOrDefaultShouldBeReplacedWithGetOrElse : Rule() {
  override val defaultRuleIdAliases = setOf("USE_GET_OR_ELSE_INSTEAD_OF_GET_OR_DEFAULT")

  override val issue: Issue = Issue(
      id = javaClass.simpleName,
      severity = Warning,
      description = "replace map.getOrDefault(key, defaultValue) with map.getOrElse(key) { defaultValue }",
      debt = FIVE_MINS
  )

  override fun visitDotQualifiedExpression(expression: KtDotQualifiedExpression) {
    super.visitDotQualifiedExpression(expression)

    val receiver = expression.receiverExpression as? KtReferenceExpression ?: return

    val references = receiver.references
    // Boo! references is an empty array!

    val type = references?.find { it is KtSimpleNameExpression }?.resolve() ?: return
    // TODO: Check if the type is a subtype of Map
  }
}

Here is my test for context:

@Test
  fun `usage of getOrDefault is flagged`() {
    val findings = GetOrDefaultShouldBeReplacedWithGetOrElse().lint(
        """
          fun usage() {
            val map = mapOf("Dan" to 3)
            
            if(map.getOrDefault("Dan", 0) > 3) {
              println("Gotcha!")
            }
          }
        """.trimIndent()
    )

    Assertions.assertThat(findings).hasSize(1)
  }

Any ideas why references is an empty array or does anyone have any other suggestions for checking the type of the receiver?