Uast: Fix getExpressionType for elvis expression

#KT-18997 Fixed Target Versions 1.1.5

plugins/uast-kotlin/src/org/jetbrains/uast/kotlin/expressions/ElvisExpression.kt

@@ -2,8 +2,11 @@ package org.jetbrains.uast.kotlin.expressions
 
 import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiMethod
+import com.intellij.psi.PsiType
 import org.jetbrains.kotlin.psi.KtBinaryExpression
 import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.resolve.BindingContext
+import org.jetbrains.kotlin.types.CommonSupertypes
 import org.jetbrains.uast.*
 import org.jetbrains.uast.kotlin.*
 import org.jetbrains.uast.kotlin.kinds.KotlinSpecialExpressionKinds
@@ -69,7 +72,7 @@ fun createElvisExpression(elvisExpression: KtBinaryExpression, containingElement
     val left = elvisExpression.left ?: return UastEmptyExpression
     val right = elvisExpression.right ?: return UastEmptyExpression
 
-    return object : UExpressionList, KotlinEvaluatableUElement, KotlinUElementWithType {
+    return object : UExpressionList, KotlinEvaluatableUElement {
         override val psi: PsiElement? = elvisExpression
         override val kind = KotlinSpecialExpressionKinds.ELVIS
         override val uastParent: UElement? = containingElement
@@ -77,9 +80,19 @@ fun createElvisExpression(elvisExpression: KtBinaryExpression, containingElement
         override val expressions: List<UExpression> by lz {
             createElvisExpressions(left, right, this, elvisExpression.parent)
         }
-        override fun asRenderString(): String = kind.name + " " +
-                expressions.joinToString(separator = "\n", prefix = "{\n", postfix = "\n}") {
-                    it.asRenderString().withMargin
-                }
+        override fun asRenderString(): String {
+            return kind.name + " " +
+                   expressions.joinToString(separator = "\n", prefix = "{\n", postfix = "\n}") {
+                       it.asRenderString().withMargin
+                   }
+        }
+        override fun getExpressionType(): PsiType? {
+            val leftType = left.analyze()[BindingContext.EXPRESSION_TYPE_INFO, left]?.type ?: return null
+            val rightType = right.analyze()[BindingContext.EXPRESSION_TYPE_INFO, right]?.type ?: return null
+
+            return CommonSupertypes
+                    .commonSupertype(listOf(leftType, rightType))
+                    .toPsiType(this, elvisExpression, boxed = false)
+        }
     }
 }

plugins/uast-kotlin/testData/ElvisType.kt

@@ -0,0 +1,6 @@
+
+fun foo(text: String?) = bar(text ?: return)
+
+fun bar(o: Any) {
+
+}

plugins/uast-kotlin/tests/KotlinUastApiTest.kt

@@ -7,7 +7,6 @@ import org.jetbrains.kotlin.psi.psiUtil.getParentOfType
 import org.jetbrains.kotlin.test.testFramework.KtUsefulTestCase
 import org.jetbrains.uast.*
 import org.jetbrains.uast.test.env.findElementByText
-import org.jetbrains.uast.visitor.UastVisitor
 import org.junit.Assert
 import org.junit.Test
 
@@ -98,4 +97,11 @@ class KotlinUastApiTest : AbstractKotlinUastTest() {
             test2.fields.find { it.name == "bar" }!!.annotations.single { it.qualifiedName == "MyAnnotation" }
         }
     }
+
+    @Test fun testElvisType() {
+        doTest("ElvisType") { _, file ->
+            val elvisExpression = file.findElementByText<UExpression>("text ?: return")
+            assertEquals("String", elvisExpression.getExpressionType()!!.presentableText)
+        }
+    }
 }