'const val' are now considered constants by Java in IDEA

#KT-12026 Fixed

compiler/light-classes/src/org/jetbrains/kotlin/asJava/KtLightField.kt

@@ -18,6 +18,7 @@ package org.jetbrains.kotlin.asJava
 
 import com.intellij.openapi.util.TextRange
 import com.intellij.psi.*
+import com.intellij.psi.impl.PsiVariableEx
 import com.intellij.psi.impl.light.LightElement
 import com.intellij.util.IncorrectOperationException
 import org.jetbrains.annotations.NonNls
@@ -27,7 +28,7 @@ import org.jetbrains.kotlin.psi.KtDeclaration
 import org.jetbrains.kotlin.psi.KtEnumEntry
 import org.jetbrains.kotlin.psi.KtNamedDeclaration
 
-interface KtLightField : PsiField, KtLightDeclaration<KtDeclaration, PsiField>
+interface KtLightField : PsiField, KtLightDeclaration<KtDeclaration, PsiField>, PsiVariableEx
 
 // Copied from com.intellij.psi.impl.light.LightField
 sealed class KtLightFieldImpl(
@@ -94,6 +95,10 @@ sealed class KtLightFieldImpl(
 
     override fun getNavigationElement() = kotlinOrigin ?: super.getNavigationElement()
 
+    override fun computeConstantValue(visitedVars: MutableSet<PsiVariable>?): Any? {
+        return (clsDelegate as PsiVariableEx).computeConstantValue(visitedVars)
+    }
+
     override fun isEquivalentTo(another: PsiElement?): Boolean {
         if (another is KtLightField && kotlinOrigin == another.kotlinOrigin && clsDelegate == another.clsDelegate) {
             return true

idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/UseKotlinConstInSwitch.java

@@ -0,0 +1,12 @@
+public class UseKotlinConstInSwitch {
+    public static void main(int i) {
+        switch (i) {
+            case a.UseKotlinConstInSwitchKt.i:
+                System.out.println("1");
+                break;
+            default:
+                System.out.println("2");
+                break;
+        }
+    }
+}

idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/UseKotlinConstInSwitch.kt

@@ -0,0 +1,3 @@
+package a
+
+const val i = 45

idea/tests/org/jetbrains/kotlin/checkers/JavaAgainstKotlinBinariesCheckerTestGenerated.java

@@ -107,6 +107,12 @@ public class JavaAgainstKotlinBinariesCheckerTestGenerated extends AbstractJavaA
         doTest(fileName);
     }
 
+    @TestMetadata("UseKotlinConstInSwitch.kt")
+    public void testUseKotlinConstInSwitch() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/UseKotlinConstInSwitch.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("UseKotlinSubclassesOfMappedTypes.kt")
     public void testUseKotlinSubclassesOfMappedTypes() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/UseKotlinSubclassesOfMappedTypes.kt");

idea/tests/org/jetbrains/kotlin/checkers/JavaAgainstKotlinSourceCheckerTestGenerated.java

@@ -109,6 +109,12 @@ public class JavaAgainstKotlinSourceCheckerTestGenerated extends AbstractJavaAga
             doTest(fileName);
         }
 
+        @TestMetadata("UseKotlinConstInSwitch.kt")
+        public void testUseKotlinConstInSwitch() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/UseKotlinConstInSwitch.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("UseKotlinSubclassesOfMappedTypes.kt")
         public void testUseKotlinSubclassesOfMappedTypes() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/UseKotlinSubclassesOfMappedTypes.kt");