Generate equals/hashCode(): Enable for classes without properties

Also:
- forbid for enum classes
- use javaClass.hashCode() instead of 0 if class has no properties

 #KT-18418 Fixed

Author: asedunov

idea/src/org/jetbrains/kotlin/idea/actions/generate/KotlinGenerateEqualsAndHashcodeAction.kt

@@ -74,12 +74,12 @@ class KotlinGenerateEqualsAndHashcodeAction : KotlinGenerateMemberActionBase<Kot
     override fun isValidForClass(targetClass: KtClassOrObject): Boolean {
         return targetClass is KtClass
                && targetClass !is KtEnumEntry
+               && !targetClass.isEnum()
                && !targetClass.isAnnotation()
                && !targetClass.isInterface()
                && (!targetClass.isData() || isValidForDataClass(targetClass))
-               && getPropertiesToUseInGeneratedMember(targetClass).isNotEmpty()
     }
-    
+
     private fun isValidForDataClass(targetClass: KtClass): Boolean {
         val constructor = targetClass.primaryConstructor ?: return false
         val context = constructor.analyze(BodyResolveMode.PARTIAL)
@@ -226,7 +226,7 @@ class KotlinGenerateEqualsAndHashcodeAction : KotlinGenerateMemberActionBase<Kot
             val initialValue = when {
                 !builtins.isMemberOfAny(superHashCode) -> "super.hashCode()"
                 propertyIterator.hasNext() -> propertyIterator.next().genVariableHashCode(false)
-                else -> "0"
+                else -> "javaClass.hashCode()"
             }
 
             val bodyText = if (propertyIterator.hasNext()) {

idea/testData/codeInsight/generate/equalsWithHashCode/explicitDefaultAccessors.kt

@@ -5,6 +5,4 @@ class Test {
     var name: String = ""
         get
     <caret>
-}
-
-// FORCED
+}

idea/testData/codeInsight/generate/equalsWithHashCode/explicitDefaultAccessors.kt.after

@@ -12,9 +12,7 @@ class Test {
     }
 
     override fun hashCode(): Int {
-        return 0
+        return javaClass.hashCode()
     }
 
-}
-
-// FORCED
+}

idea/testData/codeInsight/generate/equalsWithHashCode/noVars.kt

@@ -1,4 +1,3 @@
-// NOT_APPLICABLE
 class A {<caret>
     fun foo() {
 

idea/testData/codeInsight/generate/equalsWithHashCode/noVarsForced.kt.after renamed to idea/testData/codeInsight/generate/equalsWithHashCode/noVars.kt.after

@@ -1,4 +1,3 @@
-// FORCED
 class A {
     fun foo() {
 
@@ -11,6 +10,6 @@ class A {
     }
 
     override fun hashCode(): Int {
-        return 0
+        return javaClass.hashCode()
     }
 }

idea/testData/codeInsight/generate/equalsWithHashCode/noVarsForced.kt

@@ -1,4 +1,3 @@
-// FORCED
 open class X {
     override fun equals(other: Any?) = super.equals(other)
     override fun hashCode() = super.hashCode()

idea/testData/codeInsight/generate/equalsWithHashCode/noVarsForcedWithSuperClass.kt renamed to idea/testData/codeInsight/generate/equalsWithHashCode/noVarsWithSuperClass.kt

@@ -1,4 +1,3 @@
-// FORCED
 open class X {
     override fun equals(other: Any?) = super.equals(other)
     override fun hashCode() = super.hashCode()

idea/testData/codeInsight/generate/equalsWithHashCode/noVarsForcedWithSuperClass.kt.after renamed to idea/testData/codeInsight/generate/equalsWithHashCode/noVarsWithSuperClass.kt.after

@@ -132,15 +132,9 @@ public void testNoVars() throws Exception {
         doTest(fileName);
     }
 
-    @TestMetadata("noVarsForced.kt")
-    public void testNoVarsForced() throws Exception {
-        String fileName = KotlinTestUtils.navigationMetadata("idea/testData/codeInsight/generate/equalsWithHashCode/noVarsForced.kt");
-        doTest(fileName);
-    }
-
-    @TestMetadata("noVarsForcedWithSuperClass.kt")
-    public void testNoVarsForcedWithSuperClass() throws Exception {
-        String fileName = KotlinTestUtils.navigationMetadata("idea/testData/codeInsight/generate/equalsWithHashCode/noVarsForcedWithSuperClass.kt");
+    @TestMetadata("noVarsWithSuperClass.kt")
+    public void testNoVarsWithSuperClass() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/testData/codeInsight/generate/equalsWithHashCode/noVarsWithSuperClass.kt");
         doTest(fileName);
     }