Preserve synthetic enum methods in stub-based 'ClsClassImpl'

'ClsClassImpl' instances created by the platform contain synthetic
enum methods (added by 'ClassInnerStuffCache.calcMethods()'). Such
convention is common in IntelliJ (see KT-36095 and
'9a8b345adaded83fe13980a28db5d9f9acc7450d' in the IntelliJ repository).

This commit makes Kotlin's stub-based classes consistent with the
convention. Instead, a filter is added in place of 'ClsClassImpl' usage.

See also the following commits:
- 7c86911f44
- 43468c6d55

analysis/decompiled/light-classes-for-decompiled/src/org/jetbrains/kotlin/analysis/decompiled/light/classes/KtLightClassForDecompiledDeclaration.kt

@@ -18,6 +18,7 @@ import org.jetbrains.kotlin.analyzer.KotlinModificationTrackerService
 import org.jetbrains.kotlin.asJava.classes.KotlinClassInnerStuffCache
 import org.jetbrains.kotlin.asJava.classes.LightClassesLazyCreator
 import org.jetbrains.kotlin.asJava.classes.lazyPub
+import org.jetbrains.kotlin.asJava.isSyntheticValuesOrValueOfMethod
 import org.jetbrains.kotlin.load.java.structure.LightClassOriginKind
 import org.jetbrains.kotlin.psi.KtClassOrObject
 
@@ -155,7 +156,8 @@ open class KtLightClassForDecompiledDeclaration(
 
     private val _methods: MutableList<PsiMethod> by lazyPub {
         mutableListOf<PsiMethod>().also {
-            clsDelegate.methods.mapTo(it) { psiMethod ->
+            clsDelegate.methods.mapNotNullTo(it) { psiMethod ->
+                if (isSyntheticValuesOrValueOfMethod(psiMethod)) return@mapNotNullTo null
                 KtLightMethodForDecompiledDeclaration(
                     funDelegate = psiMethod,
                     funParent = this,

compiler/light-classes/src/org/jetbrains/kotlin/asJava/builder/ClsWrapperStubPsiFactory.java

@@ -16,8 +16,6 @@ import com.intellij.psi.stubs.StubElement;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import static org.jetbrains.kotlin.asJava.SyntheticElementUtilsKt.isSyntheticValuesOrValueOfMethod;
-
 public class ClsWrapperStubPsiFactory extends StubPsiFactory {
     public static final Key<LightElementOrigin> ORIGIN = Key.create("ORIGIN");
     public static final ClsWrapperStubPsiFactory INSTANCE = new ClsWrapperStubPsiFactory();
@@ -43,30 +41,6 @@ public class ClsWrapperStubPsiFactory extends StubPsiFactory {
             public PsiClass getSourceMirrorClass() {
                 return null;
             }
-
-            @NotNull
-            @Override
-            public PsiMethod[] getMethods() {
-                PsiMethod[] baseMethods = super.getMethods();
-                if (!isEnum()) return baseMethods;
-
-                int filteredArraySize = 0;
-                for (PsiMethod method : baseMethods) {
-                    if (!isSyntheticValuesOrValueOfMethod(method)) filteredArraySize++;
-                }
-
-                if (filteredArraySize == baseMethods.length) return baseMethods;
-
-                PsiMethod[] filteredMethods = new PsiMethod[filteredArraySize];
-                int index = 0;
-                for (PsiMethod method : baseMethods) {
-                    if (!isSyntheticValuesOrValueOfMethod(method)) {
-                        filteredMethods[index] = method;
-                        index++;
-                    }
-                }
-                return filteredMethods;
-            }
         };
     }
 

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

@@ -12,17 +12,14 @@ import com.intellij.psi.scope.PsiScopeProcessor
 import com.intellij.psi.util.MethodSignature
 import com.intellij.psi.util.MethodSignatureBackedByPsiMethod
 import com.intellij.psi.util.PsiTreeUtil
-import org.jetbrains.kotlin.asJava.LightClassUtil
+import org.jetbrains.kotlin.asJava.*
 import org.jetbrains.kotlin.asJava.builder.LightMemberOrigin
 import org.jetbrains.kotlin.asJava.builder.LightMemberOriginForDeclaration
 import org.jetbrains.kotlin.asJava.builder.MemberIndex
 import org.jetbrains.kotlin.asJava.builder.memberIndex
-import org.jetbrains.kotlin.asJava.checkIsMangled
 import org.jetbrains.kotlin.asJava.classes.KtLightClass
 import org.jetbrains.kotlin.asJava.classes.cannotModify
 import org.jetbrains.kotlin.asJava.classes.lazyPub
-import org.jetbrains.kotlin.asJava.propertyNameByAccessor
-import org.jetbrains.kotlin.asJava.unwrapped
 import org.jetbrains.kotlin.codegen.state.KotlinTypeMapper
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
@@ -222,8 +219,11 @@ open class KtLightMethodImpl protected constructor(
             return KtLightMethodImpl(computeRealDelegate, origin, containingClass, dummyDelegate)
         }
 
-        fun fromClsMethods(delegateClass: PsiClass, containingClass: KtLightClass) = delegateClass.methods.map {
-            KtLightMethodImpl.create(it, getOrigin(it), containingClass)
+        fun fromClsMethods(delegateClass: PsiClass, containingClass: KtLightClass): List<KtLightMethodImpl> = buildList {
+            for (method in delegateClass.methods) {
+                if (isSyntheticValuesOrValueOfMethod(method)) continue
+                this += create(method, getOrigin(method), containingClass)
+            }
         }
 
         fun getOrigin(method: PsiMethod) = adjustMethodOrigin(getMemberOrigin(method))