Don't register companion class from const val property (#251)

Fixes #250

Author: fzhinkin

src/main/kotlin/api/KotlinSignaturesLoading.kt

@@ -127,11 +127,11 @@ private fun FieldNode.buildFieldSignature(
         foundAnnotations.addAll(companionClass?.visibleAnnotations.orEmpty())
         foundAnnotations.addAll(companionClass?.invisibleAnnotations.orEmpty())
     } else if (isStatic(access) && isFinal(access)) {
-        companionClass = ownerClass.companionName(ownerClass.kotlinMetadata)?.let {
+        val companionClassCandidate = ownerClass.companionName(ownerClass.kotlinMetadata)?.let {
             classes[it]
         }
 
-        val property = companionClass?.kmProperty(name)
+        val property = companionClassCandidate?.kmProperty(name)
 
         if (property != null && JvmFlag.Property.IS_MOVED_FROM_INTERFACE_COMPANION(property.flags)) {
             /*
@@ -140,7 +140,11 @@ private fun FieldNode.buildFieldSignature(
              *
              * See https://github.com/Kotlin/binary-compatibility-validator/issues/90
              */
-            foundAnnotations.addAll(companionClass!!.methods.annotationsFor(property.syntheticMethodForAnnotations))
+            foundAnnotations.addAll(
+                companionClassCandidate.methods.annotationsFor(
+                    property.syntheticMethodForAnnotations
+                )
+            )
         }
     }
 

src/test/kotlin/cases/enums/EnumWithInternalCompanion.kt

@@ -0,0 +1,12 @@
+/*
+ * Copyright 2016-2024 JetBrains s.r.o.
+ * Use of this source code is governed by the Apache 2.0 License that can be found in the LICENSE.txt file.
+ */
+
+package cases.enums
+
+public enum class EnumWithInternalCompanion {
+    A, B;
+
+    internal companion object
+}

src/test/kotlin/cases/enums/enums.txt

@@ -11,6 +11,14 @@ public final class cases/enums/EnumClass : java/lang/Enum {
 	public static fun values ()[Lcases/enums/EnumClass;
 }
 
+public final class cases/enums/EnumWithInternalCompanion : java/lang/Enum {
+	public static final field A Lcases/enums/EnumWithInternalCompanion;
+	public static final field B Lcases/enums/EnumWithInternalCompanion;
+	public static fun getEntries ()Lkotlin/enums/EnumEntries;
+	public static fun valueOf (Ljava/lang/String;)Lcases/enums/EnumWithInternalCompanion;
+	public static fun values ()[Lcases/enums/EnumWithInternalCompanion;
+}
+
 public final class cases/enums/JavaEnum : java/lang/Enum {
 	public static final field JA Lcases/enums/JavaEnum;
 	public static final field JB Lcases/enums/JavaEnum;