KT-35536: Fix enum constants in KAPT

Enum constants are Pair, so make sure to unpack them correctly.

plugins/kapt3/kapt3-compiler/src/org/jetbrains/kotlin/kapt3/stubs/ClassFileToSourceStubConverter.kt

@@ -47,7 +47,9 @@ import org.jetbrains.kotlin.kapt3.stubs.ErrorTypeCorrector.TypeKind.METHOD_PARAM
 import org.jetbrains.kotlin.kapt3.stubs.ErrorTypeCorrector.TypeKind.RETURN_TYPE
 import org.jetbrains.kotlin.kapt3.util.*
 import org.jetbrains.kotlin.load.java.sources.JavaSourceElement
+import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.DelegatingBindingTrace
@@ -1194,6 +1196,21 @@ class ClassFileToSourceStubConverter(val kaptContext: KaptContextForStubGenerati
 
                 treeMaker.Select(treeMaker.Type(enumType), treeMaker.name(valueName))
             }
+            is Pair<*, *> -> {
+                assert(value.first is ClassId)
+                assert(value.second is Name)
+                val valueName = with((value.second as Name).identifier) {
+                    if (isValidIdentifier(this)) {
+                        this
+                    } else {
+                        kaptContext.compiler.log.report(kaptContext.kaptError("'$this' is an invalid Java enum value name"))
+                        "InvalidFieldName"
+                    }
+                }
+                val asSingleFqName = (value.first as ClassId).asSingleFqName()
+
+                treeMaker.Select(treeMaker.FqName(asSingleFqName), treeMaker.name(value.second.toString()))
+            }
             is List<*> -> treeMaker.NewArray(null, JavacList.nil(), mapJList(value) { convertLiteralExpression(it) })
 
             is Type -> treeMaker.Select(treeMaker.Type(value), treeMaker.name("class"))

plugins/kapt3/kapt3-compiler/testData/converter/unsafePropertyInitializers.kt

@@ -21,4 +21,13 @@ object Foo {
 object Boo {
     val z = foo()
     fun foo() = "abc"
+}
+
+class HavingState {
+    val state = State.START
+}
+
+enum class State {
+    START,
+    FINISH,
 }

plugins/kapt3/kapt3-compiler/testData/converter/unsafePropertyInitializers.txt

@@ -116,3 +116,37 @@ public final class Foo {
         super();
     }
 }
+
+////////////////////
+
+
+import java.lang.System;
+
+@kotlin.Metadata()
+public final class HavingState {
+    @org.jetbrains.annotations.NotNull()
+    private final State state = State.START;
+
+    @org.jetbrains.annotations.NotNull()
+    public final State getState() {
+        return null;
+    }
+
+    public HavingState() {
+        super();
+    }
+}
+
+////////////////////
+
+
+import java.lang.System;
+
+@kotlin.Metadata()
+public enum State {
+    /*public static final*/ START /* = new State() */,
+    /*public static final*/ FINISH /* = new State() */;
+
+    State() {
+    }
+}