Properly calculate isConst for java properties

compiler/testData/codegen/bytecodeTextMultifile/inlineJavaStaticFields/JClass.java

@@ -12,6 +12,9 @@ public class JClass {
     public final static char PrimitiveChar = 'K';
     public final static String Str = ":J";
 
+    @Nullable
+    public final static String StrNullable = "nullable";
+
     @NotNull
     public final static Integer BoxedInt = 9500;
 

compiler/testData/codegen/bytecodeTextMultifile/inlineJavaStaticFields/test.kt

@@ -1,6 +1,9 @@
 object KoKobject {
-    @JvmStatic
+    @JvmField
     val JvmStatic: Int = 1
+
+    @JvmField
+    val JvmStaticString: String? = "123"
 }
 
 fun test() {
@@ -20,10 +23,12 @@ fun test() {
 
     JClass.BoxedInt
     JClass.NonFinal
+    JClass.StrNullable
 
     JClass().NonStatic
 
     KoKobject.JvmStatic
+    KoKobject.JvmStaticString
 }
 
 // @TestKt.class:
@@ -42,6 +47,8 @@ fun test() {
 // 1 GETSTATIC JClass.BoxedInt : Ljava/lang/Integer;
 // 1 GETSTATIC JClass.NonFinal : I
 // 1 GETFIELD JClass.NonStatic : I
-// 1 INVOKESTATIC KoKobject.getJvmStatic \(\)I
+// 1 LDC "nullable"
+// 1 GETSTATIC KoKobject.JvmStatic : I
+// 1 GETSTATIC KoKobject.JvmStaticString : Ljava/lang/String
 // 3 POP2
-// 16 POP
+// 18 POP

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/descriptors/JavaPropertyDescriptor.java

@@ -18,11 +18,13 @@ package org.jetbrains.kotlin.load.java.descriptors;
 
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
 import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.descriptors.annotations.Annotations;
 import org.jetbrains.kotlin.descriptors.impl.PropertyDescriptorImpl;
 import org.jetbrains.kotlin.descriptors.impl.PropertyGetterDescriptorImpl;
 import org.jetbrains.kotlin.descriptors.impl.PropertySetterDescriptorImpl;
+import org.jetbrains.kotlin.load.java.typeEnhancement.TypeEnhancementKt;
 import org.jetbrains.kotlin.name.Name;
 import org.jetbrains.kotlin.types.KotlinType;
 
@@ -110,6 +112,8 @@ public class JavaPropertyDescriptor extends PropertyDescriptorImpl implements Ja
 
     @Override
     public boolean isConst() {
-        return isStaticFinal && ConstUtil.canBeUsedForConstVal(getType());
+        KotlinType type = getType();
+        return isStaticFinal && ConstUtil.canBeUsedForConstVal(type) &&
+               (!TypeEnhancementKt.hasEnhancedNullability(type) || KotlinBuiltIns.isString(type));
     }
 }

core/descriptors/src/org/jetbrains/kotlin/descriptors/ConstUtil.kt

@@ -20,9 +20,10 @@ package org.jetbrains.kotlin.descriptors
 
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.types.KotlinType
+import org.jetbrains.kotlin.types.TypeUtils
 
 object ConstUtil {
     @JvmStatic fun canBeUsedForConstVal(type: KotlinType) = type.canBeUsedForConstVal()
 }
 
-fun KotlinType.canBeUsedForConstVal() = KotlinBuiltIns.isPrimitiveType(this) || KotlinBuiltIns.isString(this)
+fun KotlinType.canBeUsedForConstVal() = KotlinBuiltIns.isPrimitiveType(this) && !TypeUtils.isNullableType(this) || KotlinBuiltIns.isString(this)