Add publicField annotation

compiler/backend/src/org/jetbrains/kotlin/codegen/PropertyCodegen.java

@@ -32,6 +32,7 @@ import org.jetbrains.kotlin.psi.psiUtil.PsiUtilPackage;
 import org.jetbrains.kotlin.resolve.BindingContext;
 import org.jetbrains.kotlin.resolve.DescriptorFactory;
 import org.jetbrains.kotlin.resolve.DescriptorToSourceUtils;
+import org.jetbrains.kotlin.resolve.annotations.AnnotationsPackage;
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall;
 import org.jetbrains.kotlin.resolve.constants.CompileTimeConstant;
 import org.jetbrains.kotlin.resolve.jvm.jvmSignature.JvmMethodSignature;
@@ -256,9 +257,19 @@ public class PropertyCodegen {
 
         ClassBuilder builder = v;
 
+        boolean hasPublicFieldAnnotation = AnnotationsPackage.findPublicFieldAnnotation(propertyDescriptor) != null;
+
         FieldOwnerContext backingFieldContext = context;
         if (AsmUtil.isInstancePropertyWithStaticBackingField(propertyDescriptor) ) {
-            modifiers |= ACC_STATIC | getVisibilityForSpecialPropertyBackingField(propertyDescriptor, isDelegate);
+            modifiers |= ACC_STATIC;
+
+            if (hasPublicFieldAnnotation && !isDelegate) {
+                modifiers |= ACC_PUBLIC;
+            }
+            else {
+                modifiers |= getVisibilityForSpecialPropertyBackingField(propertyDescriptor, isDelegate);
+            }
+
             if (AsmUtil.isPropertyWithBackingFieldInOuterClass(propertyDescriptor)) {
                 ImplementationBodyCodegen codegen = (ImplementationBodyCodegen) memberCodegen.getParentCodegen();
                 builder = codegen.v;
@@ -266,6 +277,9 @@ public class PropertyCodegen {
                 v.getSerializationBindings().put(STATIC_FIELD_IN_OUTER_CLASS, propertyDescriptor);
             }
         }
+        else if (!isDelegate && hasPublicFieldAnnotation) {
+            modifiers |= ACC_PUBLIC;
+        }
         else if (kind != OwnerKind.PACKAGE || isDelegate) {
             modifiers |= ACC_PRIVATE;
         }

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -114,6 +114,7 @@ public interface Errors {
     DiagnosticFactory2<PsiElement, JetModifierKeywordToken, JetModifierKeywordToken> REDUNDANT_MODIFIER = DiagnosticFactory2.create(WARNING);
     DiagnosticFactory0<PsiElement> INAPPLICABLE_ANNOTATION = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<PsiElement> INAPPLICABLE_PLATFORM_NAME = DiagnosticFactory0.create(ERROR);
+    DiagnosticFactory0<PsiElement> INAPPLICABLE_PUBLIC_FIELD = DiagnosticFactory0.create(ERROR);
 
     // Annotations
 

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -137,6 +137,7 @@ public class DefaultErrorMessages {
         MAP.put(REPEATED_MODIFIER, "Repeated ''{0}''", TO_STRING);
         MAP.put(INAPPLICABLE_ANNOTATION, "This annotation is only applicable to top level functions");
         MAP.put(INAPPLICABLE_PLATFORM_NAME, "platformName annotation is not applicable to this declaration");
+        MAP.put(INAPPLICABLE_PUBLIC_FIELD, "publicField annotation is not applicable to this declaration");
 
         MAP.put(REDUNDANT_MODIFIER, "Modifier ''{0}'' is redundant because ''{1}'' is present", TO_STRING, TO_STRING);
         MAP.put(ABSTRACT_MODIFIER_IN_TRAIT, "Modifier ''abstract'' is redundant in interface");

compiler/frontend/src/org/jetbrains/kotlin/resolve/AnnotationUtil.kt

@@ -32,6 +32,10 @@ public fun DeclarationDescriptor.hasPlatformStaticAnnotation(): Boolean {
     return getAnnotations().findAnnotation(FqName("kotlin.platform.platformStatic")) != null
 }
 
+public fun DeclarationDescriptor.findPublicFieldAnnotation(): AnnotationDescriptor? {
+    return getAnnotations().findAnnotation(FqName("kotlin.jvm.publicField"))
+}
+
 public fun DeclarationDescriptor.hasIntrinsicAnnotation(): Boolean {
     return getAnnotations().findAnnotation(FqName("kotlin.jvm.internal.Intrinsic")) != null
 }

compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.java

@@ -32,6 +32,7 @@ import org.jetbrains.kotlin.lexer.JetTokens;
 import org.jetbrains.kotlin.name.FqName;
 import org.jetbrains.kotlin.name.Name;
 import org.jetbrains.kotlin.psi.*;
+import org.jetbrains.kotlin.resolve.annotations.AnnotationsPackage;
 import org.jetbrains.kotlin.resolve.constants.CompileTimeConstant;
 import org.jetbrains.kotlin.resolve.constants.StringValue;
 
@@ -149,6 +150,7 @@ public class ModifiersChecker {
             checkVarargsModifiers(modifierListOwner, descriptor);
         }
         checkPlatformNameApplicability(descriptor);
+        checkPublicFieldApplicability(descriptor);
         runDeclarationCheckers(modifierListOwner, descriptor);
     }
 
@@ -162,6 +164,7 @@ public class ModifiersChecker {
         reportIllegalModalityModifiers(modifierListOwner);
         reportIllegalVisibilityModifiers(modifierListOwner);
         checkPlatformNameApplicability(descriptor);
+        checkPublicFieldApplicability(descriptor);
         runDeclarationCheckers(modifierListOwner, descriptor);
     }
 
@@ -320,6 +323,24 @@ public class ModifiersChecker {
 
     }
 
+    private void checkPublicFieldApplicability(@NotNull DeclarationDescriptor descriptor) {
+        AnnotationDescriptor annotation = AnnotationsPackage.findPublicFieldAnnotation(descriptor);
+        if (annotation == null) return;
+
+        JetAnnotationEntry annotationEntry = trace.get(BindingContext.ANNOTATION_DESCRIPTOR_TO_PSI_ELEMENT, annotation);
+        if (annotationEntry == null) return;
+
+        if (!(descriptor instanceof PropertyDescriptor)) {
+            trace.report(INAPPLICABLE_PUBLIC_FIELD.on(annotationEntry));
+            return;
+        }
+
+        PropertyDescriptor propertyDescriptor = (PropertyDescriptor) descriptor;
+        if (Boolean.FALSE.equals(trace.getBindingContext().get(BindingContext.BACKING_FIELD_REQUIRED, propertyDescriptor))) {
+            trace.report(INAPPLICABLE_PUBLIC_FIELD.on(annotationEntry));
+        }
+    }
+
     private static boolean isRenamableDeclaration(@NotNull DeclarationDescriptor descriptor) {
         DeclarationDescriptor containingDescriptor = descriptor.getContainingDeclaration();
 

libraries/stdlib/src/kotlin/jvm/JvmPlatformAnnotations.kt

@@ -27,3 +27,9 @@ import java.lang.annotation.RetentionPolicy
  */
 Retention(RetentionPolicy.CLASS)
 public annotation class jvmOverloads
+
+/**
+ * Instructs the Kotlin compiler to generate a public backing field for this property.
+ */
+Retention(RetentionPolicy.SOURCE)
+public annotation class publicField