Allow to use @JvmStatic in interface companion object

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/checkers/declarationCheckers.kt

@@ -17,6 +17,9 @@
 package org.jetbrains.kotlin.resolve.jvm.checkers
 
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.config.JvmTarget
+import org.jetbrains.kotlin.config.LanguageFeature
+import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationDescriptor
 import org.jetbrains.kotlin.diagnostics.DiagnosticSink
@@ -51,7 +54,12 @@ class LocalFunInlineChecker : SimpleDeclarationChecker {
     }
 }
 
-class PlatformStaticAnnotationChecker : SimpleDeclarationChecker {
+class JvmStaticChecker(jvmTarget: JvmTarget, languageVersionSettings: LanguageVersionSettings) : SimpleDeclarationChecker {
+
+    private val isLessJVM18 = jvmTarget.bytecodeVersion < JvmTarget.JVM_1_8.bytecodeVersion
+
+    private val supportJvmStaticInInterface = languageVersionSettings.supportsFeature(LanguageFeature.JvmStaticInInterface)
+
 
     override fun check(
         declaration: KtDeclaration,
@@ -75,13 +83,24 @@ class PlatformStaticAnnotationChecker : SimpleDeclarationChecker {
         diagnosticHolder: DiagnosticSink
     ) {
         val container = descriptor.containingDeclaration
-        val insideObject = container != null && DescriptorUtils.isNonCompanionObject(container)
-        val insideCompanionObjectInClass =
-            container != null && DescriptorUtils.isCompanionObject(container) &&
-                    DescriptorUtils.isClassOrEnumClass(container.containingDeclaration)
+        val insideObject = DescriptorUtils.isObject(container)
+        val insideCompanionObjectInInterface = DescriptorUtils.isCompanionObject(container) &&
+                DescriptorUtils.isInterface(container!!.containingDeclaration)
 
-        if (!insideObject && !insideCompanionObjectInClass) {
-            diagnosticHolder.report(ErrorsJvm.JVM_STATIC_NOT_IN_OBJECT.on(declaration))
+        if (!insideObject || insideCompanionObjectInInterface) {
+            if (insideCompanionObjectInInterface &&
+                supportJvmStaticInInterface &&
+                descriptor is DeclarationDescriptorWithVisibility) {
+                checkVisibility(descriptor, diagnosticHolder, declaration)
+                if (isLessJVM18) {
+                    diagnosticHolder.report(ErrorsJvm.JVM_STATIC_IN_INTERFACE_1_6.on(declaration))
+                }
+            } else {
+                diagnosticHolder.report(
+                    (if (supportJvmStaticInInterface) ErrorsJvm.JVM_STATIC_NOT_IN_OBJECT_OR_COMPANION
+                    else ErrorsJvm.JVM_STATIC_NOT_IN_OBJECT_OR_CLASS_COMPANION).on(declaration)
+                )
+            }
         }
 
         val checkDeclaration = when (declaration) {
@@ -89,7 +108,7 @@ class PlatformStaticAnnotationChecker : SimpleDeclarationChecker {
             else -> declaration
         }
 
-        if (insideObject && checkDeclaration.modifierList?.hasModifier(KtTokens.OVERRIDE_KEYWORD) == true) {
+        if (DescriptorUtils.isNonCompanionObject(container) && checkDeclaration.modifierList?.hasModifier(KtTokens.OVERRIDE_KEYWORD) == true) {
             diagnosticHolder.report(ErrorsJvm.OVERRIDE_CANNOT_BE_STATIC.on(declaration))
         }
 
@@ -97,6 +116,18 @@ class PlatformStaticAnnotationChecker : SimpleDeclarationChecker {
             diagnosticHolder.report(ErrorsJvm.JVM_STATIC_ON_CONST_OR_JVM_FIELD.on(declaration))
         }
     }
+
+    private fun checkVisibility(
+        descriptor: DeclarationDescriptorWithVisibility,
+        diagnosticHolder: DiagnosticSink,
+        declaration: KtDeclaration
+    ) {
+        if (descriptor.visibility != Visibilities.PUBLIC) {
+            diagnosticHolder.report(ErrorsJvm.JVM_STATIC_ON_NON_PUBLIC_MEMBER.on(declaration))
+        } else if (descriptor is PropertyDescriptor) {
+            descriptor.setter?.let { checkVisibility(it, diagnosticHolder, declaration) }
+        }
+    }
 }
 
 class JvmNameAnnotationChecker : SimpleDeclarationChecker {
@@ -129,8 +160,7 @@ class JvmNameAnnotationChecker : SimpleDeclarationChecker {
         }
 
         if (descriptor is CallableMemberDescriptor) {
-            val callableMemberDescriptor = descriptor
-            if (DescriptorUtils.isOverride(callableMemberDescriptor) || callableMemberDescriptor.isOverridable) {
+            if (DescriptorUtils.isOverride(descriptor) || descriptor.isOverridable) {
                 diagnosticHolder.report(ErrorsJvm.INAPPLICABLE_JVM_NAME.on(annotationEntry))
             }
         }

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/diagnostics/DefaultErrorMessagesJvm.java

@@ -50,7 +50,10 @@ public class DefaultErrorMessagesJvm implements DefaultErrorMessages.Extension {
         MAP.put(ACCIDENTAL_OVERRIDE, "Accidental override: {0}", CONFLICTING_JVM_DECLARATIONS_DATA);
         MAP.put(CONFLICTING_INHERITED_JVM_DECLARATIONS, "Inherited platform declarations clash: {0}", CONFLICTING_JVM_DECLARATIONS_DATA);
 
-        MAP.put(JVM_STATIC_NOT_IN_OBJECT, "Only functions in named objects and companion objects of classes can be annotated with '@JvmStatic'");
+        MAP.put(JVM_STATIC_NOT_IN_OBJECT_OR_CLASS_COMPANION, "Only members in named objects and companion objects of classes can be annotated with '@JvmStatic'");
+        MAP.put(JVM_STATIC_NOT_IN_OBJECT_OR_COMPANION, "Only members in named objects and companion objects can be annotated with '@JvmStatic'");
+        MAP.put(JVM_STATIC_ON_NON_PUBLIC_MEMBER, "Only public members in interface companion objects can be annotated with '@JvmStatic'");
+        MAP.put(JVM_STATIC_IN_INTERFACE_1_6, "'@JvmStatic' annotation in interface supported only with JVM target 1.8 and above. Recompile with '-jvm-target 1.8'\"");
         MAP.put(JVM_STATIC_ON_CONST_OR_JVM_FIELD, "'@JvmStatic' annotation is useless for const or '@JvmField' properties");
         MAP.put(OVERRIDE_CANNOT_BE_STATIC, "Override member cannot be '@JvmStatic' in object");
         MAP.put(OVERLOADS_WITHOUT_DEFAULT_ARGUMENTS, "'@JvmOverloads' annotation has no effect for methods without default arguments");

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/diagnostics/ErrorsJvm.java

@@ -41,7 +41,10 @@ public interface ErrorsJvm {
             DiagnosticFactory1.create(ERROR, DECLARATION_SIGNATURE_OR_DEFAULT);
 
     DiagnosticFactory0<KtDeclaration> OVERRIDE_CANNOT_BE_STATIC = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
-    DiagnosticFactory0<KtDeclaration> JVM_STATIC_NOT_IN_OBJECT = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
+    DiagnosticFactory0<KtDeclaration> JVM_STATIC_NOT_IN_OBJECT_OR_CLASS_COMPANION = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
+    DiagnosticFactory0<KtDeclaration> JVM_STATIC_NOT_IN_OBJECT_OR_COMPANION = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
+    DiagnosticFactory0<KtDeclaration> JVM_STATIC_ON_NON_PUBLIC_MEMBER = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
+    DiagnosticFactory0<KtDeclaration> JVM_STATIC_IN_INTERFACE_1_6 = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
     DiagnosticFactory0<KtDeclaration> JVM_STATIC_ON_CONST_OR_JVM_FIELD = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
 
     DiagnosticFactory0<PsiElement> INAPPLICABLE_JVM_NAME = DiagnosticFactory0.create(ERROR);

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/platform/JvmPlatformConfigurator.kt

@@ -32,7 +32,6 @@ import org.jetbrains.kotlin.types.DynamicTypesSettings
 object JvmPlatformConfigurator : PlatformConfigurator(
     DynamicTypesSettings(),
     additionalDeclarationCheckers = listOf(
-        PlatformStaticAnnotationChecker(),
         JvmNameAnnotationChecker(),
         VolatileAnnotationChecker(),
         SynchronizedAnnotationChecker(),
@@ -87,6 +86,7 @@ object JvmPlatformConfigurator : PlatformConfigurator(
     declarationReturnTypeSanitizer = JvmDeclarationReturnTypeSanitizer
 ) {
     override fun configureModuleComponents(container: StorageComponentContainer) {
+        container.useImpl<JvmStaticChecker>()
         container.useImpl<JvmReflectionAPICallChecker>()
         container.useImpl<JavaSyntheticScopes>()
         container.useImpl<SamConversionResolverImpl>()