Added deprecation for protected call within inline functions

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

@@ -866,6 +866,7 @@ public interface Errors {
     DiagnosticFactory0<PsiElement> NON_LOCAL_RETURN_IN_DISABLED_INLINE = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtDeclaration> INLINE_PROPERTY_WITH_BACKING_FIELD = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
     DiagnosticFactory0<KtAnnotationEntry> NON_INTERNAL_PUBLISHED_API = DiagnosticFactory0.create(ERROR);
+    DiagnosticFactory1<PsiElement, CallableDescriptor> PROTECTED_CALL_FROM_PUBLIC_INLINE = DiagnosticFactory1.create(WARNING);
 
 
     DiagnosticFactory0<PsiElement> NON_LOCAL_SUSPENSION_POINT = DiagnosticFactory0.create(ERROR);

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

@@ -832,6 +832,7 @@ public class DefaultErrorMessages {
         MAP.put(RECURSION_IN_INLINE, "Inline function ''{1}'' cannot be recursive", ELEMENT_TEXT, SHORT_NAMES_IN_TYPES);
         MAP.put(INLINE_PROPERTY_WITH_BACKING_FIELD, "Inline property cannot have backing field");
         MAP.put(NON_INTERNAL_PUBLISHED_API, "@PublishedApi annotation is only applicable for internal declaration");
+        MAP.put(PROTECTED_CALL_FROM_PUBLIC_INLINE, "Protected function call from public-API inline function is deprecated", NAME);
         //Inline non locals
         MAP.put(NON_LOCAL_RETURN_NOT_ALLOWED, "Can''t inline ''{0}'' here: it may contain non-local returns. Add ''crossinline'' modifier to parameter declaration ''{0}''", ELEMENT_TEXT);
         MAP.put(INLINE_CALL_CYCLE, "The ''{0}'' invocation is a part of inline cycle", NAME);

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/checkers/InlineChecker.java

@@ -17,7 +17,6 @@
 package org.jetbrains.kotlin.resolve.calls.checkers;
 
 import com.intellij.psi.PsiElement;
-import com.sun.mirror.declaration.PackageDeclaration;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.builtins.FunctionTypesKt;
@@ -254,6 +253,10 @@ class InlineChecker implements CallChecker {
         else {
             checkPrivateClassMemberAccess(declarationDescriptor, expression, context);
         }
+
+        if (isEffectivelyPublicOrPublishedApiFunction && declarationDescriptor.getVisibility() == Visibilities.PROTECTED) {
+            context.getTrace().report(Errors.PROTECTED_CALL_FROM_PUBLIC_INLINE.on(expression, declarationDescriptor));
+        }
     }
 
     private static boolean isEffectivelyPublicOrPublishedApi(@NotNull CallableDescriptor descriptor) {

compiler/testData/diagnostics/tests/inline/protectedDepecation.kt

@@ -0,0 +1,57 @@
+// !DIAGNOSTICS: -EXPOSED_PARAMETER_TYPE -NOTHING_TO_INLINE
+
+open class A {
+    protected fun test() {}
+
+    protected val z: String = "1"
+
+    public var zVar: String = "1"
+        protected set(value) {}
+
+    inline fun call() {
+        <!PROTECTED_CALL_FROM_PUBLIC_INLINE!>test<!>()
+        <!PROTECTED_CALL_FROM_PUBLIC_INLINE!>z<!>
+        zVar
+        <!PROTECTED_CALL_FROM_PUBLIC_INLINE!>zVar<!> = "123"
+    }
+
+    internal inline fun callFromInternal() {
+        test()
+        zVar
+        zVar = "123"
+    }
+
+    @PublishedApi
+    internal inline fun callFromPublished() {
+        <!PROTECTED_CALL_FROM_PUBLIC_INLINE!>test<!>()
+        <!PROTECTED_CALL_FROM_PUBLIC_INLINE!>z<!>
+        zVar
+        <!PROTECTED_CALL_FROM_PUBLIC_INLINE!>zVar<!> = "123"
+    }
+}
+
+class B : A() {
+    inline fun testB() {
+        <!PROTECTED_CALL_FROM_PUBLIC_INLINE!>test<!>()
+    }
+}
+
+
+internal class AInternal {
+    protected fun test() {}
+
+    protected val z: String = "1"
+
+    public var zVar: String = "1"
+        protected set(value) {}
+
+
+    inline fun call() {
+        test()
+    }
+
+    @PublishedApi
+    internal inline fun call2() {
+        test()
+    }
+}

compiler/testData/diagnostics/tests/inline/protectedDepecation.txt

@@ -0,0 +1,40 @@
+package
+
+public open class A {
+    public constructor A()
+    protected final val z: kotlin.String = "1"
+    public final var zVar: kotlin.String
+    public final inline fun call(): kotlin.Unit
+    internal final inline fun callFromInternal(): kotlin.Unit
+    @kotlin.PublishedApi internal final inline fun callFromPublished(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    protected final fun test(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+internal final class AInternal {
+    public constructor AInternal()
+    protected final val z: kotlin.String = "1"
+    public final var zVar: kotlin.String
+    public final inline fun call(): kotlin.Unit
+    @kotlin.PublishedApi internal final inline fun call2(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    protected final fun test(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B : A {
+    public constructor B()
+    protected final override /*1*/ /*fake_override*/ val z: kotlin.String
+    public final override /*1*/ /*fake_override*/ var zVar: kotlin.String
+    public final inline override /*1*/ /*fake_override*/ fun call(): kotlin.Unit
+    internal final inline override /*1*/ /*fake_override*/ fun callFromInternal(): kotlin.Unit
+    @kotlin.PublishedApi internal final inline override /*1*/ /*fake_override*/ fun callFromPublished(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    protected final override /*1*/ /*fake_override*/ fun test(): kotlin.Unit
+    public final inline fun testB(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -10618,6 +10618,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("protectedDepecation.kt")
+            public void testProtectedDepecation() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inline/protectedDepecation.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("publishedApi.kt")
             public void testPublishedApi() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inline/publishedApi.kt");