Ignore @Nullable annotation for vararg parameter

See the comment in code for clarification

 #KT-19786 Fixed

compiler/testData/diagnostics/tests/j+k/signatureAnnotations/notNullVarargOverride.kt

@@ -0,0 +1,22 @@
+// FILE: BaseClass.java
+import org.jetbrains.annotations.NotNull;
+
+public class BaseClass {
+    public void loadCache(@NotNull Object... args) {}
+}
+
+// FILE: main.kt
+
+class A : BaseClass() {
+    // org.jetbrains.annotations.NotNull has @Target PARAMETER, so it doesn't affect elements type
+    override fun loadCache(vararg args: Any?) {
+        super.loadCache(*args)
+    }
+}
+
+class B : BaseClass() {
+    // org.jetbrains.annotations.NotNull has @Target PARAMETER, so it doesn't affect elements type
+    override fun loadCache(vararg args: Any) {
+        super.loadCache(*args)
+    }
+}

compiler/testData/diagnostics/tests/j+k/signatureAnnotations/notNullVarargOverride.txt

@@ -0,0 +1,25 @@
+package
+
+public final class A : BaseClass {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ fun loadCache(/*0*/ vararg args: kotlin.Any? /*kotlin.Array<out kotlin.Any?>*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B : BaseClass {
+    public constructor B()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ fun loadCache(/*0*/ vararg args: kotlin.Any /*kotlin.Array<out kotlin.Any>*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class BaseClass {
+    public constructor BaseClass()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open fun loadCache(/*0*/ @org.jetbrains.annotations.NotNull vararg args: kotlin.Any! /*kotlin.Array<(out) kotlin.Any!>*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/j+k/signatureAnnotations/nullableVarargOverride.kt

@@ -0,0 +1,22 @@
+// FILE: BaseClass.java
+import org.jetbrains.annotations.Nullable;
+
+public class BaseClass {
+    public void loadCache(@Nullable Object... args) {}
+}
+
+// FILE: main.kt
+
+class A : BaseClass() {
+    // org.jetbrains.annotations.Nullable has @Target PARAMETER, so it doesn't affect elements type
+    override fun loadCache(vararg args: Any?) {
+        super.loadCache(*args)
+    }
+}
+
+class B : BaseClass() {
+    // org.jetbrains.annotations.Nullable has @Target PARAMETER, so it doesn't affect elements type
+    override fun loadCache(vararg args: Any) {
+        super.loadCache(*args)
+    }
+}

compiler/testData/diagnostics/tests/j+k/signatureAnnotations/nullableVarargOverride.txt

@@ -0,0 +1,25 @@
+package
+
+public final class A : BaseClass {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ fun loadCache(/*0*/ vararg args: kotlin.Any? /*kotlin.Array<out kotlin.Any?>*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B : BaseClass {
+    public constructor B()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ fun loadCache(/*0*/ vararg args: kotlin.Any /*kotlin.Array<out kotlin.Any>*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class BaseClass {
+    public constructor BaseClass()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open fun loadCache(/*0*/ @org.jetbrains.annotations.Nullable vararg args: kotlin.Any! /*kotlin.Array<(out) kotlin.Any!>!*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/notNullVarargsOverrides.kt

@@ -0,0 +1,23 @@
+// JAVAC_EXPECTED_FILE
+// SKIP_COMPILED_JAVA
+// FILE: BaseClass.java
+import org.checkerframework.checker.nullness.qual.*;
+
+public class BaseClass {
+    public void loadCache(@NonNull Object... args) {}
+}
+
+// FILE: main.kt
+
+class A : BaseClass() {
+    // org.checkerframework.checker.nullness.qual.NonNull has @Target TYPE_USE, so it affects only elements type
+    <!NOTHING_TO_OVERRIDE!>override<!> fun loadCache(vararg args: Any?) {
+        super.loadCache(*<!TYPE_MISMATCH!>args<!>)
+    }
+}
+
+class B : BaseClass() {
+    override fun loadCache(vararg args: Any) {
+        super.loadCache(*args)
+    }
+}

compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/notNullVarargsOverrides.txt

@@ -0,0 +1,26 @@
+package
+
+public final class A : BaseClass {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun loadCache(/*0*/ @org.checkerframework.checker.nullness.qual.NonNull vararg args: @org.checkerframework.checker.nullness.qual.NonNull kotlin.Any /*kotlin.Array<(out) @org.checkerframework.checker.nullness.qual.NonNull kotlin.Any>*/): kotlin.Unit
+    public open fun loadCache(/*0*/ vararg args: kotlin.Any? /*kotlin.Array<out kotlin.Any?>*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B : BaseClass {
+    public constructor B()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ fun loadCache(/*0*/ vararg args: kotlin.Any /*kotlin.Array<out kotlin.Any>*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class BaseClass {
+    public constructor BaseClass()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open fun loadCache(/*0*/ @org.checkerframework.checker.nullness.qual.NonNull vararg args: @org.checkerframework.checker.nullness.qual.NonNull kotlin.Any /*kotlin.Array<(out) @org.checkerframework.checker.nullness.qual.NonNull kotlin.Any>*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/nullableVarargsOverrides.kt

@@ -0,0 +1,23 @@
+// JAVAC_EXPECTED_FILE
+// SKIP_COMPILED_JAVA
+// FILE: BaseClass.java
+import org.checkerframework.checker.nullness.qual.*;
+
+public class BaseClass {
+    public void loadCache(@Nullable Object... args) {}
+}
+
+// FILE: main.kt
+
+class A : BaseClass() {
+    override fun loadCache(vararg args: Any?) {
+        super.loadCache(*args)
+    }
+}
+
+class B : BaseClass() {
+    // org.checkerframework.checker.nullness.qual.Nullable has @Target TYPE_USE, so it affects only elements type
+    <!NOTHING_TO_OVERRIDE!>override<!> fun loadCache(vararg args: Any) {
+        super.loadCache(*args)
+    }
+}

compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/nullableVarargsOverrides.txt

@@ -0,0 +1,26 @@
+package
+
+public final class A : BaseClass {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ fun loadCache(/*0*/ vararg args: kotlin.Any? /*kotlin.Array<out kotlin.Any?>*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B : BaseClass {
+    public constructor B()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun loadCache(/*0*/ @org.checkerframework.checker.nullness.qual.Nullable vararg args: @org.checkerframework.checker.nullness.qual.Nullable kotlin.Any? /*kotlin.Array<(out) @org.checkerframework.checker.nullness.qual.Nullable kotlin.Any?>!*/): kotlin.Unit
+    public open fun loadCache(/*0*/ vararg args: kotlin.Any /*kotlin.Array<out kotlin.Any>*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class BaseClass {
+    public constructor BaseClass()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open fun loadCache(/*0*/ @org.checkerframework.checker.nullness.qual.Nullable vararg args: @org.checkerframework.checker.nullness.qual.Nullable kotlin.Any? /*kotlin.Array<(out) @org.checkerframework.checker.nullness.qual.Nullable kotlin.Any?>!*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests-java8/tests/org/jetbrains/kotlin/checkers/ForeignJava8AnnotationsNoAnnotationInClasspathTestGenerated.java

@@ -102,6 +102,18 @@ public class ForeignJava8AnnotationsNoAnnotationInClasspathTestGenerated extends
             doTest(fileName);
         }
 
+        @TestMetadata("notNullVarargsOverrides.kt")
+        public void testNotNullVarargsOverrides() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/notNullVarargsOverrides.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("nullableVarargsOverrides.kt")
+        public void testNullableVarargsOverrides() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/nullableVarargsOverrides.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("returnTypeDifferentConstructor.kt")
         public void testReturnTypeDifferentConstructor() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/returnTypeDifferentConstructor.kt");

compiler/tests-java8/tests/org/jetbrains/kotlin/checkers/ForeignJava8AnnotationsNoAnnotationInClasspathWithFastClassReadingTestGenerated.java

@@ -102,6 +102,18 @@ public class ForeignJava8AnnotationsNoAnnotationInClasspathWithFastClassReadingT
             doTest(fileName);
         }
 
+        @TestMetadata("notNullVarargsOverrides.kt")
+        public void testNotNullVarargsOverrides() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/notNullVarargsOverrides.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("nullableVarargsOverrides.kt")
+        public void testNullableVarargsOverrides() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/nullableVarargsOverrides.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("returnTypeDifferentConstructor.kt")
         public void testReturnTypeDifferentConstructor() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/returnTypeDifferentConstructor.kt");

compiler/tests-java8/tests/org/jetbrains/kotlin/checkers/ForeignJava8AnnotationsTestGenerated.java

@@ -102,6 +102,18 @@ public class ForeignJava8AnnotationsTestGenerated extends AbstractForeignJava8An
             doTest(fileName);
         }
 
+        @TestMetadata("notNullVarargsOverrides.kt")
+        public void testNotNullVarargsOverrides() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/notNullVarargsOverrides.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("nullableVarargsOverrides.kt")
+        public void testNullableVarargsOverrides() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/nullableVarargsOverrides.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("returnTypeDifferentConstructor.kt")
         public void testReturnTypeDifferentConstructor() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/returnTypeDifferentConstructor.kt");

compiler/tests-java8/tests/org/jetbrains/kotlin/checkers/javac/JavacForeignJava8AnnotationsTestGenerated.java

@@ -102,6 +102,18 @@ public class JavacForeignJava8AnnotationsTestGenerated extends AbstractJavacFore
             doTest(fileName);
         }
 
+        @TestMetadata("notNullVarargsOverrides.kt")
+        public void testNotNullVarargsOverrides() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/notNullVarargsOverrides.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("nullableVarargsOverrides.kt")
+        public void testNullableVarargsOverrides() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/nullableVarargsOverrides.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("returnTypeDifferentConstructor.kt")
         public void testReturnTypeDifferentConstructor() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/foreignAnnotationsJava8/tests/typeEnhancement/returnTypeDifferentConstructor.kt");

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

@@ -13303,6 +13303,18 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("notNullVarargOverride.kt")
+                public void testNotNullVarargOverride() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/j+k/signatureAnnotations/notNullVarargOverride.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("nullableVarargOverride.kt")
+                public void testNullableVarargOverride() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/j+k/signatureAnnotations/nullableVarargOverride.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("overridesDefaultValue.kt")
                 public void testOverridesDefaultValue() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/j+k/signatureAnnotations/overridesDefaultValue.kt");

compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -13303,6 +13303,18 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                     doTest(fileName);
                 }
 
+                @TestMetadata("notNullVarargOverride.kt")
+                public void testNotNullVarargOverride() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/j+k/signatureAnnotations/notNullVarargOverride.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("nullableVarargOverride.kt")
+                public void testNullableVarargOverride() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/j+k/signatureAnnotations/nullableVarargOverride.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("overridesDefaultValue.kt")
                 public void testOverridesDefaultValue() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/j+k/signatureAnnotations/overridesDefaultValue.kt");

core/descriptors.jvm/src/org/jetbrains/kotlin/load/java/typeEnhancement/signatureEnhancement.kt

@@ -195,6 +195,9 @@ class SignatureEnhancement(
         private val containerContext: LazyJavaResolverContext,
         private val containerApplicabilityType: AnnotationTypeQualifierResolver.QualifierApplicabilityType
     ) {
+
+        private val isForVarargParameter get() = typeContainer.safeAs<ValueParameterDescriptor>()?.varargElementType != null
+
         fun enhance(predefined: TypeEnhancementInfo? = null): PartEnhancementResult {
             val qualifiers = computeIndexedQualifiersForOverride()
 
@@ -352,7 +355,12 @@ class SignatureEnhancement(
             val ownNullabilityForWarning = own.nullability
 
             val isCovariantPosition = isCovariant && isHeadTypeConstructor
-            val nullability = nullabilityFromSupertypes.select(ownNullability, isCovariantPosition)
+            val nullability =
+                nullabilityFromSupertypes.select(ownNullability, isCovariantPosition)
+                    // Vararg value parameters effectively have non-nullable type in Kotlin
+                    // and having nullable types in Java may lead to impossibility of overriding them in Kotlin
+                    ?.takeUnless { isForVarargParameter && isHeadTypeConstructor && it == NullabilityQualifier.NULLABLE }
+
             val mutability =
                 mutabilityFromSupertypes
                     .select(MutabilityQualifier.MUTABLE, MutabilityQualifier.READ_ONLY, own.mutability, isCovariantPosition)