Add NON_VARARG_SPREAD and SPREAD_OF_NULLABLE diagnostics to new inference

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

@@ -45,7 +45,7 @@ private val DEFAULT_CALL_CHECKERS = listOf(
     CallableReferenceCompatibilityChecker(), LateinitIntrinsicApplicabilityChecker,
     UnderscoreUsageChecker, AssigningNamedArgumentToVarargChecker(),
     PrimitiveNumericComparisonCallChecker, LambdaWithSuspendModifierCallChecker,
-    UselessElvisCallChecker(), ResultTypeWithNullableOperatorsChecker()
+    UselessElvisCallChecker(), ResultTypeWithNullableOperatorsChecker(), NullableVarargArgumentCallChecker
 )
 private val DEFAULT_TYPE_CHECKERS = emptyList<AdditionalTypeChecker>()
 private val DEFAULT_CLASSIFIER_USAGE_CHECKERS = listOf(

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/checkers/NullableVarargArgumentCallChecker.kt

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.resolve.calls.checkers
+
+import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.config.LanguageFeature
+import org.jetbrains.kotlin.diagnostics.Errors
+import org.jetbrains.kotlin.resolve.calls.components.stableType
+import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
+import org.jetbrains.kotlin.resolve.calls.model.VariableAsFunctionResolvedCall
+import org.jetbrains.kotlin.resolve.calls.tower.ExpressionKotlinCallArgumentImpl
+import org.jetbrains.kotlin.resolve.calls.tower.NewResolvedCallImpl
+import org.jetbrains.kotlin.resolve.calls.tower.NewVariableAsFunctionResolvedCallImpl
+import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValueWithSmartCastInfo
+import org.jetbrains.kotlin.types.FlexibleType
+import org.jetbrains.kotlin.types.TypeUtils
+import org.jetbrains.kotlin.utils.addToStdlib.safeAs
+
+object NullableVarargArgumentCallChecker : CallChecker {
+    override fun check(resolvedCall: ResolvedCall<*>, reportOn: PsiElement, context: CallCheckerContext) {
+        if (!context.languageVersionSettings.supportsFeature(LanguageFeature.NewInference)) return
+        if (resolvedCall is VariableAsFunctionResolvedCall) {
+            check(resolvedCall.functionCall, reportOn, context)
+            return
+        }
+        if (resolvedCall !is NewResolvedCallImpl<*>) return
+        for (argument in resolvedCall.argumentMappingByOriginal.values) {
+            for (arg in argument.arguments) {
+                if (!arg.isSpread || arg !is ExpressionKotlinCallArgumentImpl) continue
+                val spreadElement = arg.valueArgument.getSpreadElement() ?: continue
+
+                val receiver = arg.receiver.safeAs<ReceiverValueWithSmartCastInfo>() ?: continue
+                val type = receiver.stableType
+                if (type !is FlexibleType && TypeUtils.isNullableType(type)) {
+                    context.trace.report(Errors.SPREAD_OF_NULLABLE.on(spreadElement))
+                }
+            }
+        }
+    }
+}

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/ArgumentsUtils.kt

@@ -45,7 +45,7 @@ internal val ReceiverValueWithSmartCastInfo.unstableType: UnwrappedType?
     }
 
 // with all smart casts if stable
-internal val ReceiverValueWithSmartCastInfo.stableType: UnwrappedType
+val ReceiverValueWithSmartCastInfo.stableType: UnwrappedType
     get() {
         if (!isStable || possibleTypes.isEmpty()) return receiverValue.type.unwrap()
         return intersectWrappedTypes(possibleTypes + receiverValue.type)

compiler/testData/diagnostics/tests/varargs/NullableTypeForVarargArgument.kt

@@ -10,6 +10,15 @@ public class A {
     public static String[] ar;
 }
 
+// FILE: J.java
+
+public class J {
+    public interface Invoke {
+        void invoke(String ...args);
+    }
+
+    public static Invoke staticFun;
+}
 
 // FILE: 1.kt
 val args: Array<String>? = null
@@ -18,10 +27,12 @@ fun bar(x: Int, vararg s: String) {}
 
 fun baz(s: String) {}
 
+fun getArr(): Array<String>? = null
+
 fun f() {
-    A().foo(1, <!OI;SPREAD_OF_NULLABLE!>*<!>args)
+    A().foo(1, <!SPREAD_OF_NULLABLE!>*<!>args)
-    bar(2, <!OI;SPREAD_OF_NULLABLE!>*<!><!TYPE_MISMATCH!>args<!>)
+    bar(2, <!SPREAD_OF_NULLABLE!>*<!><!TYPE_MISMATCH!>args<!>)
-    baz(<!OI;SPREAD_OF_NULLABLE, NON_VARARG_SPREAD!>*<!><!NI;TYPE_MISMATCH!>args<!>)
+    baz(<!NON_VARARG_SPREAD, SPREAD_OF_NULLABLE!>*<!><!NI;TYPE_MISMATCH!>args<!>)
 }
 
 fun g(args: Array<String>?) {
@@ -38,8 +49,17 @@ class B {
 
 fun h(b: B) {
     if (b.args != null) {
-        A().foo(1, <!OI;SPREAD_OF_NULLABLE!>*<!><!OI;SMARTCAST_IMPOSSIBLE!>b.args<!>)
+        A().foo(1, <!SPREAD_OF_NULLABLE!>*<!><!OI;SMARTCAST_IMPOSSIBLE!>b.args<!>)
     }
 }
 
+fun k() {
+    A().foo(1, <!SPREAD_OF_NULLABLE!>*<!>getArr())
+    bar(2, <!SPREAD_OF_NULLABLE!>*<!><!TYPE_MISMATCH!>getArr()<!>)
+    baz(<!NON_VARARG_SPREAD, SPREAD_OF_NULLABLE!>*<!><!NI;TYPE_MISMATCH!>getArr()<!>)
+}
 
+fun invokeTest(goodArgs: Array<String>) {
+    J.staticFun(*goodArgs)
+    J.staticFun(<!SPREAD_OF_NULLABLE!>*<!>args)
+}

compiler/testData/diagnostics/tests/varargs/NullableTypeForVarargArgument.txt

@@ -5,7 +5,10 @@ public fun bar(/*0*/ x: kotlin.Int, /*1*/ vararg s: kotlin.String /*kotlin.Array
 public fun baz(/*0*/ s: kotlin.String): kotlin.Unit
 public fun f(): kotlin.Unit
 public fun g(/*0*/ args: kotlin.Array<kotlin.String>?): kotlin.Unit
+public fun getArr(): kotlin.Array<kotlin.String>?
 public fun h(/*0*/ b: B): kotlin.Unit
+public fun invokeTest(/*0*/ goodArgs: kotlin.Array<kotlin.String>): kotlin.Unit
+public fun k(): kotlin.Unit
 
 public open class A {
     public constructor A()
@@ -25,3 +28,20 @@ public final class B {
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
+
+public open class J {
+    public constructor J()
+    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 toString(): kotlin.String
+
+    public interface Invoke {
+        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 abstract operator fun invoke(/*0*/ vararg args: kotlin.String! /*kotlin.Array<(out) kotlin.String!>!*/): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+
+    // Static members
+    public final var staticFun: J.Invoke!
+}