Improve diagnostic on overload resolution ambiguity

Report type mismatch on argument when a nullable argument is passed to non-null parameter.

 Note that this affects only functions with simple types without generics

 #KT-2007 Fixed
 #KT-9282 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/CandidateResolver.kt

@@ -53,6 +53,7 @@ import org.jetbrains.kotlin.types.checker.ErrorTypesAreEqualToAnything
 import org.jetbrains.kotlin.types.checker.KotlinTypeChecker
 import org.jetbrains.kotlin.types.expressions.DoubleColonExpressionResolver
 import org.jetbrains.kotlin.types.typeUtil.containsTypeProjectionsInTopLevelArguments
+import org.jetbrains.kotlin.types.typeUtil.makeNotNullable
 import java.util.*
 
 class CandidateResolver(
@@ -376,7 +377,7 @@ class CandidateResolver(
                     if (!ArgumentTypeResolver.isSubtypeOfForArgumentType(type, expectedType)) {
                         val smartCast = smartCastValueArgumentTypeIfPossible(expression, newContext.expectedType, type, newContext)
                         if (smartCast == null) {
-                            resultStatus = OTHER_ERROR
+                            resultStatus = tryNotNullableArgument(type, expectedType) ?: OTHER_ERROR
                             matchStatus = ArgumentMatchStatus.TYPE_MISMATCH
                         }
                         else {
@@ -417,6 +418,14 @@ class CandidateResolver(
         }
     }
 
+    private fun tryNotNullableArgument(argumentType: KotlinType, parameterType: KotlinType): ResolutionStatus? {
+        if (!argumentType.isMarkedNullable || parameterType.isMarkedNullable) return null
+
+        val notNullableArgumentType = argumentType.makeNotNullable()
+        val isApplicable = ArgumentTypeResolver.isSubtypeOfForArgumentType(notNullableArgumentType, parameterType)
+        return if (isApplicable) NULLABLE_ARGUMENT_TYPE_MISMATCH else null
+    }
+
     private fun CallCandidateResolutionContext<*>.checkReceiverTypeError(): Unit = check {
         val extensionReceiver = candidateDescriptor.extensionReceiverParameter
         val dispatchReceiver = candidateDescriptor.dispatchReceiverParameter

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/results/ResolutionStatus.java

@@ -26,6 +26,7 @@ public enum ResolutionStatus {
     WRONG_NUMBER_OF_TYPE_ARGUMENTS_ERROR,
     UNSTABLE_SMARTCAST_ERROR,
     INVISIBLE_MEMBER_ERROR,
+    NULLABLE_ARGUMENT_TYPE_MISMATCH,
     OTHER_ERROR,
     ARGUMENTS_MAPPING_ERROR,
     // '1.foo()' shouldn't be resolved to 'fun String.foo()'
@@ -44,6 +45,7 @@ public enum ResolutionStatus {
             EnumSet.of(WRONG_NUMBER_OF_TYPE_ARGUMENTS_ERROR),
             EnumSet.of(UNSTABLE_SMARTCAST_ERROR),
             EnumSet.of(INVISIBLE_MEMBER_ERROR),
+            EnumSet.of(NULLABLE_ARGUMENT_TYPE_MISMATCH),
             EnumSet.of(OTHER_ERROR),
             EnumSet.of(ARGUMENTS_MAPPING_ERROR),
             EnumSet.of(RECEIVER_TYPE_ERROR),