Deprecate mapNotNull to change its behavior later.

#KT-4410

libraries/stdlib/src/generated/_Arrays.kt

@@ -6728,6 +6728,7 @@ public inline fun <R, C : MutableCollection<in R>> ShortArray.mapIndexedTo(desti
 /**
  * Returns a list containing the results of applying the given [transform] function to each non-null element of the original collection.
  */
+@Deprecated("This function will change its semantics soon to map&filter rather than filter&map. Use filterNotNull().map {} instead.", ReplaceWith("filterNotNull().map(transform)"))
 public inline fun <T : Any, R> Array<out T?>.mapNotNull(transform: (T) -> R): List<R> {
     return mapNotNullTo(ArrayList<R>(), transform)
 }
@@ -6736,6 +6737,7 @@ public inline fun <T : Any, R> Array<out T?>.mapNotNull(transform: (T) -> R): Li
  * Appends transformed non-null elements of original collection using the given [transform] function
  * to the given [destination].
  */
+@Deprecated("This function will change its semantics soon to map&filter rather than filter&map. Use filterNotNull().mapTo(destination) {} instead.", ReplaceWith("filterNotNull().mapTo(destination, transform)"))
 public inline fun <T : Any, R, C : MutableCollection<in R>> Array<out T?>.mapNotNullTo(destination: C, transform: (T) -> R): C {
     for (element in this) {
         if (element != null) {

libraries/stdlib/src/generated/_Collections.kt

@@ -1080,6 +1080,7 @@ public inline fun <T, R, C : MutableCollection<in R>> Iterable<T>.mapIndexedTo(d
 /**
  * Returns a list containing the results of applying the given [transform] function to each non-null element of the original collection.
  */
+@Deprecated("This function will change its semantics soon to map&filter rather than filter&map. Use filterNotNull().map {} instead.", ReplaceWith("filterNotNull().map(transform)"))
 public inline fun <T : Any, R> Iterable<T?>.mapNotNull(transform: (T) -> R): List<R> {
     return mapNotNullTo(ArrayList<R>(), transform)
 }
@@ -1088,6 +1089,7 @@ public inline fun <T : Any, R> Iterable<T?>.mapNotNull(transform: (T) -> R): Lis
  * Appends transformed non-null elements of original collection using the given [transform] function
  * to the given [destination].
  */
+@Deprecated("This function will change its semantics soon to map&filter rather than filter&map. Use filterNotNull().mapTo(destination) {} instead.", ReplaceWith("filterNotNull().mapTo(destination, transform)"))
 public inline fun <T : Any, R, C : MutableCollection<in R>> Iterable<T?>.mapNotNullTo(destination: C, transform: (T) -> R): C {
     for (element in this) {
         if (element != null) {

libraries/stdlib/src/generated/_Sequences.kt

@@ -565,6 +565,7 @@ public inline fun <T, R, C : MutableCollection<in R>> Sequence<T>.mapIndexedTo(d
 /**
  * Returns a sequence containing the results of applying the given [transform] function to each non-null element of the original sequence.
  */
+@Deprecated("This function will change its semantics soon to map&filter rather than filter&map. Use filterNotNull().map {} instead.", ReplaceWith("filterNotNull().map(transform)"))
 public fun <T : Any, R> Sequence<T?>.mapNotNull(transform: (T) -> R): Sequence<R> {
     return TransformingSequence(FilteringSequence(this, false, { it == null }) as Sequence<T>, transform)
 }
@@ -573,6 +574,7 @@ public fun <T : Any, R> Sequence<T?>.mapNotNull(transform: (T) -> R): Sequence<R
  * Appends transformed non-null elements of original collection using the given [transform] function
  * to the given [destination].
  */
+@Deprecated("This function will change its semantics soon to map&filter rather than filter&map. Use filterNotNull().mapTo(destination) {} instead.", ReplaceWith("filterNotNull().mapTo(destination, transform)"))
 public inline fun <T : Any, R, C : MutableCollection<in R>> Sequence<T?>.mapNotNullTo(destination: C, transform: (T) -> R): C {
     for (element in this) {
         if (element != null) {

libraries/tools/kotlin-stdlib-gen/src/templates/Engine.kt

@@ -65,9 +65,9 @@ class GenericFunction(val signature: String, val keyword: String = "fun") {
     open class SpecializedProperty<TKey: Any, TValue : Any>() {
         private val values = HashMap<TKey?, TValue>()
 
-        fun get(key: TKey): TValue? = values.getOrElse(key, { values.getOrElse(null, { null }) })
+        operator fun get(key: TKey): TValue? = values.getOrElse(key, { values.getOrElse(null, { null }) })
 
-        fun set(keys: Collection<TKey>, value: TValue) {
+        operator fun set(keys: Collection<TKey>, value: TValue) {
             if (keys.isEmpty())
                 values[null] = value;
             else
@@ -77,8 +77,8 @@ class GenericFunction(val signature: String, val keyword: String = "fun") {
                 }
         }
 
-        fun invoke(vararg keys: TKey, valueBuilder: ()-> TValue) = set(keys.asList(), valueBuilder())
-        fun invoke(value: TValue, vararg keys: TKey) = set(keys.asList(), value)
+        operator fun invoke(vararg keys: TKey, valueBuilder: ()-> TValue) = set(keys.asList(), valueBuilder())
+        operator fun invoke(value: TValue, vararg keys: TKey) = set(keys.asList(), value)
 
         protected open fun onKeySet(key: TKey) {}
     }

libraries/tools/kotlin-stdlib-gen/src/templates/Mapping.kt

@@ -96,6 +96,8 @@ fun mapping(): List<GenericFunction> {
         inline(true)
         exclude(Strings, ArraysOfPrimitives)
         doc { "Returns a list containing the results of applying the given [transform] function to each non-null element of the original collection." }
+        deprecate("This function will change its semantics soon to map&filter rather than filter&map. Use filterNotNull().map {} instead.")
+        deprecateReplacement("filterNotNull().map(transform)")
         typeParam("T : Any")
         typeParam("R")
         returns("List<R>")
@@ -172,6 +174,8 @@ fun mapping(): List<GenericFunction> {
             to the given [destination].
             """
         }
+        deprecate("This function will change its semantics soon to map&filter rather than filter&map. Use filterNotNull().mapTo(destination) {} instead.")
+        deprecateReplacement("filterNotNull().mapTo(destination, transform)")
         typeParam("T : Any")
         typeParam("R")
         typeParam("C : MutableCollection<in R>")