stdlib: Suppress/fix warnings in stdlib

This patch fixes redundant safe calls/casts/type projections
and suppresses some casts which are actually safe but reported
as unsafe.

runtime/src/main/kotlin/kotlin/Arrays.kt

@@ -5058,6 +5058,7 @@ public inline fun <T> Array<out T>.single(predicate: (T) -> Boolean): T {
         }
     }
     if (!found) throw NoSuchElementException("Array contains no element matching the predicate.")
+    @Suppress("UNCHECKED_CAST")
     return single as T
 }
 
@@ -10390,7 +10391,7 @@ public inline fun CharArray.copyOf(): CharArray {
  */
 @kotlin.internal.InlineOnly
 public inline fun <T> Array<T>.copyOf(newSize: Int): Array<T?> {
-    return copyOfNulls(newSize) as Array<T?>
+    return copyOfNulls(newSize)
 }
 
 /**
@@ -11443,8 +11444,6 @@ public inline fun <T> Array<out T>.subarrayContentToString(offset: Int, length:
 public infix fun <T> Array<out T>.contentDeepEquals(other: Array<out T>): Boolean {
     if (this === other)
         return true
-    if (other == null)
-        return false
 
     if (size != other.size)
         return false
@@ -11758,7 +11757,7 @@ public fun <T> Array<out T>.contentHashCode(): Int {
 public fun ByteArray.contentHashCode(): Int {
     var result = 1
     for (element in this)
-        result = 31 * result  + (element?.hashCode() ?: 0)
+        result = 31 * result  + element.hashCode()
     return result
 }
 
@@ -11769,7 +11768,7 @@ public fun ByteArray.contentHashCode(): Int {
 public fun ShortArray.contentHashCode(): Int {
     var result = 1
     for (element in this)
-        result = 31 * result  + (element?.hashCode() ?: 0)
+        result = 31 * result  + element.hashCode()
     return result
 }
 
@@ -11780,7 +11779,7 @@ public fun ShortArray.contentHashCode(): Int {
 public fun IntArray.contentHashCode(): Int {
     var result = 1
     for (element in this)
-        result = 31 * result  + (element?.hashCode() ?: 0)
+        result = 31 * result  + element.hashCode()
     return result
 }
 
@@ -11791,7 +11790,7 @@ public fun IntArray.contentHashCode(): Int {
 public fun LongArray.contentHashCode(): Int {
     var result = 1
     for (element in this)
-        result = 31 * result  + (element?.hashCode() ?: 0)
+        result = 31 * result  + element.hashCode()
     return result
 }
 
@@ -11802,7 +11801,7 @@ public fun LongArray.contentHashCode(): Int {
 public fun FloatArray.contentHashCode(): Int {
     var result = 1
     for (element in this)
-        result = 31 * result  + (element?.hashCode() ?: 0)
+        result = 31 * result  + element.hashCode()
     return result
 }
 
@@ -11813,7 +11812,7 @@ public fun FloatArray.contentHashCode(): Int {
 public fun DoubleArray.contentHashCode(): Int {
     var result = 1
     for (element in this)
-        result = 31 * result  + (element?.hashCode() ?: 0)
+        result = 31 * result  + element.hashCode()
     return result
 }
 
@@ -11824,7 +11823,7 @@ public fun DoubleArray.contentHashCode(): Int {
 public fun BooleanArray.contentHashCode(): Int {
     var result = 1
     for (element in this)
-        result = 31 * result  + (element?.hashCode() ?: 0)
+        result = 31 * result  + element.hashCode()
     return result
 }
 
@@ -11835,7 +11834,7 @@ public fun BooleanArray.contentHashCode(): Int {
 public fun CharArray.contentHashCode(): Int {
     var result = 1
     for (element in this)
-        result = 31 * result  + (element?.hashCode() ?: 0)
+        result = 31 * result  + element.hashCode()
     return result
 }
 

runtime/src/main/kotlin/kotlin/collections/AbstractIterator.kt

@@ -44,6 +44,7 @@ public abstract class AbstractIterator<T>: Iterator<T> {
     override fun next(): T {
         if (!hasNext()) throw NoSuchElementException()
         state = State.NotReady
+        @Suppress("UNCHECKED_CAST")
         return nextValue as T
     }
 

runtime/src/main/kotlin/kotlin/collections/ArrayUtil.kt

@@ -69,6 +69,7 @@ internal fun <E, T> collectionToArray(collection: Collection<E>, array: Array<T>
     }
     var i = 0
     for (v in collection) {
+        @Suppress("UNCHECKED_CAST")
         toArray[i] = v as T
         i++
     }

runtime/src/main/kotlin/kotlin/collections/Collections.kt

@@ -796,6 +796,7 @@ public inline fun <T> Iterable<T>.last(predicate: (T) -> Boolean): T {
         }
     }
     if (!found) throw NoSuchElementException("Collection contains no element matching the predicate.")
+    @Suppress("UNCHECKED_CAST")
     return last as T
 }
 
@@ -929,6 +930,7 @@ public inline fun <T> Iterable<T>.single(predicate: (T) -> Boolean): T {
         }
     }
     if (!found) throw NoSuchElementException("Collection contains no element matching the predicate.")
+    @Suppress("UNCHECKED_CAST")
     return single as T
 }
 

runtime/src/main/kotlin/kotlin/collections/Grouping.kt

@@ -109,6 +109,7 @@ public inline fun <T, K, R, M : MutableMap<in K, R>> Grouping<T, K>.aggregateTo(
  * @return a [Map] associating the key of each group with the result of accumulating the group elements.
  */
 @SinceKotlin("1.1")
+@Suppress("UNCHECKED_CAST")
 public inline fun <T, K, R> Grouping<T, K>.fold(
         initialValueSelector: (key: K, element: T) -> R,
         operation: (key: K, accumulator: R, element: T) -> R
@@ -137,6 +138,7 @@ public inline fun <T, K, R> Grouping<T, K>.fold(
  * @return the [destination] map associating the key of each group with the result of accumulating the group elements.
  */
 @SinceKotlin("1.1")
+@Suppress("UNCHECKED_CAST")
 public inline fun <T, K, R, M : MutableMap<in K, R>> Grouping<T, K>.foldTo(
         destination: M,
         initialValueSelector: (key: K, element: T) -> R,
@@ -157,6 +159,7 @@ public inline fun <T, K, R, M : MutableMap<in K, R>> Grouping<T, K>.foldTo(
  * @return a [Map] associating the key of each group with the result of accumulating the group elements.
  */
 @SinceKotlin("1.1")
+@Suppress("UNCHECKED_CAST")
 public inline fun <T, K, R> Grouping<T, K>.fold(
         initialValue: R,
         operation: (accumulator: R, element: T) -> R
@@ -179,6 +182,7 @@ public inline fun <T, K, R> Grouping<T, K>.fold(
  * @return the [destination] map associating the key of each group with the result of accumulating the group elements.
  */
 @SinceKotlin("1.1")
+@Suppress("UNCHECKED_CAST")
 public inline fun <T, K, R, M : MutableMap<in K, R>> Grouping<T, K>.foldTo(
         destination: M,
         initialValue: R,
@@ -202,6 +206,7 @@ public inline fun <T, K, R, M : MutableMap<in K, R>> Grouping<T, K>.foldTo(
  * @return a [Map] associating the key of each group with the result of accumulating the group elements.
  */
 @SinceKotlin("1.1")
+@Suppress("UNCHECKED_CAST")
 public inline fun <S, T : S, K> Grouping<T, K>.reduce(
         operation: (key: K, accumulator: S, element: T) -> S
 ): Map<K, S> =
@@ -227,6 +232,7 @@ public inline fun <S, T : S, K> Grouping<T, K>.reduce(
  * @return the [destination] map associating the key of each group with the result of accumulating the group elements.
  */
 @SinceKotlin("1.1")
+@Suppress("UNCHECKED_CAST")
 public inline fun <S, T : S, K, M : MutableMap<in K, S>> Grouping<T, K>.reduceTo(
         destination: M,
         operation: (key: K, accumulator: S, element: T) -> S

runtime/src/main/kotlin/kotlin/collections/HashMap.kt

@@ -45,7 +45,7 @@ class HashMap<K, V> private constructor(
             INITIAL_MAX_PROBE_DISTANCE,
             0)
 
-    constructor(m: Map<out K, out V>) : this(m.size) {
+    constructor(m: Map<out K, V>) : this(m.size) {
         putAll(m)
     }
 

runtime/src/main/kotlin/kotlin/collections/Maps.kt

@@ -224,6 +224,7 @@ internal inline fun <K, V> Map<K, V>.getOrElseNullable(key: K, defaultValue: ()
     if (value == null && !containsKey(key)) {
         return defaultValue()
     } else {
+        @Suppress("UNCHECKED_CAST")
         return value as V
     }
 }

runtime/src/main/kotlin/kotlin/sequences/Sequences.kt

@@ -132,6 +132,7 @@ internal class FilteringSequence<T>(private val sequence: Sequence<T>,
             val result = nextItem
             nextItem = null
             nextState = -1
+            @Suppress("UNCHECKED_CAST")
             return result as T
         }
 
@@ -388,6 +389,7 @@ constructor(private val sequence: Sequence<T>,
                 calcNext() // will change nextState
             if (nextState == 0)
                 throw NoSuchElementException()
+            @Suppress("UNCHECKED_CAST")
             val result = nextItem as T
 
             // Clean next to avoid keeping reference on yielded instance
@@ -474,6 +476,7 @@ constructor(private val sequence: Sequence<T>,
                 drop()
 
             if (dropState == 1) {
+                @Suppress("UNCHECKED_CAST")
                 val result = nextItem as T
                 nextItem = null
                 dropState = 0
@@ -787,6 +790,7 @@ public inline fun <T> Sequence<T>.last(predicate: (T) -> Boolean): T {
         }
     }
     if (!found) throw NoSuchElementException("Sequence contains no element matching the predicate.")
+    @Suppress("UNCHECKED_CAST")
     return last as T
 }
 
@@ -857,6 +861,7 @@ public inline fun <T> Sequence<T>.single(predicate: (T) -> Boolean): T {
         }
     }
     if (!found) throw NoSuchElementException("Sequence contains no element matching the predicate.")
+    @Suppress("UNCHECKED_CAST")
     return single as T
 }