[K/N] ArrayList.ensureCapacity() should ignore negative arguments

libraries/stdlib/jvm/src/kotlin/collections/builders/ListBuilder.kt

@@ -179,15 +179,6 @@ internal class ListBuilder<E> private constructor(
 
     // ---------------------------- private ----------------------------
 
-    private fun ensureCapacity(minCapacity: Int) {
-        if (backing != null) throw IllegalStateException() // just in case somebody casts subList to ListBuilder
-        if (minCapacity < 0) throw OutOfMemoryError()    // overflow
-        if (minCapacity > array.size) {
-            val newSize = AbstractList.newCapacity(array.size, minCapacity)
-            array = array.copyOfUninitializedElements(newSize)
-        }
-    }
-
     private fun checkIsMutable() {
         if (isEffectivelyReadOnly) throw UnsupportedOperationException()
     }
@@ -196,7 +187,15 @@ internal class ListBuilder<E> private constructor(
         get() = isReadOnly || root != null && root.isReadOnly
 
     private fun ensureExtraCapacity(n: Int) {
-        ensureCapacity(length + n)
+        ensureCapacityInternal(length + n)
+    }
+
+    private fun ensureCapacityInternal(minCapacity: Int) {
+        if (minCapacity < 0) throw OutOfMemoryError()    // overflow
+        if (minCapacity > array.size) {
+            val newSize = AbstractList.newCapacity(array.size, minCapacity)
+            array = array.copyOfUninitializedElements(newSize)
+        }
     }
 
     private fun contentEquals(other: List<*>): Boolean {

libraries/stdlib/native-wasm/src/kotlin/collections/ArrayList.kt

@@ -146,11 +146,8 @@ actual class ArrayList<E> private constructor(
 
     final actual fun ensureCapacity(minCapacity: Int) {
         if (backingList != null) throw IllegalStateException() // just in case somebody casts subList to ArrayList
-        if (minCapacity < 0) throw OutOfMemoryError()    // overflow
+        if (minCapacity <= backingArray.size) return
-        if (minCapacity > backingArray.size) {
+        ensureCapacityInternal(minCapacity)
-            val newSize = AbstractList.newCapacity(backingArray.size, minCapacity)
-            backingArray = backingArray.copyOfUninitializedElements(newSize)
-        }
     }
 
     override fun equals(other: Any?): Boolean {
@@ -214,7 +211,15 @@ actual class ArrayList<E> private constructor(
     }
 
     private fun ensureExtraCapacity(n: Int) {
-        ensureCapacity(length + n)
+        ensureCapacityInternal(length + n)
+    }
+
+    private fun ensureCapacityInternal(minCapacity: Int) {
+        if (minCapacity < 0) throw OutOfMemoryError()    // overflow
+        if (minCapacity > backingArray.size) {
+            val newSize = AbstractList.newCapacity(backingArray.size, minCapacity)
+            backingArray = backingArray.copyOfUninitializedElements(newSize)
+        }
     }
 
     private fun contentEquals(other: List<*>): Boolean {

libraries/stdlib/test/collections/CollectionTest.kt

@@ -1256,4 +1256,9 @@ class CollectionTest {
         val arr2: Array<String> = coll.toArray(Array(coll.size + 1) { "" })
         assertEquals(data + listOf(null), arr2.asList())
     }
+
+    @Test
+    fun ensureCapacity() {
+        ArrayList<String>().ensureCapacity(-1) // negative argument is ignored
+    }
 }