Document Array and String get() function behavior (KT-30141)

generators/builtins/arrays.kt

@@ -43,9 +43,20 @@ class GenerateArrays(out: PrintWriter) : BuiltInsSourceGenerator(out) {
             out.println("     */")
             out.println("    public inline constructor(size: Int, init: (Int) -> $s)")
             out.println()
-            out.println("    /** Returns the array element at the given [index]. This method can be called using the index operator. */")
+            out.println("    /**")
+            out.println("     * Returns the array element at the given [index].  This method can be called using the index operator.")
+            out.println("     *")
+            out.println("     * If the [index] is out of bounds of this array, throws an [IndexOutOfBoundsException] except in Kotlin/JS")
+            out.println("     * where the behavior is unspecified.")
+            out.println("     */")
             out.println("    public operator fun get(index: Int): $s")
-            out.println("    /** Sets the element at the given [index] to the given [value]. This method can be called using the index operator. */")
+            out.println()
+            out.println("    /**")
+            out.println("     * Sets the element at the given [index] to the given [value]. This method can be called using the index operator.")
+            out.println("     *")
+            out.println("     * If the [index] is out of bounds of this array, throws an [IndexOutOfBoundsException] except in Kotlin/JS")
+            out.println("     * where the behavior is unspecified.")
+            out.println("     */")
             out.println("    public operator fun set(index: Int, value: $s): Unit")
             out.println()
             out.println("    /** Returns the number of elements in the array. */")

generators/builtins/unsignedTypes.kt

@@ -428,10 +428,20 @@ class UnsignedArrayGenerator(val type: UnsignedType, out: PrintWriter) : BuiltIn
     /** Creates a new array of the specified [size], with all elements initialized to zero. */
     public constructor(size: Int) : this($storageArrayType(size))
 
-    /** Returns the array element at the given [index]. This method can be called using the index operator. */
+    /**
+     * Returns the array element at the given [index]. This method can be called using the index operator.
+     *
+     * If the [index] is out of bounds of this array, throws an [IndexOutOfBoundsException] except in Kotlin/JS
+     * where the behavior is unspecified.
+     */
     public operator fun get(index: Int): $elementType = storage[index].to$elementType()
 
-    /** Sets the element at the given [index] to the given [value]. This method can be called using the index operator. */
+    /**
+     * Sets the element at the given [index] to the given [value]. This method can be called using the index operator.
+     *
+     * If the [index] is out of bounds of this array, throws an [IndexOutOfBoundsException] except in Kotlin/JS
+     * where the behavior is unspecified.
+     */
     public operator fun set(index: Int, value: $elementType) {
         storage[index] = value.to$storageElementType()
     }