Clarify floating-point to integral conversion rounding behaviour

core/builtins/native/kotlin/Primitives.kt

@@ -1160,7 +1160,7 @@ public class Float private constructor() : Number(), Comparable<Float> {
     /**
      * Converts this [Float] value to [Int].
      *
-     * The fractional part, if any, is rounded down.
+     * The fractional part, if any, is rounded down towards zero.
      * Returns zero if this `Float` value is `NaN`, [Int.MIN_VALUE] if it's less than `Int.MIN_VALUE`,
      * [Int.MAX_VALUE] if it's bigger than `Int.MAX_VALUE`.
      */
@@ -1168,7 +1168,7 @@ public class Float private constructor() : Number(), Comparable<Float> {
     /**
      * Converts this [Float] value to [Long].
      *
-     * The fractional part, if any, is rounded down.
+     * The fractional part, if any, is rounded down towards zero.
      * Returns zero if this `Float` value is `NaN`, [Long.MIN_VALUE] if it's less than `Long.MIN_VALUE`,
      * [Long.MAX_VALUE] if it's bigger than `Long.MAX_VALUE`.
      */
@@ -1378,7 +1378,7 @@ public class Double private constructor() : Number(), Comparable<Double> {
     /**
      * Converts this [Double] value to [Int].
      *
-     * The fractional part, if any, is rounded down.
+     * The fractional part, if any, is rounded down towards zero.
      * Returns zero if this `Double` value is `NaN`, [Int.MIN_VALUE] if it's less than `Int.MIN_VALUE`,
      * [Int.MAX_VALUE] if it's bigger than `Int.MAX_VALUE`.
      */
@@ -1386,7 +1386,7 @@ public class Double private constructor() : Number(), Comparable<Double> {
     /**
      * Converts this [Double] value to [Long].
      *
-     * The fractional part, if any, is rounded down.
+     * The fractional part, if any, is rounded down towards zero.
      * Returns zero if this `Double` value is `NaN`, [Long.MIN_VALUE] if it's less than `Long.MIN_VALUE`,
      * [Long.MAX_VALUE] if it's bigger than `Long.MAX_VALUE`.
      */

generators/builtins/primitives.kt

@@ -241,7 +241,7 @@ class GeneratePrimitives(out: PrintWriter) : BuiltInsSourceGenerator(out) {
             """
         } else {
             """
-             * The fractional part, if any, is rounded down.
+             * The fractional part, if any, is rounded down towards zero.
              * Returns zero if this `$thisName` value is `NaN`, [$otherName.MIN_VALUE] if it's less than `$otherName.MIN_VALUE`,
              * [$otherName.MAX_VALUE] if it's bigger than `$otherName.MAX_VALUE`.
              */

generators/builtins/unsignedTypes.kt

@@ -349,7 +349,7 @@ class UnsignedTypeGenerator(val type: UnsignedType, out: PrintWriter) : BuiltIns
                 /**
                  * Converts this [$otherName] value to [$className].
                  *
-                 * The fractional part, if any, is rounded down.
+                 * The fractional part, if any, is rounded down towards zero.
                  * Returns zero if this `$otherName` value is negative or `NaN`, [$className.MAX_VALUE] if it's bigger than `$className.MAX_VALUE`.
                  */
                 """.trimIndent()

libraries/stdlib/js-ir/runtime/longjs.kt

@@ -336,7 +336,7 @@ internal fun fromInt(value: Int) = Long(value, if (value < 0) -1 else 0)
 
 /**
  * Converts this [Double] value to [Long].
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Double` value is `NaN`, [Long.MIN_VALUE] if it's less than `Long.MIN_VALUE`,
  * [Long.MAX_VALUE] if it's bigger than `Long.MAX_VALUE`.
  */

libraries/stdlib/js-v1/src/js/long.js

@@ -95,7 +95,7 @@ Kotlin.Long.fromInt = function(value) {
 
 /**
  * Converts this number value to `Long`.
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Double` value is `NaN`, `Long.MIN_VALUE` if it's less than `Long.MIN_VALUE`,
  * `Long.MAX_VALUE` if it's bigger than `Long.MAX_VALUE`.
  * @param {number} value The number in question.

libraries/stdlib/unsigned/src/kotlin/UInt.kt

@@ -313,7 +313,7 @@ public inline fun Long.toUInt(): UInt = UInt(this.toInt())
 /**
  * Converts this [Float] value to [UInt].
  *
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Float` value is negative or `NaN`, [UInt.MAX_VALUE] if it's bigger than `UInt.MAX_VALUE`.
  */
 @SinceKotlin("1.3")
@@ -323,7 +323,7 @@ public inline fun Float.toUInt(): UInt = doubleToUInt(this.toDouble())
 /**
  * Converts this [Double] value to [UInt].
  *
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Double` value is negative or `NaN`, [UInt.MAX_VALUE] if it's bigger than `UInt.MAX_VALUE`.
  */
 @SinceKotlin("1.3")

libraries/stdlib/unsigned/src/kotlin/ULong.kt

@@ -316,7 +316,7 @@ public inline fun Long.toULong(): ULong = ULong(this)
 /**
  * Converts this [Float] value to [ULong].
  *
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Float` value is negative or `NaN`, [ULong.MAX_VALUE] if it's bigger than `ULong.MAX_VALUE`.
  */
 @SinceKotlin("1.3")
@@ -326,7 +326,7 @@ public inline fun Float.toULong(): ULong = doubleToULong(this.toDouble())
 /**
  * Converts this [Double] value to [ULong].
  *
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Double` value is negative or `NaN`, [ULong.MAX_VALUE] if it's bigger than `ULong.MAX_VALUE`.
  */
 @SinceKotlin("1.3")