Check all whitespace characters according to Unicode standard

backend.native/tests/build.gradle

@@ -1512,6 +1512,11 @@ task to_string0(type: RunKonanTest) {
     source = "runtime/text/to_string0.kt"
 }
 
+task trim(type: RunKonanTest) {
+    goldValue = "OK\n"
+    source = "runtime/text/trim.kt"
+}
+
 task chars0(type: RunKonanTest) {
     expectedFail = (project.testTarget == 'wasm32') // Uses exceptions.
     source = "runtime/text/chars0.kt"

backend.native/tests/runtime/text/trim.kt

@@ -0,0 +1,49 @@
+package runtime.text.trim
+
+import kotlin.test.*
+
+/**
+ * Tests correct conversions of floats/doubles along with trimming of leading/trailing whitespaces.
+ * String.trim() trims all whitespaces (see kotlin/text/Strings.kt) while String.toFloat() uses
+ * the same approach as java.lang.Float.parseFloat()
+ */
+@Test fun runTest() {
+    convertToFloatingPoint()
+    convertWithWhitespaces()
+    trimWhitespaces()
+
+    println("OK")
+}
+
+private fun convertToFloatingPoint() {
+    assertEquals(expected = 3.14F, actual = " 3.14  ".toFloat(), message = "String float should be trimmed")
+    assertEquals(expected = 3.14, actual = " 3.14  ".toDouble(), message = "String double should be trimmed")
+    assertEquals(expected = 7.15F, actual = "\u0019 7.15  ".toFloat(), message = "String float should be trimmed")
+    assertEquals(expected = 42.3, actual = "\n 42.3 ".toDouble(), message = "String double should be trimmed")
+}
+
+private fun convertWithWhitespaces() {
+    val s = "\u0009 \u000A 2.71 \u000D"
+    assertEquals(expected = 2.71F, actual = s.toFloat(),
+            message = "String should be cleared of LF, CR, TAB and converted to Float")
+    assertEquals(expected = 2.71, actual = s.toDouble(),
+            message = "String should be cleared of LF, CR, TAB and converted to Double")
+
+    // Special symbols should not be trimmed during String to Float/Double conversion
+    assertFailsWith<NumberFormatException> { "\u202F3.14".toFloat() }
+    assertFailsWith<NumberFormatException> { "\u20293.14".toDouble() }
+    assertFailsWith<NumberFormatException> { "3.14\u200B".toDouble() }
+    assertFailsWith<NumberFormatException> { "3.14\u200B ABC".toDouble() }
+}
+
+private fun trimWhitespaces() {
+    assertEquals(expected = "String", actual = "  String".trim(), message = "Trim leading spaces")
+    assertEquals(expected = "String  ", actual = "    String  ".trimStart(), message = "Trim start")
+    assertEquals(expected = "  String", actual = "  String \t ".trimEnd(), message = "Trim end")
+
+    assertEquals(expected = "String", actual = "\u0020 \u202FString\u2028\u2029".trim(),
+            message = "Trim special whitespaces")
+    assertEquals(expected = "\u1FFFString", actual = "\u0085  \u1FFFString".trim(),
+            message = "Trim special whitespace but should left a unicode symbol")
+    assertEquals(expected = "String\tSTR", actual = " \nString\tSTR  ".trim(), message = "Trim newline")
+}