Scripting: support scripts starting with UTF-8 BOM

#KT-54705 fixed

libraries/scripting/common/src/kotlin/script/experimental/host/scriptHostUtil.kt

@@ -62,7 +62,7 @@ abstract class FileBasedScriptSource() : ExternalSourceCode {
  */
 open class FileScriptSource(override val file: File, private val preloadedText: String? = null) : FileBasedScriptSource(), Serializable {
     override val externalLocation: URL get() = file.toURI().toURL()
-    override val text: String by lazy { preloadedText ?: file.readText() }
+    override val text: String by lazy { preloadedText ?: file.readTextSkipUtf8Bom() }
     override val name: String? get() = file.name
     override val locationId: String? get() = file.path
 
@@ -81,7 +81,7 @@ open class FileScriptSource(override val file: File, private val preloadedText:
  * The implementation of the SourceCode for a script location pointed by the URL
  */
 open class UrlScriptSource(override val externalLocation: URL) : ExternalSourceCode, Serializable {
-    override val text: String by lazy { externalLocation.readText() }
+    override val text: String by lazy { externalLocation.readTextSkipUtf8Bom() }
     override val name: String? get() = externalLocation.file
     override val locationId: String? get() = externalLocation.toString()
 
@@ -133,3 +133,10 @@ private val ExternalSourceCode.textSafe: String?
         } catch (e: Throwable) {
             null
         }
+
+private const val UTF8_BOM = 0xfeff.toChar().toString()
+
+private fun File.readTextSkipUtf8Bom(): String = readText().removePrefix(UTF8_BOM)
+
+private fun URL.readTextSkipUtf8Bom(): String = readText().removePrefix(UTF8_BOM)
+

libraries/tools/kotlin-main-kts-test/test/org/jetbrains/kotlin/mainKts/test/mainKtsIT.kt

@@ -154,6 +154,13 @@ class MainKtsIT {
             listOf("""\{"firstName":"James","lastName":"Bond"\}""", "User\\(firstName=James, lastName=Bond\\)")
         )
     }
+
+    @Test
+    fun testUtf8Bom() {
+        val scriptPath = "$TEST_DATA_ROOT/utf8bom.main.kts"
+        Assert.assertTrue("Expect file '$scriptPath' to start with UTF-8 BOM", File(scriptPath).readText().startsWith(UTF8_BOM))
+        runWithKotlincAndMainKts(scriptPath, listOf("Hello world"))
+    }
 }
 
 fun runWithKotlincAndMainKts(
@@ -204,3 +211,5 @@ fun runWithK2JVMCompilerAndMainKts(
     }
 }
 
+internal const val UTF8_BOM = 0xfeff.toChar().toString()
+

libraries/tools/kotlin-main-kts-test/test/org/jetbrains/kotlin/mainKts/test/mainKtsTest.kt

@@ -266,6 +266,14 @@ class MainKtsTest {
         )
     }
 
+    @Test
+    fun testUtf8Bom() {
+        val scriptPath = "$TEST_DATA_ROOT/utf8bom.main.kts"
+        Assert.assertTrue("Expect file '$scriptPath' to start with UTF-8 BOM", File(scriptPath).readText().startsWith(UTF8_BOM))
+        val res = evalFile(File(scriptPath))
+        assertSucceeded(res)
+    }
+
     private fun assertSucceeded(res: ResultWithDiagnostics<EvaluationResult>) {
         Assert.assertTrue(
             "test failed:\n  ${res.reports.joinToString("\n  ") { it.severity.name + ": " + it.message + if (it.exception == null) "" else ": ${it.exception}" }}",

libraries/tools/kotlin-main-kts-test/testData/utf8bom.main.kts

@@ -0,0 +1 @@
+println("Hello world")