CLI: Allow running class files with '.class' extension in 'kotlin' script

Catch NoClassDefFoundError and print message with cause.

 #KT-11164 Fixed
 #KT-46171 Fixed

compiler/cli/cli-runner/src/org/jetbrains/kotlin/runner/Main.kt

@@ -144,7 +144,19 @@ object Main {
                 break
             }
             else {
-                setRunner(MainClassRunner(arg))
+                val workingDir = File(".")
+                val classFile = File(arg)
+
+                // Allow running class files with '.class' extension.
+                // In order to infer its fully qualified name, it should be located in the current working directory or a subdirectory of it
+                val className =
+                    if (arg.endsWith(".class") && classFile.exists() && classFile.canonicalPath.contains(workingDir.canonicalPath)) {
+                        classFile.canonicalFile.toRelativeString(workingDir.canonicalFile)
+                            .removeSuffix(".class")
+                            .replace(File.separatorChar, '.')
+                    } else arg
+
+                setRunner(MainClassRunner(className))
                 restAsArguments()
                 break
             }

compiler/cli/cli-runner/src/org/jetbrains/kotlin/runner/runners.kt

@@ -25,7 +25,7 @@ import java.net.URLClassLoader
 import java.util.jar.Attributes
 import java.util.jar.JarFile
 
-class RunnerException(message: String) : RuntimeException(message)
+class RunnerException(message: String, cause: Throwable? = null) : RuntimeException(message, cause)
 
 abstract class AbstractRunner : Runner {
     protected abstract val className: String
@@ -40,6 +40,12 @@ abstract class AbstractRunner : Runner {
         }
         catch (e: ClassNotFoundException) {
             throw RunnerException("could not find or load main class $className")
+        } catch (e: NoClassDefFoundError) {
+            val message = """
+                could not find or load main class $className
+                Caused by: $e
+            """.trimIndent()
+            throw RunnerException(message)
         }
 
         val main = try {

compiler/testData/launcher/defaultPackage.kt

@@ -0,0 +1,3 @@
+fun main() {
+    print("ok")
+}

compiler/tests/org/jetbrains/kotlin/cli/LauncherScriptTest.kt

@@ -354,4 +354,104 @@ compiler/testData/launcher/noInline.myscript:1:7: error: unresolved reference: C
             expectedExitCode = 1
         )
     }
+
+    fun testNoClassDefFoundErrorWhenClassInDefaultPackage() {
+        val testDir = File("$tmpdir/test")
+
+        runProcess("kotlinc", "$testDataDirectory/defaultPackage.kt", "-d", testDir.path)
+        assertExists(File("${testDir.path}/DefaultPackageKt.class"))
+
+        runProcess(
+            "kotlin", "test.DefaultPackageKt", workDirectory = tmpdir, expectedExitCode = 1,
+            expectedStderr = """
+            error: could not find or load main class test.DefaultPackageKt
+            Caused by: java.lang.NoClassDefFoundError: test/DefaultPackageKt (wrong name: DefaultPackageKt)
+
+        """.trimIndent()
+        )
+    }
+
+    fun testNoClassDefFoundErrorWhenClassNotInDefaultPackage() {
+        val testDir = File("$tmpdir/test")
+
+        runProcess("kotlinc", "$testDataDirectory/helloWorld.kt", "-d", tmpdir.path)
+        assertExists(File("${testDir.path}/HelloWorldKt.class"))
+
+        runProcess(
+            "kotlin", "HelloWorldKt", workDirectory = testDir, expectedExitCode = 1,
+            expectedStderr = """
+            error: could not find or load main class HelloWorldKt
+            Caused by: java.lang.NoClassDefFoundError: HelloWorldKt (wrong name: test/HelloWorldKt)
+
+        """.trimIndent()
+        )
+    }
+
+    /**
+     * A class whose full qualified name is `DefaultPackageKt` and is located in path `$tmpdir/test/DefaultPackageKt.class`
+     */
+    fun testRunClassFileWithExtensionInDefaultPackage() {
+        val subDir = File("$tmpdir/test/sub").apply { mkdirs() }
+        val testDir = File("$tmpdir/test")
+
+        runProcess("kotlinc", "$testDataDirectory/defaultPackage.kt", "-d", testDir.path)
+        assertExists(File("${testDir.path}/DefaultPackageKt.class"))
+
+        runProcess(
+            "kotlin", "test/DefaultPackageKt.class", workDirectory = tmpdir, expectedExitCode = 1,
+            expectedStderr = """
+            error: could not find or load main class test.DefaultPackageKt
+            Caused by: java.lang.NoClassDefFoundError: test/DefaultPackageKt (wrong name: DefaultPackageKt)
+            
+        """.trimIndent()
+        )
+
+        runProcess("kotlin", "DefaultPackageKt.class", expectedStdout = "ok", workDirectory = testDir)
+        runProcess("kotlin", "./sub/../DefaultPackageKt.class", expectedStdout = "ok", workDirectory = testDir)
+        runProcess(
+            "kotlin", "../DefaultPackageKt.class", expectedExitCode = 1,
+            expectedStderr = "error: could not find or load main class ../DefaultPackageKt.class\n",
+            workDirectory = subDir
+        )
+    }
+
+    /**
+     * A class whose full qualified name is `test.HelloWorldKt` and is located in path `$tmpdir/test/HelloWorldKt.class`
+     */
+    fun testRunClassFileWithExtensionNotInDefaultPackage() {
+        val subDir = File("$tmpdir/test/sub").apply { mkdirs() }
+        val testDir = File("$tmpdir/test")
+
+        runProcess("kotlinc", "$testDataDirectory/helloWorld.kt", "-d", tmpdir.path)
+        assertExists(File("${testDir.path}/HelloWorldKt.class"))
+
+        runProcess("kotlin", "test/HelloWorldKt.class", expectedStdout = "Hello!\n", workDirectory = tmpdir)
+        runProcess(
+            "kotlin", "test.HelloWorldKt.class", expectedExitCode = 1,
+            expectedStderr = "error: could not find or load main class test.HelloWorldKt.class\n",
+            workDirectory = tmpdir
+        )
+        runProcess("kotlin", "test/sub/../../test/HelloWorldKt.class", expectedStdout = "Hello!\n", workDirectory = tmpdir)
+        runProcess(
+            "kotlin", "./HelloWorldKt.class", workDirectory = testDir, expectedExitCode = 1,
+            expectedStderr = """
+            error: could not find or load main class HelloWorldKt
+            Caused by: java.lang.NoClassDefFoundError: HelloWorldKt (wrong name: test/HelloWorldKt)
+            
+        """.trimIndent()
+        )
+        runProcess(
+            "kotlin", "HelloWorldKt.class", workDirectory = testDir, expectedExitCode = 1,
+            expectedStderr = """
+            error: could not find or load main class HelloWorldKt
+            Caused by: java.lang.NoClassDefFoundError: HelloWorldKt (wrong name: test/HelloWorldKt)
+            
+        """.trimIndent()
+        )
+        runProcess(
+            "kotlin", "../HelloWorldKt.class", expectedExitCode = 1,
+            expectedStderr = "error: could not find or load main class ../HelloWorldKt.class\n",
+            workDirectory = subDir
+        )
+    }
 }