[JVM IR] Ensure class names are valid for JVM.

The JVM IR backend was producing class names with "<no name provided>"
for unnamed functions (i.e., `fun(...) {}`). This produces class files
with names invalid in Windows. This change adds validation of names
using the same set of invalid characters used in the frontend, which
should ensure class file names are valid.

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ClassCodegen.kt

@@ -35,13 +35,13 @@ import org.jetbrains.kotlin.load.java.JvmAbi
 import org.jetbrains.kotlin.load.java.JvmAnnotationNames
 import org.jetbrains.kotlin.load.kotlin.header.KotlinClassHeader
 import org.jetbrains.kotlin.name.Name
-import org.jetbrains.kotlin.name.SpecialNames
 import org.jetbrains.kotlin.resolve.jvm.AsmTypes
 import org.jetbrains.kotlin.resolve.jvm.annotations.JVM_SYNTHETIC_ANNOTATION_FQ_NAME
 import org.jetbrains.kotlin.resolve.jvm.annotations.TRANSIENT_ANNOTATION_FQ_NAME
 import org.jetbrains.kotlin.resolve.jvm.annotations.VOLATILE_ANNOTATION_FQ_NAME
 import org.jetbrains.kotlin.resolve.jvm.diagnostics.JvmDeclarationOrigin
 import org.jetbrains.kotlin.resolve.jvm.diagnostics.OtherOrigin
+import org.jetbrains.kotlin.resolve.jvm.jvmSignature.JvmClassSignature
 import org.jetbrains.kotlin.serialization.DescriptorSerializer
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 import org.jetbrains.org.objectweb.asm.Opcodes
@@ -110,6 +110,13 @@ open class ClassCodegen protected constructor(
         val superClassInfo = irClass.getSuperClassInfo(typeMapper)
         val signature = getSignature(irClass, type, superClassInfo, typeMapper)
 
+        // Ensure that the backend only produces class names that would be valid in the frontend for JVM.
+        // hasInvalidName() uses a set copied from JvmSimpleNameBacktickChecker, which in turn references JVMS 4.7.9.1:
+        // https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.9.1.
+        if (context.state.classBuilderMode.generateBodies && signature.hasInvalidName()) {
+            throw IllegalStateException("Generating class with invalid name '${type.className}': ${irClass.dump()}")
+        }
+
         visitor.defineClass(
             irClass.descriptor.psiElement,
             state.classFileVersion,
@@ -281,20 +288,14 @@ open class ClassCodegen protected constructor(
 
     companion object {
         fun generate(irClass: IrClass, context: JvmBackendContext) {
-            val state = context.state
-
-            if (irClass.name == SpecialNames.NO_NAME_PROVIDED) {
-                badClass(irClass, state.classBuilderMode)
-            }
-
             ClassCodegen(irClass, context).generate()
         }
 
-        private fun badClass(irClass: IrClass, mode: ClassBuilderMode) {
-            if (mode.generateBodies) {
-                throw IllegalStateException("Generating bad class in ClassBuilderMode = $mode: ${irClass.dump()}")
-            }
-        }
+        // Note: This is copied from JvmSimpleNameBacktickChecker.
+        private val INVALID_CHARS = setOf('.', ';', '[', ']', '/', '<', '>', ':', '\\')
+
+        private fun JvmClassSignature.hasInvalidName() =
+            name.splitToSequence('/').any { identifier -> identifier.any { it in INVALID_CHARS } }
     }
 
     private fun generateDeclaration(declaration: IrDeclaration) {

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/InventNamesForLocalClasses.kt

@@ -17,6 +17,7 @@ import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
 import org.jetbrains.kotlin.ir.util.isAnonymousObject
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.name.NameUtils
 import org.jetbrains.kotlin.resolve.jvm.JvmClassName
 import org.jetbrains.org.objectweb.asm.Type
 
@@ -102,10 +103,11 @@ class InventNamesForLocalClasses(private val context: JvmBackendContext) : FileL
             val simpleName = declaration.name.asString()
 
             val internalName = when {
-                declaration.origin == IrDeclarationOrigin.LOCAL_FUNCTION_FOR_LAMBDA -> {
+                declaration is IrFunction && !NameUtils.hasName(declaration.name) -> {
+                    // Replace "unnamed" function names with indices.
                     inventName(null, data).also { name ->
-                        // We save the name of the lambda to reuse it in the reference to it (produced by the closure conversion) later.
-                        localFunctionNames[(declaration as IrFunction).symbol] = name
+                        // We save the name of the function to reuse it in the reference to it (produced by the closure conversion) later.
+                        localFunctionNames[declaration.symbol] = name
                     }
                 }
                 enclosingName != null -> "$enclosingName$$simpleName"