Add a fallback flag -Xno-unified-null-checks for KT-22275

#KT-41482 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java

@@ -5051,7 +5051,9 @@ The "returned" value of try expression with no finally is either the last expres
                 return Unit.INSTANCE;
             }
 
-            CodegenUtilKt.generateAsCast(v, rightKotlinType, boxedRightType, safeAs, state.getLanguageVersionSettings());
+            CodegenUtilKt.generateAsCast(
+                    v, rightKotlinType, boxedRightType, safeAs, state.getLanguageVersionSettings(), state.getUnifiedNullChecks()
+            );
 
             return Unit.INSTANCE;
         });

compiler/backend/src/org/jetbrains/kotlin/codegen/codegenUtil.kt

@@ -98,11 +98,12 @@ fun generateAsCast(
     kotlinType: KotlinType,
     asmType: Type,
     isSafe: Boolean,
-    languageVersionSettings: LanguageVersionSettings
+    languageVersionSettings: LanguageVersionSettings,
+    unifiedNullChecks: Boolean,
 ) {
     if (!isSafe) {
         if (!TypeUtils.isNullableType(kotlinType)) {
-            generateNullCheckForNonSafeAs(v, kotlinType, languageVersionSettings)
+            generateNullCheckForNonSafeAs(v, kotlinType, unifiedNullChecks)
         }
     } else {
         with(v) {
@@ -122,15 +123,13 @@ fun generateAsCast(
 private fun generateNullCheckForNonSafeAs(
     v: InstructionAdapter,
     type: KotlinType,
-    languageVersionSettings: LanguageVersionSettings
+    unifiedNullChecks: Boolean,
 ) {
     with(v) {
         dup()
         val nonnull = Label()
         ifnonnull(nonnull)
-        val exceptionClass =
+        val exceptionClass = if (unifiedNullChecks) "java/lang/NullPointerException" else "kotlin/TypeCastException"
-            if (languageVersionSettings.apiVersion >= ApiVersion.KOTLIN_1_4) "java/lang/NullPointerException"
-            else "kotlin/TypeCastException"
         AsmUtil.genThrow(
             v,
             exceptionClass,

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/PsiInlineCodegen.kt

@@ -41,7 +41,10 @@ class PsiInlineCodegen(
     private val actualDispatchReceiver: Type = methodOwner
 ) : InlineCodegen<ExpressionCodegen>(
     codegen, state, function, methodOwner, signature, typeParameterMappings, sourceCompiler,
-    ReifiedTypeInliner(typeParameterMappings, PsiInlineIntrinsicsSupport(state), codegen.typeSystem, state.languageVersionSettings),
+    ReifiedTypeInliner(
+        typeParameterMappings, PsiInlineIntrinsicsSupport(state), codegen.typeSystem,
+        state.languageVersionSettings, state.unifiedNullChecks
+    ),
 ), CallGenerator {
     override fun generateAssertFieldIfNeeded(info: RootInliningContext) {
         if (info.generateAssertField) {

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/ReifiedTypeInliner.kt

@@ -53,7 +53,8 @@ class ReifiedTypeInliner<KT : KotlinTypeMarker>(
     private val parametersMapping: TypeParameterMappings<KT>?,
     private val intrinsicsSupport: IntrinsicsSupport<KT>,
     private val typeSystem: TypeSystemCommonBackendContext,
-    private val languageVersionSettings: LanguageVersionSettings
+    private val languageVersionSettings: LanguageVersionSettings,
+    private val unifiedNullChecks: Boolean,
 ) {
     enum class OperationKind {
         NEW_ARRAY, AS, SAFE_AS, IS, JAVA_CLASS, ENUM_REIFIED, TYPE_OF;
@@ -222,7 +223,7 @@ class ReifiedTypeInliner<KT : KotlinTypeMarker>(
         if (stubCheckcast !is TypeInsnNode) return false
 
         val newMethodNode = MethodNode(Opcodes.API_VERSION)
-        generateAsCast(InstructionAdapter(newMethodNode), kotlinType, asmType, safe, languageVersionSettings)
+        generateAsCast(InstructionAdapter(newMethodNode), kotlinType, asmType, safe, languageVersionSettings, unifiedNullChecks)
 
         instructions.insert(insn, newMethodNode.instructions)
         // Keep stubCheckcast to avoid VerifyErrors on 1.8+ bytecode,

compiler/backend/src/org/jetbrains/kotlin/codegen/state/GenerationState.kt

@@ -249,7 +249,9 @@ class GenerationState private constructor(
     val assertionsMode: JVMAssertionsMode = configuration.get(JVMConfigurationKeys.ASSERTIONS_MODE, JVMAssertionsMode.DEFAULT)
     val isInlineDisabled: Boolean = configuration.getBoolean(CommonConfigurationKeys.DISABLE_INLINE)
     val useTypeTableInSerializer: Boolean = configuration.getBoolean(JVMConfigurationKeys.USE_TYPE_TABLE)
-    val unifiedNullChecks: Boolean = languageVersionSettings.apiVersion >= ApiVersion.KOTLIN_1_4
+    val unifiedNullChecks: Boolean =
+        languageVersionSettings.apiVersion >= ApiVersion.KOTLIN_1_4 &&
+                !configuration.getBoolean(JVMConfigurationKeys.NO_UNIFIED_NULL_CHECKS)
     val functionsWithInlineClassReturnTypesMangled: Boolean =
         languageVersionSettings.supportsFeature(LanguageFeature.MangleClassMembersReturningInlineClasses)
 

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments.kt

@@ -352,6 +352,12 @@ class K2JVMCompilerArguments : CommonCompilerArguments() {
     )
     var noKotlinNothingValueException: Boolean by FreezableVar(false)
 
+    @Argument(
+        value = "-Xno-unified-null-checks",
+        description = "Use pre-1.4 exception types in null checks instead of java.lang.NPE. See KT-22275 for more details"
+    )
+    var noUnifiedNullChecks: Boolean by FreezableVar(false)
+
     @Argument(
         value = "-Xprofile",
         valueDescription = "<profilerPath:command:outputDir>",

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/jvmArguments.kt

@@ -166,6 +166,7 @@ fun CompilerConfiguration.configureAdvancedJvmOptions(arguments: K2JVMCompilerAr
     put(JVMConfigurationKeys.EMIT_JVM_TYPE_ANNOTATIONS, arguments.emitJvmTypeAnnotations)
     put(JVMConfigurationKeys.NO_OPTIMIZED_CALLABLE_REFERENCES, arguments.noOptimizedCallableReferences)
     put(JVMConfigurationKeys.NO_KOTLIN_NOTHING_VALUE_EXCEPTION, arguments.noKotlinNothingValueException)
+    put(JVMConfigurationKeys.NO_UNIFIED_NULL_CHECKS, arguments.noUnifiedNullChecks)
 
     if (!JVMConstructorCallNormalizationMode.isSupportedValue(arguments.constructorCallNormalizationMode)) {
         getNotNull(CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY).report(

compiler/config.jvm/src/org/jetbrains/kotlin/config/JVMConfigurationKeys.java

@@ -123,6 +123,9 @@ public class JVMConfigurationKeys {
     public static final CompilerConfigurationKey<Boolean> NO_KOTLIN_NOTHING_VALUE_EXCEPTION =
             CompilerConfigurationKey.create("Do not use KotlinNothingValueException available since 1.4");
 
+    public static final CompilerConfigurationKey<Boolean> NO_UNIFIED_NULL_CHECKS =
+            CompilerConfigurationKey.create("Use pre-1.4 exception types in null checks instead of java.lang.NPE");
+
     public static final CompilerConfigurationKey<Boolean> USE_OLD_SPILLED_VAR_TYPE_ANALYSIS =
             CompilerConfigurationKey.create("Use old, SourceInterpreter-based analysis for fields, used for spilled variables in coroutines");
 }

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

@@ -1201,7 +1201,8 @@ class ExpressionCodegen(
             mappings,
             IrInlineIntrinsicsSupport(context, typeMapper),
             IrTypeCheckerContext(context.irBuiltIns),
-            state.languageVersionSettings
+            state.languageVersionSettings,
+            state.unifiedNullChecks,
         )
 
         return IrInlineCodegen(this, state, callee, methodOwner, signature, mappings, sourceCompiler, reifiedTypeInliner)

compiler/testData/cli/jvm/extraHelp.out

@@ -73,6 +73,7 @@ where advanced options include:
                              Do not use optimized callable reference superclasses available from 1.4
   -Xno-param-assertions      Don't generate not-null assertions on parameters of methods accessible from Java
   -Xno-receiver-assertions   Don't generate not-null assertion for extension receiver arguments of platform types
+  -Xno-unified-null-checks   Use pre-1.4 exception types in null checks instead of java.lang.NPE. See KT-22275 for more details
   -Xno-use-ir                Do not use the IR backend. Useful for a custom-built compiler where IR backend is enabled by default
   -Xprofile=<profilerPath:command:outputDir>
                              Debug option: Run compiler with async profiler, save snapshots to outputDir, command is passed to async-profiler on start

compiler/testData/codegen/box/nullCheckOptimization/exclExclThrowsKnpe_1_3.kt

@@ -1,4 +1,4 @@
-// !API_VERSION: 1.3
+// KOTLIN_CONFIGURATION_FLAGS: +JVM.NO_UNIFIED_NULL_CHECKS
 // WITH_RUNTIME
 // TARGET_BACKEND: JVM
 

compiler/testData/codegen/box/nullCheckOptimization/javaNullCheckThrowsIse_1_3.kt

@@ -1,4 +1,4 @@
-// !API_VERSION: 1.3
+// KOTLIN_CONFIGURATION_FLAGS: +JVM.NO_UNIFIED_NULL_CHECKS
 // IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 // FILE: A.java

compiler/testData/codegen/box/nullCheckOptimization/parameterNullCheckThrowsIae_1_3.kt

@@ -1,4 +1,4 @@
-// !API_VERSION: 1.3
+// KOTLIN_CONFIGURATION_FLAGS: +JVM.NO_UNIFIED_NULL_CHECKS
 // TARGET_BACKEND: JVM
 // FILE: A.java
 

compiler/testData/codegen/boxInline/reified/checkCast/simple_1_3.kt

@@ -1,4 +1,4 @@
-// !API_VERSION: 1.3
+// KOTLIN_CONFIGURATION_FLAGS: +JVM.NO_UNIFIED_NULL_CHECKS
 // TARGET_BACKEND: JVM
 // FILE: 1.kt
 // WITH_RUNTIME