[dart2wasm] Split --omit-type-checks into --omit-{implicit,explicit}-checks

This aligns the behavior of --omit-implicit-type-checks with dart2js

Change-Id: I453652339f23b89873d070422cf61eca77a2b68d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/348164
Reviewed-by: Slava Egorov <[email protected]>

Author: mkustermann

pkg/dart2wasm/lib/code_generator.dart

@@ -488,7 +488,7 @@ class CodeGenerator extends ExpressionVisitor1<w.ValueType, w.ValueType>
 
   void generateTypeChecks(List<TypeParameter> typeParameters,
       FunctionNode function, ParameterInfo paramInfo) {
-    if (translator.options.omitTypeChecks) {
+    if (translator.options.omitImplicitTypeChecks) {
       return;
     }
 
@@ -3047,7 +3047,7 @@ class CodeGenerator extends ExpressionVisitor1<w.ValueType, w.ValueType>
 
   @override
   w.ValueType visitAsExpression(AsExpression node, w.ValueType expectedType) {
-    if (translator.options.omitTypeChecks || node.isUnchecked) {
+    if (translator.options.omitExplicitTypeChecks || node.isUnchecked) {
       return wrap(node.operand, expectedType);
     }
 
@@ -3425,7 +3425,7 @@ class CodeGenerator extends ExpressionVisitor1<w.ValueType, w.ValueType>
       }
     }
 
-    if (!translator.options.omitTypeChecks) {
+    if (!translator.options.omitImplicitTypeChecks) {
       // Check type parameter bounds
       for (TypeParameter typeParameter in memberTypeParams) {
         if (typeParameter.bound != translator.coreTypes.objectNullableRawType) {

pkg/dart2wasm/lib/dart2wasm.dart

@@ -42,9 +42,19 @@ final List<Option> options = [
   Flag(
       "enable-asserts", (o, value) => o.translatorOptions.enableAsserts = value,
       defaultsTo: _d.translatorOptions.enableAsserts),
-  Flag("omit-type-checks",
-      (o, value) => o.translatorOptions.omitTypeChecks = value,
-      defaultsTo: _d.translatorOptions.omitTypeChecks),
+  Flag("omit-explicit-checks",
+      (o, value) => o.translatorOptions.omitExplicitTypeChecks = value,
+      defaultsTo: _d.translatorOptions.omitExplicitTypeChecks),
+  Flag("omit-implicit-checks",
+      (o, value) => o.translatorOptions.omitImplicitTypeChecks = value,
+      defaultsTo: _d.translatorOptions.omitImplicitTypeChecks),
+  // TODO(http://dartbug.com/54675): Deprecate & Remove this one.
+  Flag("omit-type-checks", (o, value) {
+    o.translatorOptions.omitImplicitTypeChecks = value;
+    o.translatorOptions.omitExplicitTypeChecks = value;
+  },
+      defaultsTo: _d.translatorOptions.omitImplicitTypeChecks &&
+          _d.translatorOptions.omitExplicitTypeChecks),
   Flag("verbose", (o, value) => o.translatorOptions.verbose = value,
       defaultsTo: _d.translatorOptions.verbose),
   Flag("verify-type-checks",

pkg/dart2wasm/lib/dispatch_table.dart

@@ -131,9 +131,9 @@ class SelectorInfo {
                 // parameter.
                 return translator.coreTypes.objectNullableRawType;
               }
-              if (!translator.options.omitTypeChecks) {
+              if (!translator.options.omitImplicitTypeChecks) {
                 // A runtime type check of the parameter will be generated.
-                // The value therefore must be boxed.
+                // The value must therefore be boxed.
                 ensureBoxed[index] = true;
               }
             }

pkg/dart2wasm/lib/dynamic_forwarders.dart

@@ -712,7 +712,7 @@ void generateDynamicFunctionCall(
   b.br_if(noSuchMethodBlock);
 
   // Shape check passed, check types
-  if (!translator.options.omitTypeChecks) {
+  if (!translator.options.omitImplicitTypeChecks) {
     b.local_get(functionTypeLocal);
     b.local_get(typeArgsLocal);
     b.local_get(posArgsLocal);

pkg/dart2wasm/lib/translator.dart

@@ -34,7 +34,8 @@ class TranslatorOptions {
   bool inlining = true;
   bool jsCompatibility = false;
   bool nameSection = true;
-  bool omitTypeChecks = false;
+  bool omitImplicitTypeChecks = false;
+  bool omitExplicitTypeChecks = false;
   bool polymorphicSpecialization = false;
   bool printKernel = false;
   bool printWasm = false;
@@ -450,7 +451,7 @@ class Translator with KernelNodes {
     final namedParameters = List.of(staticType.namedParameters);
     assert(namedParameters.length == method.function.namedParameters.length);
 
-    if (!options.omitTypeChecks) {
+    if (!options.omitImplicitTypeChecks) {
       for (int i = 0; i < positionalParameters.length; i++) {
         final param = method.function.positionalParameters[i];
         if (param.isCovariantByDeclaration || param.isCovariantByClass) {

tests/web/wasm_js_shared/omit_implicit_checks_test.dart

@@ -0,0 +1,59 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// dart2jsOptions=--omit-implicit-checks
+// dart2wasmOptions=--omit-implicit-checks
+
+import 'package:expect/expect.dart';
+import 'package:expect/config.dart';
+
+final kTrue = int.parse('1') == 1;
+
+void main() {
+  // This test is specific to testing dart2wasm & dart2js.
+  if (!isDart2jsConfiguration && !isDart2WasmConfiguration) return;
+
+  testExplicitAsCheck();
+
+  testCovariantMethodCheck();
+  testDynamicCall();
+  testCovariantKeyword();
+}
+
+void testExplicitAsCheck() {
+  final dynamic x = kTrue ? A() : B();
+  Expect.throws(() => x as B);
+}
+
+void testCovariantMethodCheck() {
+  final List<dynamic> list = kTrue ? <String>['a'] : <int>[1];
+  list.add('b');
+  list.add(3);
+  Expect.equals('a', list[0]);
+  Expect.equals('b', list[1]);
+  Expect.equals(3, list[2]);
+}
+
+void testDynamicCall() {
+  final dynamic a = kTrue ? (String a) => 'closure($a)' : A();
+  Expect.equals('closure(B)', a(B()));
+}
+
+void testCovariantKeyword() {
+  final object = kTrue ? B() : A();
+
+  // Normally the `covariant String` would cause a type error to be thrown, but
+  // due to --omit-implicit-checks it works just fine.
+  Expect.equals('B.foo(42)', object.foo(42));
+}
+
+class A {
+  String foo(Object arg) => 'A.foo($arg)';
+}
+
+class B extends A {
+  String foo(covariant String arg) => 'B.foo($arg)';
+
+  String toString() => 'B';
+}