[dart2wasm] Fix dynamic modules bugs. - For direct calls in selector branch, ensure 'if' branches have correct inputs. - For overrideable selectors, the receiver type cannot be known in the main module so use 'top' type. Technically we could do better if selectors tracked interfaces they targeted. Then we could take the LUB of all those classes. But this would be a significant refactor for a small benefit. - Type checks on classes defined in the main module should use the class ID ranges from the main module rather than those from the dynamic submodule. This only applies to non-dynamic module extendable types (otherwise we'd use the RTT checks). So we know the class can only exist in one of the range sets, not both. I discovered (1) from running Flutter which led me to create this test which uncovered (2) and (3). Change-Id: I80f39835f66aa7cf0cff527341e3f4a948a7a0cb Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/430360 Reviewed-by: Martin Kustermann <kustermann@google.com> Commit-Queue: Nate Biggs <natebiggs@google.com>

diff --git a/pkg/dart2wasm/lib/class_info.dart b/pkg/dart2wasm/lib/class_info.dart
index fa5c731..31a20d6 100644
--- a/pkg/dart2wasm/lib/class_info.dart
+++ b/pkg/dart2wasm/lib/class_info.dart

@@ -678,10 +678,18 @@
         _concreteSubclassIdRangeForDynamicSubmodule);
   }
 
-  List<Range> getConcreteClassIdRangeForCurrentModule(Class klass) {
-    return translator.isDynamicSubmodule
-        ? getConcreteClassIdRangeForDynamicSubmodule(klass)
-        : getConcreteClassIdRangeForMainModule(klass);
+  /// In case the [klass] is from a dynamic module the returned class id
+  /// ranges may be relative. The caller has to ensure to use them
+  /// appropriately.
+  List<Range> getConcreteClassIdRangeForClass(Class klass) {
+    // We cannot return class id ranges for [klass] if there can be more
+    // classes in future dynamic module compilations.
+    assert(!klass.isDynamicSubmoduleExtendable(translator.coreTypes));
+
+    return !translator.isDynamicSubmodule ||
+            klass.enclosingLibrary.isFromMainModule(translator.coreTypes)
+        ? getConcreteClassIdRangeForMainModule(klass)
+        : getConcreteClassIdRangeForDynamicSubmodule(klass);
   }
 
   List<Range> _getConcreteClassIdRange(Class klass,

diff --git a/pkg/dart2wasm/lib/dispatch_table.dart b/pkg/dart2wasm/lib/dispatch_table.dart
index cf74f0e..483bc84 100644
--- a/pkg/dart2wasm/lib/dispatch_table.dart
+++ b/pkg/dart2wasm/lib/dispatch_table.dart

@@ -202,7 +202,9 @@
         }
       }
       assert(returns.length <= outputSets.length);
-      inputSets[0].add(translator.translateType(receiver));
+      inputSets[0].add(isDynamicSubmoduleOverridable
+          ? translator.topInfo.nonNullableType
+          : translator.translateType(receiver));
       for (int i = 0; i < positional.length; i++) {
         DartType type = positional[i];
         inputSets[1 + i].add(translator.translateType(type));

diff --git a/pkg/dart2wasm/lib/dynamic_modules.dart b/pkg/dart2wasm/lib/dynamic_modules.dart
index 59baf8f..b7001aa 100644
--- a/pkg/dart2wasm/lib/dynamic_modules.dart
+++ b/pkg/dart2wasm/lib/dynamic_modules.dart

@@ -835,7 +835,7 @@
           // Check if the invocation is checked or unchecked and use the
           // appropriate offset.
           ib.local_get(ib.locals[function.type.inputs.length - 1]);
-          ib.if_(const [], localSignature.outputs);
+          ib.if_(localSignature.inputs, localSignature.outputs);
           ib.invoke(translator.directCallTarget(uncheckedTarget));
           ib.else_();
           ib.invoke(translator.directCallTarget(checkedTarget));

diff --git a/pkg/dart2wasm/lib/types.dart b/pkg/dart2wasm/lib/types.dart
index 936a863..45f6e17 100644
--- a/pkg/dart2wasm/lib/types.dart
+++ b/pkg/dart2wasm/lib/types.dart

@@ -767,7 +767,7 @@
     // Always inline single class-id range checks (no branching, simply loads,
     // arithmetic and unsigned compare).
     final ranges = translator.classIdNumbering
-        .getConcreteClassIdRangeForCurrentModule(interfaceClass);
+        .getConcreteClassIdRangeForClass(interfaceClass);
     return ranges.length <= 1;
   }
 
@@ -883,10 +883,37 @@
         b.ref_test(translator.closureInfo.nonNullableType);
       } else {
         final ranges = translator.classIdNumbering
-            .getConcreteClassIdRangeForCurrentModule(interfaceClass);
+            .getConcreteClassIdRangeForClass(interfaceClass);
         b.local_get(operand);
         b.struct_get(translator.topInfo.struct, FieldIndex.classId);
-        b.emitClassIdRangeCheck(ranges);
+        if (translator.isDynamicSubmodule) {
+          // Only types that are not dynamic module extendable can get here.
+          final classIdLocal = b.addLocal(w.NumType.i32);
+          b.local_tee(classIdLocal);
+          translator.callReference(translator.classIdToModuleId.reference, b);
+          b.i32_wrap_i64();
+          // Check if the class ID belongs to this module or the main module.
+          b.global_get(translator.dynamicModuleInfo!.moduleIdGlobal);
+          b.i32_wrap_i64();
+          b.i32_eq();
+          b.local_get(classIdLocal);
+          b.i32_const(translator.classIdNumbering.firstDynamicSubmoduleClassId);
+          b.i32_lt_u();
+          b.i32_or();
+          b.if_(const [], const [w.NumType.i32]);
+          // If it is in a known range, then localize the class ID to this
+          // module. If the class is from the main module this will do nothing.
+          b.local_get(classIdLocal);
+          translator.callReference(translator.localizeClassId.reference, b);
+          b.emitClassIdRangeCheck(ranges);
+          b.else_();
+          // If it's not in the main module or this submodule then the type is
+          // unknown to this module so the test fails.
+          b.i32_const(0);
+          b.end();
+        } else {
+          b.emitClassIdRangeCheck(ranges);
+        }
       }
       b.br(resultLabel);
     }
@@ -922,7 +949,9 @@
       this.testedAgainstType,
       this.operandIsNullable,
       this.checkArguments,
-      this.argumentCount);
+      this.argumentCount)
+      : assert(!testedAgainstType.classNode
+            .isDynamicSubmoduleExtendable(translator.coreTypes));
 
   @override
   String get name {

diff --git a/pkg/dynamic_modules/test/data/invoke_checked/dynamic_interface.yaml b/pkg/dynamic_modules/test/data/invoke_checked/dynamic_interface.yaml
new file mode 100644
index 0000000..b5842a0
--- /dev/null
+++ b/pkg/dynamic_modules/test/data/invoke_checked/dynamic_interface.yaml

@@ -0,0 +1,17 @@
+# Copyright (c) 2025, 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.
+callable:
+  - library: 'shared/shared.dart'
+    class: 'Base'
+    member: ''
+  - library: 'shared/shared.dart'
+    class: 'Tester'
+extendable:
+  - library: 'shared/shared.dart'
+    class: 'Base'
+
+can-be-overridden:
+  - library: 'shared/shared.dart'
+    class: 'Base'
+    member: 'foo'

diff --git a/pkg/dynamic_modules/test/data/invoke_checked/main.dart b/pkg/dynamic_modules/test/data/invoke_checked/main.dart
new file mode 100644
index 0000000..29e42c9
--- /dev/null
+++ b/pkg/dynamic_modules/test/data/invoke_checked/main.dart

@@ -0,0 +1,23 @@
+// Copyright (c) 2025, 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.
+
+import '../../common/testing.dart' as helper;
+import 'package:expect/expect.dart';
+
+import 'shared/shared.dart';
+
+class MyChild extends Base {
+  @override
+  Tester foo(covariant Tester x) {
+    return Tester(x.val + 1);
+  }
+}
+
+/// A dynamic module is allowed to extend a class in the dynamic interface and
+/// override its members.
+void main() async {
+  final c = (await helper.load('entry1.dart')) as Base;
+  Expect.equals(3, c.foo(Tester(3)).val);
+  helper.done();
+}

diff --git a/pkg/dynamic_modules/test/data/invoke_checked/modules/entry1.dart b/pkg/dynamic_modules/test/data/invoke_checked/modules/entry1.dart
new file mode 100644
index 0000000..08c16bf
--- /dev/null
+++ b/pkg/dynamic_modules/test/data/invoke_checked/modules/entry1.dart

@@ -0,0 +1,15 @@
+// Copyright (c) 2025, 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.
+
+import '../shared/shared.dart';
+
+class Child extends Base {
+  @override
+  Tester foo(covariant Tester x) {
+    return x;
+  }
+}
+
+@pragma('dyn-module:entry-point')
+Object? dynamicModuleEntrypoint() => Child();

diff --git a/pkg/dynamic_modules/test/data/invoke_checked/shared/shared.dart b/pkg/dynamic_modules/test/data/invoke_checked/shared/shared.dart
new file mode 100644
index 0000000..d65cc02
--- /dev/null
+++ b/pkg/dynamic_modules/test/data/invoke_checked/shared/shared.dart

@@ -0,0 +1,12 @@
+// Copyright (c) 2025, 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.
+
+abstract class Base {
+  Tester foo(Tester t);
+}
+
+class Tester {
+  final int val;
+  Tester(this.val);
+}