[vm, lib] Teach mirrors about the Never type and member signatures.

Bug: https://github.com/dart-lang/sdk/issues/12478
Bug: https://github.com/dart-lang/sdk/issues/40497
Bug: https://github.com/dart-lang/sdk/issues/40510
Change-Id: I841d7e239b8235555ec26fbcb74ca41b5de60f58
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/134806
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>

CHANGELOG.md

@@ -22,6 +22,10 @@ used (see Issue [39627][]).
   options. Previously setting a socket options would be ignored and getting a
   socket option would return `null`.
 
+#### `dart:mirrors`
+
+* Added `MirrorSystem.neverType`.
+
 ### Dart VM
 
 ### Tools

runtime/lib/mirrors.cc

@@ -272,7 +272,7 @@ static RawInstance* CreateMethodMirror(const Function& func,
                  << Mirrors::kFactoryCtor);
   kind_flags |=
       (static_cast<intptr_t>(func.is_external()) << Mirrors::kExternal);
-  bool is_synthetic = func.is_no_such_method_forwarder();
+  bool is_synthetic = func.is_synthetic();
   kind_flags |= (static_cast<intptr_t>(is_synthetic) << Mirrors::kSynthetic);
   kind_flags |= (static_cast<intptr_t>(func.is_extension_member())
                  << Mirrors::kExtensionMember);
@@ -311,7 +311,9 @@ static RawInstance* CreateClassMirror(const Class& cls,
     ASSERT(ref_type.IsCanonical());
     return CreateClassMirror(cls, ref_type, is_declaration, owner_mirror);
   }
-  ASSERT(!cls.IsDynamicClass() && !cls.IsVoidClass());
+  ASSERT(!cls.IsDynamicClass());
+  ASSERT(!cls.IsVoidClass());
+  ASSERT(!cls.IsNeverClass());
   ASSERT(!type.IsNull());
   ASSERT(type.IsFinalized());
 
@@ -625,6 +627,10 @@ static RawInstance* CreateTypeMirror(const AbstractType& type) {
       Array& args = Array::Handle(Array::New(1));
       args.SetAt(0, Symbols::Dynamic());
       return CreateMirror(Symbols::_SpecialTypeMirror(), args);
+    } else if (cls.IsNeverClass()) {
+      Array& args = Array::Handle(Array::New(1));
+      args.SetAt(0, Symbols::Never());
+      return CreateMirror(Symbols::_SpecialTypeMirror(), args);
     }
     // TODO(regis): Until mirrors reflect nullability, force kLegacy, except for
     // Null type, which should remain nullable.
@@ -830,7 +836,8 @@ DEFINE_NATIVE_ENTRY(Mirrors_makeLocalClassMirror, 0, 1) {
   ASSERT(type.HasTypeClass());
   const Class& cls = Class::Handle(type.type_class());
   ASSERT(!cls.IsNull());
-  if (cls.IsDynamicClass() || cls.IsVoidClass() || cls.IsTypedefClass()) {
+  if (cls.IsDynamicClass() || cls.IsVoidClass() || cls.IsNeverClass() ||
+      cls.IsTypedefClass()) {
     Exceptions::ThrowArgumentError(type);
     UNREACHABLE();
   }
@@ -1172,8 +1179,7 @@ DEFINE_NATIVE_ENTRY(LibraryMirror_members, 0, 2) {
     entry = entries.GetNext();
     if (entry.IsClass()) {
       const Class& klass = Class::Cast(entry);
-      // We filter out dynamic.
-      // TODO(12478): Should not need to filter out dynamic.
+      ASSERT(!klass.IsVoidClass() && !klass.IsNeverClass());
       if (!klass.IsDynamicClass()) {
         error = klass.EnsureIsFinalized(thread);
         if (!error.IsNull()) {
@@ -1700,6 +1706,8 @@ DEFINE_NATIVE_ENTRY(DeclarationMirror_location, 0, 1) {
     ASSERT(!script.IsNull());
     const String& uri = String::Handle(zone, script.url());
     return CreateSourceLocation(uri, 1, 1);
+  } else {
+    FATAL1("Unexpected declaration type: %s", decl.ToCString());
   }
 
   ASSERT(!script.IsNull());

runtime/vm/compiler/frontend/bytecode_reader.cc

@@ -2261,8 +2261,7 @@ void BytecodeReaderHelper::ReadFunctionDeclarations(const Class& cls) {
     function.set_is_declared_in_bytecode(true);
     function.set_has_pragma(has_pragma);
     function.set_end_token_pos(end_position);
-    function.set_is_no_such_method_forwarder(
-        (flags & kIsNoSuchMethodForwarderFlag) != 0);
+    function.set_is_synthetic((flags & kIsNoSuchMethodForwarderFlag) != 0);
     function.set_is_reflectable((flags & kIsReflectableFlag) != 0);
     function.set_is_debuggable((flags & kIsDebuggableFlag) != 0);
     function.set_is_extension_member(is_extension_member);

runtime/vm/compiler/frontend/kernel_translation_helper.h

@@ -545,6 +545,7 @@ class ProcedureHelper {
     kRedirectingFactoryConstructor = 1 << 6,
     kNoSuchMethodForwarder = 1 << 7,
     kExtensionMember = 1 << 8,
+    kMemberSignature = 1 << 9,
   };
 
   explicit ProcedureHelper(KernelReaderHelper* helper)
@@ -571,6 +572,7 @@ class ProcedureHelper {
     return (flags_ & kNoSuchMethodForwarder) != 0;
   }
   bool IsExtensionMember() const { return (flags_ & kExtensionMember) != 0; }
+  bool IsMemberSignature() const { return (flags_ & kMemberSignature) != 0; }
 
   NameIndex canonical_name_;
   TokenPosition start_position_;

runtime/vm/kernel_loader.cc

@@ -1917,8 +1917,8 @@ void KernelLoader::LoadProcedure(const Library& library,
                        script_class, procedure_helper.start_position_));
   function.set_has_pragma(has_pragma_annotation);
   function.set_end_token_pos(procedure_helper.end_position_);
-  function.set_is_no_such_method_forwarder(
-      procedure_helper.IsNoSuchMethodForwarder());
+  function.set_is_synthetic(procedure_helper.IsNoSuchMethodForwarder() ||
+                            procedure_helper.IsMemberSignature());
   if (register_function) {
     functions_.Add(&function);
   } else {

runtime/vm/object.cc

@@ -7892,7 +7892,7 @@ RawFunction* Function::New(const String& name,
   result.set_is_generated_body(false);
   result.set_has_pragma(false);
   result.set_is_polymorphic_target(false);
-  result.set_is_no_such_method_forwarder(false);
+  result.set_is_synthetic(false);
   NOT_IN_PRECOMPILED(result.set_state_bits(0));
   result.set_owner(owner);
   NOT_IN_PRECOMPILED(result.set_token_pos(token_pos));

runtime/vm/object.h

@@ -3395,7 +3395,7 @@ class Function : public Object {
   V(GeneratedBody, is_generated_body)                                          \
   V(PolymorphicTarget, is_polymorphic_target)                                  \
   V(HasPragma, has_pragma)                                                     \
-  V(IsNoSuchMethodForwarder, is_no_such_method_forwarder)                      \
+  V(IsSynthetic, is_synthetic)                                                 \
   V(IsExtensionMember, is_extension_member)
 
 #define DEFINE_ACCESSORS(name, accessor_name)                                  \

runtime/vm/source_report.cc

@@ -105,7 +105,7 @@ bool SourceReport::ShouldSkipFunction(const Function& func) {
       return true;
   }
   if (func.is_abstract() || func.IsImplicitConstructor() ||
-      func.IsRedirectingFactory() || func.is_no_such_method_forwarder()) {
+      func.IsRedirectingFactory() || func.is_synthetic()) {
     return true;
   }
   // Note that context_scope() remains null for closures declared in bytecode,

sdk/lib/_internal/vm/lib/mirrors_impl.dart

@@ -84,6 +84,7 @@ bool _subtypeTest(Type a, Type b) native 'TypeMirror_subtypeTest';
 class _MirrorSystem extends MirrorSystem {
   final TypeMirror dynamicType = new _SpecialTypeMirror._('dynamic');
   final TypeMirror voidType = new _SpecialTypeMirror._('void');
+  final TypeMirror neverType = new _SpecialTypeMirror._('Never');
 
   var _libraries;
   Map<Uri, LibraryMirror> get libraries {
@@ -685,13 +686,15 @@ class _ClassMirror extends _ObjectMirror implements ClassMirror, _TypeMirror {
 
   bool isSubtypeOf(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     return _subtypeTest(_reflectedType, (other as _TypeMirror)._reflectedType);
   }
 
   bool isAssignableTo(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     final otherReflectedType = (other as _TypeMirror)._reflectedType;
     return _subtypeTest(_reflectedType, otherReflectedType) ||
         _subtypeTest(otherReflectedType, _reflectedType);
@@ -893,13 +896,15 @@ class _TypeVariableMirror extends _DeclarationMirror
 
   bool isSubtypeOf(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     return _subtypeTest(_reflectedType, (other as _TypeMirror)._reflectedType);
   }
 
   bool isAssignableTo(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     final otherReflectedType = (other as _TypeMirror)._reflectedType;
     return _subtypeTest(_reflectedType, otherReflectedType) ||
         _subtypeTest(otherReflectedType, _reflectedType);
@@ -995,13 +1000,15 @@ class _TypedefMirror extends _DeclarationMirror
 
   bool isSubtypeOf(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     return _subtypeTest(_reflectedType, (other as _TypeMirror)._reflectedType);
   }
 
   bool isAssignableTo(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     final otherReflectedType = (other as _TypeMirror)._reflectedType;
     return _subtypeTest(_reflectedType, otherReflectedType) ||
         _subtypeTest(otherReflectedType, _reflectedType);

sdk/lib/mirrors/mirrors.dart

@@ -60,6 +60,7 @@
 library dart.mirrors;
 
 import 'dart:async' show Future;
+import "dart:_internal" show Since;
 
 /**
  * A [MirrorSystem] is the main interface used to reflect on a set of
@@ -110,6 +111,12 @@ abstract class MirrorSystem {
    */
   TypeMirror get voidType;
 
+  /**
+   * A mirror on the [:Never:] type.
+   */
+  @Since("2.8")
+  TypeMirror get neverType;
+
   /**
    * Returns the name of [symbol].
    *

sdk_nnbd/lib/_internal/vm/lib/mirrors_impl.dart

@@ -82,6 +82,7 @@ bool _subtypeTest(Type a, Type b) native 'TypeMirror_subtypeTest';
 class _MirrorSystem extends MirrorSystem {
   final TypeMirror dynamicType = new _SpecialTypeMirror._('dynamic');
   final TypeMirror voidType = new _SpecialTypeMirror._('void');
+  final TypeMirror neverType = new _SpecialTypeMirror._('Never');
 
   var _libraries;
   Map<Uri, LibraryMirror> get libraries {
@@ -682,13 +683,15 @@ class _ClassMirror extends _ObjectMirror implements ClassMirror, _TypeMirror {
 
   bool isSubtypeOf(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     return _subtypeTest(_reflectedType, (other as _TypeMirror)._reflectedType);
   }
 
   bool isAssignableTo(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     final otherReflectedType = (other as _TypeMirror)._reflectedType;
     return _subtypeTest(_reflectedType, otherReflectedType) ||
         _subtypeTest(otherReflectedType, _reflectedType);
@@ -890,13 +893,15 @@ class _TypeVariableMirror extends _DeclarationMirror
 
   bool isSubtypeOf(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     return _subtypeTest(_reflectedType, (other as _TypeMirror)._reflectedType);
   }
 
   bool isAssignableTo(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     final otherReflectedType = (other as _TypeMirror)._reflectedType;
     return _subtypeTest(_reflectedType, otherReflectedType) ||
         _subtypeTest(otherReflectedType, _reflectedType);
@@ -992,13 +997,15 @@ class _TypedefMirror extends _DeclarationMirror
 
   bool isSubtypeOf(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     return _subtypeTest(_reflectedType, (other as _TypeMirror)._reflectedType);
   }
 
   bool isAssignableTo(TypeMirror other) {
     if (other == currentMirrorSystem().dynamicType) return true;
-    if (other == currentMirrorSystem().voidType) return false;
+    if (other == currentMirrorSystem().voidType) return true;
+    if (other == currentMirrorSystem().neverType) return false;
     final otherReflectedType = (other as _TypeMirror)._reflectedType;
     return _subtypeTest(_reflectedType, otherReflectedType) ||
         _subtypeTest(otherReflectedType, _reflectedType);

sdk_nnbd/lib/mirrors/mirrors.dart

@@ -58,6 +58,7 @@
 library dart.mirrors;
 
 import 'dart:async' show Future;
+import "dart:_internal" show Since;
 
 /**
  * A [MirrorSystem] is the main interface used to reflect on a set of
@@ -108,6 +109,12 @@ abstract class MirrorSystem {
    */
   TypeMirror get voidType;
 
+  /**
+   * A mirror on the [:Never:] type.
+   */
+  @Since("2.8")
+  TypeMirror get neverType;
+
   /**
    * Returns the name of [symbol].
    *