[VM/nnbd] Print nullability of types by default.

Only '?' is shown by default.
To print '*' and '%', use debugging flag --show-internal-names.
Fix expectations in tests.

Change-Id: Idc60fbfb4d477602eb0c713f4bdcc1e573a3328a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/135790
Commit-Queue: Régis Crelier <regis@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Liam Appelbe <liama@google.com>

Author: crelier

runtime/vm/dart_api_impl_test.cc

@@ -6086,7 +6086,7 @@ TEST_CASE(DartAPI_GetNullableType) {
   EXPECT_VALID(name);
   const char* name_cstr = "";
   EXPECT_VALID(Dart_StringToCString(name, &name_cstr));
-  EXPECT_STREQ("Class", name_cstr);
+  EXPECT_STREQ("Class?", name_cstr);
 
   name = Dart_GetField(type, NewString("name"));
   EXPECT_VALID(name);

runtime/vm/debugger.cc

@@ -1542,7 +1542,7 @@ RawTypeArguments* ActivationFrame::BuildParameters(
       mapping_offset -= size;
       for (intptr_t j = 0; j < size; ++j) {
         type_param = TypeParameter::RawCast(type_params.TypeAt(j));
-        name = type_param.Name();
+        name = type_param.name();
         // Write the names in backwards in terms of chain of functions.
         // But keep the order of names within the same function. so they
         // match up with the order of the types in 'type_arguments'.

runtime/vm/object.cc

@@ -73,9 +73,8 @@ DEFINE_FLAG(
     show_internal_names,
     false,
     "Show names of internal classes (e.g. \"OneByteString\") in error messages "
-    "instead of showing the corresponding interface names (e.g. \"String\")");
-// TODO(regis): Remove this temporary flag used to debug nullability.
-DEFINE_FLAG(bool, show_nullability, false, "Show nullability in type names");
+    "instead of showing the corresponding interface names (e.g. \"String\"). "
+    "Also show legacy nullability in type names.");
 DEFINE_FLAG(bool, use_lib_cache, false, "Use library name cache");
 DEFINE_FLAG(bool, use_exp_cache, false, "Use library exported name cache");
 
@@ -5664,7 +5663,11 @@ void TypeArguments::PrintSubvectorName(intptr_t from_index,
   for (intptr_t i = 0; i < len; i++) {
     if (from_index + i < Length()) {
       type = TypeAt(from_index + i);
-      type.PrintName(name_visibility, printer);
+      if (type.IsNull()) {
+        printer->AddString("null");  // Unfinalized vector.
+      } else {
+        type.PrintName(name_visibility, printer);
+      }
     } else {
       printer->AddString("dynamic");
     }
@@ -18084,17 +18087,26 @@ RawString* AbstractType::PrintURIs(URIs* uris) {
   return Symbols::FromConcatAll(thread, pieces);
 }
 
-static const char* NullabilitySuffix(Nullability value) {
+const char* AbstractType::NullabilitySuffix(
+    NameVisibility name_visibility) const {
+  if (IsDynamicType() || IsVoidType() || IsNullType()) {
+    // Hide nullable suffix.
+    return "";
+  }
   // Keep in sync with Nullability enum in runtime/vm/object.h.
-  switch (value) {
+  switch (nullability()) {
     case Nullability::kUndetermined:
-      return "%";
+      return (FLAG_show_internal_names || name_visibility == kInternalName)
+                 ? "%"
+                 : "";
     case Nullability::kNullable:
       return "?";
     case Nullability::kNonNullable:
       return "";
     case Nullability::kLegacy:
-      return "*";
+      return (FLAG_show_internal_names || name_visibility == kInternalName)
+                 ? "*"
+                 : "";
     default:
       UNREACHABLE();
   }
@@ -18121,9 +18133,7 @@ void AbstractType::PrintName(NameVisibility name_visibility,
   Zone* zone = thread->zone();
   if (IsTypeParameter()) {
     printer->AddString(String::Handle(zone, TypeParameter::Cast(*this).name()));
-    if (FLAG_show_nullability) {
-      printer->AddString(NullabilitySuffix(nullability()));
-    }
+    printer->AddString(NullabilitySuffix(name_visibility));
     return;
   }
   const TypeArguments& args = TypeArguments::Handle(zone, arguments());
@@ -18136,9 +18146,14 @@ void AbstractType::PrintName(NameVisibility name_visibility,
     const Function& signature_function =
         Function::Handle(zone, Type::Cast(*this).signature());
     if (!cls.IsTypedefClass()) {
-      signature_function.PrintSignature(kUserVisibleName, printer);
-      if (FLAG_show_nullability) {
-        printer->AddString(NullabilitySuffix(nullability()));
+      const char* suffix = NullabilitySuffix(name_visibility);
+      if (suffix[0] != '\0') {
+        printer->AddString("(");
+      }
+      signature_function.PrintSignature(name_visibility, printer);
+      if (suffix[0] != '\0') {
+        printer->AddString(")");
+        printer->AddString(suffix);
       }
       return;
     }
@@ -18148,9 +18163,7 @@ void AbstractType::PrintName(NameVisibility name_visibility,
     if (!IsFinalized() || IsBeingFinalized()) {
       // TODO(regis): Check if this is dead code.
       printer->AddString(class_name);
-      if (FLAG_show_nullability) {
-        printer->AddString(NullabilitySuffix(nullability()));
-      }
+      printer->AddString(NullabilitySuffix(name_visibility));
       return;
     }
     // Print the name of a typedef as a regular, possibly parameterized, class.
@@ -18188,9 +18201,7 @@ void AbstractType::PrintName(NameVisibility name_visibility,
     args.PrintSubvectorName(first_type_param_index, num_type_params,
                             name_visibility, printer);
   }
-  if (FLAG_show_nullability) {
-    printer->AddString(NullabilitySuffix(nullability()));
-  }
+  printer->AddString(NullabilitySuffix(name_visibility));
   // The name is only used for type checking and debugging purposes.
   // Unless profiling data shows otherwise, it is not worth caching the name in
   // the type.
@@ -19251,32 +19262,42 @@ const char* Type::ToCString() const {
     return "Type: null";
   }
   Zone* zone = Thread::Current()->zone();
+  ZoneTextBuffer args(zone);
   const TypeArguments& type_args = TypeArguments::Handle(zone, arguments());
-  const char* args_cstr = type_args.IsNull() ? "null" : type_args.ToCString();
+  const char* args_cstr = "";
+  if (!type_args.IsNull()) {
+    type_args.PrintSubvectorName(0, type_args.Length(), kInternalName, &args);
+    args_cstr = args.buffer();
+  }
   const Class& cls = Class::Handle(zone, type_class());
   const char* class_name;
   const String& name = String::Handle(zone, cls.Name());
   class_name = name.IsNull() ? "<null>" : name.ToCString();
+  const char* suffix = NullabilitySuffix(kInternalName);
   if (IsFunctionType()) {
     const Function& sig_fun = Function::Handle(zone, signature());
     ZoneTextBuffer sig(zone);
+    if (suffix[0] != '\0') {
+      sig.AddString("(");
+    }
     sig_fun.PrintSignature(kInternalName, &sig);
+    if (suffix[0] != '\0') {
+      sig.AddString(")");
+      sig.AddString(suffix);
+    }
     if (cls.IsClosureClass()) {
       ASSERT(type_args.IsNull());
       return OS::SCreate(zone, "Function Type: %s", sig.buffer());
     }
-    return OS::SCreate(zone, "Function Type: %s (class: %s, args: %s)",
-                       sig.buffer(), class_name, args_cstr);
+    return OS::SCreate(zone, "Function Type: %s (%s%s%s)", sig.buffer(),
+                       class_name, args_cstr, suffix);
   }
-  if (type_args.IsNull()) {
-    return OS::SCreate(zone, "Type: class '%s'", class_name);
-  } else if (IsFinalized() && IsRecursive()) {
+  if (IsFinalized() && IsRecursive()) {
     const intptr_t hash = Hash();
-    return OS::SCreate(zone, "Type: (H%" Px ") class '%s', args:[%s]", hash,
-                       class_name, args_cstr);
+    return OS::SCreate(zone, "Type: (H%" Px ") %s%s%s", hash, class_name,
+                       args_cstr, suffix);
   } else {
-    return OS::SCreate(zone, "Type: class '%s', args:[%s]", class_name,
-                       args_cstr);
+    return OS::SCreate(zone, "Type: %s%s%s", class_name, args_cstr, suffix);
   }
 }
 
@@ -19713,7 +19734,8 @@ const char* TypeParameter::ToCString() const {
   Thread* thread = Thread::Current();
   ZoneTextBuffer printer(thread->zone());
   printer.Printf("TypeParameter: name ");
-  printer.AddString(String::Handle(Name()));
+  printer.AddString(String::Handle(name()));
+  printer.AddString(NullabilitySuffix(kInternalName));
   printer.Printf("; index: %" Pd ";", index());
   if (IsFunctionTypeParameter()) {
     const Function& function = Function::Handle(parameterized_function());

runtime/vm/object.h

@@ -7051,6 +7051,13 @@ class TypeArguments : public Instance {
   // Names of internal classes are mapped to their public interfaces.
   RawString* UserVisibleName() const;
 
+  // Print the internal or public name of a subvector of this type argument
+  // vector, e.g. "<T, dynamic, List<T>, int>".
+  void PrintSubvectorName(intptr_t from_index,
+                          intptr_t len,
+                          NameVisibility name_visibility,
+                          ZoneTextBuffer* printer) const;
+
   // Check if the subvector of length 'len' starting at 'from_index' of this
   // type argument vector consists solely of DynamicType.
   bool IsRaw(intptr_t from_index, intptr_t len) const {
@@ -7227,13 +7234,6 @@ class TypeArguments : public Instance {
                       intptr_t from_index,
                       intptr_t len) const;
 
-  // Return the internal or public name of a subvector of this type argument
-  // vector, e.g. "<T, dynamic, List<T>, int>".
-  void PrintSubvectorName(intptr_t from_index,
-                          intptr_t len,
-                          NameVisibility name_visibility,
-                          ZoneTextBuffer* printer) const;
-
   RawArray* instantiations() const;
   void set_instantiations(const Array& value) const;
   RawAbstractType* const* TypeAddr(intptr_t index) const;
@@ -7364,6 +7364,10 @@ class AbstractType : public Instance {
   // Return a formatted string of the uris.
   static RawString* PrintURIs(URIs* uris);
 
+  // Returns a C-String (possibly "") representing the nullability of this type.
+  // Legacy and undetermined suffixes are only displayed with kInternalName.
+  virtual const char* NullabilitySuffix(NameVisibility name_visibility) const;
+
   // The name of this type, including the names of its type arguments, if any.
   virtual RawString* Name() const;
 

tests/language_2/type_object/runtime_type_function_test.dart

@@ -68,7 +68,7 @@ main() {
 
   check(fn('dynamic', ''), main); //        Top-level tear-off.
   check(fn('void', ''), Xyzzy.foo); //      Class static member tear-off.
-  check(fn('void', 'Object'), [].add); //  Instance tear-off.
+  check(fn('void', 'Object'), new MyList().add); //  Instance tear-off.
   check(fn('int', ''), () => 1); //       closure.
 
   var s = new Xyzzy().runtimeType.toString();
@@ -83,8 +83,8 @@ main() {
   check(fn('String', 'String', {'a': 'String', 'b': 'dynamic'}), Xyzzy.nam);
 
   // Instance method tear-offs.
-  check(fn('void', 'Object'), <String>[].add);
-  check(fn('void', 'Object'), <int>[].add);
+  check(fn('void', 'Object'), new MyList<String>().add);
+  check(fn('void', 'Object'), new MyList<int>().add);
   check(fn('void', 'int'), new Xyzzy().intAdd);
 
   check(fn('String', 'Object'), new G<String, int>().foo);
@@ -122,6 +122,12 @@ class Xyzzy {
   void intAdd(int x) {}
 }
 
+// Using 'MyList' instead of core lib 'List' keeps covariant parameter type of
+// tear-offs 'Object' (legacy lib) instead of 'Object?' (opted-in lib).
+class MyList<E> {
+  void add(E value) {}
+}
+
 class G<U, V> {
   U foo(V x) => null;
   U moo(V f(U x)) => null;