Fix #28740 demangle constructors in stack traces (A.A becomes new A) REDO

runtime/vm/object.cc

 // Copyright (c) 2012, 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.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/become.h"
@@ skipping 7141 matching lines @@
     ASSERT(!fun.IsNull());
     if (!fun.IsAsyncGenerator() && !fun.IsAsyncFunction() &&
         !fun.IsSyncGenerator()) {
       // Parent function is not the generator of an asynchronous body closure,
       // start at |this|.
       fun = raw();
     }
   }
   // A function's scrubbed name and its user visible name are identical.
   String& result = String::Handle(fun.UserVisibleName());
-  if (IsClosureFunction()) {
-    while (fun.IsLocalFunction() && !fun.IsImplicitClosureFunction()) {
+  if (IsClosureFunction() && fun.IsLocalFunction() &&
+      !fun.IsImplicitClosureFunction()) {
+    fun = fun.parent_function();
+    if (fun.IsAsyncClosure() || fun.IsSyncGenClosure() ||
+        fun.IsAsyncGenClosure()) {
+      // Skip the closure and use the real function name found in
+      // the parent.
       fun = fun.parent_function();
-      if (fun.IsAsyncClosure() || fun.IsSyncGenClosure() ||
-          fun.IsAsyncGenClosure()) {
-        // Skip the closure and use the real function name found in
-        // the parent.
-        fun = fun.parent_function();
-      }
-      result = String::Concat(Symbols::Dot(), result, Heap::kOld);
-      result = String::Concat(String::Handle(fun.UserVisibleName()), result,
-                              Heap::kOld);
     }
+    result = String::Concat(Symbols::Dot(), result, Heap::kOld);
+    result = String::Concat(String::Handle(fun.QualifiedName(name_visibility)),

[siva, 2017/04/20 00:14:59]

Is it necessary to convert the iteration into a recursive call to QualifiedName
which again goes through all the checks and Handle creation etc.

+                            result, Heap::kOld);
+
+    return result.raw();
   }
   const Class& cls = Class::Handle(Owner());
   if (!cls.IsTopLevel()) {
-    result = String::Concat(Symbols::Dot(), result, Heap::kOld);
-    const String& cls_name = String::Handle(name_visibility == kScrubbedName
-                                                ? cls.ScrubbedName()
-                                                : cls.UserVisibleName());
-    result = String::Concat(cls_name, result, Heap::kOld);
+    if (kind() == RawFunction::kConstructor) {

[siva, 2017/04/20 00:14:59]

I tried your cl and changed this line to
if (fun.kind() == RawFunction::kConstructor) {

and the failing test works.

+      result = String::Concat(Symbols::ConstructorStacktracePrefix(), result,
+                              Heap::kOld);
+    } else {
+      result = String::Concat(Symbols::Dot(), result, Heap::kOld);
+      const String& cls_name = String::Handle(name_visibility == kScrubbedName
+                                                  ? cls.ScrubbedName()
+                                                  : cls.UserVisibleName());
+      result = String::Concat(cls_name, result, Heap::kOld);
+    }
   }
   return result.raw();
 }
 
 
 RawString* Function::GetSource() const {
   if (IsImplicitConstructor() || IsSignatureFunction()) {
     // We may need to handle more cases when the restrictions on mixins are
     // relaxed. In particular we might start associating some source with the
     // forwarding constructors when it becomes possible to specify a particular
@@ skipping 15993 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart