Sort the Dart vm flags before printing them out with the --print-flags option.

runtime/vm/flags.cc

Index: runtime/vm/flags.cc
diff --git a/runtime/vm/flags.cc b/runtime/vm/flags.cc
index d02a0a246879bdb8bfa7aed442d8ca17762f4576..7d07db79f2b7d030af92e24ee931cdcbb219a01d 100644
--- a/runtime/vm/flags.cc
+++ b/runtime/vm/flags.cc
@@ -301,15 +301,41 @@ bool Flags::ProcessCommandLineFlags(int number_of_vm_flags,
     }
   }
   if (FLAG_print_flags) {
+    PrintFlags();
+  }
+  return true;
+}
+
+
+int Flags::CompareFlagNames(const void* left, const void* right) {
+  const Flag* left_flag = *reinterpret_cast<const Flag* const *>(left);
+  const Flag* right_flag = *reinterpret_cast<const Flag* const *>(right);
+  return strcmp(left_flag->name_, right_flag->name_);
+}
+
+
+void Flags::PrintFlags() {
     OS::Print("Flag settings:\n");
     Flag* flag = Flags::flags_;
+    int num_flags = 0;
     while (flag != NULL) {
-      flag->Print();
+      num_flags++;

[Ivan Posva, 2012/08/20 23:50:35]

You could increment this as part of registration of flags and keep it around
with the rest of the flags. Although I am not sure of the usefulness of the
count beyond PrintFlags.

+      flag = flag->next_;
+    }
+    Flag** flag_array = new Flag*[num_flags];
+    flag = Flags::flags_;
+    int flag_index = 0;
+    while (flag != NULL) {

[Ivan Posva, 2012/08/20 23:50:35]

for (int i = 0; i <  num_flags; i++) {
  ASSERT(flag != NULL);
  flag_array[i] = flag;
  flag = flag->next_;
}
ASSERT(flag = NULL);

To be consistent with the other loop going over the flags array.
You could also put the flag = flag->next_ into the for-loop. I am not a big fan
of multiple things happening there, but in this case it almost makes sense.

[Bill Hesse, 2012/08/21 09:21:02]

Done.

+      flag_array[flag_index] = flag;
+      flag_index++;
       flag = flag->next_;
     }
-  }
 
-  return true;
-}
+    qsort(flag_array, num_flags, sizeof flag_array[0], CompareFlagNames);
 
+    for (int i = 0; i < num_flags; ++i) {
+      flag_array[i]->Print();
+    }
+    delete[] flag_array;
+  }
 }  // namespace dart