IDL bindings: Avoid extended attributes leaking onto merged interface.

third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py

Index: third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py
diff --git a/third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py b/third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py
index 2fa6409d7420b52f6b84d695c97d1e0ce0b79370..f58bee3bda4bdd72f73f679f2010fd1330dc05e1 100644
--- a/third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py
+++ b/third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py
@@ -253,17 +253,26 @@ def transfer_extended_attributes(dependency_interface, dependency_interface_base
     interface post-merging).
 
     The data storing consists of:
-    * applying certain extended attributes from the dependency interface
-      to its members
+    * moving certain extended attributes from the dependency interface
+      to its members (deleting the extended attribute from the interface)
     * storing the C++ class of the implementation in an internal
       extended attribute of each member, [PartialInterfaceImplementedAs]
 
     No return: modifies dependency_interface in place.
     """
-    merged_extended_attributes = dict(
-        (key, value)
-        for key, value in dependency_interface.extended_attributes.iteritems()
-        if key in DEPENDENCY_EXTENDED_ATTRIBUTES)
+    merged_extended_attributes = {}
+    for key in DEPENDENCY_EXTENDED_ATTRIBUTES:
+        try:
+            value = dependency_interface.extended_attributes[key]

[bashi, 2016/04/15 05:50:54]

value = dependency_interface.extended_attributes.get(key)
if not value:
  continue

[Matt Giuca, 2016/04/15 06:21:43]

Done. (Though I think the exception checking style would be considered more
Pythonic than get-and-test; I don't feel strongly about it in this case.)

+        except KeyError:
+            continue
+
+        merged_extended_attributes[key] = value
+        # Remove the merged attributes from the original dependency interface.
+        # This ensures that if other dependency interfaces are merged onto this
+        # one, its extended_attributes do not leak through
+        # (https://crbug.com/603782).
+        del dependency_interface.extended_attributes[key]
 
     # A partial interface's members are implemented as static member functions
     # in a separate C++ class. This class name is stored in
@@ -293,6 +302,10 @@ def transfer_extended_attributes(dependency_interface, dependency_interface_base
         merged_extended_attributes['PartialInterfaceImplementedAs'] = (
             dependency_interface.extended_attributes.get(
                 'ImplementedAs', dependency_interface_basename))
+        try:

[bashi, 2016/04/15 05:50:54]

if 'ImplementedAs' in dependency_interface.extended_attributes:
  del dependency_interface.extended_attributes['ImplementedAs']

[Matt Giuca, 2016/04/15 06:21:43]

That way involves looking up the value in the dictionary twice. Found a much
simpler way which is to just change the 'get' into a 'pop'. If it isn't in the
dict, it just returns the default and doesn't throw any error.

+            del dependency_interface.extended_attributes['ImplementedAs']
+        except KeyError:
+            pass
 
     def update_attributes(attributes, extras):
         for key, value in extras.items():