Bug 929512. Fix null default values for non-nullable unions containing a nullable type. r=dzbarsky, r=smaug pending

dom/bindings/Codegen.py

@@ -3061,14 +3061,21 @@ for (uint32_t i = 0; i < length; ++i) {
             typeName = "Nullable<" + typeName + " >"
 
         def handleNull(templateBody, setToNullVar, extraConditionForNull=""):
-            null = CGGeneric("if (%s${val}.isNullOrUndefined()) {\n"
-                             "  %s.SetNull();\n"
-                             "}" % (extraConditionForNull, setToNullVar))
-            templateBody = CGWrapper(CGIndenter(templateBody), pre="{\n", post="\n}")
-            return CGList([null, templateBody], " else ")
+            nullTest = "%s${val}.isNullOrUndefined()" % extraConditionForNull
+            return CGIfElseWrapper(nullTest,
+                                   CGGeneric("%s.SetNull();" % setToNullVar),
+                                   templateBody)
 
         if type.hasNullableType:
-            templateBody = handleNull(templateBody, unionArgumentObj)
+            assert not nullable
+            # Make sure to handle a null default value here
+            if defaultValue and isinstance(defaultValue, IDLNullValue):
+                assert defaultValue.type == type
+                extraConditionForNull = "!(${haveValue}) || "
+            else:
+                extraConditionForNull = ""
+            templateBody = handleNull(templateBody, unionArgumentObj,
+                                      extraConditionForNull=extraConditionForNull)
 
         declType = CGGeneric(typeName)
         holderType = CGGeneric(argumentTypeName) if not isMember else None
@@ -3124,6 +3131,22 @@ for (uint32_t i = 0; i < length; ++i) {
                 extraConditionForNull = ""
             templateBody = handleNull(templateBody, declLoc,
                                       extraConditionForNull=extraConditionForNull)
+        elif (not type.hasNullableType and defaultValue and
+              isinstance(defaultValue, IDLNullValue)):
+            assert type.hasDictionaryType
+            assert defaultValue.type.isDictionary()
+            if not isMember and typeNeedsRooting(defaultValue.type):
+                ctorArgs = "cx"
+            else:
+                ctorArgs = ""
+            initDictionaryWithNull = CGIfWrapper(
+                CGGeneric("return false;"),
+                ('!%s.SetAs%s(%s).Init(cx, JS::NullHandleValue, "Member of %s")'
+                 % (declLoc, getUnionMemberName(defaultValue.type),
+                    ctorArgs, type)))
+            templateBody = CGIfElseWrapper("!(${haveValue})",
+                                           initDictionaryWithNull,
+                                           templateBody)
 
         templateBody = CGList([constructDecl, templateBody], "\n")
 

dom/bindings/parser/WebIDL.py

@@ -2440,7 +2440,10 @@ class IDLValue(IDLObject):
         # We first check for unions to ensure that even if the union is nullable
         # we end up with the right flat member type, not the union's type.
         if type.isUnion():
-            for subtype in type.unroll().memberTypes:
+            # We use the flat member types here, because if we have a nullable
+            # member type, or a nested union, we want the type the value
+            # actually coerces to, not the nullable or nested union type.
+            for subtype in type.unroll().flatMemberTypes:
                 try:
                     coercedValue = self.coerceToType(subtype, location)
                     # Create a new IDLValue to make sure that we have the
@@ -2513,6 +2516,13 @@ class IDLNullValue(IDLObject):
                               [location])
 
         nullValue = IDLNullValue(self.location)
+        if type.isUnion() and not type.nullable() and type.hasDictionaryType:
+            # We're actually a default value for the union's dictionary member.
+            # Use its type.
+            for t in type.flatMemberTypes:
+                if t.isDictionary():
+                    nullValue.type = t
+                    return nullValue
         nullValue.type = type
         return nullValue
 

dom/bindings/test/TestBindingHeader.h

@@ -513,6 +513,9 @@ public:
   void PassUnion9(JSContext*, const ObjectOrStringOrLongOrBoolean& arg);
   void PassUnion10(const EventInitOrLong& arg);
   void PassUnion11(JSContext*, const CustomEventInitOrLong& arg);
+  void PassUnion12(const EventInitOrLong& arg);
+  void PassUnion13(JSContext*, const ObjectOrLongOrNull& arg);
+  void PassUnion14(JSContext*, const ObjectOrLongOrNull& arg);
 #endif
   void PassNullableUnion(JSContext*, const Nullable<ObjectOrLong>&);
   void PassOptionalUnion(JSContext*, const Optional<ObjectOrLong>&);

dom/bindings/test/TestCodeGen.webidl

@@ -453,6 +453,9 @@ interface TestInterface {
   void passUnion9((object or DOMString or long or boolean) arg);
   void passUnion10(optional (EventInit or long) arg);
   void passUnion11(optional (CustomEventInit or long) arg);
+  void passUnion12(optional (EventInit or long) arg = 5);
+  void passUnion13(optional (object or long?) arg = null);
+  void passUnion14(optional (object or long?) arg = 5);
 #endif
   void passUnionWithNullable((object? or long) arg);
   void passNullableUnion((object or long)? arg);

dom/bindings/test/TestExampleGen.webidl

@@ -349,6 +349,9 @@ interface TestExampleInterface {
   void passUnion9((object or DOMString or long or boolean) arg);
   void passUnion10(optional (EventInit or long) arg);
   void passUnion11(optional (CustomEventInit or long) arg);
+  void passUnion12(optional (EventInit or long) arg = 5);
+  void passUnion13(optional (object or long?) arg = null);
+  void passUnion14(optional (object or long?) arg = 5);
 #endif
   void passUnionWithNullable((object? or long) arg);
   void passNullableUnion((object or long)? arg);

dom/bindings/test/TestJSImplGen.webidl

@@ -371,6 +371,9 @@ interface TestJSImplInterface {
   void passUnion9((object or DOMString or long or boolean) arg);
   void passUnion10(optional (EventInit or long) arg);
   void passUnion11(optional (CustomEventInit or long) arg);
+  void passUnion12(optional (EventInit or long) arg = 5);
+  void passUnion13(optional (object or long?) arg = null);
+  void passUnion14(optional (object or long?) arg = 5);
 #endif
   void passUnionWithNullable((object? or long) arg);
   // FIXME: Bug 863948 Nullable unions not supported yet