IDL: Clean up argument conversion error handling

Source/bindings/scripts/v8_types.py

Index: Source/bindings/scripts/v8_types.py
diff --git a/Source/bindings/scripts/v8_types.py b/Source/bindings/scripts/v8_types.py
index da381cf4a365fb5c7b03137c6007f34941f5d33e..a63a39326c34290d437e66f575a8979d8e177ec1 100644
--- a/Source/bindings/scripts/v8_types.py
+++ b/Source/bindings/scripts/v8_types.py
@@ -565,50 +565,60 @@ def v8_value_to_local_cpp_value(idl_type, extended_attributes, v8_value, variabl
 
     # FIXME: Support union type.
     if idl_type.is_union_type:
-        return ''
+        return '/* no V8 -> C++ conversion for IDL union type: %s */' % idl_type.name

[haraken, 2014/09/26 09:49:29]

Can we raise an exception instead?

 
     this_cpp_type = idl_type.cpp_type_args(extended_attributes=extended_attributes, raw_type=True)
-
     idl_type = idl_type.preprocessed_type
+
+    if idl_type.base_type in ('void', 'object', 'EventHandler', 'EventListener'):

[Jens Widell, 2014/09/26 09:45:57]

These are IDL types where we don't have meaningful conversion support, and
previously returned some bogus code, and that doesn't (currently) matter because
whatever we return from here won't be used.

All methods with |object| arguments are [Custom], |EventHandler|/|EventListener|
have special handling in the templates, and |void| obviously doesn't really make
sense to convert.

Returning this C++ comment is just meant to aid debugging if this return value
is ever actually used (which will be a compilation error too, since this is not
a valid C++ expression.)

+        return '/* no V8 -> C++ conversion for IDL type: %s */' % idl_type.name
+
     cpp_value = v8_value_to_cpp_value(idl_type, extended_attributes, v8_value, index, isolate)
-    args = [variable_name, cpp_value]
-    if idl_type.base_type == 'DOMString':
-        if return_promise:
+    if idl_type.is_string_type or idl_type.v8_conversion_needs_exception_state:
+        # Types that need error handling and use one of a group of (C++) macros
+        # to take care of this.
+
+        args = [variable_name, cpp_value]
+
+        if idl_type.v8_conversion_needs_exception_state:
+            macro = 'TONATIVE_DEFAULT_EXCEPTIONSTATE' if used_in_private_script else 'TONATIVE_VOID_EXCEPTIONSTATE'
+        elif return_promise:
             macro = 'TOSTRING_VOID_EXCEPTIONSTATE'
         else:
             macro = 'TOSTRING_DEFAULT' if used_in_private_script else 'TOSTRING_VOID'
-    elif idl_type.v8_conversion_needs_exception_state:
-        macro = 'TONATIVE_DEFAULT_EXCEPTIONSTATE' if used_in_private_script else 'TONATIVE_VOID_EXCEPTIONSTATE'
-    elif idl_type.v8_conversion_is_trivial:
-        assignment = '%s = %s' % (variable_name, cpp_value)
-        if declare_variable:
-            return '%s %s' % (this_cpp_type, assignment)
-        return assignment
-    else:
-        macro = 'TONATIVE_DEFAULT' if used_in_private_script else 'TONATIVE_VOID'
 
-    if macro.endswith('_EXCEPTIONSTATE'):
-        args.append('exceptionState')
+        if macro.endswith('_EXCEPTIONSTATE'):
+            args.append('exceptionState')
 
-    if used_in_private_script:
-        args.append('false')
+        if used_in_private_script:
+            args.append('false')
 
-    # Macros come in several variants, to minimize expensive creation of
-    # v8::TryCatch.
-    suffix = ''
+        suffix = ''
 
-    if return_promise:
-        suffix += '_PROMISE'
-        args.append('info')
-        if macro.endswith('_EXCEPTIONSTATE'):
-            args.append('ScriptState::current(%s)' % isolate)
+        if return_promise:
+            suffix += '_PROMISE'
+            args.append('info')
+            if macro.endswith('_EXCEPTIONSTATE'):
+                args.append('ScriptState::current(%s)' % isolate)
+
+        if declare_variable:
+            args.insert(0, this_cpp_type)
+        else:
+            suffix += '_INTERNAL'
+
+        return '%s(%s)' % (macro + suffix, ', '.join(args))
+
+    # Types that don't need error handling, and simply assign a value to the
+    # local variable.
 
+    if not idl_type.v8_conversion_is_trivial:
+        raise Exception('unclassified V8 -> C++ conversion for IDL type: %s' % idl_type.name)
+
+    assignment = '%s = %s' % (variable_name, cpp_value)
     if declare_variable:
-        args.insert(0, this_cpp_type)
-    else:
-        suffix += '_INTERNAL'
+        return '%s %s' % (this_cpp_type, assignment)
+    return assignment
 
-    return '%s(%s)' % (macro + suffix, ', '.join(args))
 
 IdlTypeBase.v8_value_to_local_cpp_value = v8_value_to_local_cpp_value