Bug 31720 – Incorrect code generated from IDL for document.cookie unless declaration syntax is carefully adjusted

• Status: RESOLVED
• Resolution: CONFIGURATION CHANGED
• Component: DOM

[Patrik Persson]

Some exception specifications for DOM attribute accessors seem to
result in incorrect generated Objective-C++ code. I have seen two
cases, and suspect they are related, so I have bundled them into a
single report.

These cases are both based on an attribute named 'cookie', originally
specified in Document.idl as follows:

  attribute [ConvertNullToNullString] DOMString cookie;

The observed output concerns the generated DOMDocument.mm.

I verified these results on r51076, host Mac OS X 10.6.2.
Nov 20, 2009.


CASE 1
======

The first case was encountered when trying to make the getter raise an
exception, but not the setter. I specified this in Document.idl as
follows:

  attribute [ConvertNullToNullString] DOMString cookie
      getter raises (DOMException);

I would expect the generated DOMDocument.mm to handle exceptions in
the getter, but not the setter. However, it seems to expect an
exception to be raised by the setter as well:

expected:

  - (void)setCookie:(NSString *)newCookie
  {
      IMPL->setCookie(newCookie);
  }

actual:

  - (void)setCookie:(NSString *)newCookie
  {
      WebCore::ExceptionCode ec = 0;
      IMPL->setCookie(newCookie, ec);
      WebCore::raiseOnDOMError(ec);
  }

A work-around appears to be to use a 'raises' clause with an empty
exception list:

  attribute [ConvertNullToNullString] DOMString cookie
      getter raises (DOMException),
      setter raises (/*DOMException*/);


CASE 2
======

The second case was encountered when trying to make both setter and
getter raise exceptions. I believe this could be specified as follows:

  attribute [ConvertNullToNullString] DOMString cookie
      raises (DOMException);

This also resulted in incorrect generated code (Document.cpp raises
errors, but DOMDocument.mm does not expect them):

expected:

  - (NSString *)cookie
  {
      WebCore::ExceptionCode ec = 0;
      NSString *result = IMPL->cookie(ec);
      WebCore::raiseOnDOMError(ec);
      return result;
  }

  - (void)setCookie:(NSString *)newCookie
  {
      WebCore::ExceptionCode ec = 0;
      IMPL->setCookie(newCookie, ec);
      WebCore::raiseOnDOMError(ec);
  }

actual:

  - (NSString *)cookie
  {
      return IMPL->cookie();
  }

  - (void)setCookie:(NSString *)newCookie
  {
      IMPL->setCookie(newCookie);
  }

A work-around appears to be separate 'raises' clauses for getter and
setter:

  attribute [ConvertNullToNullString] DOMString cookie
      getter raises (DOMException),
      setter raises (DOMException);

[Ahmad Saleem]

[e-mail] - I am not sure, this might be needed but can you look into it?

https://github.com/WebKit/WebKit/blob/main/Source/WebCore/dom/Document.idl

I searched "cookie" word but didn't get it. Further, I know WebIDL specs have been changed a lot from 2009, I don't know whether these will be applicable or not.

Or this is also applicable with these IDL test cases from WPT:

https://wpt.fyi/results/cookie-store?label=master&label=experimental&aligned&view=subtest&q=cookie

Appreciate if you can share input (also for my learning). Thanks!

[Anne van Kesteren]

From code inspection (Document::setCookie and Document+HTML.idl) this looks correct now.