Jacek Caban jacek@codeweavers.com wrote:
I don't really follow your objections. It's pretty clear that Wine .idl files with defaultvalue("") statements for BSTR type are broken. There are two ways to fix them:
- fix .idl files, widl and midl already have proper support for L"" syntax.
- don't fix .idl files (just because PSDK has them that way) and add magic
handling for BSTR to widl. Fixing .idl files is a natural and easy fix, what syntax uses PSDK doesn't matter al all, it's even better to differ from PSDK headers in this case.
Well, out of those two options I'd prefer option 1. That's a real bug. Option 2 just changes IDLs that are perfectly fine, just misinterpreted by widl.
FWIW think that it's all broken really badly by Microsoft. BSTR strings are supposed to be allocated by SysAllocString* allocators and can't be static strings. It will fail as soon as someone tries things like SysStringLen() call on it. What midl does is promoting broken use of BSTR type.
Yes, BSTRs are length-prefixed WCHAR strings, but BSTR and WCHAR* are often freely interchanged in the APIs, and that's not our fault.
But, well, we should follow that for compatibility :/
Not the first time :)
> > Generated headers should use L"", like you said. But only in > > case of empty strings.
midl always generates L"" syntax, regardless whether it's an empty string or not.
I don't see this in mshtml.h when default value is not an empty string.
Probably midl doesn't correctly handle even the magic that it's supposed to support. That just confirms that adding "magic" support for defaultvalue() to widl wouldn't solve the problem completely, and support for this "magic" would need adding even more magic to match midl brokeness.
You both seem to misinterpret what's heppening with mshtm.idl. C++ default values can be emitted only for last arguments. There may be a few of them, but they can't be followed by an argument without a default value. That's why midl doesn't emit default values for non-empty strings found in mshtml.idl. I checked that with tests and midl emits L"..." strings as expected.
Thanks for explaining Jacek, much appreciated.