oleaut32: ITypeInfo_fnInvoke behavior on PARAMFLAG_FOPT without PARAMFLAG_FHASDEFAULT

[Alex Villací­s Lasso]

Robert Shearman escribió:
> a_villacis at palosanto.com wrote:
>> In a tax app written in Visual Basic/ADO, I found the following problem:
>>
>> In dlls/oleaut32/typelib.c, in function ITypeInfo_fnInvoke(), the
>> following code is found (around line 5569).
>>
>> VARIANTARG *missing_arg = INVBUF_GET_MISSING_ARG_ARRAY(buffer,
>> func_desc->cParams);
>>
>> V_VT(arg) = VT_VARIANT | VT_BYREF;
>> V_VARIANTREF(arg) = &missing_arg[i];
>> V_VT(V_VARIANTREF(arg)) = VT_ERROR;
>> V_ERROR(V_VARIANTREF(arg)) = DISP_E_PARAMNOTFOUND;
>>
>> This code runs when a parameter is found that has the PARAMFLAG_FIN and
>> PARAMFLAG_FOPT flags, but not the PARAMFLAG_FHASDEFAULT flag. As far 
>> as I
>> understand, this code is supposed to supply a variant that might hold an
>> output value. However, in the Append method of the Fields object within
>> the Recordset object of Microsoft ADODB 2.7, the following 
>> declaration is
>> found:
>>
>> trace:ole:ITypeInfo_fnInvoke invoking:
>> L"Append"(5)
>>     parm0: L"Name"
>>     parm1: L"Type"
>>     parm2: L"DefinedSize"
>>     parm3: L"Attrib"
>>     parm4: L"FieldValue"
>> memid is 00000003
>> Param 0:
>>         tdesc.vartype 8 (VT_BSTR)
>>         u.paramdesc.wParamFlags PARAMFLAG_FIN
>>         u.paramdesc.lpex (nil)
>> Param 1:
>>         tdesc.vartype 29 (VT_USERDEFINED ref = 2bc)
>>         u.paramdesc.wParamFlags PARAMFLAG_FIN
>>         u.paramdesc.lpex (nil)
>> Param 2:
>>         tdesc.vartype 29 (VT_USERDEFINED ref = 1c84)
>>         u.paramdesc.wParamFlags PARAMFLAG_FIN PARAMFLAG_FOPT 
>> PARAMFLAG_FHASDEFAULT
>>         u.paramdesc.lpex 0x199868
>> Param 3:
>>         tdesc.vartype 29 (VT_USERDEFINED ref = 320)
>>         u.paramdesc.wParamFlags PARAMFLAG_FIN PARAMFLAG_FOPT 
>> PARAMFLAG_FHASDEFAULT
>>         u.paramdesc.lpex 0x1998d0
>> Param 4:
>>         tdesc.vartype 12 (VT_VARIANT)
>>         u.paramdesc.wParamFlags PARAMFLAG_FIN PARAMFLAG_FOPT
>>         u.paramdesc.lpex (nil)
>>     funckind: 1 (pure virtual)
>>     invkind: 1 (func)
>>     callconv: 4 (stdcall)
>>     oVft: 52
>>     cParamsOpt: 1
>>     wFlags: 0
>>     elemdescFunc (return value type):
>>         tdesc.vartype 25 (VT_HRESULT)
>>         u.paramdesc.wParamFlags PARAMFLAGS_NONE
>>         u.paramdesc.lpex (nil)
>>     helpstring: (null)
>>     entry (ordinal): 0x0000
>>
>> The implementation of the method in Microsoft ADODB 2.7 last parameter
>> (FieldValue) absolutely refuses to accept a VT_VARIANT | VT_BYREF 
>> variant.
>> This result is not dependent of the type of variant pointed to by the
>> first-level variant - changing VT_ERROR to VT_EMPTY has no effect. 
>> Only by
>> passing a VT_EMPTY instead of a VT_VARIANT | VT_BYREF can the 
>> application
>> proceed normally. All oleaut32 tests still pass. Please comment if 
>> this is
>> an appropriate fix for this issue.
>>
>> Changelog:
>> * (PARAMFLAG_FIN | PARAMFLAG_FOPT) & ~PARAMFLAG_FHASDEFAULT should 
>> result
>> in a default parameter of VT_EMPTY, not a VT_VARIANT | VT_BYREF in
>> ITypeInfo_fnInvoke
>>
>>   
>
> I don't believe this is fix is correct. See the tests not included in 
> Wine yet here: 
> http://www.winehq.org/pipermail/wine-patches/2006-August/029511.html
>
> In particular, this code:
>> +HRESULT WINAPI Widget_DoSomething(
>> +    IWidget __RPC_FAR * iface,
>> +    /* [in] */ double number,
>> +    /* [out] */ BSTR *str1,
>> +    /* [defaultvalue][in] */ BSTR str2,
>> +    /* [optional][in] */ VARIANT __RPC_FAR *opt)
>> +{
>> +    static const WCHAR szString[] = { 'S','t','r','i','n','g',0 };
>> +    trace("DoSomething()\n");
>> +
>> +    ok(number == 3.141, "number(%f) != 3.141\n", number);
>> +    ok(*str2 == '\0', "str2(%s) != \"\"\n", wine_dbgstr_w(str2));
>> +    ok(V_VT(opt) == VT_ERROR, "V_VT(opt) should be VT_ERROR instead 
>> of 0x%x\n", V_VT(opt));
>> +    ok(V_ERROR(opt) == DISP_E_PARAMNOTFOUND, "V_ERROR(opt) should be 
>> DISP_E_PARAMNOTFOUND instead of 0x%08lx\n", V_ERROR(opt));
>> +    *str1 = SysAllocString(szString);
>> +
>> +    return S_FALSE;
>> +}
>
>
Bug http://bugs.winehq.org/show_bug.cgi?id=6638 was opened for this 
problem. I have reasons to believe that this is a case of 
(undocumented?) overloading with builtin oleaut32 calling the wrong 
version of a method. The bug report has a full explanation of this, and 
the reasons why I arrived at the overloading theory. However I need an 
OLE Automation expert to verify my hypothesis. Please comment on this 
(especially from the Codeweavers people).

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