Re: [Quickfix-developers] Confused by possible bug in Utility.cpp / thread_spawn

[Djalma R. d. S. F. <drs...@gm...>]

On Tue, Jan 22, 2013 at 4:38 PM, K. Frank <kfr...@gm...> wrote:

> "func" in the thread_spawn call is a formal argument (that
> happens to be a pointer to a function), and is stored on
> the stack when thread_spawn is called.  "func" is not a
> function, in the technical sense that "f" is a function in the
> example above.  So &func is the address on the stack where
> the value of the argument func is stored.  &func and func
> are not the same, and (if you want a pointer to a pointer)
> there is nothing optional about the '&'.
>

Well, I think you are correct here. Indeed, if you get the function pointer
declaration in utility.h it is missing the expected * just after _stdcall,
but the compiler does not care.

#ifdef _MSC_VER
typedef unsigned int (_stdcall THREAD_START_ROUTINE)(void *);

After fixing the declaration,

typedef unsigned int (_stdcall *THREAD_START_ROUTINE)(void *);

and trying to use &func the compiler starts to complain as expected,
although with a weired error message.

1>.\Utility.cpp(517) : error C2664: '_beginthreadex' : cannot convert
parameter 3 from 'FIX::THREAD_START_ROUTINE *' to 'unsigned int (__cdecl
*)(void *)'

I believe that for some kind of magic behind the scenes (that I
definitively would not dare to try to explain), everything works fine and
the compiler currently generates the correct code for Windows platform.

It is really very confusing issue.

Unfortunately I don't have VC11/VC12 at the momento to check whether this
is something that was fixed in newer versions of Microsoft compiler.