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Re: misdefined macro _T in winnt.h


"J. J. Farrell" wrote:
> 
> > From: Earnie Boyd <earnie_boyd@yahoo.com>
> >
> > Eric Paire wrote:
> > >
> > > Sorry folks, I have forgotten to tell you to compile it with the _UNICODE
> > > and UNICODE defined. Here is a corrected  version that has some problems
> > > when compiled:
> > >
> > > ------  Cut Here  ------  Cut Here  ------  Cut Here  ------  Cut Here  ------
> > >  #define __DIR "dir"
> > >  #define _UNICODE
> > >
> > >  #include <stddef.h>
> > >  #include <tchar.h>
> > >  main() {
> > >         size_t len = wcslen(_T(__DIR)) + wcslen(_T("dir"));
> > >         size_t len2 = wcslen(_TEXT(__DIR)) + wcslen(_TEXT("dir"));
> > >         exit(len);
> > >  }
> > > ------  Cut Here  ------  Cut Here  ------  Cut Here  ------  Cut Here  ------
> > >
> > > You will see that the problem is around the evaluation of the __DIR macro
> > > (there is no problem with "dir"), both for _TEXT and _T. In addition, this
> > > should be fixed also for the _T and _TEXT definitions in <winnt.h>, which
> > > should be coherent with those in <tchar.h> (They are not for now, as _T is
> > > defined either as an object-like macro (in <winnt.h>) or as a function-like
> > > macro (in <tchar.h>)).
> > >
> > > If you want me to provide you with a patch (and a ChangeLog), let me know...
> >
> > No, I don't need a patch.  I do need to know if
> >   L"dir" == L("dir")
> > ?  The problem with this macro is the use of the macro concatenation ##
> > and the order in which the macros are resolved.  Currently we have
> >   #define _T(x) L ## x
> > and if you pass a macro FOO as an argument to this macro you get LFOO
> > returned and not the value of FOO appended to L.  If I change this to
> >   #define _T(x) L(x)
> > then I get returned L("bar") where "bar" is the value of FOO.  This
> > allows the program to compile but does L"bar" == L("bar")?
> 
> No. I'm certain of that, more or less ...
> 

1) If that is true then what is the purpose of function L()?
2) Can someone who has MSVC++ tell me what the _T(__dir) expands to
using the above example?
3) Is it legal to pass a MACRO as an argument to the _T() macro?

Earnie.

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