Re: msvcp90/msvcp90.h: right-hand operand of comma expression has no effect (PING)

[Alexandre Julliard]

Gerald Pfeifer  writes:
> On Wed, 16 Apr 2014, Paul Chitescu wrote:
> > > Digging into this in more detail I see
> > >
> > > ../msvcp90/ios.c: In function 'basic_streambuf_char__Xsgetn_s':
> > >   ../msvcp90/msvcp90.h:529:75: warning: right-hand operand of comma
> > > expression has no effect [-Wunused-value]
> > >   #define memcpy_s( dst, size, src, count ) (memcpy( (dst), (src), (count)
> > > ), 0) ^ ../msvcp90/ios.c:1218:13: note: in expansion of macro 'memcpy_s'
> > > memcpy_s(ptr+copied, size, *this->prpos, chunk);
> > >              ^
> >
> > memcpy_s() returns an errno_t so the author tried to force returning 
> > zero (no error).
>
> Since, clearly, the result is never intended to be used, we can as
> well simply cast the result away instead of using ", 0".

memcpy_s is supposed to return a value, and callers could (and probably
should) check it.

msvcp90/msvcp90.h: right-hand operand of comma expression has no effect (PING)

[Gerald Pfeifer]

On Thu, 12 Jun 2014, Alexandre Julliard wrote:
> > > > ../msvcp90/ios.c: In function 'basic_streambuf_char__Xsgetn_s':
> > > >   ../msvcp90/msvcp90.h:529:75: warning: right-hand operand of comma
> > > > expression has no effect [-Wunused-value]
> > > >   #define memcpy_s( dst, size, src, count ) (memcpy( (dst), (src), (count)
> > > > ), 0) ^ ../msvcp90/ios.c:1218:13: note: in expansion of macro 'memcpy_s'
> > > > memcpy_s(ptr+copied, size, *this->prpos, chunk);
> > > >              ^
> > >
> > > memcpy_s() returns an errno_t so the author tried to force returning 
> > > zero (no error).
> >
> > Since, clearly, the result is never intended to be used, we can as
> > well simply cast the result away instead of using ", 0".
>
> memcpy_s is supposed to return a value, and callers could (and probably
> should) check it.

Okay, so how about this patch which removes the ", 0" as part of the
#define?

That does not establish what you are suggesting, but at least removes 
this unconditional silencing (and dozens of warnings for GCC).

Gerald

diff --git a/dlls/msvcp90/msvcp90.h b/dlls/msvcp90/msvcp90.h
index 0d5e124..5d85639 100644
--- a/dlls/msvcp90/msvcp90.h
+++ b/dlls/msvcp90/msvcp90.h
@@ -526,7 +526,7 @@ typedef struct {
 } complex_double;

#if _MSVCP_VER < 80
-#define memcpy_s( dst, size, src, count ) (memcpy( (dst), (src), (count) ), 0)
+#define memcpy_s( dst, size, src, count ) (memcpy( (dst), (src), (count) ))
 #define memmove_s( dst, size, src, count ) (memmove( (dst), (src), (count) ), 0)
 #define mbstowcs_s( ret, wcs, size, mbs, count ) (mbstowcs( (wcs), (mbs), (count) ), 0)
 #define hypotf( x, y ) ((float)hypot( (double)(x), (double)(y) ))