[Privoxy-devel] incompatible pointer type

[Fabian Keil]

Lee <ler762 at gmail.com> wrote:

> On 1/9/19, Fabian Keil <fk at fabiankeil.de> wrote:
> > Lee <ler762 at gmail.com> wrote:
> >
> >> All pointers are the same size - correct?
> >
> > Correct.
> >
> >> I get a couple of warnings in jbsockets.c about incompatible pointer types
> >> - eg:
> >> jbsockets.c: In function ‘set_no_delay_flag’:
> >> jbsockets.c:140:49: warning: passing argument 4 of ‘setsockopt’ from
> >> incompatible pointer type [-Wincompatible-pointer-types]
> >>     if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &mi, sizeof(int)))
> >>                                                  ^
> >> In file included from jbsockets.c:52:0:
> >> /usr/i686-w64-mingw32/sys-root/mingw/include/winsock2.h:999:34: note:
> >> expected ‘const char *’ but argument is of type ‘int *’
> >>    WINSOCK_API_LINKAGE int WSAAPI setsockopt(SOCKET s,int level,int
> >> optname,const char *optval,int optlen);
> >>                                   ^~~~~~~~~~
> >>
> >> that boils down to Windows expects a 'char*' pointer & *nix expects a
> >> 'int*' pointer.
> >
> > On ElectroBSD the prototype is:
> >
> >      int
> >      setsockopt(int s, int level, int optname, const void *optval,
> >          socklen_t optlen);
> 
> Which means you're not going to get a compiler warning on ElectroBSD if you have
> char* optval or int* optval?  And either will work?

Either should "work" but it seems more appropriate to cast to "void *"
which should silence the error for you to.

> >> I can make the warnings go away by casting the 4th parameter to (char*)
> >> -   if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &mi, sizeof(int)))
> >> +   if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, (char*)&mi,
> >> sizeof(int)))
> >>
> >> but a 'char*' pointer is the same size as an 'int*' pointer, so this
> >> is just a cosmetic issue that can safely be ignored.  Correct?
> >
> > Correct.
> 
> What's the expected expertise level of somebody looking at the code?
> As in, is it worth adding a comment that with the mingw gcc headers
> you're going to get a [-Wincompatible-pointer-types] warning from the
> compiler here & it's a cosmetic issue that isn't worth the effort to
> fix?

I don't think such a comment would be worth it.

Fabian
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