>Number:         18763
>Category:       toolchain
>Synopsis:       rpcgen expands macros that should be preserved
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Oct 22 04:39:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Andreas Johansson
>Release:        NetBSD 1.6
>Organization:
Rockstorm Technology AB
>Environment:
System: NetBSD bmw 1.6 NetBSD 1.6 (GENERIC) #0: Sun Sep 8 19:43:40 UTC 2002 autobuild@tgm.daemon.org:/autobuild/i386/OBJ/autobuild/src/sys/arch/i386/compile/GENERIC i386
Architecture: i386
Machine: i386
>Description:
rpcgen expands some macros built into cpp that should be passed on to the
output file. rpcgen doesn't really do any replacing, but it calls cpp in
order to evaluate #ifdef RPC_HDR statements and such, and it the process
some predefined macros gets expanded by cpp.

The macro I've been bitten by is __STDC__ which is replaced by '1', but I'm
sure this is not the only potential problem. Interrestingly, cpp -dM doesn't
even report that __STDC__ is defined. It can be undefined by cpp -U __STDC__,
but this always gives me a warning.
>How-To-Repeat:
cd src/include/rpc
rpcgen -C -h rpcb_prot.x

Line 171 in rpcb_prot.x:

%#if __STDC__
%extern  bool_t xdr_rpcblist(XDR *, rpcblist**);
%#else /* K&R C */
%bool_t xdr_rpcblist();
%#endif

will be replaced with:

#if 1
extern  bool_t xdr_rpcblist(XDR *, rpcblist**);
#else /* K&R C */
bool_t xdr_rpcblist();
#endif


This doesn't really break anything as long as you compile with a standard
compiler, but it works only because __STDC__ was tested with #if. In
previous versions of NetBSD, it was tested with #ifdef, and this makes old
code uncompilable with a new toolchain (this is my real problem).
>Fix:

Maybe an option to cpp not to expand any macros (i.e. only respond to lines
that starts with '#'), and use this option in rpcgen?

The -undef option of cpp does not undefine __STDC__, so this option can't
solve the problem by itself. cpp -undef -U __STDC__ -U ... could be a fix,
but this leads to annoying warnings.
>Release-Note:
>Audit-Trail:
>Unformatted: