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Hi Eric, On Jan 23 15:09, Eric Blake wrote: > I'm trying to build readline 6.3 for cygwin (in preparation for bash > 4.3), but ran into a snag. Readline tries to redefine 'setjmp' in terms > of 'sigsetjmp' via a wrapper header (presumably faster to wrap the > problem away than auditing lots of old code to find where setjmp was > used?), which works on Linux but fails miserably on Cygwin: > > ... > #if defined (HAVE_POSIX_SIGSETJMP) > # define procenv_t sigjmp_buf > # if !defined (__OPENNT) > # undef setjmp > # define setjmp(x) sigsetjmp((x), 1) > ... > > $ printf '#include "config.h" > #include <setjmp.h> > #include "posixjmp.h" > sigsetjmp(a,0)\n' | gcc -E - | tail -n1 > __extension__ ({ sigjump_buf *_sjbuf = &(a); ((*_sjbuf)[(13 * 4)] = 0, > pthread_sigmask (0, 0, (sigset_t *)((*_sjbuf) + ((13 * 4)+1))), > sigsetjmp (*_sjbuf)); }) > > Basically, because readline's causes two macros to be defined in terms > of each other, the expansion of sigsetjmp is trying to invoke a function > named sigsetjmp, but no such function exists on Cygwin, leading to this > compilation failure: > > readline.c: In function 'readline_internal_char': > readline.c:541:7: error: implicit declaration of function 'sigsetjmp' > [-Werror=implicit-function-declaration] > > Reading POSIX, I see that Cygwin is compliant, and readline is at fault. > http://pubs.opengroup.org/onlinepubs/9699919799/functions/setjmp.html > is clear: > > "It is unspecified whether setjmp() is a macro or a function. If a macro > definition is suppressed in order to access an actual function, or a > program defines an external identifier with the name setjmp, the > behavior is undefined." This needs fixing in readline's autoconf stuff in the first place. > > But as the redefine works in Linux, I'm wondering if we tweak things in > Cygwin and/or newlib to allow it to work here too. Maybe by making an > entry point __setjmp() as an alias for setjmp(), and defining > sigsetjmp() in terms of __setjmp(), so that when someone adds a #define > wrapper for setjmp, it is no longer a mutually recursive macro naming > scenario. > > In the meantime, I'm resorting to patching up readline code to quit > trying to (re)define setjmp. Right. What we could do, but only for Cygwin, is to call _setjmp/ _longjmp in the sigsetjmp/siglongjmp macros. On Cygwin _setjmp/_longjmp are just aliases for setjmp/longjmp. Corinna -- Corinna Vinschen Cygwin Maintainer Red Hat
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