On 13 December 2014 at 03:15, Daiki Ueno <u...@gnu.org> wrote: > Will Newton <will.new...@linaro.org> writes: > >>>> -#if defined _LIBC_REENTRANT || HAVE_DECL_FGETS_UNLOCKED >>>> +#if defined _LIBC_REENTRANT || defined HAVE_DECL_FGETS_UNLOCKED >>> >>> This is no-no. On some platforms (e.g. Mac OS X), >>> HAVE_DECL_FGETS_UNLOCKED will be defined as 0: >>> >>> $ grep 'define HAVE_DECL_FGETS' gettext-runtime/config.h >>> #define HAVE_DECL_FGETS_UNLOCKED 0 >>> >>> What's the rationale behind this change? According to C99 and C11, the >>> C preprocessor shall convert undefined identifiers to pp-number 0 before >>> evaluation. >> >> glibc quite recently switched to passing -Wundef to the compiler which >> requires that #if is only used on defined values in order to catch >> bugs where somebody forgets or typos the name of a define. > > Ah, I just remembered the related discussion on bug-gnulib. > >> The usual way of testing config variables that start with HAVE_ is to >> use #ifdef as they are binary on/off switches. Is there a reason this >> constant must distinguish between not-defined and zero? > > It is an expansion of a standard autoconf macro AC_CHECK_DECLS and is > a documented behavior: > http://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.69/html_node/Generic-Declarations.html#index-AC_005fCHECK_005fDECLS-680 > > Perhaps we could special case this in intl/, but it would be non-trivial > and I doubt that it is worth doing just in order to suppress the > compiler warnings. So, IMO, > >> Converting it to: >> >> #if defined _LIBC_REENTRANT || (defined HAVE_DECL_FGETS_UNLOCKED && >> HAVE_DECL_FGETS_UNLOCKED) >> >> should work but it is a bit ugly. > > This is the easier way to work around it (and it seems argp/ already > does that).
Would you like me to re-submit the patch with this change or are you happy to fix it up? Thanks, -- Will Newton Toolchain Working Group, Linaro
