* zdump.c (HAVE_GENERIC): Define if not already defined, with the same definiens as private.h. (tformat): Prefer _Generic if it works, as this is more reliable than guessing via sizeof. --- zdump.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/zdump.c b/zdump.c index f08afbd..79ff1fd 100644 --- a/zdump.c +++ b/zdump.c @@ -56,6 +56,21 @@ */ enum { SECSPER400YEARS_FITS = SECSPERLYEAR <= INTMAX_MAX / 400 }; +#if !defined HAVE_GENERIC && defined __has_extension +# if __has_extension(c_generic_selections) +# define HAVE_GENERIC 1 +# else +# define HAVE_GENERIC 0 +# endif +#endif +/* _Generic is buggy in pre-4.9 GCC. */ +#if !defined HAVE_GENERIC && defined __GNUC__ +# define HAVE_GENERIC (4 < __GNUC__ + (9 <= __GNUC_MINOR__)) +#endif +#ifndef HAVE_GENERIC +# define HAVE_GENERIC (201112 <= __STDC_VERSION__) +#endif + #if HAVE_GETTEXT #include <locale.h> /* for setlocale */ #endif /* HAVE_GETTEXT */ @@ -1123,12 +1138,33 @@ abbr(struct tm const *tmp) /* ** The code below can fail on certain theoretical systems; -** it works on all known real-world systems as of 2004-12-30. +** it works on all known real-world systems as of 2021-01-25. */ static const char * tformat(void) { +#if HAVE_GENERIC + /* C11-style _Generic is more likely to return the correct + format when distinct types have the same size. */ + char const *fmt = + _Generic((time_t) 0, + signed char: "%d", short: "%d", int: "%d", + long: "%ld", long long: "%lld", + char: CHAR_MAX <= INT_MAX ? "%d" : "%u", + unsigned char: UCHAR_MAX <= INT_MAX ? "%d" : "%u", + unsigned short: USHRT_MAX <= INT_MAX ? "%d" : "%u", + unsigned: "%u", unsigned long: "%lu", + unsigned long long: "%llu", + default: NULL); + if (fmt) + return fmt; + fmt = _Generic((time_t) 0, + intmax_t: "%"PRIdMAX, uintmax_t: "%"PRIuMAX, + default: NULL); + if (fmt) + return fmt; +#endif if (0 > (time_t) -1) { /* signed */ if (sizeof(time_t) == sizeof(intmax_t)) return "%"PRIdMAX; -- 2.34.1