Re: useless cast warning
Paul Eggert <[email protected]>
| Newsgroups | gmane.comp.lib.gnulib.bugs,gmane.emacs.devel |
|---|---|
| Organization | UCLA Computer Science Department |
| Message-ID | <[email protected]> |
On 2026-07-17 00:28, Eli Zaretskii wrote: >> Date: Fri, 17 Jul 2026 09:09:02 +0200 >> From: Thomas Klausner <[email protected]> >> >> Hi! >> >> When compiling emacs git head on NetBSD, I see: >> >> getopt1.c: In function 'rpl_getopt_long': >> getopt1.c:31:34: warning: useless cast to type 'char **' [-Wuseless-cast] >> 31 | return _getopt_internal (argc, (char **) argv, options, long_options, >> | ^ >> getopt1.c: In function 'rpl_getopt_long_only': >> getopt1.c:54:34: warning: useless cast to type 'char **' [-Wuseless-cast] >> 54 | return _getopt_internal (argc, (char **) argv, options, long_options, >> | ^ > > That's likely a Gnulib issue, so I'm adding Paul to the discussion. Thanks for reporting that. Collin's suggested fix[1] would provoke -Wdiscarded-qualifiers on some other platforms, so I instead installed the attached patch into Gnulib, and merged recent Gnulib changes into Emacs master. Thomas, please give it a try. [1]: https://lists.gnu.org/r/emacs-devel/2026-07/msg00172.html
gnulib-getopt.patch
(text/x-patch, 2.1 KB)
diff --git a/ChangeLog b/ChangeLog index d1ea69185f..224bcf30b3 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,13 @@ 2026-07-17 Paul Eggert <[email protected]> + getopt: port to NetBSD git head gcc -Wuseless cast + Problem reported by Thomas Klausner in: + https://lists.gnu.org/r/emacs-devel/2026-07/msg00169.html + * lib/getopt-pfx-ext.h (__getopt_argv_const_is_empty): New macro, + defined to 1 when we define __getopt_argv_const to empty. + * lib/getopt1.c (ARGV_CAST): New macro. + (getopt_long, getopt_long_only): Use it. + gendocs: output human-readable file sizes * build-aux/gendocs.sh (calcsize): Output human-readable file size, rather than always size in KiB mislabled as "K bytes". diff --git a/lib/getopt-pfx-ext.h b/lib/getopt-pfx-ext.h index db2e27f36c..189598a125 100644 --- a/lib/getopt-pfx-ext.h +++ b/lib/getopt-pfx-ext.h @@ -58,6 +58,7 @@ #ifndef __getopt_argv_const # if defined __GETOPT_PREFIX # define __getopt_argv_const /* empty */ +# define __getopt_argv_const_is_empty 1 # else # define __getopt_argv_const const # endif diff --git a/lib/getopt1.c b/lib/getopt1.c index a5f9988828..c127c627ee 100644 --- a/lib/getopt1.c +++ b/lib/getopt1.c @@ -24,11 +24,19 @@ #include <getopt.h> #include "getopt_int.h" +/* Convert char *__getopt_argv_const * to char ** without provoking + gcc -Wuseless-cast when __getopt_argv_const is empty. */ +#ifdef __getopt_argv_const_is_empty +# define ARGV_CAST(argv) (argv) +#else +# define ARGV_CAST(argv) ((char **) (argv)) +#endif + int getopt_long (int argc, char *__getopt_argv_const *argv, const char *options, const struct option *long_options, int *opt_index) { - return _getopt_internal (argc, (char **) argv, options, long_options, + return _getopt_internal (argc, ARGV_CAST (argv), options, long_options, opt_index, 0, 0); } @@ -51,7 +59,7 @@ getopt_long_only (int argc, char *__getopt_argv_const *argv, const char *options, const struct option *long_options, int *opt_index) { - return _getopt_internal (argc, (char **) argv, options, long_options, + return _getopt_internal (argc, ARGV_CAST (argv), options, long_options, opt_index, 1, 0); }