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sim: Check known getopt definition existence

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Clang generates a warning if there is a function declaration/definition
with zero arguments.  Such declarations/definitions without a prototype (an
argument list) are deprecated forms of indefinite arguments
("-Wdeprecated-non-prototype").  On the default configuration, it causes a
build failure (unless "--disable-werror" is specified).

include/getopt.h defines some getopt function definitions but one of them
has a form "extern int getopt ();".  If this form is selected in
include/getopt.h, Clang generates a warning and the build fails by default.

In really old environments, this getopt definition with no arguments is
necessary (because the definition may change between environments).
However, this definition is now a cause of problems on modern environments.

A good news is, this definition is not always selected (e.g. if used by
binutils/*.c).  This is because configuration scripts of binutils, gas,
gprof and ld tries to find known definition of getopt function is used and
defines HAVE_DECL_GETOPT macro.  If this macro is defined when getopt.h is
included, a good form of getopt is used and Clang won't generate warnings.

This commit adds a modified portion of ld/configure.ac to find the known
getopt definition.  If we could find one (and we *will* in most modern
environments), we don't need to rely on the deprecated definition.
This commit is contained in:
Tsukasa OI 2022-10-06 06:43:52 +00:00 • committed by Andrew Burgess
parent 96894c19ad
commit 340aa4f687
3 changed files with 45 additions and 0 deletions
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3
sim/config.h.in
View file

@ -41,6 +41,9 @@
/* Define to 1 if you have the `chmod' function. */
#undef HAVE_CHMOD
/* Is the prototype for getopt in <unistd.h> in the expected format? */
#undef HAVE_DECL_GETOPT
/* Define to 1 if you have the declaration of `tzname', and to 0 if you don't.
*/
#undef HAVE_DECL_TZNAME

32
sim/configure vendored
View file

@ -16428,6 +16428,38 @@ $as_echo "${WARN_CFLAGS} ${WERROR_CFLAGS}" >&6; }
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for a known getopt prototype in unistd.h" >&5
$as_echo_n "checking for a known getopt prototype in unistd.h... " >&6; }
if ${sim_cv_decl_getopt_unistd_h+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <unistd.h>
int
main ()
{
extern int getopt (int, char *const*, const char *);
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
sim_cv_decl_getopt_unistd_h=yes
else
sim_cv_decl_getopt_unistd_h=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $sim_cv_decl_getopt_unistd_h" >&5
$as_echo "$sim_cv_decl_getopt_unistd_h" >&6; }
if test $sim_cv_decl_getopt_unistd_h = yes; then
$as_echo "#define HAVE_DECL_GETOPT 1" >>confdefs.h
fi

10
sim/configure.ac
View file

@ -177,6 +177,16 @@ SIM_AC_OPTION_STDIO
SIM_AC_OPTION_TRACE
SIM_AC_OPTION_WARNINGS
AC_MSG_CHECKING(for a known getopt prototype in unistd.h)
AC_CACHE_VAL(sim_cv_decl_getopt_unistd_h,
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <unistd.h>], [extern int getopt (int, char *const*, const char *);])],
sim_cv_decl_getopt_unistd_h=yes, sim_cv_decl_getopt_unistd_h=no)])
AC_MSG_RESULT($sim_cv_decl_getopt_unistd_h)
if test $sim_cv_decl_getopt_unistd_h = yes; then
AC_DEFINE([HAVE_DECL_GETOPT], 1,
[Is the prototype for getopt in <unistd.h> in the expected format?])
fi
dnl These are unfortunate. They are conditionally called by other sim macros
dnl but always used by common/Make-common.in. So we have to subst here even
dnl when the rest of the code is in the respective macros. Once we merge the