Re: [PATCH v3 4/5] sim: Check known getopt definition existence

[Tsukasa OI <research_trasio@irq.a4lg.com>]

Hi Tom,

On 2022/10/13 1:28, Tom de Vries wrote:
> On 10/6/22 08:43, Tsukasa OI via Gdb-patches wrote:
>> 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.
> 
> I'm guessing this cause the build breakage on buildbot gdb-centos-x86_64 .
> 
> https://builder.sourceware.org/buildbot/#/builders/71/builds/1392
> 
> Thanks,
> - Tom

I didn't see that error and it seems this error is very strange
considering sim/m32c/main.c is the **only** file which should not be
affected by my change as long as <unistd.h> correctly declares getopt.

Adding
#include <getopt.h>
after
#include <sys/types.h>
might change something but I cannot guarantee whether this change would
fix the issue.

Thanks,
Tsukasa

> 
> 
>> ---
>>   sim/config.h.in  |  3 +++
>>   sim/configure    | 32 ++++++++++++++++++++++++++++++++
>>   sim/configure.ac | 10 ++++++++++
>>   3 files changed, 45 insertions(+)
>>
>> diff --git a/sim/config.h.in b/sim/config.h.in
>> index 84c363c0aec..9a94b289e46 100644
>> --- a/sim/config.h.in
>> +++ b/sim/config.h.in
>> @@ -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
>> diff --git a/sim/configure b/sim/configure
>> index 75d1935df38..dac7f085be1 100755
>> --- a/sim/configure
>> +++ b/sim/configure
>> @@ -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
>> +
>>       diff --git a/sim/configure.ac b/sim/configure.ac
>> index 66a1020efe0..be0cfdbea32 100644
>> --- a/sim/configure.ac
>> +++ b/sim/configure.ac
>> @@ -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
>