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

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

On 2022/10/23 21:16, Mike Frysinger wrote:
> On 06 Oct 2022 06:43, Tsukasa OI 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.
>> ---
>>  sim/config.h.in  |  3 +++
>>  sim/configure    | 32 ++++++++++++++++++++++++++++++++
>>  sim/configure.ac | 10 ++++++++++
> 
> this logic belongs in m4/sim_ac_platform.m4, not configure.ac
> 
> should leave a comment above the code too indicating that this logic is
> purely for local getopt.h usage, and is copied from other dirs (e.g. the
> binutils files).
> -mike

OK, I'll submit a patch to move this portion to
sim/m4/sim_ac_platform.m4 with proper commit message.

Thanks,
Tsukasa