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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: Casting the return value of ...
Date: Mon, 08 Apr 2024 23:01:17 -0700
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scott@slp53.sl.home (Scott Lurndal) writes:

> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>
>> scott@slp53.sl.home (Scott Lurndal) writes:
>>
>>> Kaz Kylheku <433-929-6894@kylheku.com> writes:
>>>
>>>> On 2024-03-28, Kenny McCormack <gazelle@shell.xmission.com> wrote:
>>>
>>>  * Each shared object that simulates a Data Link Processor (DLP),
>>>  * will contain a single namespace-scope function <b>get_dlp</b>
>>>  * which constructs a DLP object of the specified type (for example,
>>>  * a #c_uniline_dlp, #c_card_reader_dlp, et alia).  <b>get_dlp</b>
>>>  * returns the constructed object as a #c_dlp object to the #channel
>>>  * function, which is then used by the I/O subsystem to request
>>>  * services of the DLP at the MLI level.
>>>  */
>>> typedef c_dlp* (*get_dlp_t)(const char *, uint64_t, c_logger *);
>>> ...
>>>     get_dlp_t   sym;
>>> ...
>>>
>>>     sym = (get_dlp_t)dlsym(handle, "get_dlp");
>>>     if (sym == NULL) {
>>>         lp->log("Invalid DLP shared object format: %s\n", dlerror());
>>>         unregister_handle(channel);
>>>         dlclose(handle);
>>>         return 1;
>>>     }
>>>
>>>
>>>> I think there was a time in the development of GCC when there was
>>>> a warning even with the cast.  I don't think it's enabled by default
>>>> now?
>>>
>>> We compile with -Wall -Werror and have never seen any warnings related
>>> to casting the result of dlsym(), and we build with GCC[4..13].
>>
>> Do you use -pedantic?  Compiling with -pedantic using gcc 8.4.0
>> gives a warning diagnostic (and a fatal error if -pedantic-errors
>> is specified in place of -pedantic).
>
> Of course not.  We write production code not standard C (or in this
> case, C++) code.    Portability to compilers other than gcc is
> not a requirement for the several million line codebase.

It's quite amusing to hear of a team that insists on -Wall but
avoids -pedantic, saving a tiny drizzle of cases (all of which
are easy to remedy) while enduring the ever-changing force 5
blizzard of conditions tested by -Wall.