From: Carlo Arenas <carenas@gmail.com>
To: Johannes Sixt <j6t@kdbg.org>
Cc: Git Mailing List <git@vger.kernel.org>
Subject: Re: [PATCH cb/pedantic-build-for-developers] lazyload.h: fix warnings about mismatching function pointer types
Date: Wed, 22 Sep 2021 13:16:38 -0700 [thread overview]
Message-ID: <CAPUEspguHsx+BtViT5tO3eyZSJf7mJ0of-K3vAMqB0-ju4fpsg@mail.gmail.com> (raw)
In-Reply-To: <4381472f-a9db-b8a7-a395-81c3935309ae@kdbg.org>
On Wed, Sep 22, 2021 at 12:56 PM Johannes Sixt <j6t@kdbg.org> wrote:
>
> Here, GCC warns about every use of the INIT_PROC_ADDR macro, for example:
>
> In file included from compat/mingw.c:8:
> compat/mingw.c: In function 'mingw_strftime':
> compat/win32/lazyload.h:38:12: warning: assignment to
> 'size_t (*)(char *, size_t, const char *, const struct tm *)'
> {aka 'long long unsigned int (*)(char *, long long unsigned int,
> const char *, const struct tm *)'} from incompatible pointer type
> 'FARPROC' {aka 'long long int (*)()'} [-Wincompatible-pointer-types]
> 38 | (function = get_proc_addr(&proc_addr_##function))
> | ^
> compat/mingw.c:1014:6: note: in expansion of macro 'INIT_PROC_ADDR'
> 1014 | if (INIT_PROC_ADDR(strftime))
> | ^~~~~~~~~~~~~~
did you have CFLAGS adding -Wincompatible-pointer-types explicitly?
This is the reason why the code that got merged to master had -Wno
for this case.
> (message wrapper for convenience). Insert a cast to keep the compiler
> happy. A cast is fine in these cases because they are generic function
> pointer values that have been looked up in a DLL.
I have a more complete "fix" which I got stuck testing GGG[1]; you are likely
going to also hit -Wcast-function-type otherwise.
>
> Signed-off-by: Johannes Sixt <j6t@kdbg.org>
> ---
> How can this have worked ever without a warning?
POSIX have a specific exception that allows (void *) for this, it is incorrect
though in platforms where pointers to code and data might be different
(ex DOS with its segmented model)
Carlo
[1] https://github.com/git/git/pull/1094
next prev parent reply other threads:[~2021-09-22 20:16 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 19:56 [PATCH cb/pedantic-build-for-developers] lazyload.h: fix warnings about mismatching function pointer types Johannes Sixt
2021-09-22 20:16 ` Carlo Arenas [this message]
2021-09-22 21:21 ` Johannes Sixt
2021-09-23 6:20 ` Carlo Arenas
2021-09-23 6:03 ` [PATCH] lazyload.h: use an even more generic function pointer than FARPROC Carlo Marcelo Arenas Belón
2021-09-23 6:33 ` Johannes Sixt
2021-09-23 6:49 ` Carlo Arenas
2021-09-23 6:52 ` [PATCH v2] " Carlo Marcelo Arenas Belón
2021-09-26 10:05 ` [PATCH v3 0/2] js/win-lazyload-buildfix Carlo Marcelo Arenas Belón
2021-09-26 10:05 ` [PATCH v3 1/2] lazyload.h: fix warnings about mismatching function pointer types Carlo Marcelo Arenas Belón
2021-09-27 2:58 ` Eric Sunshine
2021-09-26 10:05 ` [PATCH v3 2/2] lazyload.h: use an even more generic function pointer than FARPROC Carlo Marcelo Arenas Belón
2021-09-27 16:35 ` Junio C Hamano
2021-09-27 18:50 ` Carlo Arenas
2021-09-27 20:13 ` Junio C Hamano
2021-09-29 0:48 ` [PATCH v4 0/3] js/win-lazyload-buildfix Carlo Marcelo Arenas Belón
2021-09-29 0:48 ` [PATCH v4 1/3] lazyload.h: fix warnings about mismatching function pointer types Carlo Marcelo Arenas Belón
2021-09-29 0:48 ` [PATCH v4 2/3] lazyload.h: use an even more generic function pointer than FARPROC Carlo Marcelo Arenas Belón
2021-09-29 0:48 ` [PATCH v4 3/3] Makefile: restrict -Wpedantic and -Wno-pedantic-ms-format better Carlo Marcelo Arenas Belón
2021-09-29 1:14 ` Ramsay Jones
2021-09-29 3:19 ` [PATCH v5 0/3] js/win-lazyload-buildfix Carlo Marcelo Arenas Belón
2021-09-29 3:19 ` [PATCH v5 1/3] lazyload.h: fix warnings about mismatching function pointer types Carlo Marcelo Arenas Belón
2021-09-29 3:19 ` [PATCH v5 2/3] lazyload.h: use an even more generic function pointer than FARPROC Carlo Marcelo Arenas Belón
2021-09-29 3:19 ` [PATCH v5 3/3] Makefile: restrict -Wpedantic and -Wno-pedantic-ms-format better Carlo Marcelo Arenas Belón
2021-09-23 21:00 ` [PATCH cb/pedantic-build-for-developers] lazyload.h: fix warnings about mismatching function pointer types Carlo Arenas
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