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Re: [PATCH 2/2] mingw: avoid const warning

From
Karsten Blees <karsten.blees@gmail.com>
Date
Jun 6, 2014, 15:08 UTC
Message-ID
<5391D956.7050903@gmail.com>
In-Reply-To
<20140529104716.GC24021@camelia.ucw.cz>
Am 29.05.2014 12:47, schrieb Stepan Kasal:
Show 6 quoted lines
> Fix const warnings in http-fetch.c and remote-curl.c main() where is
> argv declared as const.
> 
> The fix should work for all future declarations of main, no matter
> whether the second parameter's type is "char**", "const char**", or
> "char *[]".
I'm 100% in favor of a solution that doesn't restrict main to non-const char**! Thanks.
Show 23 quoted lines
> Signed-off-by: Stepan Kasal <kasal@ucw.cz>
> ---
>  compat/mingw.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/compat/mingw.h b/compat/mingw.h
> index 15f0c9d..8745d19 100644
> --- a/compat/mingw.h
> +++ b/compat/mingw.h
> @@ -369,10 +369,11 @@ extern CRITICAL_SECTION pinfo_cs;
>  void mingw_startup();
>  #define main(c,v) dummy_decl_mingw_main(); \
>  static int mingw_main(c,v); \
> -int main(int argc, char **argv) \
> +int main(c, char **main_argv_not_used) \
>  { \
> +	typedef v, **argv_type; \
>  	mingw_startup(); \
> -	return mingw_main(__argc, __argv); \
> +	return mingw_main(__argc, (argv_type)__argv); \
>  } \
>  static int mingw_main(c,v)
>  
I have to admit I had trouble understanding what 'typedef v, **arv_type;' does (looks invalid at first glance), and why you would need main_argv_not_used instead of just main(c,v).
So, I'd like to award +10 points for cleverness, but -10 for obscurity ;-) Probably deserves a comment or an explanation in the commit message.
A simpler solution that works with all definitions of main() is to cast to void* (tell the compiler all responsibility is on us). I.e.:
void mingw_startup();
#define main(c,v) dummy_decl_mingw_main(); \
static int mingw_main(c,v); \
int main(c,v) \
{ \
	mingw_startup(); \
	return mingw_main(__argc, (void *) __argv); \
} \
static int mingw_main(c,v)
-- 
-- 
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Previous: Stepan KasalNext: Junio C Hamano
Message 4 of 9 in “mingw: macro main(), const warnings”
  1. 0/2 mingw: macro main(), const warningsStepan Kasal, May 29, 2014
  2. 1/2 Win32: move main macro to a functionStepan Kasal, May 29, 2014
  3. 2/2 mingw: avoid const warningStepan Kasal, May 29, 2014
  4. Karsten BleesJun 6, 2014
  5. Junio C HamanoJun 6, 2014
  6. Karsten BleesJun 6, 2014
  7. 0/2 mingw: macro main(), const warningsStepan Kasal, Jun 7, 2014
  8. 1/2 Win32: move main macro to a functionStepan Kasal, Jun 7, 2014
  9. 2/2 mingw: avoid const warningStepan Kasal, Jun 7, 2014

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