From: René Scharfe <rene.scharfe@lsrfire.ath.cx>
Date: Thu, 09 May 2013 14:32:55 GMT
Subject: Re: [PATCH 3/3] Initialize variables with values
Message-ID: <518BB397.901@lsrfire.ath.cx>
In-Reply-To: <20130509132115.GA3375@elie>

Am 09.05.2013 15:21, schrieb Jonathan Nieder:
> Hi,
>
> Sven Strickroth wrote:
>
>> With MSVC initializing a variable with "int a=a" causes a warning about
>> using an uninitialized value.
> [...]
>> --- a/builtin/rev-list.c
>> +++ b/builtin/rev-list.c
>> @@ -338,7 +338,7 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
>>   		mark_edges_uninteresting(revs.commits, &revs, show_edge);
>>
>>   	if (bisect_list) {
>> -		int reaches = reaches, all = all;
>> +		int reaches = 0, all = 0;
>
> A correct way to spell this is
>
> 		int reaches, all;
>
> which, as a bonus, lets the compiler warn if they are used
> uninitialized.  Does that provoke warnings?

Only find_bisection() (defined in bisect.c) is used to set these 
variables in that block.  While it sets "all" unconditionally, it 
doesn't always set "reaches" -- only if it actually finds something. 
That's still safe because the following code path errors out early if 
nothing was found before it uses "reaches".

Are there C compilers that can analyse initialization and usage of 
variables across compilation units like that?

Anyway, initializing the variables to zero makes this code consistent 
with the second call-site of find_bisection().  Making sure this 
function sets "reaches" unconditionally as well and dropping the 
initialization from both places may be even better.

René