Re: [PATCH v2] for_each_string_list_item: avoid undefined behavior for empty list

From: Andreas Schwab <schwab@linux-m68k.org>
Date: Sep 20, 2017, 21:51 UTC
Message-ID: <87lgl9rqbq.fsf@linux-m68k.org>
In-Reply-To: <20170920173134.GZ27425@aiede.mtv.corp.google.com>

On Sep 20 2017, Jonathan Nieder <jrnieder@gmail.com> wrote:

Show 20 quoted lines

> Andreas Schwab wrote:
>> On Sep 19 2017, Jonathan Nieder <jrnieder@gmail.com> wrote:
>
>>> B. #define for_each_string_list_item(item, list) \
>>> 	if (list->items) \
>>> 		for (item = ...; ...; ... )
>>>
>>>    This breaks a caller like
>>> 	if (foo)
>>> 		for_each_string_list_item(item, list)
>>> 			...
>>> 	else
>>> 		...
>>>
>>>    making it a non-starter.
>>
>> That can be fixed with a dangling else.
>
> I believe the fix you're referring to is option C, from the same email
> you are replying to.  If not, please correct me.

A variant thereof, yes.

Andreas.

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Andreas Schwab, schwab@linux-m68k.org
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