From: Andrzej Hunt <andrzej@ahunt.org>
Date: Sun, 11 Apr 2021 09:14:31 GMT
Subject: Re: [PATCH] merge-ort: only do pointer arithmetic for non-empty lists
Message-ID: <2cac1b8b-fe53-01c0-825c-0e10edb8a320@ahunt.org>
In-Reply-To: <xmqq8s5pkav2.fsf@gitster.g>


On 11/04/2021 00:56, Junio C Hamano wrote:
> René Scharfe <l.s.r@web.de> writes:
> 
> [...] >> Reading the diff I was wondering if QSORT now gets handed uninitialized
>> values if version-nr is 0.  The answer is no -- relevant_entries is
>> initialized at declaration.  Otherwise the compiler would have probably
>> warned, but sometimes it gets confused.
>>
>> I wonder why relevant_entries is introduced at all, though.  It's not
>> referenced later.  So how about this instead?
>>
>> 	if (versions->nr)
>> 		QSORT(versions->items + offset, nr, tree_entry_order);
>>
>> The intent to sort the last versions->nr-offset entries of versions,
>> but only if it's not empty, is easier to see like this, I think.
> 
> That does make sense.  I wonder if there needs some assertion to
> ensure that "offset" does not exceed "versions.nr", though.
> 

I think so - I will add the assertion. Following the original offset 
calculations is not trivial- which seems like a good enough reason for 
the assert.