From: Phillip Wood <phillip.wood123@gmail.com>
Date: Tue, 30 Aug 2022 15:22:03 GMT
Subject: Re: validating signed/unsigned comparisons with Coccinelle, was Re: [PATCH 0/3] A couple of CI fixes regarding the built-in add --patch
Message-ID: <dc48ce59-530e-da74-93ad-9eb4a17e391c@gmail.com>
In-Reply-To: <p9p431r8-nq64-02sq-3049-n10rrn1o89o7@tzk.qr>

Hi Dscho

On 30/08/2022 15:19, Johannes Schindelin wrote:
> Hi,
> 
> On Tue, 30 Aug 2022, Johannes Schindelin via GitGitGadget wrote:
> 
>> Note: This patch series is based on ds/github-actions-use-newer-ubuntu (but
>> probably applies cleanly even on maint) because I tried to develop a
>> semantic patch to fix similar issues in the code base. However, I've since
>> run into what looks like a bug in Coccinelle
>> [https://github.com/coccinelle/coccinelle/issues/284]. My latest version of
>> that semantic patch looks like this, but I stopped when running it on Git's
>> source code triggered the bug for 66 of Git's .c files:
>>
>> @@
>> type T = { unsigned int };
>> T:n b;
>> type S != { unsigned int, size_t };
>> S s;
>> binary operator o != { &&, || };
>> @@
>> -s o b
>> +s o (S)b
>>
>> @@
>> type T = { unsigned int };
>> T:n b;
>> type S != { unsigned int, size_t };
>> S s;
>> binary operator o != { &&, || };
>> @@
>> -b o s
>> +(S)b o s
> 
> The bug in Coccinelle is already fixed (are you impressed? I certainly
> am at the incredible speed and at the wonderful conversation I had!), and
> I verified with this semantic patch that our code is clean:

Wow that's fast, I wonder if they would be interested in fixing the 
parsing bug we found with Peff's UNUSED() series. It's good news that 
the patch does not find any other problems.

Best Wishes

Phillip

> 
> -- snip --
> @@
> type T = { unsigned int };
> T:n b;
> type S != { unsigned int, size_t, float, double };
> S s;
> binary operator o != { &&, || };
> @@
>   s o
> -b
> +(S)b
> 
> @@
> type T = { unsigned int };
> T:n b;
> type S != { unsigned int, size_t, float, double };
> S s;
> binary operator o != { &&, || };
> @@
> -b
> +(S)b
>   o s
> -- snap --
> 
> I do not currently plan on integrating this into `contrib/coccinelle/`,
> though, because it will take a while until we can benefit from the fix in
> Git's CI/PR runs.
> 
> Ciao,
> Dscho