Re: validating signed/unsigned comparisons with Coccinelle, was Re: [PATCH 0/3] A couple of CI fixes regarding the built-in add --patch

> 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:

> 
> -- 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