Re: [PATCH] CodingGuidelines: mention "static" and "extern"

> On Thu, Feb 08, 2018 at 01:04:08PM -0800, Stefan Beller wrote:
>
>> You may sense a pattern here: I currently have the very firm understanding
>> we use the extern keyword in our codebase.
>>
>> And I can also attest that this was not always the case, as back in the
>> day I remember writing patches without the extern keyword only to be told:
>> (A) be similar to the function in the next lines
>> (B) the standard is to use extern
>> and I was convinced it was a bad decision to prefix declarations with
>> the extern keyword, but followed along as I don't want to have style
>> in the way of writing features.
>
> It definitely was the case that people used to suggest "extern". I think
> this was a Linus-ism from the early days, and I have been hating it for
> almost 12 years now. ;)
>
>>   $ cat Documentation/CodingGuidelines |grep extern
>>   $ # oh no it's empty!
>>
>> Care to add a section to our coding guidelines?
>
> Here's a patch.
>
> -- >8 --
> Subject: [PATCH] CodingGuidelines: mention "static" and "extern"
>
> It perhaps goes without saying that file-local stuff should
> be marked static, but it does not hurt to remind people.
>
> Less obvious is that we are settling on "do not include
> extern in function declarations". It is already the default
> unless the function was previously declared static (but if
> you are following a static declaration with an unmarked one,
> you should think about why you are declaring the thing
> twice). And so it just becomes an extra noise-word in our
> header files.
>
> We used to give the opposite advice, so there are quite a
> few "extern" markers in early Git code. But this at least
> makes a concrete suggestion that we can follow going
> forward.
>
> Signed-off-by: Jeff King <peff@peff.net>

> ---
>  Documentation/CodingGuidelines | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
> index c4cb5ff0d4..48aa4edfbd 100644
> --- a/Documentation/CodingGuidelines
> +++ b/Documentation/CodingGuidelines
> @@ -386,6 +386,11 @@ For C programs:
>   - Use Git's gettext wrappers to make the user interface
>     translatable. See "Marking strings for translation" in po/README.
>
> + - Variables and functions local to a given source file should be marked
> +   with "static". Variables that are visible to other source files
> +   must be declared with "extern" in header files. However, function
> +   declarations should not use "extern", as that is already the default.
> +
>  For Perl programs:
>
>   - Most of the C guidelines above apply.
> --
> 2.16.1.365.g89f5777adf
>