[PATCH] build: announce requirement for C11

[Tyler Retzlaff]

On Wed, May 03, 2023 at 04:14:13PM +0100, Bruce Richardson wrote:
> Add a deprecation notice informing users that we will require a C11
> compiler from 23.11 release onwards. This requirement was agreed by
> technical board to enable use of newer C language features, e.g.
> standard atomics. [1]
> 
> [1] http://inbox.dpdk.org/dev/DBAPR08MB58148CEC3E1454E8848A938998AB9@DBAPR08MB5814.eurprd08.prod.outlook.com/
> 
> Signed-off-by: Bruce Richardson <bruce.richardson at intel.com>
> ---
>  doc/guides/rel_notes/deprecation.rst | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
> index dcc1ca1696..9a391d2c49 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -11,6 +11,12 @@ here.
>  Deprecation Notices
>  -------------------
>  
> +* C Compiler: From DPDK 23.11 onwards,
> +  building DPDK will require a C compiler which supports the C11 standard, or later.
> +  Please note:
> +     - C11 is supported from GCC version 5 onwards, and is the default language version in that release
> +     - C11 is the default compilation mode in Clang from version 3.6

suggest adding an additional qualification that

  C11 conformant compiler including support for optional standard atomics

  does NOT #define __STDC_NO_ATOMICS__ 1

  which requires providing the stdatomic.h header and feature. this
  shouldn't be contentious since both gcc and clang have support.
  
Acked-by: Tyler Retzlaff <roretzla at linux.microsoft.com>

> +
>  * kvargs: The function ``rte_kvargs_process`` will get a new parameter
>    for returning key match count. It will ease handling of no-match case.
>  
> -- 
> 2.39.2