[libcamera-devel] [PATCH 4/4] Documentation: coding-style: Discourage move on shared_ptr<>

[Niklas Söderlund]

Hi Jacopo,

Thanks for your work.

On 2019-02-12 23:20:21 +0100, Jacopo Mondi wrote:
> Using std::move() on return statement of a method or on the its returned
> value prevents the compiler from implementing copy-elision. Discourage
> that in the coding style document.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>

Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>

> ---
>  Documentation/coding-style.rst | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/coding-style.rst b/Documentation/coding-style.rst
> index 51afef27e9c1..065fbe0ab07b 100644
> --- a/Documentation/coding-style.rst
> +++ b/Documentation/coding-style.rst
> @@ -151,6 +151,10 @@ reference for the duration of the operation that borrows it.
>       never by reference. The caller can decide whether to transfer its ownership
>       of the std::shared_ptr<> with std::move() or retain it. The callee shall
>       use std::move() if it needs to store the shared pointer.
> +   * Do not over-use std::move(), as it may prevent copy-elision. In particular
> +     a function returning a std::shared_ptr<> value shall not use std::move() in
> +     its return statements, and its callers shall not wrap the function call
> +     with std::move().
>     * Borrowed references to shared objects are passed as references to the
>       objects themselves, not to the std::shared_ptr<>, with the same rules as
>       for single owner objects.
> -- 
> 2.20.1
> 
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-- 
Regards,
Niklas Söderlund