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

[Laurent Pinchart]

Hi Jacopo,

Thank you for the patch.

On Tue, Feb 12, 2019 at 11:20:21PM +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>

I haven't explicitly given my SoB for this one, so please don't add it
yourself. To record the advices I gave you, you could use Suggested-by.

This being said, I hereby give you my

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

:-)

> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> ---
>  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.

-- 
Regards,

Laurent Pinchart