[libcamera-devel] [PATCH] libcamera: controls: Replace array designated initializer

[Laurent Pinchart]

Hi Jacopo,

Thank you for the patch.

On Wed, May 13, 2020 at 11:12:55AM +0200, Jacopo Mondi wrote:
> Since version 10.0 the LLVM clang++ compiler emits warning to report
> usage of array designated initializer, a C99 feature that was only
> supported through an extension of the compiler and will be not valid
> anymore in C++20.
> 
> From https://releases.llvm.org/10.0.0/tools/clang/docs/ReleaseNotes.html
> The new warnings -Wc99-designator and -Wreorder-init-list warn about
> uses of C99 initializers in C++ mode for cases that are valid in C99 but
> not in C++20.
> 
> This generates the following build error in the controls.cpp file:
> ../src/libcamera/controls.cpp:54:2: error: array designators are a C99 extension [-Werror,-Wc99-designator]
>         [ControlTypeNone]               = 0,
>         ^~~~~~~~~~~~~~~~~
> 
> Fix this by replacing the plain C array with an std:map<>.
> 
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> 
> ---
> I would have liked the map to be immutable, but I can't due to missing
> overloading for operator[]:
> error: no viable overloaded operator[] for type 'const std::map<unsigned int, size_t>'
> 
> Tested with clang++ 10.0.0 and g++ 9.3.0.1
> ---
>  src/libcamera/controls.cpp | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
> index 08df7f29e938..eaef45a5f62c 100644
> --- a/src/libcamera/controls.cpp
> +++ b/src/libcamera/controls.cpp
> @@ -8,6 +8,7 @@
>  #include <libcamera/controls.h>
> 
>  #include <iomanip>
> +#include <map>
>  #include <sstream>
>  #include <string>
>  #include <string.h>
> @@ -50,16 +51,16 @@ LOG_DEFINE_CATEGORY(Controls)
> 
>  namespace {
> 
> -static constexpr size_t ControlValueSize[] = {
> -	[ControlTypeNone]		= 0,
> -	[ControlTypeBool]		= sizeof(bool),
> -	[ControlTypeByte]		= sizeof(uint8_t),
> -	[ControlTypeInteger32]		= sizeof(int32_t),
> -	[ControlTypeInteger64]		= sizeof(int64_t),
> -	[ControlTypeFloat]		= sizeof(float),
> -	[ControlTypeString]		= sizeof(char),
> -	[ControlTypeRectangle]		= sizeof(Rectangle),
> -	[ControlTypeSize]		= sizeof(Size),
> +std::map<unsigned int, size_t> ControlValueSize = {
> +	{ ControlTypeNone,	0  },
> +	{ ControlTypeBool,	sizeof(bool) },
> +	{ ControlTypeByte,	sizeof(uint8_t) },
> +	{ ControlTypeInteger32,	sizeof(int32_t) },
> +	{ ControlTypeInteger64,	sizeof(int64_t) },
> +	{ ControlTypeFloat,	sizeof(float) },
> +	{ ControlTypeString,	sizeof(char) },
> +	{ ControlTypeRectangle,	sizeof(Rectangle) },
> +	{ ControlTypeSize,	sizeof(Size) },
>  };

Efficiency will take a hit :-S And making it non-const is asking for
trouble. I think we need a better solution.

First of all I'd like to know where the warning comes from, as I don't
hit it when compiling with clang++ 10.0.0.

> 
>  } /* namespace */

-- 
Regards,

Laurent Pinchart