[libcamera-devel] [PATCH 01/17] meson: Allow partially initializing objects
Kieran Bingham
kieran.bingham at ideasonboard.com
Sun Jun 9 02:26:00 CEST 2019
Hi Laurent,
On 08/06/2019 17:20, Laurent Pinchart wrote:
> Hi Kieran,
>
> On Fri, May 31, 2019 at 11:10:10AM +0100, Kieran Bingham wrote:
>> On 29/05/2019 22:13, Kieran Bingham wrote:
>>> On 27/05/2019 10:18, Jacopo Mondi wrote:
>>>> On Mon, May 27, 2019 at 02:15:27AM +0200, Niklas Söderlund wrote:
>>>>> There are valid use-cases where one might wish to partially initialize a
>>>>> structure when creating it without needing to initialize all members.
>>>>> This is especially common when working with V4L2.
>>>>>
>>>>> struct foo {
>>>>> int bar;
>>>>> int baz;
>>>>> };
>>>>>
>>>>> struct foo f = {
>>>>> .bar = 1;
>>>>> };
>>>>>
>>>>> Without -Wno-missing-field-initializers fails to compile with the error,
>>>>
>>>> I asked for the same a few weeks ago, so I welcome this change
>>>> Acked-by: Jacopo Mondi <jacopo at jmondi.org>
>>>
>>> I was uncertain before, but I can't deny it would be useful to simplify
>>> code /iff/ you know certain members do not need to be initialised.
>>>
>>> We'll have to watch our reviews more closely on initialising structures :-)
>>>
>>> Acked-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>>
>> Errr,,, uhmmm ... sorry - Ack retracted? :-(
>>
>> This breaks compilation on GCC v5 and GCC v6.
>>
>> (Raspbian has GCC v6.3, and compilation on the target fails.)
>
> Could you please share the error messages ?
>
Ah yes, sorry - that might have been useful content:
c++ -Isrc/libcamera/4ab8042@@camera at sha -Isrc/libcamera
-I../src/libcamera -Iinclude -I../include -I../src/libcamera/include
-fdiagnostics-color=always -pipe -D_FILE_OFFSET_BITS=64 -Wall
-Winvalid-pch -Wnon-virtual-dtor -Wextra -Werror -std=c++11 -g
-Wno-unused-parameter -Wno-missing-field-initializers -include config.h
-fPIC -MD -MQ 'src/libcamera/4ab8042@@camera at sha/v4l2_subdevice.cpp.o'
-MF 'src/libcamera/4ab8042@@camera at sha/v4l2_subdevice.cpp.o.d' -o
'src/libcamera/4ab8042@@camera at sha/v4l2_subdevice.cpp.o' -c
../src/libcamera/v4l2_subdevice.cpp
../src/libcamera/v4l2_subdevice.cpp: In member function
‘std::vector<unsigned int>
libcamera::V4L2Subdevice::enumPadCodes(unsigned int)’:
../src/libcamera/v4l2_subdevice.cpp:517:3: sorry, unimplemented:
non-trivial designated initializers not supported
};
^
../src/libcamera/v4l2_subdevice.cpp: In member function
‘std::vector<libcamera::SizeRange>
libcamera::V4L2Subdevice::enumPadSizes(unsigned int, unsigned int)’:
../src/libcamera/v4l2_subdevice.cpp:549:3: sorry, unimplemented:
non-trivial designated initializers not supported
};
^
"Sorry, unimplemented:" - well at least they apologised :-D
I'm not sure what we could do here. It sounds like they simply hadn't
implemented the 'feature' at this point.
We could explicitly state that our minimum compiler requirement is
GCCv7+ (once we verify GCCv7 supports our requirements)?
--
Kieran
(gcc version information from the target below:)
gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/arm-linux-gnueabihf/6/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: ../src/configure -v --with-pkgversion='Raspbian
6.3.0-18+rpi1+deb9u1'
--with-bugurl=file:///usr/share/doc/gcc-6/README.Bugs
--enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++
--prefix=/usr --program-suffix=-6 --program-prefix=arm-linux-gnueabihf-
--enable-shared --enable-linker-build-id --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --libdir=/usr/lib
--enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-libitm --disable-libquadmath --enable-plugin
--with-system-zlib --disable-browser-plugin --enable-java-awt=gtk
--enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-6-armhf/jre
--enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-6-armhf
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-6-armhf
--with-arch-directory=arm --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--with-target-system-zlib --enable-objc-gc=auto --enable-multiarch
--disable-sjlj-exceptions --with-arch=armv6 --with-fpu=vfp
--with-float=hard --enable-checking=release --build=arm-linux-gnueabihf
--host=arm-linux-gnueabihf --target=arm-linux-gnueabihf
Thread model: posix
gcc version 6.3.0 20170516 (Raspbian 6.3.0-18+rpi1+deb9u1)
>> To fix, I had to make the following change for this series.
>> Other solutions may also exist :-)
>>
>>> @@ -309,15 +309,15 @@ std::vector<unsigned int> V4L2Subdevice::enumPadCodes(unsigned int pad)
>>> {
>>> std::vector<unsigned int> codes;
>>> int ret;
>>>
>>> for (unsigned int index = 0;; index++) {
>>> - struct v4l2_subdev_mbus_code_enum mbusEnum = {
>>> - .pad = pad,
>>> - .index = index,
>>> - .which = V4L2_SUBDEV_FORMAT_ACTIVE,
>>> - };
>>> + struct v4l2_subdev_mbus_code_enum mbusEnum;
>>> +
>>> + mbusEnum.pad = pad;
>>> + mbusEnum.index = index;
>>> + mbusEnum.which = V4L2_SUBDEV_FORMAT_ACTIVE;
>>>
>>> ret = ioctl(fd_, VIDIOC_SUBDEV_ENUM_MBUS_CODE, &mbusEnum);
>>> if (ret)
>>> break;
>>>
>>> @@ -340,16 +340,16 @@ std::vector<SizeRange> V4L2Subdevice::enumPadSizes(unsigned int pad,
>>> {
>>> std::vector<SizeRange> sizes;
>>> int ret;
>>>
>>> for (unsigned int index = 0;; index++) {
>>> - struct v4l2_subdev_frame_size_enum sizeEnum = {
>>> - .index = index,
>>> - .pad = pad,
>>> - .code = code,
>>> - .which = V4L2_SUBDEV_FORMAT_ACTIVE,
>>> - };
>>> + struct v4l2_subdev_frame_size_enum sizeEnum;
>>> +
>>> + sizeEnum.index = index;
>>> + sizeEnum.pad = pad;
>>> + sizeEnum.code = code;
>>> + sizeEnum.which = V4L2_SUBDEV_FORMAT_ACTIVE;
>>>
>>> ret = ioctl(fd_, VIDIOC_SUBDEV_ENUM_FRAME_SIZE, &sizeEnum);
>>> if (ret)
>>> break;
>>>
>>>>> error: missing initializer for member ‘foo::baz’ [-Werror=missing-field-initializers]
>>>>>
>>>>> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
>>>>> ---
>>>>> meson.build | 1 +
>>>>> 1 file changed, 1 insertion(+)
>>>>>
>>>>> diff --git a/meson.build b/meson.build
>>>>> index 4d3e99d3e58f71d5..90ad58328f9a2bd5 100644
>>>>> --- a/meson.build
>>>>> +++ b/meson.build
>>>>> @@ -22,6 +22,7 @@ endif
>>>>>
>>>>> common_arguments = [
>>>>> '-Wno-unused-parameter',
>>>>> + '-Wno-missing-field-initializers',
>>>>> '-include', 'config.h',
>>>>> ]
>>>>>
>
--
Regards
--
Kieran
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