[Buildroot] [PATCH 1/1] package/opencv4: fix build with gcc 4.8

[Fabrice Fontaine]

Fix the following build failure with gcc 4.8 raised since the addition
of the package in commit c23612b5db036fe89accb8db48690d1ce1be4b1b:

In file included from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/cap_ffmpeg_impl.hpp:100:0,
                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/cap_ffmpeg.cpp:50:
/home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/cap_ffmpeg_hw.hpp: In constructor 'HWAccelIterator::HWAccelIterator(cv::VideoAccelerationType, bool, AVDictionary*)':
/home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/cap_ffmpeg_hw.hpp:939:23: error: use of deleted function 'std::basic_istringstream<char>& std::basic_istringstream<char>::operator=(const std::basic_istringstream<char>&)'
             s_stream_ = std::istringstream(accel_list);
                       ^
In file included from /home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/arm-none-linux-gnueabi/include/c++/4.8.3/complex:45:0,
                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/core/include/opencv2/core/cvstd.inl.hpp:47,
                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/core/include/opencv2/core.hpp:3306,
                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/include/opencv2/videoio.hpp:46,
                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/precomp.hpp:57,
                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/cap_ffmpeg.cpp:42:
/home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/arm-none-linux-gnueabi/include/c++/4.8.3/sstream:272:11: note: 'std::basic_istringstream<char>& std::basic_istringstream<char>::operator=(const std::basic_istringstream<char>&)' is implicitly deleted because the default definition would be ill-formed:
     class basic_istringstream : public basic_istream<_CharT, _Traits>
           ^
/home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/arm-none-linux-gnueabi/include/c++/4.8.3/sstream:272:11: error: use of deleted function 'std::basic_istream<char>& std::basic_istream<char>::operator=(const std::basic_istream<char>&)'

Fixes:
 - http://autobuild.buildroot.org/results/60f8846b435dafda0ced412d59ffe15bdff0810d

Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
---
 ...src-cap_ffmpeg_impl.hpp-fix-build-wi.patch | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 package/opencv4/0001-modules-videoio-src-cap_ffmpeg_impl.hpp-fix-build-wi.patch

diff --git a/package/opencv4/0001-modules-videoio-src-cap_ffmpeg_impl.hpp-fix-build-wi.patch b/package/opencv4/0001-modules-videoio-src-cap_ffmpeg_impl.hpp-fix-build-wi.patch
new file mode 100644
index 0000000000..6d5d6d0647
--- /dev/null
+++ b/package/opencv4/0001-modules-videoio-src-cap_ffmpeg_impl.hpp-fix-build-wi.patch
@@ -0,0 +1,52 @@
+From 4c92a2869b9a8f736a12ba859b74e5cadce62387 Mon Sep 17 00:00:00 2001
+From: Fabrice Fontaine <fontaine.fabrice at gmail.com>
+Date: Fri, 12 Nov 2021 09:50:17 +0100
+Subject: [PATCH] modules/videoio/src/cap_ffmpeg_impl.hpp: fix build with gcc
+ 4.8
+
+Fix the following build failure with gcc 4.8:
+
+In file included from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/cap_ffmpeg_impl.hpp:100:0,
+                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/cap_ffmpeg.cpp:50:
+/home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/cap_ffmpeg_hw.hpp: In constructor 'HWAccelIterator::HWAccelIterator(cv::VideoAccelerationType, bool, AVDictionary*)':
+/home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/cap_ffmpeg_hw.hpp:939:23: error: use of deleted function 'std::basic_istringstream<char>& std::basic_istringstream<char>::operator=(const std::basic_istringstream<char>&)'
+             s_stream_ = std::istringstream(accel_list);
+                       ^
+In file included from /home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/arm-none-linux-gnueabi/include/c++/4.8.3/complex:45:0,
+                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/core/include/opencv2/core/cvstd.inl.hpp:47,
+                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/core/include/opencv2/core.hpp:3306,
+                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/include/opencv2/videoio.hpp:46,
+                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/precomp.hpp:57,
+                 from /home/buildroot/autobuild/instance-3/output-1/build/opencv4-4.5.4/modules/videoio/src/cap_ffmpeg.cpp:42:
+/home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/arm-none-linux-gnueabi/include/c++/4.8.3/sstream:272:11: note: 'std::basic_istringstream<char>& std::basic_istringstream<char>::operator=(const std::basic_istringstream<char>&)' is implicitly deleted because the default definition would be ill-formed:
+     class basic_istringstream : public basic_istream<_CharT, _Traits>
+           ^
+/home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/arm-none-linux-gnueabi/include/c++/4.8.3/sstream:272:11: error: use of deleted function 'std::basic_istream<char>& std::basic_istream<char>::operator=(const std::basic_istream<char>&)'
+
+Fixes:
+ - http://autobuild.buildroot.org/results/60f8846b435dafda0ced412d59ffe15bdff0810d
+
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
+[Retrieved from:
+https://github.com/opencv/opencv/commit/4c92a2869b9a8f736a12ba859b74e5cadce62387]
+---
+ modules/videoio/src/cap_ffmpeg_impl.hpp | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+diff --git a/modules/videoio/src/cap_ffmpeg_impl.hpp b/modules/videoio/src/cap_ffmpeg_impl.hpp
+index d393b73ff4a2..76e1b855b7c8 100644
+--- a/modules/videoio/src/cap_ffmpeg_impl.hpp
++++ b/modules/videoio/src/cap_ffmpeg_impl.hpp
+@@ -93,6 +93,12 @@ extern "C" {
+ }
+ #endif
+ 
++// GCC 4.x compilation bug. Details: https://github.com/opencv/opencv/issues/20292
++#if (defined(__GNUC__) && __GNUC__ < 5) && !defined(__clang__)
++#undef USE_AV_HW_CODECS
++#define USE_AV_HW_CODECS 0
++#endif
++
+ //#define USE_AV_HW_CODECS 0
+ #ifndef USE_AV_HW_CODECS
+ #if LIBAVUTIL_VERSION_MAJOR >= 56 // FFMPEG 4.0+
-- 
2.33.0