#7059: Compile error in ffmpeg git master with opencv 3.4.1 -------------------------------------+------------------------------------- Reporter: bermond | Type: defect Status: new | Priority: normal Component: | Version: undetermined | unspecified Keywords: | Blocked By: Blocking: | Reproduced by developer: 0 Analyzed by developer: 0 | -------------------------------------+------------------------------------- I'm getting the following error at configure time when trying to compile ffmpeg git-master with the newly released opencv 3.4.1: {{{ ERROR: libopencv not found }}} Relevant `ffbuild/config.log` section: {{{ In file included from /usr/include/opencv2/core/types_c.h:59:0, from /usr/include/opencv2/core/core_c.h:48, from /tmp/ffconf.Rgo00uNd/test.c:1: /usr/include/opencv2/core/cvdef.h:485:1: error: unknown type name 'namespace' namespace cv { ^~~~~~~~~ /usr/include/opencv2/core/cvdef.h:485:14: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token namespace cv { ^ ERROR: libopencv not found }}} It compiles fine when using opencv 3.4.0. How to reproduce: {{{ $ git clone https://git.ffmpeg.org/ffmpeg.git $ cd ffmpeg $ ./configure --enable-libopencv }}} A relevant [https://github.com/opencv/opencv/issues/10963 issue (#10963)] is opened at the official opencv github repository regarding the same error when compiling vlc. Here is a quote of opencv developer Alexander Alekhin when answering this issue: ''"OpenCV 3.x doesn't not support C compilation mode officially. There are still legacy C API calls (from OpenCV 1.x) but they should be compiled in C++ compilation mode".'' '''System information:''' '''OS:''' Arch Linux x86_64 '''Compiler:''' gcc 7.3.0 '''FFmpeg:''' git master '''OpenCV:''' 3.4.1 -- Ticket URL: <https://trac.ffmpeg.org/ticket/7059> FFmpeg <https://ffmpeg.org> FFmpeg issue tracker