GCC 6.0/6.x build problems

[samtux]

I get the next error compiling Opencv v2.4.12 in Arch linux https://aur.archlinux.org/packages/opencv2/:

---

[ 0%] Built target opencv_core_pch_dephelp
[ 0%] Generating precomp.hpp.gch/opencv_core_Release.gch
cc1plus: aviso: la opción de línea de órdenes ‘-Wmissing-prototypes’ es válida para C/ObjC pero no para C++
cc1plus: aviso: la opción de línea de órdenes ‘-Wstrict-prototypes’ es válida para C/ObjC pero no para C++
In file included from /usr/include/c++/6.1.1/bits/stl_algo.h:59:0,
from /usr/include/c++/6.1.1/algorithm:62,
from /tmp/packerbuild-1001/opencv2/opencv2/src/opencv-2.4.12.3/modules/core/include/opencv2/core/core.hpp:53,
from /tmp/packerbuild-1001/opencv2/opencv2/src/opencv-2.4.12.3/modules/core/precomp.hpp:48:
/usr/include/c++/6.1.1/cstdlib:75:25: error fatal: stdlib.h: No existe el fichero o el directorio

include_next <stdlib.h>

^
compilación terminada.
modules/core/CMakeFiles/pch_Generate_opencv_core.dir/build.make:62: fallo en las instrucciones para el objetivo 'modules/core/precomp.hpp.gch/opencv_core_Release.gch'
make[2]: *** [modules/core/precomp.hpp.gch/opencv_core_Release.gch] Error 1
CMakeFiles/Makefile2:862: fallo en las instrucciones para el objetivo 'modules/core/CMakeFiles/pch_Generate_opencv_core.dir/all'
make[1]: *** [modules/core/CMakeFiles/pch_Generate_opencv_core.dir/all] Error 2
Makefile:160: fallo en las instrucciones para el objetivo 'all'
make: *** [all] Error 2

---

[StevenPuttemans]

Hello there. Let me give you some pointers here

• Spanish error output won't help you get a solution fast. The main language supported here is English, so sometimes simply translating the whole block could help out.
• Could you please provide us with the full CMAKE output and the configuration you are using?
• To me it seems that your system does not recognize the standard C++ compiler libraries. So could you check which gcc or g++ compiler is installed on your system?

[alalek]

/usr/include/c++/6.1.1/cstdlib:75:25: error fatal: stdlib.h

Both headers are "system" so I agree with @StevenPuttemans and I believe there is nothing to fix in OpenCV directly.
Could you should check your C/C++ compiler and C++ developer library (try to compile some little program with #include <algorithm>).

[reisub-de]

Here is the error message in english:

[  1%] Generating precomp.hpp
[  1%] Generating precomp.hpp.gch/opencv_core_Release.gch
In file included from /usr/include/c++/6.1.1/bits/stl_algo.h:59:0,
                 from /usr/include/c++/6.1.1/algorithm:62,
                 from /home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/core/include/opencv2/core/core.hpp:53,
                 from /home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/core/precomp.hpp:48:
/usr/include/c++/6.1.1/cstdlib:75:25: fatal error: stdlib.h: No such file or directory
 #include_next <stdlib.h>
                         ^
compilation terminated.
modules/core/CMakeFiles/pch_Generate_opencv_core.dir/build.make:62: recipe for target 'modules/core/precomp.hpp.gch/opencv_core_Release.gch' failed
make[2]: *** [modules/core/precomp.hpp.gch/opencv_core_Release.gch] Error 1
CMakeFiles/Makefile2:862: recipe for target 'modules/core/CMakeFiles/pch_Generate_opencv_core.dir/all' failed
make[1]: *** [modules/core/CMakeFiles/pch_Generate_opencv_core.dir/all] Error 2
Makefile:160: recipe for target 'all' failed
make: *** [all] Error 2

This is a behaviour change in GCC 6.1 for -isystem includes
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70129 closed as WONTFIX
Sadly, I'm not that good with complex include dependencies, but I think this should be fixed to be compatible with upcoming gcc releases

[alalek]

@reisub-de Thanks for investigation!

We build OpenCV with enabled warnings (-Wall) to detect possible problems in the contributed code.
And we use -isystem to suppress warnings from 3rdparty includes (there is no way to fix them).

All warnings, other than those generated by ‘#warning’ (see Diagnostics), are suppressed while GCC is processing a system header

https://gcc.gnu.org/onlinedocs/cpp/System-Headers.html

Second reason is problem with some system-wide pre-installed OpenCV packages which put their includes into /usr/include/ directly (Ubuntu, Fedora and many others). Also OpenCV may use some 3rdparty library which INCLUDE_DIR is /usr/include/ and put it into include directories list for compiler. And when OpenCV sources may use mismatched system-wide OpenCV headers...
Unfortunately, current build scripts doesn't provide reliable way to manage include directories order, so some terrible things may arrive (like #6403).
With -isystem we "put" all 3rdparty include directories after OpenCV directories (which are handled with "-I").

All directories named by -isystem are searched after all directories named by -I, no matter what their order was on the command line.

The same link: https://gcc.gnu.org/onlinedocs/cpp/System-Headers.html

@reisub-de Could you try this hack with GCC 6.1?

[reisub-de]

@alalek Ahh, that makes sense

I tried the workaround but it doesn't change it, I get the exact same error message. It looks like the -I for system includes is not applied everywhere (A grep for -isystem still finds some occurences but not as many as without the workaround.

A (hacky) solution I came up with is this:

--- opencv-2.4.12.3/cmake/OpenCVPCHSupport.cmake
+++ opencv-2.4.12.3-patched/cmake/OpenCVPCHSupport.cmake
@@ -24,7 +24,7 @@
     ENDIF()

     SET(_PCH_include_prefix "-I")
-    SET(_PCH_isystem_prefix "-isystem")
+    SET(_PCH_isystem_prefix "-I")
     SET(_PCH_define_prefix "-D")

 ELSEIF(CMAKE_GENERATOR MATCHES "^Visual.*$")

Now it fails much later in the compile process with

[ 47%] Building CXX object modules/contrib/CMakeFiles/opencv_contrib.dir/src/chamfermatching.cpp.o
/home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/contrib/src/chamfermatching.cpp: In member
 function ‘void cv::ChamferMatcher::Matching::computeDistanceTransform(cv::Mat&, cv::Mat&, cv::Mat&
, float, float, float)’:
/home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/contrib/src/chamfermatching.cpp:969:30: er
ror: the compiler can assume that the address of ‘annotate_img’ will never be NULL [-Werror=address
]
             if (&annotate_img!=NULL) {
                              ^
/home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/contrib/src/chamfermatching.cpp:1016:34: e
rror: the compiler can assume that the address of ‘annotate_img’ will never be NULL [-Werror=addres
s]
                 if (&annotate_img!=NULL) {
                                  ^
/home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/contrib/src/chamfermatching.cpp: In member
 function ‘cv::ChamferMatcher::Match* cv::ChamferMatcher::Matching::localChamferDistance(cv::Point,
 cv::Mat&, cv::Mat&, cv::ChamferMatcher::Template*, float)’:
/home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/contrib/src/chamfermatching.cpp:1111:25: e
rror: the compiler can assume that the address of ‘orientation_img’ will never be NULL [-Werror=add
ress]
     if (&orientation_img!=NULL) {
                         ^
/home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/contrib/src/chamfermatching.cpp:1111:5: wa
rning: nonnull argument ‘orientation_img’ compared to NULL [-Wnonnull-compare]
     if (&orientation_img!=NULL) {
     ^~
/home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/contrib/src/chamfermatching.cpp: In member
 function ‘void cv::ChamferMatcher::Matching::computeDistanceTransform(cv::Mat&, cv::Mat&, cv::Mat&
, float, float, float)’:
/home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/contrib/src/chamfermatching.cpp:1016:17: w
arning: nonnull argument ‘annotate_img’ compared to NULL [-Wnonnull-compare]
                 if (&annotate_img!=NULL) {
                 ^~
/home/user/build/opencv2_2/src/opencv-2.4.12.3/modules/contrib/src/chamfermatching.cpp:969:13: wa
rning: nonnull argument ‘annotate_img’ compared to NULL [-Wnonnull-compare]
             if (&annotate_img!=NULL) {
             ^~
cc1plus: some warnings being treated as errors
modules/contrib/CMakeFiles/opencv_contrib.dir/build.make:158: recipe for target 'modules/contrib/CM
akeFiles/opencv_contrib.dir/src/chamfermatching.cpp.o' failed
make[2]: *** [modules/contrib/CMakeFiles/opencv_contrib.dir/src/chamfermatching.cpp.o] Error 1
CMakeFiles/Makefile2:2711: recipe for target 'modules/contrib/CMakeFiles/opencv_contrib.dir/all' fa
iled
make[1]: *** [modules/contrib/CMakeFiles/opencv_contrib.dir/all] Error 2
Makefile:160: recipe for target 'all' failed
make: *** [all] Error 2

[reisub-de]

That last error was fixed here in #5674, after cherrypicking this to 2.4.12.3 it compiles fine with the aforementioned hack.

[alalek]

Thanks for update! I will try to create some workaround for this problem.

[samtux]

I've already solved the installation with solution applied in the Arch Linux package.

Thank you very much for the answers.

[reisub-de]

@alalek @samtux
This should be reopened until opencv itself is patched

[ttsesm]

I can confirm that this issue affects also the master version

[alalek]

This workaround works in some cases (see #6541): cmake -DENABLE_PRECOMPILED_HEADERS=OFF ...