Merge pull request #9218 from alalek:backport_2.4

(2.4) Backport changes from master

CMakeLists.txt

@@ -4,11 +4,16 @@
 #    From the off-tree build directory, invoke:
 #      $ cmake <PATH_TO_OPENCV_ROOT>
 #
-#
-#   - OCT-2008: Initial version <joseluisblancoc@gmail.com>
-#
 # ----------------------------------------------------------------------------
 
+# Disable in-source builds to prevent source tree corruption.
+if(" ${CMAKE_SOURCE_DIR}" STREQUAL " ${CMAKE_BINARY_DIR}")
+  message(FATAL_ERROR "
+FATAL: In-source builds are not allowed.
+       You should create separate directory for build files.
+")
+endif()
+
 set(CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS true)
 
 # Following block can broke build in case of cross-compilng
@@ -1094,13 +1099,6 @@ status("")
 
 ocv_finalize_status()
 
-# ----------------------------------------------------------------------------
-# Warn in the case of in-source build
-# ----------------------------------------------------------------------------
-if("${CMAKE_CURRENT_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_BINARY_DIR}")
-  message(WARNING "The source directory is the same as binary directory. \"make clean\" may damage the source tree")
-endif()
-
 # ----------------------------------------------------------------------------
 # CPack stuff
 # ----------------------------------------------------------------------------

cmake/OpenCVModule.cmake

@@ -172,7 +172,7 @@ macro(ocv_add_module _name)
     project(${the_module})
     add_definitions(
         -D_USE_MATH_DEFINES  # M_PI constant in MSVS
-        -D__STDC_CONSTANT_MACROS -D__STDC_LIMIT_MACROS  # to use C libraries from C++ code (ffmpeg)
+        -D__STDC_CONSTANT_MACROS -D__STDC_LIMIT_MACROS -D__STDC_FORMAT_MACROS  # to use C libraries from C++ code (ffmpeg)
     )
   endif(OPENCV_INITIAL_PASS)
 endmacro()

cmake/OpenCVPCHSupport.cmake

@@ -69,6 +69,9 @@ MACRO(_PCH_GET_COMPILE_FLAGS _out_compile_flags)
     FOREACH(item ${DIRINC})
         if(item MATCHES "^${OpenCV_SOURCE_DIR}/modules/")
           LIST(APPEND ${_out_compile_flags} "${_PCH_include_prefix}\"${item}\"")
+        elseif(CMAKE_COMPILER_IS_GNUCXX AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "6.0" AND
+               item MATCHES "/usr/include$")
+          # workaround for GCC 6.x bug
         else()
           LIST(APPEND ${_out_compile_flags} "${_PCH_isystem_prefix}\"${item}\"")
         endif()
@@ -78,6 +81,9 @@ MACRO(_PCH_GET_COMPILE_FLAGS _out_compile_flags)
     FOREACH(item ${DIRINC})
         if(item MATCHES "^${OpenCV_SOURCE_DIR}/modules/")
           LIST(APPEND ${_out_compile_flags} "${_PCH_include_prefix}\"${item}\"")
+        elseif(CMAKE_COMPILER_IS_GNUCXX AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "6.0" AND
+               item MATCHES "/usr/include$")
+          # workaround for GCC 6.x bug
         else()
           LIST(APPEND ${_out_compile_flags} "${_PCH_isystem_prefix}\"${item}\"")
         endif()

modules/highgui/src/cap_v4l.cpp

@@ -1164,12 +1164,12 @@ static int read_frame_v4l2(CvCaptureCAM_V4L* capture) {
    //printf("got data in buff %d, len=%d, flags=0x%X, seq=%d, used=%d)\n",
    //	  buf.index, buf.length, buf.flags, buf.sequence, buf.bytesused);
 
-   if (-1 == ioctl (capture->deviceHandle, VIDIOC_QBUF, &buf))
-       perror ("VIDIOC_QBUF");
-
    //set timestamp in capture struct to be timestamp of most recent frame
    capture->timestamp = buf.timestamp;
 
+   if (-1 == ioctl (capture->deviceHandle, VIDIOC_QBUF, &buf))
+       perror ("VIDIOC_QBUF");
+
    return 1;
 }