Fix for #8105 (compiling with mingw32)

[msk-repo01]

This pull request fixes #8105

It fixes error for compiling with mingw32
In google/googletest#721 similar issue was fixed for MinGW

[alalek]

👍

[AdeelH]

It seems like the issue has not been entirely fixed. I'm getting the following error when compiling on Windows 10. Any ideas?

[ 45%] Building CXX object modules/ts/CMakeFiles/opencv_ts.dir/src/ts_gtest.cpp.obj
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp: In constructor 'testing::internal::Mutex::Mutex()':
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:8829:45: error: cannot convert 'CRITICAL_SECTION* {aka _RTL_CRITICAL_SECTION*}' to 'GTEST_CRITICAL_SECTION* {aka CRITICAL_SECTION*}' in initialization
critical_section(new CRITICAL_SECTION) {
^
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:8830:48: error: cannot convert 'GTEST_CRITICAL_SECTION* {aka _CRITICAL_SECTION*}' to 'LPCRITICAL_SECTION {aka RTL_CRITICAL_SECTION*}' for argument '1' to 'void InitializeCriticalSection(LPCRITICAL_SECTION)'
::InitializeCriticalSection(critical_section);
^
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp: In destructor 'testing::internal::Mutex::~Mutex()':
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:8840:46: error: cannot convert 'GTEST_CRITICAL_SECTION* {aka CRITICAL_SECTION*}' to 'LPCRITICAL_SECTION {aka RTL_CRITICAL_SECTION*}' for argument '1' to 'void DeleteCriticalSection(LPCRITICAL_SECTION)'
::DeleteCriticalSection(critical_section);
^
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:8841:12: warning: possible problem detected in invocation of delete operator: [enabled by default]
delete critical_section;
^
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:8841:12: warning: invalid use of incomplete type 'struct _CRITICAL_SECTION' [enabled by default]
In file included from D:/opencv/source/opencv/modules/ts/include/opencv2/ts.hpp:28:0,
from D:\opencv\source\opencv\modules\ts\src\precomp.hpp:3,
from D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:39:
D:/opencv/source/opencv/modules/ts/include/opencv2/ts/ts_gtest.h:726:19: warning: forward declaration of 'struct _CRITICAL_SECTION' [enabled by default]
typedef struct CRITICAL_SECTION GTEST_CRITICAL_SECTION;
^
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:8841:12: note: neither the destructor nor the class-specific operator delete will be called, even if they are declared when the class is defined
delete critical_section;
^
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp: In member function 'void testing::internal::Mutex::Lock()':
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:8848:43: error: cannot convert 'GTEST_CRITICAL_SECTION* {aka _CRITICAL_SECTION*}' to 'LPCRITICAL_SECTION {aka RTL_CRITICAL_SECTION*}' for argument '1' to 'void EnterCriticalSection(LPCRITICAL_SECTION)'
::EnterCriticalSection(critical_section);
^
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp: In member function 'void testing::internal::Mutex::Unlock()':
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:8858:43: error: cannot convert 'GTEST_CRITICAL_SECTION* {aka _CRITICAL_SECTION*}' to 'LPCRITICAL_SECTION {aka RTL_CRITICAL_SECTION*}' for argument '1' to 'void LeaveCriticalSection(LPCRITICAL_SECTION)'
::LeaveCriticalSection(critical_section);
^
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp: In member function 'void testing::internal::Mutex::ThreadSafeLazyInit()':
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:8879:27: error: cannot convert 'CRITICAL_SECTION* {aka _RTL_CRITICAL_SECTION*}' to 'GTEST_CRITICAL_SECTION* {aka CRITICAL_SECTION*}' in assignment
critical_section = new CRITICAL_SECTION;
^
D:\opencv\source\opencv\modules\ts\src\ts_gtest.cpp:8880:54: error: cannot convert 'GTEST_CRITICAL_SECTION* {aka _CRITICAL_SECTION*}' to 'LPCRITICAL_SECTION {aka RTL_CRITICAL_SECTION*}' for argument '1' to 'void InitializeCriticalSection(LPCRITICAL_SECTION)'
::InitializeCriticalSection(critical_section);
^
modules\ts\CMakeFiles\opencv_ts.dir\build.make:237: recipe for target 'modules/ts/CMakeFiles/opencv_ts.dir/src/ts_gtest.cpp.obj' failed
mingw32-make[2]: *** [modules/ts/CMakeFiles/opencv_ts.dir/src/ts_gtest.cpp.obj] Error 1
CMakeFiles\Makefile2:9401: recipe for target 'modules/ts/CMakeFiles/opencv_ts.dir/all' failed
mingw32-make[1]: *** [modules/ts/CMakeFiles/opencv_ts.dir/all] Error 2
Makefile:159: recipe for target 'all' failed
mingw32-make: *** [all] Error 2

[alalek]

@AdeelH Could you check this patch from Google tests upstream and create PR into OpenCV?

[Linukl]

KC