Some changes to support mingw-w64

- IPP is disabled by default when compiler is mingw (couldn't make it
work)
- fixed some warnings
- fixed some `__GNUC__` version checks (for correctness and convenience)
- removed UTF-8 BOM from hough.cpp (fixes #5253)

CMakeLists.txt

@@ -171,7 +171,7 @@ OCV_OPTION(WITH_GSTREAMER      "Include Gstreamer support"                   ON
 OCV_OPTION(WITH_GSTREAMER_0_10 "Enable Gstreamer 0.10 support (instead of 1.x)"                              OFF )
 OCV_OPTION(WITH_GTK            "Include GTK support"                         ON   IF (UNIX AND NOT APPLE AND NOT ANDROID) )
 OCV_OPTION(WITH_GTK_2_X        "Use GTK version 2"                           OFF  IF (UNIX AND NOT APPLE AND NOT ANDROID) )
-OCV_OPTION(WITH_IPP            "Include Intel IPP support"                   ON   IF (X86_64 OR X86) AND NOT WINRT)
+OCV_OPTION(WITH_IPP            "Include Intel IPP support"                   ON   IF (X86_64 OR X86) AND NOT WINRT AND NOT MINGW )
 OCV_OPTION(WITH_JASPER         "Include JPEG2K support"                      ON   IF (NOT IOS) )
 OCV_OPTION(WITH_JPEG           "Include JPEG support"                        ON)
 OCV_OPTION(WITH_WEBP           "Include WebP support"                        ON   IF (NOT IOS AND NOT WINRT) )

modules/core/include/opencv2/core/base.hpp

@@ -271,7 +271,7 @@ enum BorderTypes {
 #  endif
 #endif
 #ifndef CV_StaticAssert
-#  if defined(__GNUC__) && (__GNUC__ > 3) && (__GNUC_MINOR__ > 2)
+#  if defined(__GNUC__) && (__GNUC__*100 + __GNUC_MINOR__ > 302)
 #    define CV_StaticAssert(condition, reason) ({ extern int __attribute__((error("CV_StaticAssert: " reason " " #condition))) CV_StaticAssert(); ((condition) ? 0 : CV_StaticAssert()); })
 #  else
      template <bool x> struct CV_StaticAssert_failed;
@@ -296,7 +296,7 @@ enum BorderTypes {
     CV_DO_PRAGMA(warning(push)) \
     CV_DO_PRAGMA(warning(disable: 4996))
 #define CV_SUPPRESS_DEPRECATED_END CV_DO_PRAGMA(warning(pop))
-#elif defined (__clang__) || ((__GNUC__)  && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 5))))
+#elif defined (__clang__) || ((__GNUC__)  && (__GNUC__*100 + __GNUC_MINOR__ > 405))
 #define CV_SUPPRESS_DEPRECATED_START \
     CV_DO_PRAGMA(GCC diagnostic push) \
     CV_DO_PRAGMA(GCC diagnostic ignored "-Wdeprecated-declarations")

modules/core/include/opencv2/core/cuda.inl.hpp

@@ -578,7 +578,7 @@ int DeviceInfo::deviceID() const
 inline
 size_t DeviceInfo::freeMemory() const
 {
-    size_t _totalMemory, _freeMemory;
+    size_t _totalMemory = 0, _freeMemory = 0;
     queryMemory(_totalMemory, _freeMemory);
     return _freeMemory;
 }
@@ -586,7 +586,7 @@ size_t DeviceInfo::freeMemory() const
 inline
 size_t DeviceInfo::totalMemory() const
 {
-    size_t _totalMemory, _freeMemory;
+    size_t _totalMemory = 0, _freeMemory = 0;
     queryMemory(_totalMemory, _freeMemory);
     return _totalMemory;
 }

modules/core/src/system.cpp

@@ -1191,6 +1191,9 @@ TLSData<CoreTLSData>& getCoreTlsData()
     #pragma warning(disable:4447) // Disable warning 'main' signature found without threading model
 #endif
 
+extern "C"
+BOOL WINAPI DllMain(HINSTANCE, DWORD fdwReason, LPVOID lpReserved);
+
 extern "C"
 BOOL WINAPI DllMain(HINSTANCE, DWORD fdwReason, LPVOID lpReserved)
 {

modules/cudalegacy/include/opencv2/cudalegacy/NCVHaarObjectDetection.hpp

@@ -69,7 +69,7 @@
 // Guaranteed size cross-platform classifier structures
 //
 //==============================================================================
-#if defined __GNUC__ && __GNUC__ > 2 && __GNUC_MINOR__  > 4
+#if defined __GNUC__ && (__GNUC__*100 + __GNUC_MINOR__ > 204)
 typedef Ncv32f __attribute__((__may_alias__)) Ncv32f_a;
 #else
 typedef Ncv32f Ncv32f_a;
@@ -208,7 +208,7 @@ struct HaarClassifierNodeDescriptor32
     }
 };
 
-#if defined __GNUC__ && __GNUC__ > 2 && __GNUC_MINOR__  > 4
+#if defined __GNUC__ && (__GNUC__*100 + __GNUC_MINOR__ > 204)
 typedef Ncv32u __attribute__((__may_alias__)) Ncv32u_a;
 #else
 typedef Ncv32u Ncv32u_a;

modules/cudalegacy/src/cuda/NPP_staging.cu

@@ -1593,7 +1593,7 @@ NCVStatus nppsStCompact_32s(Ncv32s *d_src, Ncv32u srcLen,
 }
 
 
-#if defined __GNUC__ && __GNUC__ > 2 && __GNUC_MINOR__  > 4
+#if defined __GNUC__ && (__GNUC__*100 + __GNUC_MINOR__ > 204)
 typedef Ncv32u __attribute__((__may_alias__)) Ncv32u_a;
 #else
 typedef Ncv32u Ncv32u_a;

modules/features2d/src/agast.cpp

@@ -45,7 +45,7 @@ The references are:
 #include "precomp.hpp"
 #include "agast_score.hpp"
 
-#ifdef _WIN32
+#ifdef _MSC_VER
 #pragma warning( disable : 4127 )
 #endif
 

modules/features2d/src/agast_score.cpp

@@ -44,7 +44,7 @@ The references are:
 
 #include "agast_score.hpp"
 
-#ifdef _WIN32
+#ifdef _MSC_VER
 #pragma warning( disable : 4127 )
 #endif
 

modules/highgui/src/window_w32.cpp

@@ -2036,8 +2036,8 @@ icvCreateTrackbar( const char* trackbar_name, const char* window_name,
     trackbar = icvFindTrackbarByName(window,trackbar_name);
     if( !trackbar )
     {
-        TBBUTTON tbs = {0};
-        TBBUTTONINFO tbis = {0};
+        TBBUTTON tbs = {};
+        TBBUTTONINFO tbis = {};
         RECT rect;
         int bcount;
         int len = (int)strlen( trackbar_name );

modules/imgcodecs/src/grfmt_jpeg.cpp

@@ -213,7 +213,7 @@ ImageDecoder JpegDecoder::newDecoder() const
 
 bool  JpegDecoder::readHeader()
 {
-    bool result = false;
+    volatile bool result = false;
     close();
 
     JpegState* state = new JpegState;

modules/imgcodecs/src/grfmt_png.cpp

@@ -140,7 +140,7 @@ void  PngDecoder::readDataFromBuf( void* _png_ptr, uchar* dst, size_t size )
 
 bool  PngDecoder::readHeader()
 {
-    bool result = false;
+    volatile bool result = false;
     close();
 
     png_structp png_ptr = png_create_read_struct( PNG_LIBPNG_VER_STRING, 0, 0, 0 );

modules/imgproc/src/hough.cpp

@@ -1,4 +1,4 @@
-/*M///////////////////////////////////////////////////////////////////////////////////////
+/*M///////////////////////////////////////////////////////////////////////////////////////
 //
 //  IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
 //

modules/videoio/src/cap_dshow.cpp

@@ -93,6 +93,11 @@ Thanks to:
 #pragma warning(disable: 4995)
 #endif
 
+#ifdef __MINGW32__
+// MinGW does not understand COM interfaces
+#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
+#endif
+
 #include <tchar.h>
 #include <stdlib.h>
 #include <stdio.h>

platforms/android/build_sdk.py

@@ -10,16 +10,16 @@ class Fail(Exception):
     def __str__(self):
         return "ERROR" if self.t is None else self.t
 
-def execute(cmd):
+def execute(cmd, shell=False):
     try:
         log.info("Executing: %s" % cmd)
-        retcode = subprocess.call(cmd)
+        retcode = subprocess.call(cmd, shell=shell)
         if retcode < 0:
             raise Fail("Child was terminated by signal:" %s -retcode)
         elif retcode > 0:
             raise Fail("Child returned: %s" % retcode)
     except OSError as e:
-        raise Fail("Execution failed: %s" % e)
+        raise Fail("Execution failed: %s" % e.strerror)
 
 def rm_one(d):
     d = os.path.abspath(d)
@@ -180,7 +180,7 @@ class Builder:
             log.info("Generating XML config: %s", xmlname)
             ET.ElementTree(r).write(xmlname, encoding="utf-8")
         execute(["ninja", "opencv_engine"])
-        execute(["ant", "-f", os.path.join(apkdest, "build.xml"), "debug"])
+        execute(["ant", "-f", os.path.join(apkdest, "build.xml"), "debug"], shell=True)
         # TODO: Sign apk
 
     def build_javadoc(self):
@@ -278,12 +278,13 @@ if __name__ == "__main__":
     log.info("Detected OpenCV version: %s", builder.opencv_version)
     log.info("Detected Engine version: %s", builder.engine_version)
 
-    for one in args.extra_pack:
-        i = one.find(":")
-        if i > 0 and i < len(one) - 1:
-            builder.add_extra_pack(one[:i], one[i+1:])
-        else:
-            raise Fail("Bad extra pack provided: %s, should be in form '<version>:<path-to-native-libs>'" % one)
+    if args.extra_pack:
+        for one in args.extra_pack:
+            i = one.find(":")
+            if i > 0 and i < len(one) - 1:
+                builder.add_extra_pack(one[:i], one[i+1:])
+            else:
+                raise Fail("Bad extra pack provided: %s, should be in form '<version>:<path-to-native-libs>'" % one)
 
     engines = []
     for i, abi in enumerate(ABIs):