From 81c5fae56fdd3566703b970f1cebfc8266ab609f Mon Sep 17 00:00:00 2001
From: Alexander Alekhin <alexander.alekhin@intel.com>
Date: Wed, 24 Jan 2018 14:53:04 +0300
Subject: [PATCH] core(lapack): fix build issues related to 'extern "C"'

---
 cmake/OpenCVFindLAPACK.cmake      | 2 +-
 cmake/checks/lapack_check.cpp     | 1 +
 modules/core/src/hal_internal.cpp | 1 +
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/cmake/OpenCVFindLAPACK.cmake b/cmake/OpenCVFindLAPACK.cmake
index f4f9415..6848180 100644
--- a/cmake/OpenCVFindLAPACK.cmake
+++ b/cmake/OpenCVFindLAPACK.cmake
@@ -31,7 +31,7 @@ macro(ocv_lapack_check)
   else()
     # adding proxy opencv_lapack.h header
     set(CBLAS_H_PROXY_PATH ${CMAKE_BINARY_DIR}/opencv_lapack.h)
-    if(APPLE)
+    if((APPLE OR OPENCV_SKIP_LAPACK_EXTERN_C) AND NOT OPENCV_FORCE_LAPACK_EXTERN_C)
         set(_lapack_include_str_extern_C "")
         set(_lapack_include_str_extern_C_end "")
     else()
diff --git a/cmake/checks/lapack_check.cpp b/cmake/checks/lapack_check.cpp
index 0457c44..6ac104b 100644
--- a/cmake/checks/lapack_check.cpp
+++ b/cmake/checks/lapack_check.cpp
@@ -1,3 +1,4 @@
+#include <complex.h>
 #include "opencv_lapack.h"
 
 static char* check_fn1 = (char*)sgesv_;
diff --git a/modules/core/src/hal_internal.cpp b/modules/core/src/hal_internal.cpp
index d98cd30..ecf5ffa 100644
--- a/modules/core/src/hal_internal.cpp
+++ b/modules/core/src/hal_internal.cpp
@@ -46,6 +46,7 @@
 
 #ifdef HAVE_LAPACK
 
+#include <complex.h>
 #include "opencv_lapack.h"
 
 #include <cmath>
-- 
2.7.4