From c92c99ed0b8c176bf19e82e1ba84c21de7e706b4 Mon Sep 17 00:00:00 2001
From: Maksim Shabunin <maksim.shabunin@gmail.com>
Date: Thu, 7 Sep 2017 11:35:14 +0300
Subject: [PATCH] Enabled forEach for const Mats

---
 modules/core/include/opencv2/core/mat.inl.hpp |  2 +-
 modules/core/test/test_mat.cpp                | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/modules/core/include/opencv2/core/mat.inl.hpp b/modules/core/include/opencv2/core/mat.inl.hpp
index 84452881e9..2ef7aec3c6 100644
--- a/modules/core/include/opencv2/core/mat.inl.hpp
+++ b/modules/core/include/opencv2/core/mat.inl.hpp
@@ -1214,7 +1214,7 @@ void Mat::forEach(const Functor& operation) {
 template<typename _Tp, typename Functor> inline
 void Mat::forEach(const Functor& operation) const {
     // call as not const
-    (const_cast<Mat*>(this))->forEach<const _Tp>(operation);
+    (const_cast<Mat*>(this))->forEach<_Tp>(operation);
 }
 
 template<typename _Tp> inline
diff --git a/modules/core/test/test_mat.cpp b/modules/core/test/test_mat.cpp
index 70675127ba..6c2ab85c3c 100644
--- a/modules/core/test/test_mat.cpp
+++ b/modules/core/test/test_mat.cpp
@@ -671,6 +671,13 @@ struct InitializerFunctor5D{
     }
 };
 
+template<typename Pixel>
+struct EmptyFunctor
+{
+    void operator()(const Pixel &, const int *) const {}
+};
+
+
 void Core_ArrayOpTest::run( int /* start_from */)
 {
     int errcount = 0;
@@ -799,6 +806,17 @@ void Core_ArrayOpTest::run( int /* start_from */)
         }
     }
 
+    // test const cv::Mat::forEach
+    {
+        const Mat a(10, 10, CV_32SC3);
+        Mat b(10, 10, CV_32SC3);
+        const Mat & c = b;
+        a.forEach<Point3i>(EmptyFunctor<Point3i>());
+        b.forEach<Point3i>(EmptyFunctor<const Point3i>());
+        c.forEach<Point3i>(EmptyFunctor<Point3i>());
+        // tests compilation, no runtime check is needed
+    }
+
     RNG rng;
     const int MAX_DIM = 5, MAX_DIM_SZ = 10;
     // sparse matrix operations