Merge pull request #15966 from saskatchewancatch:issue-15760

Add checks for empty operands in Matrix expressions that don't check properly

* Starting to add checks for empty operands in Matrix expressions that
don't check properly.

* Adding checks and delcarations for checker functions

* Fix signatures and add checks for each class of Matrix Expr operation

* Make it catch the right exception

* Don't expose helper functions to public API

modules/calib3d/test/test_undistort_badarg.cpp

@@ -270,7 +270,7 @@ void CV_UndistortPointsBadArgTest::run(int)
     cvReleaseMat(&temp);
 
     src_points = cv::Mat();
-    errcount += run_test_case( CV_StsAssert, "Input data matrix is not continuous" );
+    errcount += run_test_case( CV_StsBadArg, "Input data matrix is not continuous" );
     src_points = cv::cvarrToMat(&_src_points_orig);
     cvReleaseMat(&temp);
 

modules/core/test/test_operations.cpp

@@ -1467,4 +1467,19 @@ TEST(Core_sortIdx, regression_8941)
         "expected=" << std::endl << expected;
 }
 
+
+//These tests guard regressions against running MatExpr
+//operations on empty operands and giving bogus
+//results.
+TEST(Core_MatExpr, empty_check_15760)
+{
+    EXPECT_THROW(Mat c = min(Mat(), Mat()), cv::Exception);
+    EXPECT_THROW(Mat c = abs(Mat()), cv::Exception);
+    EXPECT_THROW(Mat c = min(Mat(), Mat()), cv::Exception);
+    EXPECT_THROW(Mat c = Mat() | Mat(), cv::Exception);
+    EXPECT_THROW(Mat c = Mat() + Mat(), cv::Exception);
+    EXPECT_THROW(Mat c = Mat().t(), cv::Exception);
+    EXPECT_THROW(Mat c = Mat().cross(Mat()), cv::Exception);
+}
+
 }} // namespace