From ef2548778c173fe77495a0f41f3c6106c48949a0 Mon Sep 17 00:00:00 2001
From: Alexander Alekhin <alexander.alekhin@intel.com>
Date: Tue, 24 Apr 2018 14:27:17 +0300
Subject: [PATCH] build: -Wimplicit-fallthrough warning for GCC 7+ only

---
 cmake/OpenCVCompilerOptions.cmake | 4 +++-
 modules/videoio/src/cap.cpp       | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/cmake/OpenCVCompilerOptions.cmake b/cmake/OpenCVCompilerOptions.cmake
index b9293df1b6..774103af3a 100644
--- a/cmake/OpenCVCompilerOptions.cmake
+++ b/cmake/OpenCVCompilerOptions.cmake
@@ -120,7 +120,9 @@ if(CV_GCC OR CV_CLANG)
     add_extra_compiler_option(-Wno-unnamed-type-template-args)
     add_extra_compiler_option(-Wno-comment)
     if(NOT OPENCV_SKIP_IMPLICIT_FALLTHROUGH
-        AND NOT " ${CMAKE_CXX_FLAGS} ${OPENCV_EXTRA_FLAGS} ${OPENCV_EXTRA_CXX_FLAGS}" MATCHES "implicit-fallthrough")
+        AND NOT " ${CMAKE_CXX_FLAGS} ${OPENCV_EXTRA_FLAGS} ${OPENCV_EXTRA_CXX_FLAGS}" MATCHES "implicit-fallthrough"
+        AND (CV_GCC AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 7.0.0)
+    )
       add_extra_compiler_option(-Wimplicit-fallthrough=3)
     endif()
     if(CV_GCC AND CMAKE_CXX_COMPILER_VERSION VERSION_EQUAL 7.2.0)
diff --git a/modules/videoio/src/cap.cpp b/modules/videoio/src/cap.cpp
index 33f7973636..67e1befca2 100644
--- a/modules/videoio/src/cap.cpp
+++ b/modules/videoio/src/cap.cpp
@@ -65,7 +65,7 @@ using namespace std;
 #if defined(__clang__)
 #pragma clang diagnostic ignored "-Wimplicit-fallthrough"
 #endif
-#if defined(__GNUC__)
+#if defined(__GNUC__) && __GNUC__ >= 7
 #pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
 #endif