From 14032c665335c69d7c9a9944a5be5cae14263324 Mon Sep 17 00:00:00 2001
From: Alexander Alekhin <alexander.alekhin@intel.com>
Date: Mon, 12 Feb 2018 17:30:53 +0300
Subject: [PATCH] cmake: reset __content variable if file doesn't exist

Resolves CMake error after relaunch with updated source code:
Cannot find source file:
    modules/dnn/layers/layers_common.avx512_skx.cpp
---
 cmake/OpenCVCompilerOptimizations.cmake | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/cmake/OpenCVCompilerOptimizations.cmake b/cmake/OpenCVCompilerOptimizations.cmake
index 1ed95eac42..eca540f12b 100644
--- a/cmake/OpenCVCompilerOptimizations.cmake
+++ b/cmake/OpenCVCompilerOptimizations.cmake
@@ -760,6 +760,8 @@ macro(ocv_add_dispatched_file filename)
       set(__file "${CMAKE_CURRENT_BINARY_DIR}/${filename}.${OPT_LOWER}.cpp")
       if(EXISTS "${__file}")
         file(READ "${__file}" __content)
+      else()
+        set(__content "")
       endif()
       if(__content STREQUAL __codestr)
         #message(STATUS "${__file} contains up-to-date content")