From 2d778434f177078ca183be1c299c180befe88461 Mon Sep 17 00:00:00 2001
From: Augusto Fraga Giachero <augustofg96@gmail.com>
Date: Tue, 7 Jan 2020 08:36:35 -0300
Subject: [PATCH] Enable cmake CMP0077 policy

When building OpenCV as a sub-project using cmake's add_subdirectory()
the OpenCV's build options would be overwritten to its default
state. With cmake 3.13+ the CMP0077 policy, option() honors previous
definitions via set().
---
 CMakeLists.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 019f918896..f4a2568db6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -68,6 +68,9 @@ if(POLICY CMP0075)
   cmake_policy(SET CMP0075 NEW)  # CMake 3.12+: Include file check macros honor `CMAKE_REQUIRED_LIBRARIES`
 endif()
 
+if(POLICY CMP0077)
+  cmake_policy(SET CMP0077 NEW)  # CMake 3.13+: option() honors normal variables.
+endif()
 
 #
 # Configure OpenCV CMake hooks