Enable CMake policy CMP0077

Projects that import json via [FetchContent](https://cmake.org/cmake/help/latest/module/FetchContent.html) or `add_subdirectory` pointed at a git submodule may want to set `JSON_BuildTests` to "NO". However, this doesn't work without creating an identical `option()` in the importing project. Enabling CMP0077 in supported versions of CMake changes the behavior of `option()` to allow importing projects to set default values for the variables without touching the cache.

See the documentation for CMP0077 here: https://cmake.org/cmake/help/latest/policy/CMP0077.html
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Alex Reinking 2020-06-26 11:47:36 -07:00 committed by GitHub
parent 635b9a0ae4
commit ec43371e07
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@ -15,6 +15,12 @@ include(ExternalProject)
##
## OPTIONS
##
if (POLICY CMP0077)
# Allow CMake 3.13+ to override options when using FetchContent / add_subdirectory.
cmake_policy(SET CMP0077 NEW)
endif ()
option(JSON_BuildTests "Build the unit tests when BUILD_TESTING is enabled." ON)
option(JSON_Install "Install CMake targets during install step." ON)
option(JSON_MultipleHeaders "Use non-amalgamated version of the library." OFF)