CMake Deprecation Warning at CMakeLists.txt:23 (cmake_policy):
The OLD behavior for policy CMP0046 will be removed from a future version
of CMake.

The cmake-policies(7) manual explains that the OLD behaviors of all
policies are deprecated and that a policy should be set to OLD only under
specific short-term circumstances. Projects should be ported to the NEW
behavior and not rely on setting a policy to OLD.

-- The C compiler identification is AppleClang 11.0.3.11030032
-- The CXX compiler identification is AppleClang 11.0.3.11030032
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc - works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ - broken
CMake Error at /usr/local/Cellar/cmake/3.17.3/share/cmake/Modules/CMakeTestCXXCompiler.cmake:53 (message):
The C++ compiler

"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++"
is not able to compile a simple test program.

It fails with the following output:

Change Dir: /Users/user/Documents/gitpackages/LibreSprite/build/CMakeFiles/CMakeTmp

Run Build Command(s):/Users/user/deps/depot_tools/ninja cmTC_ca431 && [1/2] Building CXX object CMakeFiles/cmTC_ca431.dir/testCXXCompiler.cxx.o
clang: warning: include path for libstdc++ headers not found; pass '-stdlib=libc++' on the command line to use the libc++ standard library instead [-Wstdlibcxx-not-found]
[2/2] Linking CXX executable cmTC_ca431
FAILED: cmTC_ca431
: && /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++  -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk -mmacosx-version-min=10.7 -Wl,-search_paths_first -Wl,-headerpad_max_install_names  CMakeFiles/cmTC_ca431.dir/testCXXCompiler.cxx.o  -o cmTC_ca431   && :
clang: warning: libstdc++ is deprecated; move to libc++ with a minimum deployment target of OS X 10.9 [-Wdeprecated]
ld: library not found for -lstdc++
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.
CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
CMakeLists.txt:39 (project)

-- Configuring incomplete, errors occurred!
See also "/Users/user/Documents/gitpackages/LibreSprite/build/CMakeFiles/CMakeOutput.log".
See also "/Users/user/Documents/gitpackages/LibreSprite/build/CMakeFiles/CMakeError.log".