change in cmake files such that eval_expr.cpp is compiled only once #99

	name: CI testing

	on:
	push:
	branches: [ master ]
	paths-ignore:
	- 'docs/**'
	- 'README.md'
	pull_request:
	branches: [ master ]
	paths-ignore:
	- 'docs/**'
	- 'README.md'

	env:
	# Customize the CMake build type here (Release, Debug, RelWithDebInfo, etc.)
	BUILD_TYPE: Release

	jobs:
	linux-build:
	# The CMake configure and build commands are platform agnostic and should work equally
	# well on Windows or Mac. You can convert this to a matrix build if you need
	# cross-platform coverage.
	# See: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/managing-complex-workflows#using-a-build-matrix
	runs-on: ubuntu-latest

	steps:
	- uses: actions/checkout@v2

	- name: Install packages
	run: \|
	sudo apt update
	sudo apt install cmake cmake-data build-essential
	sudo apt install libgmp-dev
	- name: Configure CMake
	# Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.
	# See https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html?highlight=cmake_build_type
	run: cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}}

	- name: Build
	# Build your program with the given configuration
	run: cmake --build ${{github.workspace}}/build --config ${{env.BUILD_TYPE}}

	- name: Test
	working-directory: ${{github.workspace}}/build
	# Execute tests defined by the CMake configuration.
	# See https://cmake.org/cmake/help/latest/manual/ctest.1.html for more detail
	run: ctest -C ${{env.BUILD_TYPE}}

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