feat: add chars method for builtin str #767

	name: Build and Test on centos7 amd64
	on:
	pull_request:
	branches:
	- main
	push:
	branches:
	- main
	jobs:
	build-and-test-centos7:
	name: Build and Test on centos7 amd64
	runs-on: ubuntu-latest
	steps:
	- name: Check out code
	uses: actions/checkout@v3
	with:
	submodules: "true"

	- name: Set up QEMU
	uses: docker/setup-qemu-action@v2
	with:
	platforms: linux/amd64

	- name: Set up Docker Buildx
	uses: docker/setup-buildx-action@v2

	- name: Pull custom centos7 Docker image
	run: \|
	docker pull kcllang/kcl-builder:centos7

	# Use llvm7 to build kcl in centos7
	- name: Release
	run: \|
	docker run --rm \
	-v ${{ github.workspace }}:/workspace -w /workspace \
	kcllang/kcl-builder:centos7 \
	/bin/bash -c "export KCL_BUILD_GIT_SHA=$(git rev-parse HEAD) && source ~/.bash_profile && export PATH=$PATH:/opt/build/bin/ && sed -i 's/llvm12/llvm7/g' kclvm/compiler/Cargo.toml && git config --global --add safe.directory /workspace && git config --global user.name 'GitHub Action' && git config --global user.email '[email protected]' && git add . && git commit -m 'chore: bump llvm version to 7.0' && make && make release"

	- name: Show Artifact Version
	run: _build/dist/linux/kclvm/bin/kclvm_cli version

	- name: Read VERSION file
	id: read_version
	run: \|
	VERSION=$(cat VERSION)
	echo "VERSION=v${VERSION}" >> $GITHUB_ENV

	- name: Upload Artifact
	uses: actions/upload-artifact@v4
	with:
	name: kcl-${{ env.VERSION }}-linux-amd64
	if-no-files-found: error
	path: _build/kclvm-${{ env.VERSION }}-linux-amd64.tar.gz

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