build.py

#!/usr/bin/env python3

# Copyright (c) Microsoft Corporation.
# Licensed under the MIT License.

import argparse
import os
import platform
import sys
import time
import venv
import shutil
import subprocess
import functools
import tomllib

from prereqs import check_prereqs, add_wasm_tools_to_path

# Disable buffered output so that the log statements and subprocess output get interleaved in proper order
print = functools.partial(print, flush=True)

parser = argparse.ArgumentParser(
    description="Builds all projects in the repo, unless specific projects to build are passed "
    "as options, in which case only those projects are built."
)

parser.add_argument(
    "--cli", action="store_true", help="Build the command-line compiler"
)
parser.add_argument("--pip", action="store_true", help="Build the pip wheel")
parser.add_argument("--widgets", action="store_true", help="Build the Python widgets")
parser.add_argument("--qdk", action="store_true", help="Build the qdk meta-package")
parser.add_argument("--wasm", action="store_true", help="Build the WebAssembly files")
parser.add_argument("--npm", action="store_true", help="Build the npm package")
parser.add_argument("--play", action="store_true", help="Build the web playground")
parser.add_argument("--vscode", action="store_true", help="Build the VS Code extension")
parser.add_argument(
    "--jupyterlab", action="store_true", help="Build the JupyterLab extension"
)

parser.add_argument(
    "--debug", action="store_true", help="Create a debug build (default is release)"
)
parser.add_argument(
    "--test",
    action=argparse.BooleanOptionalAction,
    default=True,
    help="Run the tests (default is --test)",
)

# Below allows for passing --no-check to avoid the default of True
parser.add_argument(
    "--check",
    action=argparse.BooleanOptionalAction,
    default=True,
    help="Run the linting and formatting checks (default is --check)",
)

parser.add_argument(
    "--check-prereqs",
    action=argparse.BooleanOptionalAction,
    default=True,
    help="Run the prerequisites check (default is --check-prereqs)",
)

parser.add_argument(
    "--integration-tests",
    action=argparse.BooleanOptionalAction,
    default=False,
    help="Build and run the integration tests (default is --no-integration-tests)",
)

parser.add_argument(
    "--web-only",
    action=argparse.BooleanOptionalAction,
    default=False,
    help="Build only the web version of the wasm package",
)

parser.add_argument(
    "--ci-bench",
    action=argparse.BooleanOptionalAction,
    default=False,
    help="Run the benchmarking script that is run in CI (default is --no-ci-bench)",
)

parser.add_argument(
    "--gpu-tests",
    action=argparse.BooleanOptionalAction,
    default=False,
    help="Run the GPU simulator tests (default is --no-gpu-tests)",
)

parser.add_argument(
    "--optional-dependencies",
    action=argparse.BooleanOptionalAction,
    default=True,
    help="Include optional dependencies (default is --optional-dependencies)",
)

args = parser.parse_args()

if args.check_prereqs:
    check_prereqs()

# If no specific project given then build all
build_all = (
    not args.cli
    and not args.pip
    and not args.widgets
    and not args.qdk
    and not args.wasm
    and not args.npm
    and not args.play
    and not args.vscode
    and not args.jupyterlab
    and not args.ci_bench
)
build_cli = build_all or args.cli
build_pip = build_all or args.pip
build_widgets = build_all or args.widgets
build_qdk = build_all or args.qdk
build_wasm = build_all or args.wasm
build_npm = build_all or args.npm
build_play = build_all or args.play
build_vscode = build_all or args.vscode
build_jupyterlab = build_all or args.jupyterlab
ci_bench = args.ci_bench

# JavaScript projects and eslint, prettier depend on npm_install
# However the JupyterLab extension uses yarn in a separate workspace
npm_install_needed = (
    build_npm or build_play or build_vscode or build_jupyterlab or args.check
)
npm_cmd = "npm.cmd" if platform.system() == "Windows" else "npm"

build_type = "debug" if args.debug else "release"
wasm_targets = ["web", "nodejs"] if not args.web_only else ["web"]
run_tests = args.test

root_dir = os.path.dirname(os.path.abspath(__file__))
qdk_src_dir = os.path.join(root_dir, "source")
wasm_src = os.path.join(qdk_src_dir, "wasm")
wasm_bld = os.path.join(root_dir, "target", "wasm32", build_type)
samples_src = os.path.join(root_dir, "samples")
npm_src = os.path.join(qdk_src_dir, "npm", "qsharp")
play_src = os.path.join(qdk_src_dir, "playground")
pip_src = os.path.join(qdk_src_dir, "pip")
widgets_src = os.path.join(qdk_src_dir, "widgets")
qdk_python_src = os.path.join(qdk_src_dir, "qdk_package")
wheels_dir = os.path.join(root_dir, "target", "wheels")
raw_wheels_dir = os.path.join(root_dir, "target", "raw_wheels")
vscode_src = os.path.join(qdk_src_dir, "vscode")
jupyterlab_src = os.path.join(qdk_src_dir, "jupyterlab")

QISKIT_VERSION_MATRIX = [
    {
        "label": "qiskit>=1.3.0,<2.0.0",
        "requirements": ["qiskit>=1.3.0,<2.0.0"],
    },
    {
        "label": "qiskit>=2.0.0,<3.0.0",
        "requirements": ["qiskit>=2.0.0,<3.0.0"],
    },
]


def step_start(description):
    global start_time
    prefix = "::group::" if os.getenv("GITHUB_ACTIONS") == "true" else ""
    print(f"{prefix}build.py: {description}")
    start_time = time.time()


def step_end():
    global start_time
    duration = time.time() - start_time
    print(f"build.py: Finished in {duration:.3f}s.")
    if os.getenv("GITHUB_ACTIONS") == "true":
        print(f"::endgroup::")


def install_build_package(cwd, interpreter):
    # Ensure that the 'build' package is installed in the given interpreter
    command_args = [
        interpreter,
        "-m",
        "pip",
        "install",
        "build",
        "-v",
    ]
    subprocess.run(command_args, check=True, text=True, cwd=cwd)


def use_python_env(folder):
    # Copy the process env vars to modify for pip subprocess calls
    pip_env = os.environ.copy()

    # Check if in a virtual environment
    if (
        os.environ.get("VIRTUAL_ENV") is None
        and os.environ.get("CONDA_PREFIX") is None
        and os.environ.get("CI") is None
    ):
        print("Not in a virtual python environment")

        venv_dir = os.path.join(folder, ".venv")
        # Create virtual environment under repo root
        if not os.path.exists(venv_dir):
            print(f"Creating a virtual environment under {venv_dir}")
            venv.main([venv_dir])

        # Check if .venv/bin/python exists, otherwise use .venv/Scripts/python.exe (Windows)
        python_bin = os.path.join(venv_dir, "bin", "python")
        if not os.path.exists(python_bin):
            python_bin = os.path.join(venv_dir, "Scripts", "python.exe")
        print(f"Using python from {python_bin}")

        # Update the PATH in the pip_env to include the current interpreter's bin/ directory
        pip_env["PATH"] = (
            os.path.dirname(python_bin) + os.pathsep + pip_env.get("PATH", "")
        )
        pip_env["VIRTUAL_ENV"] = os.path.dirname(os.path.dirname(python_bin))
    else:
        # Already in a virtual environment, use current Python
        python_bin = sys.executable

    install_build_package(qdk_python_src, python_bin)

    return (python_bin, pip_env)


if npm_install_needed:
    command = [npm_cmd, "install"]
    if not args.optional_dependencies:
        command.append("--omit")
        command.append("optional")

    step_start("Running npm install")
    subprocess.run(command, check=True, text=True, cwd=root_dir)
    step_end()

if args.check:
    step_start("Running eslint and prettier checks")
    try:
        subprocess.run([npm_cmd, "run", "check"], check=True, text=True, cwd=root_dir)
    except subprocess.CalledProcessError:
        print("Consider running 'npm run prettier:fix' to fix prettier errors.")
        raise

    if build_wasm or build_cli:
        # If we're going to check the Rust code, do this before we try to compile it
        print("Running the cargo fmt and clippy checks")
        subprocess.run(
            ["cargo", "fmt", "--all", "--", "--check"],
            check=True,
            text=True,
            cwd=root_dir,
        )
        subprocess.run(
            [
                "cargo",
                "clippy",
                "--all-targets",
                "--all-features",
                "--",
                "-D",
                "warnings",
            ],
            check=True,
            text=True,
            cwd=root_dir,
        )

    if build_cli:
        print("Running Q# format check")
        subprocess.run(
            [
                "cargo",
                "run",
                "--bin",
                "qsc_formatter",
                "--",
                "./library/",
                "./samples/",
                "-r",
            ],
            check=True,
            text=True,
            cwd=root_dir,
        )
    step_end()

if build_cli:
    if run_tests:
        step_start("Running Rust unit tests")
        cargo_test_args = ["cargo", "test"]
        if build_type == "release":
            cargo_test_args.append("--release")
            # Disable LTO for release tests to speed up compilation
            cargo_test_args.append("--config")
            cargo_test_args.append('profile.release.lto="off"')
        subprocess.run(cargo_test_args, check=True, text=True, cwd=root_dir)
        step_end()


def install_qsharp_python_package(cwd, wheelhouse, interpreter):
    command_args = [
        interpreter,
        "-m",
        "pip",
        "install",
        "--force-reinstall",
        "--no-index",
        "--find-links=" + wheelhouse,
        "qsharp",
    ]
    subprocess.run(command_args, check=True, text=True, cwd=cwd)


# If any package fails to install when using a requirements file, the entire
# process will fail with unpredicatable state of installed packages. To avoid
# this, we install each package individually from the requirements file.
#
# The reason we allow failures is that tooling for integration tests may not
# be available on all platforms, so we don't want to fail the build if we can't
# run the tests. The CI will run the tests on the platforms where the tooling
# is available giving us the confidence that the tests pass on those platforms.
def install_python_test_requirements(cwd, interpreter, check: bool = True):
    requirements_file_path = os.path.join(cwd, "test_requirements.txt")
    with open(requirements_file_path, "r", encoding="utf-8") as f:
        # Skip empty or commented lines so version-specific packages can be injected separately.
        requirements = [
            line.strip()
            for line in f
            if line.strip() and not line.strip().startswith("#")
        ]
    for requirement in requirements:
        command_args = [
            interpreter,
            "-m",
            "pip",
            "install",
            requirement,
            "--only-binary",
            "qirrunner",
            "--only-binary",
            "pyqir",
        ]
        subprocess.run(command_args, check=check, text=True, cwd=cwd)


def build_qsharp_wheel(cwd, interpreter, pip_env):
    # Read the build dependencies out of the pyproject.toml and install them first.
    with open(os.path.join(cwd, "pyproject.toml"), "rb") as f:
        requires = tomllib.load(f)["build-system"]["requires"]

    command_args = [interpreter, "-m", "pip", "install", *requires]
    subprocess.run(command_args, check=True, text=True, cwd=cwd, env=pip_env)

    command_args = [
        interpreter,
        "-m",
        "build",
        "--no-isolation",
        "--wheel",
        "-v",
    ]

    # On Linux, add the --compatibility flag to ensure manylinux wheels are built
    if platform.system() == "Linux":
        command_args.append("--config-setting=build-args='--compatibility'")

    # maturin will build into this folder and copy it to target/wheels.
    # setting out --outdir to target/wheels will cause the build to fail
    # as the input and output path will be the same when maturin tries
    # to copy the built wheel after processing. So we build into a raw_wheels folder
    command_args.append("--outdir")
    command_args.append(raw_wheels_dir)

    command_args.append(cwd)

    subprocess.run(command_args, check=True, text=True, cwd=cwd, env=pip_env)


def run_python_tests(cwd, interpreter, pip_env):
    test_env = pip_env.copy()
    if args.gpu_tests:
        test_env["QDK_GPU_TESTS"] = "1"

    command_args = [interpreter, "-m", "pytest"]
    subprocess.run(command_args, check=True, text=True, cwd=cwd, env=test_env)


def run_python_integration_tests(cwd, interpreter):
    # don't check to see if pip succeeds. We'll see if the import works later.
    # If it doesn't, we'll skip the tests.
    command_args = [interpreter, "-m", "pytest"]
    subprocess.run(command_args, check=True, text=True, cwd=cwd)


def run_ci_historic_benchmark():
    branch = "main"
    output = subprocess.check_output(
        [
            "git",
            "rev-list",
            "--since=1 week ago",
            "--pretty=format:%ad__%h",
            "--date=short",
            branch,
        ]
    ).decode("utf-8")
    print("\n".join([line for i, line in enumerate(output.split("\n")) if i % 2 == 1]))

    output = subprocess.check_output(
        [
            "git",
            "rev-list",
            "--since=1 week ago",
            "--pretty=format:%ad__%h",
            "--date=short",
            branch,
        ]
    ).decode("utf-8")
    date_and_commits = [line for i, line in enumerate(output.split("\n")) if i % 2 == 1]

    for date_and_commit in date_and_commits:
        print("benching commit", date_and_commit)
        result = subprocess.run(
            [
                "cargo",
                "criterion",
                "--message-format=json",
                "--history-id",
                date_and_commit,
            ],
            capture_output=True,
            text=True,
        )
        with open(f"{date_and_commit}.json", "w") as f:
            f.write(result.stdout)


if build_pip:
    step_start("Building the pip package")

    (python_bin, pip_env) = use_python_env(pip_src)

    build_qsharp_wheel(pip_src, python_bin, pip_env)
    step_end()

    if run_tests:
        step_start("Running tests for the pip package")

        install_python_test_requirements(pip_src, python_bin)
        install_qsharp_python_package(pip_src, wheels_dir, python_bin)
        run_python_tests(os.path.join(pip_src, "tests"), python_bin, pip_env)

        step_end()

    if args.integration_tests:
        test_dir = os.path.join(pip_src, "tests-integration")
        install_python_test_requirements(test_dir, python_bin, check=False)

        for version in QISKIT_VERSION_MATRIX:
            step_start(
                f"Running integration tests for the pip package ({version['label']})"
            )

            version_install_args = [
                python_bin,
                "-m",
                "pip",
                "install",
                "--upgrade",
                "--upgrade-strategy",
                "eager",
            ] + version["requirements"]
            subprocess.run(version_install_args, check=True, text=True, cwd=test_dir)

            install_qsharp_python_package(pip_src, wheels_dir, python_bin)

            run_python_integration_tests(test_dir, python_bin)

            step_end()


if build_qdk:
    step_start("Building the qdk python package")

    # Reuse (or create) the pip environment so qsharp wheel can be built/installed consistently.
    (python_bin, pip_env) = use_python_env(qdk_python_src)

    # Build the qdk wheel (no dependency build needed; it's a thin meta-package)
    qdk_build_args = [
        python_bin,
        "-m",
        "build",
        "--wheel",
        "-v",
        "--outdir",
        wheels_dir,
        qdk_python_src,
    ]
    subprocess.run(qdk_build_args, check=True, text=True, cwd=qdk_python_src)
    step_end()

    if run_tests:
        step_start("Running tests for the qdk python package")
        # Install per-package test requirements (pytest, etc.)
        install_python_test_requirements(qdk_python_src, python_bin)

        # Install qsharp wheel first so dependency resolution is offline & version-synced.
        install_qsharp_python_package(qdk_python_src, wheels_dir, python_bin)

        # Install qdk itself from the freshly built wheel (force to ensure isolation)
        install_args = [
            python_bin,
            "-m",
            "pip",
            "install",
            "--force-reinstall",
            "--no-index",
            "--no-deps",
            "--find-links=" + wheels_dir,
            "qdk",
            "qsharp",
        ]
        subprocess.run(install_args, check=True, text=True, cwd=qdk_python_src)

        # Run its test suite
        run_python_tests(os.path.join(qdk_python_src, "tests"), python_bin, pip_env)
        step_end()

if build_widgets:
    step_start("Building the Python widgets")

    (python_bin, _) = use_python_env(qdk_python_src)

    widgets_build_args = [
        python_bin,
        "-m",
        "build",
        "--wheel",
        "-v",
        "--outdir",
        wheels_dir,
        widgets_src,
    ]
    subprocess.run(widgets_build_args, check=True, text=True, cwd=widgets_src)

    step_end()

if build_wasm:
    step_start("Building the wasm files")

    add_wasm_tools_to_path()  # Run again here in case --no-check-prereqs was passed

    platform_sys = platform.system().lower()  # 'windows', 'darwin', or 'linux'

    # First build the wasm crate with something like:
    #   cargo build --lib [--release] --target wasm32-unknown-unknown --target-dir ./target
    #
    # Binary will be written to ./target/wasm32-unknown-unknown/{debug,release}/qsc_wasm.wasm
    cargo_args = [
        "cargo",
        "build",
        "--lib",
        "--target",
        "wasm32-unknown-unknown",
    ]
    if build_type == "release":
        cargo_args.append("--release")
    subprocess.run(cargo_args, check=True, text=True, cwd=wasm_src)

    # Next, create the JavaScript glue code using wasm-bindgen with something like:
    #   wasm-bindgen --target <nodejs|web> [--debug] --out-dir ./target/wasm32/{release,debug}/{nodejs|web} <infile>
    #
    # The output will be written to {out-dir}/qsc_wasm_bg.wasm
    for target_platform in wasm_targets:
        out_dir = os.path.join(wasm_bld, target_platform)
        in_file = os.path.join(
            root_dir, "target", "wasm32-unknown-unknown", build_type, "qsc_wasm.wasm"
        )

        wasm_bindgen_args = [
            "wasm-bindgen",
            "--target",
            target_platform,
            "--out-dir",
            out_dir,
        ]
        if build_type == "debug":
            wasm_bindgen_args.append("--debug")
        wasm_bindgen_args.append(in_file)

        subprocess.run(wasm_bindgen_args, check=True, text=True, cwd=wasm_src)

        # Also run wasm-opt to optimize the wasm file for release builds with:
        #   wasm-opt -Oz --enable-{<as needed>} --output <outfile> <infile>
        #
        # -Oz does extra size optimizations, and features are enabled to match Rust defaults
        # to avoid mismatch errors, as wasm-opt currently disables some of these by default.
        # See <https://doc.rust-lang.org/rustc/platform-support/wasm32-unknown-unknown.html#enabled-webassembly-features>
        #
        # This updates the wasm file in place.
        #
        # Note: wasm-opt is not needed for debug builds, so we only run it for release builds.
        if build_type == "release":
            wasm_file = os.path.join(out_dir, "qsc_wasm_bg.wasm")
            wasm_opt_args = [
                "wasm-opt",
                "-Oz",
                "--enable-bulk-memory",
                "--enable-nontrapping-float-to-int",
                "--output",
                wasm_file,
                wasm_file,
            ]
            subprocess.run(wasm_opt_args, check=True, text=True, cwd=wasm_src)

        # After building, copy the artifacts to the npm location
        lib_dir = os.path.join(npm_src, "lib", target_platform)
        os.makedirs(lib_dir, exist_ok=True)

        for filename in ["qsc_wasm_bg.wasm", "qsc_wasm.d.ts", "qsc_wasm.js"]:
            fullpath = os.path.join(out_dir, filename)

            # To make the node files CommonJS modules, the extension needs to change
            # (This is because the package is set to ECMAScript modules by default)
            if target_platform == "nodejs" and filename == "qsc_wasm.js":
                filename = "qsc_wasm.cjs"
            if target_platform == "nodejs" and filename == "qsc_wasm.d.ts":
                filename = "qsc_wasm.d.cts"

            shutil.copy2(fullpath, os.path.join(lib_dir, filename))

    step_end()

if build_npm:
    step_start("Building the npm package")

    npm_args = [npm_cmd, "run", "build"]
    subprocess.run(npm_args, check=True, text=True, cwd=npm_src)

    if run_tests:
        print("Running tests for the npm package")
        npm_test_args = ["node", "--test"]
        subprocess.run(npm_test_args, check=True, text=True, cwd=npm_src)
    step_end()

if build_play:
    step_start("Building the playground")
    play_args = [npm_cmd, "run", "build"]
    subprocess.run(play_args, check=True, text=True, cwd=play_src)
    step_end()

if build_vscode:
    step_start("Building the VS Code extension")
    vscode_args = [npm_cmd, "run", "build"]
    subprocess.run(vscode_args, check=True, text=True, cwd=vscode_src)
    step_end()
    if args.integration_tests:
        step_start("Running the VS Code integration tests")
        vscode_args = [npm_cmd, "test"]
        subprocess.run(vscode_args, check=True, text=True, cwd=vscode_src)
        step_end()


if build_jupyterlab:
    step_start("Building the JupyterLab extension")

    (python_bin, _) = use_python_env(jupyterlab_src)

    pip_build_args = [
        python_bin,
        "-m",
        "build",
        "--wheel",
        "-v",
        "--outdir",
        wheels_dir,
        jupyterlab_src,
    ]
    subprocess.run(pip_build_args, check=True, text=True, cwd=jupyterlab_src)
    step_end()

if build_pip and build_widgets and args.integration_tests:
    step_start("Running notebook samples integration tests")
    # Find all notebooks in the samples directory. Skip some of the samples since these won't run.
    notebook_files = [
        os.path.join(dp, f)
        for dp, _, filenames in os.walk(samples_src)
        for f in filenames
        if f.endswith(".ipynb")
        and not (
            f.startswith("sample.")
            or f.startswith("azure_submission.")
            or f.startswith("circuits.")
            or f.startswith("iterative_phase_estimation.")
            or f.startswith("repeat_until_success.")
            or f.startswith("python-deps.")
            or f.startswith("submit_qiskit_circuit_to_azure.")
            or f.startswith("cirq_submission_to_azure.")
            or f.startswith("pennylane_submission_to_azure.")
            or f.startswith("benzene.")
            or f.startswith("parallel_teleport.")
            or f.startswith("carbon.")
        )
    ]
    (python_bin, pip_env) = use_python_env(samples_src)

    # Install the qsharp package
    pip_install_args = [
        python_bin,
        "-m",
        "pip",
        "install",
        "--force-reinstall",
        "--no-index",
        "--find-links=" + wheels_dir,
        f"qsharp",
    ]
    subprocess.run(pip_install_args, check=True, text=True, cwd=pip_src, env=pip_env)

    # Install the widgets package from the folder so dependencies are installed properly
    pip_install_args = [
        python_bin,
        "-m",
        "pip",
        "install",
        widgets_src,
    ]
    subprocess.run(
        pip_install_args, check=True, text=True, cwd=widgets_src, env=pip_env
    )

    # Install other dependencies
    pip_install_args = [
        python_bin,
        "-m",
        "pip",
        "install",
        "ipykernel",
        "nbconvert",
        "pandas",
        "qutip",
    ]
    subprocess.run(pip_install_args, check=True, text=True, cwd=root_dir, env=pip_env)

    qiskit_notebooks = [
        notebook
        for notebook in notebook_files
        if (
            "qiskit" in os.path.basename(notebook).lower()
            or "estimation-openqasm" in os.path.basename(notebook).lower()
        )
    ]
    other_notebooks = [
        notebook for notebook in notebook_files if notebook not in qiskit_notebooks
    ]

    def _run_notebooks(files):
        for notebook in files:
            print(f"Running {notebook}")
            # Run the notebook process, capturing stdout and only displaying it if there is an error
            result = subprocess.run(
                [
                    python_bin,
                    "-m",
                    "nbconvert",
                    "--to",
                    "notebook",
                    "--stdout",
                    "--ExecutePreprocessor.timeout=90",
                    "--sanitize-html",
                    "--execute",
                    notebook,
                ],
                check=False,
                text=True,
                cwd=root_dir,
                env=pip_env,
                stdout=subprocess.PIPE,
                stderr=subprocess.STDOUT,
                encoding="utf-8",
            )
            if result.returncode != 0:
                print(result.stdout)
                raise Exception(f"Error running {notebook}")

    if other_notebooks:
        print("Executing notebooks")
        _run_notebooks(other_notebooks)

    if qiskit_notebooks:
        for version in QISKIT_VERSION_MATRIX:
            print(f"Executing Qiskit notebooks with {version['label']}")
            version_install_args = [
                python_bin,
                "-m",
                "pip",
                "install",
                "--upgrade",
                "--upgrade-strategy",
                "eager",
            ] + version["requirements"]
            subprocess.run(
                version_install_args, check=True, text=True, cwd=root_dir, env=pip_env
            )

            _run_notebooks(qiskit_notebooks)

    step_end()

    step_start("Running qsharp testing samples")
    project_directories = [
        dir for dir in os.walk(samples_src) if "qsharp.json" in dir[2]
    ]

    test_projects_directories = [
        dir for dir, _, _ in project_directories if dir.find("testing") != -1
    ]

    install_python_test_requirements(pip_src, python_bin)
    for test_project_dir in test_projects_directories:
        run_python_tests(test_project_dir, python_bin, pip_env)
    step_end()

if ci_bench:
    step_start("Running CI benchmarking script")
    run_ci_historic_benchmark()
    step_end()