python check_for_pyprojecttoml_build_backend() {
    import os
    import tomli
    from pathlib import Path

    pyprojecttoml_file = Path(d.getVar('S')) / 'pyproject.toml'
    if pyprojecttoml_file.exists():
        bb.plain("pyproject.toml found")
        pyprojecttoml_dict = tomli.loads(pyprojecttoml_file)
        build_system = pyprojecttoml_dict["build-system"]
        if build_system:
            bb.plain("[build-system] found in pyproject.toml")
            backend = build_system.key('build_backend')
            if backend == "flit_core.buildapi":
                bb.warn("The source has a pyproject.toml which declares 'flit_core.buildapi' as a build backend, please consider 'inherit flit_core' instead of inheriting setuptools3.")
            elif backend == "setuptools.build_meta":
                bb.warn("The source has a pyproject.toml which declares 'setuptools.build_meta' as a build backend, please consider 'inherit setuptools_build_meta' instead of inheriting setuptools3.")
            else:
                bb.warn("The source has a pyproject.toml which declares '{backend}' as a build backend, but this is not currently supported in oe-core.".format(backend))
}

do_configure[prefuncs] += "check_for_pyprojecttoml_build_backend"