On 2/21/23 02:24, John Snow wrote:
> At the moment, we look for just "python3" and "python", which is good
> enough almost all of the time. But ... if you are on a platform that
> uses an older Python by default and only offers a newer Python as an
> option, you'll have to specify --python=/usr/bin/foo every time.
>
> As a courtesy, we can make a cursory attempt to locate a suitable Python
> binary ourselves, looking for the remaining well-known binaries. This
> also has the added benefit of making configure "just work" more often
> on various BSD distributions that do not have the concept of a
> "platform default python".
>
> This configure loop will prefer, in order:
>
> 1. Whatever is specified in $PYTHON
> 2. python3
> 3. python (Which is usually 2.x, but might be 3.x on some platforms.)
> 4. python3.11 down through python3.6
>
> Notes:
>
> - Python virtual environments provide binaries for "python3", "python",
> and whichever version you used to create the venv,
> e.g. "python3.8". If configure is invoked from inside of a venv, this
> configure loop will not "break out" of that venv unless that venv is
> created using an explicitly non-suitable version of Python that we
> cannot use.
>
> - In the event that no suitable python is found, the first python found
> is the version used to generate the human-readable error message.
>
> - The error message isn't printed right away to allow later
> configuration code to pick up an explicitly configured python.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
> configure | 34 ++++++++++++++++++++++++++--------
> 1 file changed, 26 insertions(+), 8 deletions(-)
>
> diff --git a/configure b/configure
> index cf6db3d5518..6abf5a72078 100755
> --- a/configure
> +++ b/configure
> @@ -592,20 +592,40 @@ esac
>
> : ${make=${MAKE-make}}
>
> -# We prefer python 3.x. A bare 'python' is traditionally
> -# python 2.x, but some distros have it as python 3.x, so
> -# we check that too
> +
> +check_py_version() {
> + # We require python >= 3.6.
> + # NB: a True python conditional creates a non-zero return code (Failure)
> + "$1" -c 'import sys; sys.exit(sys.version_info < (3,6))'
> +}
> +
> python=
> +first_python=
> explicit_python=no
> -for binary in "${PYTHON-python3}" python
> +# Check for $PYTHON, python3, python, then explicitly-versioned interpreters.
> +for binary in "${PYTHON-python3}" ${PYTHON:+python3} python \
> + python3.11 python3.10 python3.9 \
> + python3.8 python3.7 python3.6
I think if PYTHON is set we shouldn't look at anything else.
Paolo
PYTHON is one we made up, right?
> do
> if has "$binary"
> then
> python=$(command -v "$binary")
> - break
> + if test -z "$first_python"; then
> + first_python=$python
> + fi
> + if check_py_version "$python"; then
> + # This one is good.
> + first_python=
> + break
> + fi
> fi
> done
>
> +# If first_python is set, we didn't find a suitable binary.
> +# Use this one for possible future error messages.
> +if test -n "$first_python"; then
> + python="$first_python"
> +fi
>
> # Check for ancillary tools used in testing
> genisoimage=
> @@ -1037,9 +1057,7 @@ then
> error_exit "GNU make ($make) not found"
> fi
>
> -# Note that if the Python conditional here evaluates True we will exit
> -# with status 1 which is a shell 'false' value.
> -if ! $python -c 'import sys; sys.exit(sys.version_info < (3,6))'; then
> +if ! check_py_version "$python"; then
> error_exit "Cannot use '$python', Python >= 3.6 is required." \
> "Use --python=/path/to/python to specify a supported Python."
> fi