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}" ${PYTHON:+python3} python \
+ python3.11 python3.10 python3.9 \
+ python3.8 python3.7 python3.6
do
if has "$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