[PATCH 09/10] Python: Drop support for Python 3.6

[Paolo Bonzini]

Python 3.6 was EOL 2021-12-31. Newer versions of upstream libraries have
begun dropping support for this version and it is becoming more
cumbersome to support. Avocado-framework and qemu.qmp each have their
own reasons for wanting to drop Python 3.6, but won't until QEMU does.

Versions of Python available in our supported build platforms as of today,
with optional versions available in parentheses:

openSUSE Leap 15.4: 3.6.15 (3.9.10, 3.10.2)
CentOS Stream 8:    3.6.8  (3.8.13, 3.9.16)
CentOS Stream 9:    3.9.13
Fedora 36:          3.10
Fedora 37:          3.11
Debian 11:          3.9.2
Alpine 3.14, 3.15:  3.9.16
Alpine 3.16, 3.17:  3.10.10
Ubuntu 20.04 LTS:   3.8.10
Ubuntu 22.04 LTS:   3.10.4
NetBSD 9.3:         3.9.13*
FreeBSD 12.4:       3.9.16
FreeBSD 13.1:       3.9.16
OpenBSD 7.2:        3.9.16

Note: Our VM tests install 3.7 specifically for freebsd and netbsd; the
default for "python" or "python3" in FreeBSD is 3.9.16. NetBSD does not
appear to have a default meta-package, but offers several options, the
lowest of which is 3.7.15. "python39" appears to be a pre-requisite to
one of the other packages we request in tests/vm/netbsd.

Since it is safe to under our supported platform policy, bump our
minimum supported version of Python to 3.7.

Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 configure                |  8 ++++----
 python/Makefile          | 10 +++++-----
 python/setup.cfg         |  7 +++----
 python/tests/minreqs.txt |  2 +-
 scripts/qapi/mypy.ini    |  2 +-
 5 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/configure b/configure
index 762b8397a7b7..476d8a38b900 100755
--- a/configure
+++ b/configure
@@ -594,9 +594,9 @@ esac
 
 
 check_py_version() {
-    # We require python >= 3.6.
+    # We require python >= 3.7.
     # NB: a True python conditional creates a non-zero return code (Failure)
-    "$1" -c 'import sys; sys.exit(sys.version_info < (3,6))'
+    "$1" -c 'import sys; sys.exit(sys.version_info < (3,7))'
 }
 
 python=
@@ -605,7 +605,7 @@ if test -z "${PYTHON}"; then
     explicit_python=no
     # A bare 'python' is traditionally python 2.x, but some distros
     # have it as python 3.x, so check in both places.
-    for binary in python3 python python3.11 python3.10 python3.9 python3.8 
python3.7 python3.6; do
+    for binary in python3 python python3.11 python3.10 python3.9 python3.8 
python3.7; do
         if has "$binary"; then
             python=$(command -v "$binary")
             if check_py_version "$python"; then
@@ -1069,7 +1069,7 @@ then
 fi
 
 if ! check_py_version "$python"; then
-  error_exit "Cannot use '$python', Python >= 3.6 is required." \
+  error_exit "Cannot use '$python', Python >= 3.7 is required." \
       "Use --python=/path/to/python to specify a supported Python."
 fi
 
diff --git a/python/Makefile b/python/Makefile
index c5bd6ff83ac9..f660d9991437 100644
--- a/python/Makefile
+++ b/python/Makefile
@@ -9,14 +9,14 @@ help:
        @echo "make check-minreqs:"
        @echo "    Run tests in the minreqs virtual environment."
        @echo "    These tests use the oldest dependencies."
-       @echo "    Requires: Python 3.6"
-       @echo "    Hint (Fedora): 'sudo dnf install python3.6'"
+       @echo "    Requires: Python 3.7"
+       @echo "    Hint (Fedora): 'sudo dnf install python3.7'"
        @echo ""
        @echo "make check-tox:"
        @echo "    Run tests against multiple python versions."
        @echo "    These tests use the newest dependencies."
-       @echo "    Requires: Python 3.6 - 3.10, and tox."
-       @echo "    Hint (Fedora): 'sudo dnf install python3-tox python3.10'"
+       @echo "    Requires: Python 3.7 - 3.11, and tox."
+       @echo "    Hint (Fedora): 'sudo dnf install python3-tox python3.11'"
        @echo "    The variable QEMU_TOX_EXTRA_ARGS can be use to pass extra"
        @echo "    arguments to tox".
        @echo ""
@@ -58,7 +58,7 @@ pipenv check-pipenv:
 min-venv: $(QEMU_MINVENV_DIR) $(QEMU_MINVENV_DIR)/bin/activate
 $(QEMU_MINVENV_DIR) $(QEMU_MINVENV_DIR)/bin/activate: setup.cfg 
tests/minreqs.txt
        @echo "VENV $(QEMU_MINVENV_DIR)"
-       @python3.6 -m venv $(QEMU_MINVENV_DIR)
+       @python3.7 -m venv $(QEMU_MINVENV_DIR)
        @(                                                              \
                echo "ACTIVATE $(QEMU_MINVENV_DIR)";                    \
                . $(QEMU_MINVENV_DIR)/bin/activate;                     \
diff --git a/python/setup.cfg b/python/setup.cfg
index 9e923d97628f..1e8392a045c3 100644
--- a/python/setup.cfg
+++ b/python/setup.cfg
@@ -14,7 +14,6 @@ classifiers =
     Natural Language :: English
     Operating System :: OS Independent
     Programming Language :: Python :: 3 :: Only
-    Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
@@ -23,7 +22,7 @@ classifiers =
     Typing :: Typed
 
 [options]
-python_requires = >= 3.6
+python_requires = >= 3.7
 packages =
     qemu.qmp
     qemu.machine
@@ -76,7 +75,7 @@ exclude = __pycache__,
 
 [mypy]
 strict = True
-python_version = 3.6
+python_version = 3.7
 warn_unused_configs = True
 namespace_packages = True
 warn_unused_ignores = False
@@ -158,7 +157,7 @@ multi_line_output=3
 # of python available on your system to run this test.
 
 [tox:tox]
-envlist = py36, py37, py38, py39, py310, py311
+envlist = py37, py38, py39, py310, py311
 skip_missing_interpreters = true
 
 [testenv]
diff --git a/python/tests/minreqs.txt b/python/tests/minreqs.txt
index dfb8abb155f4..55cc6b41d85b 100644
--- a/python/tests/minreqs.txt
+++ b/python/tests/minreqs.txt
@@ -1,5 +1,5 @@
 # This file lists the ***oldest possible dependencies*** needed to run
-# "make check" successfully under ***Python 3.6***. It is used primarily
+# "make check" successfully under ***Python 3.7***. It is used primarily
 # by GitLab CI to ensure that our stated minimum versions in setup.cfg
 # are truthful and regularly validated.
 #
diff --git a/scripts/qapi/mypy.ini b/scripts/qapi/mypy.ini
index 662535642974..3463307ddc72 100644
--- a/scripts/qapi/mypy.ini
+++ b/scripts/qapi/mypy.ini
@@ -1,7 +1,7 @@
 [mypy]
 strict = True
 disallow_untyped_calls = False
-python_version = 3.6
+python_version = 3.7
 
 [mypy-qapi.schema]
 disallow_untyped_defs = False
-- 
2.39.1