[PATCH v2 12/12] docs: kdoc: emit a warning for ancient versions of Python

[Jonathan Corbet <corbet@xxxxxxx>]

Versions of Python prior to 3.7 do not guarantee to remember the insertion
order of dicts; since kernel-doc depends on that guarantee, running with
such older versions could result in output with reordered sections.

Python 3.9 is the minimum for the kernel as a whole, so this should not be
a problem, but put in a warning just in case somebody tries to use
something older.

Suggested-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Signed-off-by: Jonathan Corbet <corbet@xxxxxxx>
---
 scripts/lib/kdoc/kdoc_parser.py | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/scripts/lib/kdoc/kdoc_parser.py b/scripts/lib/kdoc/kdoc_parser.py
index fdde14b045fe..23ac4ad204f4 100644
--- a/scripts/lib/kdoc/kdoc_parser.py
+++ b/scripts/lib/kdoc/kdoc_parser.py
@@ -12,6 +12,7 @@ Read a C language source or header FILE and extract embedded
 documentation comments
 """
 
+import sys
 import re
 from pprint import pformat
 
@@ -238,6 +239,14 @@ class KernelDoc:
         # Place all potential outputs into an array
         self.entries = []
 
+        #
+        # We need Python 3.7 for its "dicts remember the insertion
+        # order" guarantee
+        #
+        if sys.version_info.major == 3 and sys.version_info.minor < 7:
+            self.emit_message(0,
+                              'Python 3.7 or later is required for correct results')
+
     def emit_msg(self, ln, msg, warning=True):
         """Emit a message"""
 
-- 
2.49.0