Restore kernel-doc support for Python 3.6

Hi Jon,

While discussing patch v2 12/12 from your kdoc series, I realized that kernel-doc command line should not crash with Python 3.6, nor cause compilation breakages with older versions.

The problem mainly affect builds with CONFIG_DRM enabled, due to:

drivers/gpu/drm/Makefile:                PYTHONDONTWRITEBYTECODE=1 $(KERNELDOC) -none $(if $(CONFIG_WERROR)$(CONFIG_DRM_WERROR),-Werror) $<; \
drivers/gpu/drm/i915/Makefile:    cmd_checkdoc = PYTHONDONTWRITEBYTECODE=1 $(KERNELDOC) -none -Werror $<
include/drm/Makefile:           PYTHONDONTWRITEBYTECODE=1 $(KERNELDOC) -none $(if $(CONFIG_WERROR)$(CONFIG_DRM_WERROR),-Werror) $<; \

This small series prevent Kernel build breakages on such case, and it is meant to be merged after your kdoc patches.

Patch 1 emits a warning wih Python 3.7 siilar to kdoc class, but on an early stage. More importantly, it emits a warning and exits the script for versions <= 3.6.

We still need the kdoc warning, as it detect troubles when calling kernel-doc as a class.

Patch 2 fix a backward-compatibility issue that otherwise would require Python 3.9.

With that, building the Kernel with older versions won't break.

Regards,
Mauro

Mauro Carvalho Chehab (2):
docs: kernel-doc: emit warnings for ancient versions of Python
scripts: kdoc: make it backward-compatible with Python 3.7

 scripts/kernel-doc.py           | 10 ++++++++++
 scripts/lib/kdoc/kdoc_parser.py |  4 +++-
 2 files changed, 13 insertions(+), 1 deletion(-)

2.50.0

Kernel-doc requires at least version 3.6 to run, as it uses f-string. Yet, Kernel build currently calls kernel-doc with -none on some places. Better not to bail out when older versions are found.

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.

Check Python version when called via command line.

---
 scripts/kernel-doc.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

index 12ae66f40bd7..fc3d46ef519f 100755
@@ -271,6 +271,16 @@ def main():
 
     logger.addHandler(handler)
 
+    python_ver = sys.version_info[:2]
+    if python_ver < (3,6):
+        logger.warning("Python 3.6 or later is required by kernel-doc")
+
+        # Return 0 here to avoid breaking compilation
+        sys.exit(0)
+
+    if python_ver < (3,7):
+        logger.warning("Python 3.7 or later is required for correct results")
+
     if args.man:
         out_style = ManFormat(modulename=args.modulename)
     elif args.none:

2.50.0

There was a change at kdoc that ended breaking compatibility with Python 3.7: str.removesuffix() was introduced on version 3.9.

Restore backward compatibility.

---
 scripts/lib/kdoc/kdoc_parser.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

index 831f061f61b8..6273141033a8 100644
@@ -1214,7 +1214,9 @@ class KernelDoc:
         # Found an export, trim out any special suffixes
         #
         for suffix in suffixes:
-            symbol = symbol.removesuffix(suffix)
+            # Be backward compatible with Python < 3.9
+            if symbol.endswith(suffix):
+                symbol = symbol[:-len(suffix)]
         function_set.add(symbol)
         return True
 

2.50.0