docs: kdoc: handle the obsolescensce of docutils.ErrorString()

The ErrorString() and SafeString() docutils functions were helpers meant to
ease the handling of encodings during the Python 3 transition.  There is no
real need for them after Python 3.6, and docutils 0.22 removes them,
breaking the docs build

Handle this by just injecting our own one-liner version of ErrorString(),
and removing the sole SafeString() call entirely.

Reported-by: Zhixu Liu <zhixu.liu@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Upstream: https://git.kernel.org/linus/00d95fcc4dee66dfb6980de6f2973b32f973a1eb
[j.ne: Adapted from Linux to U-Boot]
Signed-off-by: J. Neuschäfer <j.ne@posteo.net>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

doc/sphinx/kernel_abi.py

@@ -44,7 +44,9 @@ from os import path
 from docutils import nodes, statemachine
 from docutils.statemachine import ViewList
 from docutils.parsers.rst import directives, Directive
-from docutils.utils.error_reporting import ErrorString
+
+def ErrorString(exc):  # Shamelessly stolen from docutils
+    return f'{exc.__class__.__name}: {exc}'
 
 #
 # AutodocReporter is only good up to Sphinx 1.7

doc/sphinx/kernel_feat.py

@@ -41,7 +41,9 @@ from os import path
 from docutils import nodes, statemachine
 from docutils.statemachine import ViewList
 from docutils.parsers.rst import directives, Directive
-from docutils.utils.error_reporting import ErrorString
+
+def ErrorString(exc):  # Shamelessly stolen from docutils
+    return f'{exc.__class__.__name}: {exc}'
 
 #
 # AutodocReporter is only good up to Sphinx 1.7

doc/sphinx/kernel_include.py

@@ -34,11 +34,13 @@ u"""
 import os.path
 
 from docutils import io, nodes, statemachine
-from docutils.utils.error_reporting import SafeString, ErrorString
 from docutils.parsers.rst import directives
 from docutils.parsers.rst.directives.body import CodeBlock, NumberLines
 from docutils.parsers.rst.directives.misc import Include
 
+def ErrorString(exc):  # Shamelessly stolen from docutils
+    return f'{exc.__class__.__name}: {exc}'
+
 __version__  = '1.0'
 
 # ==============================================================================
@@ -109,7 +111,7 @@ class KernelInclude(Include):
             raise self.severe('Problems with "%s" directive path:\n'
                               'Cannot encode input file path "%s" '
                               '(wrong locale?).' %
-                              (self.name, SafeString(path)))
+                              (self.name, path))
         except IOError as error:
             raise self.severe('Problems with "%s" directive path:\n%s.' %
                       (self.name, ErrorString(error)))

doc/sphinx/maintainers_include.py

@@ -22,10 +22,12 @@ import re
 import os.path
 
 from docutils import statemachine
-from docutils.utils.error_reporting import ErrorString
 from docutils.parsers.rst import Directive
 from docutils.parsers.rst.directives.misc import Include
 
+def ErrorString(exc):  # Shamelessly stolen from docutils
+    return f'{exc.__class__.__name}: {exc}'
+
 __version__  = '1.0'
 
 def setup(app):