Re: [PATCH v5] qapi: Add documentation format validation

[Markus Armbruster <armbru@redhat.com>]

Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> writes:

> On 04.11.25 13:07, Markus Armbruster wrote:
>> Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> writes:
>> 
>>> Add explicit validation for QAPI documentation formatting rules:
>>>
>>> 1. Lines must not exceed 70 columns in width (including '# ' prefix)
>>> 2. Sentences must be separated by two spaces
>>>
>>> Example sections and literal :: blocks (seldom case) are excluded, we
>>> don't require them to be <= 70, that would be too restrictive. Anyway,
>>> they share common 80-columns recommendations (not requirements).
>>>
>>> Add two simple tests, illustrating the change.
>>>
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
>>> ---
>>>
>>> Hi all!
>>>
>>> v5: - break "literal" block at any decreasing the indent,
>>>        not only at no-indent
>>>      - add two simple tests
>>>
>>> This is based on
>>> [PATCH 0/8] A QAPI schema doc markup fix, and style cleanup
>>> Based-on: <20251031094751.2817932-1-armbru@redhat.com>
>>>
>>>   scripts/qapi/parser.py                     | 52 +++++++++++++++++++++-
>>>   tests/qapi-schema/doc-bad-long-line.err    |  1 +
>>>   tests/qapi-schema/doc-bad-long-line.json   |  6 +++
>>>   tests/qapi-schema/doc-bad-long-line.out    |  0
>>>   tests/qapi-schema/doc-bad-whitespaces.err  |  2 +
>>>   tests/qapi-schema/doc-bad-whitespaces.json |  6 +++
>>>   tests/qapi-schema/doc-bad-whitespaces.out  |  0
>>>   tests/qapi-schema/meson.build              |  2 +
>>>   8 files changed, 68 insertions(+), 1 deletion(-)
>>>   create mode 100644 tests/qapi-schema/doc-bad-long-line.err
>>>   create mode 100644 tests/qapi-schema/doc-bad-long-line.json
>>>   create mode 100644 tests/qapi-schema/doc-bad-long-line.out
>>>   create mode 100644 tests/qapi-schema/doc-bad-whitespaces.err
>>>   create mode 100644 tests/qapi-schema/doc-bad-whitespaces.json
>>>   create mode 100644 tests/qapi-schema/doc-bad-whitespaces.out
>>>
>>> diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py
>>> index 9fbf80a541..ffb149850d 100644
>>> --- a/scripts/qapi/parser.py
>>> +++ b/scripts/qapi/parser.py
>>> @@ -108,6 +108,11 @@ def __init__(self,
>>>           self.exprs: List[QAPIExpression] = []
>>>           self.docs: List[QAPIDoc] = []
>>>   
>>> +        # State for tracking qmp-example blocks and simple
>>> +        # :: literal blocks.
>>> +        self._literal_mode = False
>>> +        self._literal_mode_indent = 0
>>> +
>>>           # Showtime!
>>>           self._parse()
>>>   
>>> @@ -423,12 +428,57 @@ def get_doc_line(self) -> Optional[str]:
>>>               if self.val != '##':
>>>                   raise QAPIParseError(
>>>                       self, "junk after '##' at end of documentation comment")
>>> +            self._literal_mode = False
>>>               return None
>>>           if self.val == '#':
>>>               return ''
>>>           if self.val[1] != ' ':
>>>               raise QAPIParseError(self, "missing space after #")
>>> -        return self.val[2:].rstrip()
>>> +
>>> +        line = self.val[2:].rstrip()
>>> +
>>> +        if re.match(r'(\.\. +qmp-example)? *::$', line):
>> 
>> After a closer reading of ReST docs and some testing: this isn't quite
>> right, although it works okay for what we have.
>> 
>> A directive's '::' need not be at the end of a line.  The regexp fails
>> to match a qmp-example directive with text after '::'.  No such
>> directives exist right now.
>> 
>> A literal block starts after a '::' at the end of a paragraph,
>> i.e. after '::' and a blank line.  The regexp only matches '::' on its
>> own line, not at the end of a line of text.  It matches it even when
>> it's not followed by a blank line.
>> 
>> In review of v4, I claimed we don't use the contracted form "text::".
>> Not true.  For instance, in block-core.json:
>> 
>>     # @bins: list of io request counts corresponding to histogram
>>     #     intervals, one more element than @boundaries has.  For the
>>     #     example above, @bins may be something like [3, 1, 5, 2], and
>>     #     corresponding histogram looks like::
>>     #
>>     #        5|           *
>>     #        4|           *
>>     #        3| *         *
>>     #        2| *         *    *
>>     #        1| *    *    *    *
>>     #         +------------------
>>     #             10   50   100
>>     #
>
> Ow, my old histograms)

Haha!

>>     # Since: 4.0
>>     ##
>> 
>> The literal block starts after "like::" and ends before "Since:'.
>> 
>>> +            self._literal_mode = True
>>> +            self._literal_mode_indent = 0
>>> +        elif self._literal_mode and line:
>>> +            indent = re.match(r'^ *', line).end()
>>> +            if self._literal_mode_indent == 0:
>>> +                self._literal_mode_indent = indent
>>> +            elif indent < self._literal_mode_indent:
>>> +                # ReST directives stop at decreasing indentation
>>> +                self._literal_mode = False
>> 
>> This isn't quite right, either.  We need to stop when indentation of
>> non-blank lines drops below the indentation of the line containing the
>> '::'.
>> 
>> Perhaps it's easier for both of us if I fix this on top.  Thoughts?
>
> No objections, good for me!

I can merge this with a brief note, like so:

    Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

    The detection of example and literal blocks isn't quite correct, but
    it works well enough, and we can improve on top.

    Reviewed-by: Markus Armbruster <armbru@redhat.com>

>>> +
>>> +        if not self._literal_mode:
>>> +            self._validate_doc_line_format(line)
>>> +
>>> +        return line
>>> +
>>> +    def _validate_doc_line_format(self, line: str) -> None:
>>> +        """
>>> +        Validate documentation format rules for a single line:
>>> +        1. Lines should not exceed 70 columns
>>> +        2. Sentences should be separated by two spaces
>>> +        """
>>> +        full_line_length = len(line) + 2  # "# " = 2 characters
>>> +        if full_line_length > 70:
>>> +            # Skip URL lines - they can't be broken
>>> +            if re.match(r' *(https?|ftp)://[^ ]*$', line):
>>> +                pass
>>> +            else:
>>> +                raise QAPIParseError(
>>> +                    self, "documentation line exceeds 70 columns"
>>> +                )
>>> +
>>> +        single_space_pattern = r'(\be\.g\.|^ *\d\.|([.!?])) [A-Z0-9(]'
>>> +        for m in list(re.finditer(single_space_pattern, line)):
>>> +            if not m.group(2):
>>> +                continue
>>> +            # HACK so the error message points to the offending spot
>>> +            self.pos = self.line_pos + 2 + m.start(2) + 1
>>> +            raise QAPIParseError(
>>> +                self, "Use two spaces between sentences\n"
>>> +                "If this not the end of a sentence, please report the bug",
>>> +            )
>>>   
>>>       @staticmethod
>>>       def _match_at_name_colon(string: str) -> Optional[Match[str]]:
>>> diff --git a/tests/qapi-schema/doc-bad-long-line.err b/tests/qapi-schema/doc-bad-long-line.err
>>> new file mode 100644
>>> index 0000000000..611a3b1fef
>>> --- /dev/null
>>> +++ b/tests/qapi-schema/doc-bad-long-line.err
>>> @@ -0,0 +1 @@
>>> +doc-bad-long-line.json:4:1: documentation line exceeds 70 columns
>>> diff --git a/tests/qapi-schema/doc-bad-long-line.json b/tests/qapi-schema/doc-bad-long-line.json
>>> new file mode 100644
>>> index 0000000000..d7f887694d
>>> --- /dev/null
>>> +++ b/tests/qapi-schema/doc-bad-long-line.json
>>> @@ -0,0 +1,6 @@
>>> +##
>>> +# @foo:
>>> +#
>>> +# This line has exactly 71 characters, including spaces and punctuation!
>> 
>> Really?
>
> Oh, it's 72 characters actually! AI tricked me. Didn't I check it out?
>
> Maybe:
>
> # This line has exactly 71 chars, including the leading hash and space.

Works!

>>> +##
>>> +{ 'command': 'foo' }
>>> diff --git a/tests/qapi-schema/doc-bad-long-line.out b/tests/qapi-schema/doc-bad-long-line.out
>>> new file mode 100644
>>> index 0000000000..e69de29bb2
>>> diff --git a/tests/qapi-schema/doc-bad-whitespaces.err b/tests/qapi-schema/doc-bad-whitespaces.err
>>> new file mode 100644
>>> index 0000000000..5cca1954c0
>>> --- /dev/null
>>> +++ b/tests/qapi-schema/doc-bad-whitespaces.err
>>> @@ -0,0 +1,2 @@
>>> +doc-bad-whitespaces.json:4:48: Use two spaces between sentences
>>> +If this not the end of a sentence, please report the bug
>>> diff --git a/tests/qapi-schema/doc-bad-whitespaces.json b/tests/qapi-schema/doc-bad-whitespaces.json
>>> new file mode 100644
>>> index 0000000000..b0c318c670
>>> --- /dev/null
>>> +++ b/tests/qapi-schema/doc-bad-whitespaces.json
>>> @@ -0,0 +1,6 @@
>>> +##
>>> +# @foo:
>>> +#
>>> +# Sentences should be split by two whitespaces. But here is only one.
>> 
>> two spaces
>> 
>>> +##
>>> +{ 'command': 'foo' }
>>> diff --git a/tests/qapi-schema/doc-bad-whitespaces.out b/tests/qapi-schema/doc-bad-whitespaces.out
>>> new file mode 100644
>>> index 0000000000..e69de29bb2
>>> diff --git a/tests/qapi-schema/meson.build b/tests/qapi-schema/meson.build
>>> index c47025d16d..b24b27db21 100644
>>> --- a/tests/qapi-schema/meson.build
>>> +++ b/tests/qapi-schema/meson.build
>>> @@ -61,8 +61,10 @@ schemas = [
>>>     'doc-bad-event-arg.json',
>>>     'doc-bad-feature.json',
>>>     'doc-bad-indent.json',
>>> +  'doc-bad-long-line.json',
>>>     'doc-bad-symbol.json',
>>>     'doc-bad-union-member.json',
>>> +  'doc-bad-whitespaces.json',
>>>     'doc-before-include.json',
>>>     'doc-before-pragma.json',
>>>     'doc-duplicate-features.json',

Thanks!