Re: [PATCH 16/19] scripts/qapi: strip trailing whitespaces

[Paolo Bonzini <pbonzini@redhat.com>]

On 12/9/25 09:48, Markus Armbruster wrote:
> Paolo Bonzini <pbonzini@redhat.com> writes:
> 
>> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>>
>> This help workaround a rustfmt issue.
> 
> Which one?  Pointer suffices.
> 
>>
>> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
>> Link: https://lore.kernel.org/r/20210907121943.3498701-16-marcandre.lureau@redhat.com
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>>   scripts/qapi/gen.py | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py
>> index 0c9b8db3b02..c9721545ea7 100644
>> --- a/scripts/qapi/gen.py
>> +++ b/scripts/qapi/gen.py
>> @@ -58,7 +58,11 @@ def add(self, text: str) -> None:
>>           self._body += text
>>   
>>       def get_content(self) -> str:
>> -        return self._top() + self._preamble + self._body + self._bottom()
>> +        content = self._top() + self._preamble + self._body + self._bottom()
>> +        # delete trailing white-spaces (working around
>> +        # https://github.com/rust-lang/rustfmt/issues/4248)
>> +        content = re.sub(r'\s+$', '\n', content, 0, re.M)
>> +        return content
>>   
>>       def _top(self) -> str:
>>           # pylint: disable=no-self-use
> 
> This doesn't just delete trailing whitespace, it also collapses multiple
> blank lines into one: \s matches newlines.
> 
> We lose the ability to generate multiple blank lines for all generators
> based on QAPIGen: C (.c and .h), trace events, Rust.  Hmm.
> 
> Is collapsing blank lines necessary for working around the rustfmt
> issue?
> 
> The generators other than the Rust generator do not emit trailing
> whitespace.  Would that be practical for the Rust generator, too?

The main source is stuff like %(cfg)s and %(serde_skip_if)s.  Rust's 
syntax makes it more natural to write in this style, compared to C where 
you have "#ifdef"..."#endif", but it results in empty lines.  I'll see 
if there's another way to clean up the output.

Paolo