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

[Markus Armbruster <armbru@redhat.com>]

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?