On Thu, Jun 11, 2026 at 5:56 PM Zhao Liu <[email protected]> wrote:
>
> On Tue, May 26, 2026 at 07:56:14PM +0200, Paolo Bonzini wrote:
> > Date: Tue, 26 May 2026 19:56:14 +0200
> > From: Paolo Bonzini <[email protected]>
> > Subject: [PATCH v3 15/19] scripts/qapi: generate high-level Rust bindings
> > X-Mailer: git-send-email 2.54.0
> >
> > From: Marc-André Lureau <[email protected]>
> >
> > Generate high-level native Rust declarations for the QAPI types.
> >
> > - char* is mapped to String, scalars to there corresponding Rust types
> >
> > - enums use #[repr(u32)] and can be transmuted to their C counterparts
> >
> > - has_foo/foo members are mapped to Option<T>
> >
> > - lists are represented as Vec<T>
> >
> > - structures map fields 1:1 to Rust
> >
> > - alternate are represented as Rust enum, each variant being a 1-element
> >   tuple
> >
> > - unions are represented in a similar way as in C: a struct S with a "u"
> >   member (since S may have extra 'base' fields). The discriminant
> >   isn't a member of S, since Rust enum already include it, but it can be
> >   recovered with "mystruct.u.into()"
> >
> > Anything that includes a recursive struct puts it in a Box.  Lists are
> > not considered recursive, because Vec breaks the recursion (it's possible
> > to construct an object containing an empty Vec of its own type).
> >
> > Given the experimental nature of Rust, and the incompleteness of the
> > backend (it lacks commands and events), QAPIRsBackend is not modular
> > and is not built together with the C and trace-event files.  It can
> > be used by specifying "-B qapi.backend.QAPIRsBackend" on the qapi-gen
> > command line.
> >
> > Signed-off-by: Marc-André Lureau <[email protected]>
> > Link: 
> > https://lore.kernel.org/r/[email protected]
> > [Paolo: rewrite conversion of leaf types]
> > Signed-off-by: Paolo Bonzini <[email protected]>
> > ---
> >  meson.build              |   4 +-
> >  scripts/qapi/backend.py  |  25 +++
> >  scripts/qapi/common.py   |  49 ++++++
> >  scripts/qapi/rs.py       |  50 ++++++
> >  scripts/qapi/rs_types.py | 372 +++++++++++++++++++++++++++++++++++++++
> >  scripts/qapi/schema.py   |  59 +++++--
> >  6 files changed, 540 insertions(+), 19 deletions(-)
> >  create mode 100644 scripts/qapi/rs.py
> >  create mode 100644 scripts/qapi/rs_types.py
>
> [snip]
>
> > +def rs_name(name: str) -> str:
> > +    """
> > +    Map @name to a valid, possibly raw Rust identifier.
> > +    """
> > +    name = re.sub(r'[^A-Za-z0-9_]', '_', name)
> > +    if name[0].isnumeric():
> > +        name = '_' + name
> > +    # based from the list:
> > +    # https://doc.rust-lang.org/reference/keywords.html
> > +    if name in ('Self', 'abstract', 'as', 'async',
>                     ^^^^
> > +                'await', 'become', 'box', 'break',
> > +                'const', 'continue', 'crate', 'do',
>                                          ^^^^^
> > +                'dyn', 'else', 'enum', 'extern',
> > +                'false', 'final', 'fn', 'for',
> > +                'if', 'impl', 'in', 'let',
> > +                'loop', 'macro', 'match', 'mod',
> > +                'move', 'mut', 'override', 'priv',
> > +                'pub', 'ref', 'return', 'self',
>                                             ^^^^
> > +                'static', 'struct', 'super', 'trait',
>                                         ^^^^^
> > +                'true', 'try', 'type', 'typeof',
> > +                'union', 'unsafe', 'unsized', 'use',
> > +                'virtual', 'where', 'while', 'yield'):
> > +        name = 'r#' + name
>
> EMM, r#self, r#Self, r#crate and r#super are "RESERVED_RAW_IDENTIFIER",
> and "It is an error to use the RESERVED_RAW_IDENTIFIER token". [*]
>
> [*]: 
> https://doc.rust-lang.org/reference/identifiers.html#grammar-RESERVED_RAW_IDENTIFIER
>
> We can't use 'q_' prefix for these special case, or what about
> name + '_'?

This is what bindgen does also:

https://github.com/rust-lang/rust-bindgen/blob/2048231f45c87cd65d7891f55090aac81cc0d66b/bindgen-tests/tests/headers/keywords.h

becomes:

https://github.com/rust-lang/rust-bindgen/blob/2048231f45c87cd65d7891f55090aac81cc0d66b/bindgen-tests/tests/expectations/tests/keywords.rs

>
> e.g.,
>
> if name in ('self', 'Self', 'crate', 'super'):
>    name = name + '_'
> elif name in (...)
>    name = 'r#' + name
>
> > +
> > +    return name
> > +
>
> [snip]
>
> > @@ -502,6 +515,9 @@ def is_implicit(self) -> bool:
> >      def c_type(self) -> str:
> >          return c_name(self.name) + POINTER_SUFFIX
> >
> > +    def rs_type(self) -> str:
>
> Only a nit, it's better to check _checked before accessing element_type
> (just refer Markus' suggestion in v2)
>
> assert self._checked
>
> > +        return 'Vec<%s>' % self.element_type.rs_type()
> > +
>
> Regards,
> Zhao
>
>

-- 
Manos Pitsidianakis
Emulation and Virtualization Engineer at Linaro Ltd

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