Re: [PATCH v5 00/11] rust: bindings: Auto-generate inline static functions

[Tamir Duberstein]

On Tue, Mar 18, 2025 at 2:53 AM Alistair Francis <alistair23@xxxxxxxxx> wrote:
>
> On Tue, Jan 14, 2025 at 4:02 PM Alistair Francis <alistair23@xxxxxxxxx> wrote:
> >
> > On Tue, Jan 7, 2025 at 9:48 PM Andreas Hindborg <a.hindborg@xxxxxxxxxx> wrote:
> > >
> > > Thanks! Since Gary just sent v2 of the LTO patch [1], could you rebase
> > > on that and list it as a dependency? If you are using b4 there is a nice
> >
> > I can't get Gary's series to apply on rust-next (it does apply on
> > master though).
> >
> > I might just wait until Gary's series gets picked up to rust-next as
> > there is already a lot of manual rebasing going on and my series
> > currently applies on rust-next.
> >
> > Unfortunately there are just constant conflicts as the number of
> > manual C helpers are continually growing.
> >
> > Obviously when/if this series is approved I can do a final rebase, I
> > would just like to avoid unnecessary churn in the meantime
>
> Any more thoughts on this?

Hi Alistair,

I can't speak for Gary as I don't know what his plans are for that LTO
series, but I did review that series and this one, and at first glance
the two seem orthogonal. The goal of Gary's series is to LTO C helpers
into Rust, while the goal of this series is to machine-generate those
helpers. Do I have that right?

If yes, I think it's important to think about how the two fit
together, at least conceptually. Mechanically I think there's an issue
with this trick:

#ifdef __BINDGEN__
#define __rust_helper
#else
#define __rust_helper inline
#endif

which the LTO series uses to generate Rust stubs for these functions
while also keeping them marked inline in LLVM IR/bitcode.

That said, I see some discussion of cross-language LTO in "How to
handle static inline functions" [1], so maybe there's another way that
makes more sense in light of this series.

Updating the cover letter to elucidate these details is where I'd
suggest you start.

Cheers.
Tamir

[1] https://github.com/rust-lang/rust-bindgen/discussions/2405