Bug#1057586: nvda2speechd: FTBFS: error: failed to run custom build command for `speech-dispatcher-sys v0.7.0`

[Samuel Thibault]

Sebastian Ramacher, le lun. 15 avril 2024 05:41:48 +0200, a ecrit:
> On 2024-04-14 14:19:18 +0200, Santiago Vila wrote:
> > El 14/4/24 a las 13:25, Sylvestre Ledru escribió:
> > > I am sorry but I am not sure to see how it is actionable.
> > > 
> > > Without a test case, i don't think there is much I can do here.
> > 
> > The test case is that nvda2speechd fails to build from source.
> > > With rust, cargo, custom build script, there are many things that can go wrong before LLVM.
> > > 
> > > Sebastian, I think it could be move to normal. From LLVM perspective, it isn't serious severity (many programs are built with LLVM 16).
> > 
> > We can release trixie with compilers having bugs, but I don't think it would be ok at
> > all to release trixie as stable with packages which do not build from source, that would
> > be against Release Policy.
> > 
> > So, in my opinion, this is still RC, either in the compiler or in the package failing
> > to build. If solving this in the compiler is too complex, then the bug should be reassigned back to src:nvda2speechd.
> 
> Given that nvda2speechd downloads rust and plenty of crates during the
> build, it will have to prevent odd interactions with the system provided
> LLVM. Let's keep this as RC bug against nvda2speechd.

The problem is that bindgen insists on interacting with the
system-provided LLVM:

https://github.com/rust-lang/rust-bindgen/blob/main/bindgen/lib.rs#L620

It force-loads libclang, and when that's libclang16, we get the bug.

For now I "fixed" the bug by dropping the rust/cargo/clang build-deps
entirely, and build-dep on libclang 14 rather than 16.

I don't know why the issue shows up only when building
speech-dispatcher-sys, perhaps that's just because it's the only crate
that uses bindgen.

Samuel