On Tue, Dec 7, 2021 at 3:25 PM Wedson Almeida Filho [off-list ref] wrote:

On Tue, 7 Dec 2021 at 23:21, Nick Desaulniers [off-list ref] wrote:

quoted

On Tue, Dec 7, 2021 at 2:45 PM Nick Desaulniers [off-list ref] wrote:

quoted

On Mon, Dec 6, 2021 at 6:07 AM Miguel Ojeda [off-list ref] wrote:

quoted

... snip ...

Miguel and team,
I'm happy to see progress here! Just some quick notes after a first pass.

Testing this series applied on mainline, I see:
$ make LLVM=1 -j72 defconfig
$ grep RUST .config
CONFIG_HAS_RUST=y
CONFIG_RUSTC_VERSION=14000
# CONFIG_RUST is not set
...
$ make LLVM=1 -j72 menuconfig
# enable CONFIG_RUST
$ make LLVM=1
...
  CALL    scripts/checksyscalls.sh
error: @path is unstable - use -Z unstable-options to enable its use

error: @path is unstable - use -Z unstable-options to enable its use
$ rustc --version
rustc 1.40.0 (73528e339 2019-12-16)

Can we update some Kconfig checks to fix that?

After now reading though the Documentation/ patch:

$ rustup update
$ rustc --version
rustc 1.57.0 (f1edd0429 2021-11-29)
$ make LLVM=1 -j72
...
make[1]: *** No rule to make target
'/usr/local/google/home/ndesaulniers/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/lib.rs',
needed by 'rust/core.o'.  Stop.

Can you run `rustup component add rust-src`?

When we change the compiler version, we need to install the source
code for `core` for the new version. (We'll update the documentation
to reflect that.)

Cool, yeah please add that to the docs.  Kconfig checks should be
added to make this idiot-proof; starting from everything uninstalled,
I should be able to read the Kconfig dependencies in `make menuconfig`
to understand what I'm missing. And if I'm missing anything, I
shouldn't be able to select CONFIG_RUST.

I get slightly further now.

$ make LLVM=1 -j72
...
  BINDGEN rust/bindings_helpers_generated.rs
thread 'main' panicked at 'called `Result::unwrap()` on an `Err`
value: "could not run executable `/android0/llvm-project/clang`:
Permission denied (os error 13)"',
/usr/local/google/home/ndesaulniers/.cargo/registry/src/github.com-1ecc6299db9ec823/clang-sys-1.3.0/src/support.rs:196:58
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread 'main' panicked at 'called `Result::unwrap()` on an `Err`
value: "could not run executable `/android0/llvm-project/clang`:
Permission denied (os error 13)"',
/usr/local/google/home/ndesaulniers/.cargo/registry/src/github.com-1ecc6299db9ec823/clang-sys-1.3.0/src/support.rs:196:58
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
make[1]: *** [rust/Makefile:261: rust/bindings_helpers_generated.rs] Error 1
make[1]: *** Deleting file 'rust/bindings_helpers_generated.rs'
make[1]: *** Waiting for unfinished jobs....
make[1]: *** [rust/Makefile:248: rust/bindings_generated.rs] Error 1
make[1]: *** Deleting file 'rust/bindings_generated.rs'
make: *** [Makefile:1271: prepare0] Error 2

It looks like bindgen found part of the path to llvm-project that I
have checked out to disk for when I do development on LLVM for work.
So this might only be an issue if folks have a copy of clang built
from source in their $PATH?

$ which clang
/android0/llvm-project/llvm/build/bin/clang

Looking at the output of `make LLVM=1 -j72 V=1`, I see two invocations
of bindgen, and can repro if I just run the full command manually.

I don't see my path to my source code checkout of llvm-project in the
command line invocation of bindgen; this might be an issue itself with
bindgen.

Googling for "could not run executable" and bindgen, I find this
thread with a similar failure string:
https://bugzilla.mozilla.org/show_bug.cgi?id=1363655
No hits in their issue tracker: https://github.com/rust-lang/rust-bindgen.

$ bindgen --version
bindgen 0.59.2
$ cargo install --locked --version 0.56.0 bindgen
$ bindgen --version
bindgen 0.56.0
$ make LLVM=1 -j72
# produces the same error.

I guess the error is coming not from bindgen, but a dependency of its;
"clang-sys?"
https://github.com/KyleMayes/clang-sys/blob/master/src/support.rs

I've filed an issue in
https://github.com/KyleMayes/clang-sys/issues/138; let's follow up
there?
-- 
Thanks,
~Nick Desaulniers