Cannot create expander for ...

[crptz]

Hi there,

I set up a project with cargo generate for Arduino Uno, although it's running perfectly, rust-analyzer gives me an error

proc macro `entry` not expanded: Cannot create expander for /home/path/to/project/target/debug/deps/libavr_device_macros-8c55ff3523662538.so: unsupported ABI `rustc 1.64.0-nightly (6dba4ed21 2022-07-09)`rust-analyzer[unresolved-proc-macro](https://rust-analyzer.github.io/manual.html#unresolved-proc-macro)

I've been searching for possible fixes but I couldn't find anything here in issues.

Any hint would be much appreciated, cheers !

[crptz]

I've found a "solution"
I basically disabled the errors for unresolved-proc-macro in rust-analyzer settings but is this the correct way to resolve this?

    "rust-analyzer.diagnostics.disabled": [
        "unresolved-proc-macro"
    ],

[Rahix]

Hi,

I think you need to post this issue on the rust-analyzer bug tracker. I don't think this is something strictly related to avr-hal.

[crptz]

hey, ok ! I'll search for advice there, thank you, closing the issue

[BoManev]

Here's an article explaining the root cause of this issue. This was fixed for versions starting 2022-08-*.
Im nor sure how this could be fixed. @Rahix can the rustc version be bumped

[Rahix]

rustc version bump is currently blocked on rust-lang/rust#106619 unfortunately...

[crptz]

I'll give a read to the article once a I have free time although I haven't checked the issue for a while now.

[BoManev]

I found a solution. VS Code starts 2 processes one for rust-analyzer and one for the proc_macro server. It searches for the proc_macro executable in the nightly-xxx/libexec. Install nightly-2022-08-03-x86_64-unknown-linux-gnu (the earliest version to include the executable) and then copy the libexec/rust-analyzer-proc-macro-srv from the 08-03 nightly to the 07-10.

@Rahix maybe we should add this fix to the repo readme (assuming that a lot of ppl use VSCode)