IDE support in fn-like proc macro arguments

[nitsky]

With support for fn-like proc macros as expressions becoming stable in rust 1.45 (rust-lang/rust#68717), I am opening this issue to track rust-analyzer support for language features within them.

For example, given the code below that uses a proc macro that implements jsx-like syntax...

let items = &["a", "b", "c"];
let html = html!(<ul>{items.iter().map(|item| html!(<li>{item}</li>))}</ul>);

... it would be awesome to be able to use "go to definition", "rename", "find references", etc when my cursor is over the last item identifier.

[nitsky]

Thanks to recent improvements by @jonas-schievink, language features in the example above now work perfectly. Thank you!

[ivnsch]

@nitsky Which version? I'm using Rust-Analyzer v0.2.489 (most recent version) and Yew 0.17, followed the intro tutorial in the docs, and it doesn't work.

[bjorn3]

Did you enable proc-macro support using

{
    "rust-analyzer.cargo.loadOutDirsFromCheck": true,
    "rust-analyzer.procMacro.enable": true,
}

[nitsky]

@i-schuetz in my experience macro not found errors are resolved by reloading the editor.

[ivnsch]

Hmm sadly still not working, I restarted VSCode multiple times and double checked that the settings are in the workspace's settings.json (added them to the user's as well just in case) and the macro still doesn't work

could not resolve macro htmlrust-analyzer macro-error

[memoryruins]

html! uses proc_macro_hack https://docs.rs/yew/0.17.4/src/yew/lib.rs.html#101. which tends to cause that error due to lack of attribute macro support #6029. Oh, after visiting that issue again, looks like another html! issue #7221 was closed for that reason.

To silence those warnings for now, "macro-error" can be added to "rust-analyzer.diagnostics.disabled"

[nitsky]

@i-schuetz I am not seeing the issue because I am using an in-house html! macro, which does not use proc_macro_hack, and which we designed to ensure it emits the correct span information for rust-analyzer.

[ivnsch]

Was able to fix it by using yew master yewstack/yew#1754