DX regression in view macro for rust-analyzer 2024-03-18 (v0.3.1885) and newer

[Ar4ys]

• Affected Leptos version: v0.6.11
• Affected Rust Analyzer version: 2024-03-18 (v0.3.1885) and newer
• Related PR: Fix error reporting in view macro #2289

In rust-analyzer 2024-03-18 (v0.3.1885) they updated how they handle overlapping spans, which resulted in a degraded DX of #2289 (worse syntax highlighting, hover tooltips, go to definition etc.).

Examples

Note: This is not a full list of regressions

Hover over items used inside view! macro

Working (rust-analyzer 2024-03-11 (v0.3.1877))
Broken (rust-analyzer 2024-03-18 (v0.3.1885))

Component's syntax highlighting

Working (rust-analyzer 2024-03-11 (v0.3.1877))
Broken (rust-analyzer 2024-03-18 (v0.3.1885))

Go to definition

Working (rust-analyzer 2024-03-11 (v0.3.1877))
Broken (rust-analyzer 2024-03-18 (v0.3.1885))

Temporary workarounds

Until the issue is resolved, users can:

1. Downgrade to rust-analyzer 2024-03-11 (v0.3.1877)
   • by following official installation guide here and using downloaded rust-analyzer binary in your IDE instead of a bundled one
   • in VSCode users can select "install another version" from the rust-analyzer context menu (thanks @zenlex for suggestion)
2. Or use latest stable rustc version (rustc 1.78.0 (9b00956e5 2024-04-29) at the time of writing), instead on nightly

Proposed solutions

I see two possible solutions to this issue:

1. Remove overlapping spans introduced in Fix error reporting in view macro #2289. While this will fix the problem, it will also worsen error reporting in view! macro.
2. File an issue against rust-analyzer and try to fix the problem upstream.

[jensmeindertsma]

Yeah, I've noticed this as well. Highlighting any part of the view! macro now shows a useless overlay:

|----------------------------------------------------------|
| clippy::needless_borrows_for_generic_args                |
| ---------------------------------------------------------|
| Checks for borrow operations (&) that used as a          |
| generic argument to a function when the borrowed         |
| value could be used.                                     |
|----------------------------------------------------------|

[SeraphyBR]

I also had the same problem.. I tried some ways to ignore clippy (because when it hovers that's what appears), but I couldn't.

[zenlex]

same, didn't have much luck with any allow or config options and it also seemed to bork the syntax highlighting in vscode a tad too - primarily that the Component name lost it's coloration after rust-analyzer finished indexing leptos.

Confirmed that reverting rust-analyzer to https://github.com/rust-lang/rust-analyzer/releases/tag/2024-03-11 addressed both issues. In VSCode you can select "install another version" from the rust-analyzer context menu and not need to manually install any binaries.

[gbj]

I don't know the first thing about how rust-analyzer works. Is there a reason to think this was an intentional decision by rust-analyzer, not a bug/regression? If it was an intentional decision to no longer support overlapping spans in this way, then I guess we should revert the changes made in #2289. If not, opening an issue there makes sense and @Ar4ys I'd appreciate it if you could do that, as you know what you're talking about more than I do!

[Ar4ys]

While trying to make a reproduction repository for my issue against rust-analyzer, I found out that DX regressions are not present when using latest stable rustc (rustc 1.78.0 (9b00956e5 2024-04-29) at the time of writing) instead of nightly. I added this as a possible workaround to the current issue.

Still investigating why nightly breaks....