The :RustAnalyzer config { cargo = { features = {"<feature name>"}}} doesn't working in rustc 1.95.0?

[aniketnarvekar]

Checked other resources

• This is not a bug report or feature request (Please use issues for those).
• This is a question about rustaceanvim, not rust-analyzer or Neovim.
• This is not a question about autocompletion.
• I have read the README.
• I have read the FAQ.
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Description

I always use the :RustAnalyzer config { cargo = { features = {"<feature name>"}}} command to enable the feature that I'm working on. Today I upgraded Rust using rustup update it updated to the stable-aarch64-apple-darwin unchanged - rustc 1.95.0 version. After this, the :RustAnalyzer config { cargo = { features = {"<feature name>"}}} command stops working. The command doesn't give any error, but the autocompletion and documentation commands are not working on APIs under this specific feature, but the autocompletion and documentation are working on default APIs (which are not hidden under any feature flags). Then I again run the rustup update and get the following output:

info: syncing channel updates for stable-aarch64-apple-darwin
info: syncing channel updates for 1.90-aarch64-apple-darwin

  stable-aarch64-apple-darwin unchanged - rustc 1.95.0 (59807... 2026-04-14)
    1.90-aarch64-apple-darwin unchanged - rustc 1.90.0 (1159e7.... 2025-09-14)

info: checking for self-update (current version: 1.29.0)
info: cleaning up downloads & tmp directories

After I check the default toolchain rustup default i got stable-aarch64-apple-darwin (default). Then i change to rustup default 1.90-aarch64-apple-darwin using rustup default rustup default 1.90-aarch64-apple-darwin and try using :RustAnalyzer config { cargo = { features = {"<feature name>"}}} and this works.

I don't know what went wrong with stable-aarch64-apple-darwin unchanged - rustc 1.95.0?

Example Code

RustAnalyzer config { cargo = { features = {"<feature name>"}}}

Neovim version (nvim -v)

v0.12.2

Operating system/version

MacOS 26.4.1

Output of :checkhealth rustaceanvim

==============================================================================
rustaceanvim:                                                               ✅

Checking for Lua dependencies ~
- ✅ OK [mfussenegger/nvim-dap](https://github.com/mfussenegger/nvim-dap) installed.

Checking external dependencies ~
- ✅ OK rust-analyzer: found rust-analyzer 0.3.2693-standalone (4a2b38f49f 2025-11-23)
- ✅ OK Cargo: found cargo 1.95.0 (f2d3ce0bd 2026-03-21)
- ✅ OK rustc: found rustc 1.95.0 (59807616e 2026-04-14)
- ✅ OK debug adapter: found 

Checking config ~
- ✅ OK No errors found in config.

Checking for conflicting plugins ~
- ✅ OK No conflicting plugins detected.

Checking for tree-sitter parser ~
- ✅ OK tree-sitter parser for Rust detected.

[mrcjkb]

Hey 👋

This looks like a rust-analyzer issue.
I suggest you:

• Try configuring the feature in your init.lua (e.g. using vim.g.rustaceanvim or vim.lsp.config) and see if rust-analyzer picks it up properly.
• If not, report the issue in the rust-analyzer repo.
• If it does work when you configure it upon startup, that means it's the workspace/didChangeConfiguration notification that's not working, which would also be a rust-analyzer issue (given that it works with rustc 1.90.0).

[ZX41R]

The suspicious line in your health output is this one:

rust-analyzer: found rust-analyzer 0.3.2693-standalone (4a2b38f49f 2025-11-23)
Cargo/rustc: 1.95.0 from 2026-04

So when you switch back to Rust 1.90, you are also moving closer to the age of the rust-analyzer binary you have installed. That makes this look less like a rustaceanvim command issue and more like a rust-analyzer/toolchain mismatch.

I would test these two things:

which rust-analyzer
rust-analyzer --version
rustup which rust-analyzer
rustup run stable rust-analyzer --version

If Neovim is picking up an older standalone / Mason / manually installed rust-analyzer, put the rustup one first in PATH or configure rustaceanvim to use it explicitly:

vim.g.rustaceanvim = {
  server = {
    cmd = { "rustup", "run", "stable", "rust-analyzer" },
    default_settings = {
      ["rust-analyzer"] = {
        cargo = {
          features = { "your-feature" },
        },
      },
    },
  },
}

That also tests the maintainer's point: if startup config works but :RustAnalyzer config ... does not, then the runtime workspace/didChangeConfiguration path is the thing to report upstream to rust-analyzer.

Small syntax note: features should be a Lua list, not a set-like table:

:RustAnalyzer config { cargo = { features = { "your-feature" } } }

The command does not validate the table, so a shape that is accepted by Lua can still be ignored by rust-analyzer if it is not the config shape it expects.