Develop using latest stable Rust

The latest Clippy has a lint that checks that calls follow MSRV. It's
not perfect - it misses some cases like trait items, `Arc::default()`
for example. Spellbook is not changed often enough that it should be a
pain point however.

Also Spellbook is not meant to increase MSRV without good reason (unlike
an application like Helix) so eventually it will run further behind on
Rust versions than rust-analyzer supports. The MSRV CI will catch actual
violations not caught by Clippy before a release.

.envrc

@@ -1,5 +1,4 @@
 watch_file flake.lock
-watch_file rust-toolchain.toml
 
 # try to use flakes, if it fails use normal nix (ie. shell.nix)
 use flake || use nix

.github/workflows/ci.yml

@@ -19,12 +19,6 @@ jobs:
       - name: Checkout sources
         uses: actions/checkout@v4
 
-      - name: Remove the rust-toolchain.toml
-        # `rustup` will attempt to use the toolchain from
-        # the file which will conflict with the custom versions
-        # we use in the matrix.
-        run: rm rust-toolchain.toml
-
       - name: Install toolchain
         uses: dtolnay/rust-toolchain@master
         with:
@@ -44,9 +38,6 @@ jobs:
       - name: Checkout sources
         uses: actions/checkout@v4
 
-      - name: Remove the rust-toolchain.toml
-        run: rm rust-toolchain.toml
-
       - name: Install MSRV toolchain
         uses: dtolnay/rust-toolchain@master
         with:
@@ -67,9 +58,6 @@ jobs:
       - name: Checkout sources
         uses: actions/checkout@v4
 
-      - name: Remove the rust-toolchain.toml
-        run: rm rust-toolchain.toml
-
       - name: Install MSRV toolchain
         uses: dtolnay/rust-toolchain@master
         with:

docs/CONTRIBUTING.md

@@ -4,17 +4,15 @@ New to contributing to projects on GitHub? GitHub provides [getting started docu
 
 ## Installing Rust
 
-To build and test Spellbook you will need a Rust compiler and the `cargo` command. [rustup](https://rustup.rs/) is the recommended way to install Rust. It manages versions and components of Rust like cargo and clippy and it will install the expected versions of each component specified in the `rust-toolchain.toml` file in the root of the repository. Install `rustup` as [the Rust documentation recommends](https://www.rust-lang.org/tools/install).
-
-You may also install Rust through a system package manager but it might not be the version pinned in `rust-toolchain.toml`. Also see the [MSRV](#msrv) section below.
+To build and test Spellbook you will need a Rust compiler and the `cargo` command. [rustup](https://rustup.rs/) is the recommended way to install Rust: it manages versions and components and tools of Rust like `cargo`, `clippy` and `rust-analyzer`. Install `rustup` as [the Rust documentation recommends](https://www.rust-lang.org/tools/install).
 
 If you use [Nix or NixOS](https://nixos.org/) you can use the [flake](https://nixos.wiki/wiki/flakes) via `nix develop` or `shell.nix` via `nix-shell` in the repository root to spawn a shell with the necessary dependencies. Using Nix is entirely optional and is only provided for convenience.
 
 ## MSRV
 
 Spellbook keeps an intentionally low <b>m</b>inimum <b>s</b>upported <b>R</b>ust <b>v</b>ersion for the sake of easy compatibility with consuming applications.
 
-The MSRV should never rise higher than allowed by [Mozilla's Firefox MSRV policy](https://firefox-source-docs.mozilla.org/writing-rust-code/update-policy.html) and should lag behind by as many more versions as is practical.
+The MSRV should never rise higher than allowed by [Mozilla's Firefox MSRV policy](https://firefox-source-docs.mozilla.org/writing-rust-code/update-policy.html) and should lag behind by as many more versions as is practical. The current MSRV can be found in `Cargo.toml` under the `package.rust-version` key.
 
 ## Linting
 
@@ -37,7 +35,7 @@ The testsuite has three parts:
 
 * Unit tests. These are in `src/**.rs` in `test` modules at the end of each file.
 * Doc tests. These are in markdown codefences in documentation comments (comments starting with `///`).
-* "Legacy" tests. These tests live under `tests/legacy/` and are run by `tests/legacy.rs`. These cases are ported originally from the Hunspell codebase and should not be added to unless an equivalent test exists upstream in Hunspell or Nuspell.
+* "Legacy" tests. These tests live under `tests/legacy/` and are run by `tests/legacy.rs`. These cases are ported originally from the Hunspell codebase and should not be modified or expanded unless an equivalent test exists upstream in Hunspell or Nuspell.
 
 ### Adding a test case
 
@@ -51,8 +49,8 @@ You can generate a human readable coverage report using [`cargo-llvm-cov`](https
 cargo llvm-cov --html test
 ```
 
-For this to work you also need `llvm-tools-preview`. This component is specified in `rust-toolchain.toml` so it should be installed by `rustup`. `cargo-llvm-cov` and `llvm-tools-preview` are included in the Nix development shell for convenience.
+For this to work you also need `llvm-tools-preview` which can be installed by `rustup`. `cargo-llvm-cov` and `llvm-tools-preview` are included in the Nix development shell for convenience.
 
 ## Benchmarking
 
-There are a few benchmarks in the `examples/` directory built with [`brunch`](https://github.com/Blobfolio/brunch). The main benchmark to pay attention to is `bench-api` which covers some common cases of Spellbook usage. Run `cargo run --release --example bench-api` before and after a change to see the difference in timings. Note that the timing each benchmark might vary slightly between runs: the timing of a case swaying plus or minus 5% is not unusual. Run the benchmark multiple times to get a feel for how a change impacted performance.
+There are a few benchmarks in the `examples/` directory which use the nightly benchmarking feature. When using Rustup, use `cargo +nightly bench` before and after a change to see the difference in timings. Note that the timing each benchmark might vary slightly between runs: the timing of a case swaying plus or minus 5% is not unusual. Run the benchmark multiple times to get a feel for how a change impacted performance.

flake.nix

@@ -20,7 +20,7 @@
             inherit system;
             overlays = [ rust-overlay.overlays.default ];
           };
-          toolchain = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
+          toolchain = pkgs.rust-bin.stable.latest.default;
         in
         pkgs.mkShell {
           nativeBuildInputs = with pkgs; [