style: switch rustfmt from the nightly to the stable toolchain

.github/workflows/rust.yml

@@ -44,10 +44,10 @@ jobs:
           persist-credentials: false
 
       - name: Install toolchain
-        run: rustup toolchain install nightly --component rustfmt
+        run: rustup component add rustfmt
 
       - name: Run rustfmt checks
-        run: rustup run nightly cargo fmt --check --all
+        run: cargo fmt --check --all
 
   lint:
     name: Lint

.vscode/settings.json

@@ -14,9 +14,6 @@
     "**/Cargo.lock": true,
     ".git/": true
   },
-  "rust-analyzer.rustfmt.extraArgs": [
-    "+nightly"
-  ],
   "[json]": {
     "editor.defaultFormatter": "vscode.json-language-features",
     "editor.tabSize": 2

README.md

@@ -15,7 +15,7 @@ Opinionated template for multi-crate Rust workspaces, with:
 
 The following software is expected to be installed and available in `PATH`:
 
-- [rustup][rustup] – Rust toolchain manager. Both the stable and nightly toolchains are used: nightly for `rustfmt` (`rustfmt.toml` contains unstable options), stable for everything else.
+- [rustup][rustup] – Rust toolchain manager. Only the stable toolchain is used.
 - [just][just] – Command runner. See the `justfile` for available recipes.
 - [taplo][taplo] – TOML formatter. Configured by `taplo.toml`.
 - [markdownlint-cli2][markdownlint-cli2] – Markdown linter. Configured by `.markdownlint.json`.

justfile

@@ -6,7 +6,7 @@ default:
 
 # Run rustfmt
 fmt:
-  cargo +nightly fmt --all
+  cargo fmt --all
 
 # Check whether the code compiles
 check:

rustfmt.toml

@@ -1,17 +1,22 @@
 # Reference: https://rust-lang.github.io/rustfmt/
 
-condense_wildcard_suffixes     = true
-format_macro_bodies            = false
-format_macro_matchers          = false
-group_imports                  = "Preserve"
-imports_granularity            = "One"
 match_block_trailing_comma     = true
-normalize_comments             = true
-normalize_doc_attributes       = true
-overflow_delimited_expr        = true
-reorder_impl_items             = true
 single_line_if_else_max_width  = 0
 single_line_let_else_max_width = 0
 style_edition                  = "2024"
 use_field_init_shorthand       = true
 use_try_shorthand              = true
+
+# The following options are nightly-only. They are commented out because we
+# format with the stable toolchain; uncomment when any one of them becomes
+# available in stable.
+
+# condense_wildcard_suffixes = true
+# format_macro_bodies        = false
+# format_macro_matchers      = false
+# group_imports              = "Preserve"
+# imports_granularity        = "One"
+# normalize_comments         = true
+# normalize_doc_attributes   = true
+# overflow_delimited_expr    = true
+# reorder_impl_items         = true