Add a restricted set of clippy lints, required to pass

This sets up CI to check clippy with a restricted set of clippy groups.
Some of the default groups have some excessive sets of lints that are
either wrong or style choices that I would prefer to not mess over at
this time. The lint groups can be adjusted later if it looks like
something that would be helpful.

.github/workflows/main.yml

@@ -88,6 +88,16 @@ jobs:
       - name: Build and run tests (+ GUI)
         run: cargo test --locked --target x86_64-unknown-linux-gnu --test gui
 
+  # Ensure there are no clippy warnings
+  clippy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        run: bash ci/install-rust.sh stable x86_64-unknown-linux-gnu
+      - run: rustup component add clippy
+      - run: cargo clippy --workspace --all-targets --no-deps -- -D warnings
+
   # The success job is here to consolidate the total success/failure state of
   # all other jobs. This job is then included in the GitHub branch protection
   # rule which prevents merges unless all other jobs are passing. This makes
@@ -101,6 +111,7 @@ jobs:
       - rustfmt
       - aarch64-cross-builds
       - gui
+      - clippy
     runs-on: ubuntu-latest
     steps:
       - run: jq --exit-status 'all(.result == "success")' <<< '${{ toJson(needs) }}'

Cargo.toml

@@ -1,6 +1,12 @@
 [workspace]
 members = [".", "examples/remove-emphasis/mdbook-remove-emphasis"]
 
+[workspace.lints.clippy]
+all = { level = "allow", priority = -2 }
+correctness = { level = "warn", priority = -1 }
+complexity = { level = "warn", priority = -1 }
+needless-lifetimes = "allow"  # Remove once 1.87 is stable, https://github.com/rust-lang/rust-clippy/issues/13514
+
 [package]
 name = "mdbook"
 version = "0.4.48"
@@ -91,3 +97,6 @@ test = false
 name = "gui"
 path = "tests/gui/runner.rs"
 crate-type = ["bin"]
+
+[lints]
+workspace = true

src/book/mod.rs

@@ -5,7 +5,6 @@
 //!
 //! [1]: ../index.html
 
-#[allow(clippy::module_inception)]
 mod book;
 mod init;
 mod summary;

src/preprocess/links.rs

@@ -148,7 +148,6 @@ enum RangeOrAnchor {
 }
 
 // A range of lines specified with some include directive.
-#[allow(clippy::enum_variant_names)] // The prefix can't be removed, and is meant to mirror the contained type
 #[derive(PartialEq, Debug, Clone)]
 enum LineRange {
     Range(Range<usize>),

src/renderer/html_handlebars/hbs_renderer.rs

@@ -207,7 +207,6 @@ impl HtmlHandlebars {
         Ok(())
     }
 
-    #[allow(clippy::let_and_return)]
     fn post_process(
         &self,
         rendered: String,

tests/rendered_output.rs

@@ -780,7 +780,6 @@ mod search {
     }
 
     #[test]
-    #[allow(clippy::float_cmp)]
     fn book_creates_reasonable_search_index() {
         let temp = DummyBook::new().build().unwrap();
         let md = MDBook::load(temp.path()).unwrap();