[ci] enable non_exhaustive_omitted_patterns lint with a nightly check (…

…#358)

This lint is useful to detect missed match statements.

Also add a Justfile to make this easy to run.

.cargo/nightly-config.toml

@@ -0,0 +1,18 @@
+# Extra configuration for nightly Rust.
+#
+# Use manually by passing this path into `--config`, or via the Justfile: `just
+# nightly check` or `just bootstrap check`.
+
+[build]
+# Detect if non-exhaustive patterns are missing:
+# https://github.com/rust-lang/rust/issues/89554
+#
+# To allow this lint for some statements, use
+# `#[cfg_attr(guppy_nightly, expect(non_exhaustive_omitted_patterns))]`.
+rustflags = [
+    "--warn",
+    "non_exhaustive_omitted_patterns",
+    "-Zcrate-attr=feature(non_exhaustive_omitted_patterns_lint)",
+    "--cfg",
+    "guppy_nightly",
+]

.github/workflows/ci.yml

@@ -20,8 +20,12 @@ jobs:
         with:
           components: rustfmt, clippy
       - uses: Swatinem/rust-cache@82a92a6e8fbeee089604da2575dc567ae9ddeaab # v2
+      - name: Install just
+        uses: taiki-e/install-action@just
       - name: Lint (clippy)
-        run: cargo clippy --all-features --all-targets
+        run: just bootstrap clippy
+        env:
+          RUSTC_BOOTSTRAP: 1
       - name: Install cargo-hack
         uses: taiki-e/install-action@cargo-hack
       - name: Lint (rustfmt)

Cargo.toml

@@ -29,7 +29,7 @@ miette = "7.2.0"
 rust-version = "1.78"
 
 [workspace.lints.rust]
-unexpected_cfgs = { level = "warn", check-cfg = ['cfg(doc_cfg)'] }
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(doc_cfg)', 'cfg(guppy_nightly)'] }
 
 [patch.crates-io.guppy-workspace-hack]
 path = "workspace-hack"

Justfile

@@ -0,0 +1,13 @@
+# Note: help messages should be 1 line long as required by just.
+
+# Print a help message.
+help:
+    just --list
+
+# Run the nightly check command: `just nightly check` or `just nightly clippy --fix`
+nightly arg1 *args:
+    cargo +nightly {{arg1}} {{args}} --all-features --all-targets --config .cargo/nightly-config.toml
+
+# Run with nightly features enabled: `just bootstrap check`, `just bootstrap +beta clippy`
+bootstrap arg1 *args:
+    RUSTC_BOOTSTRAP=1 cargo {{arg1}} {{args}} --all-features --all-targets --config .cargo/nightly-config.toml

guppy/tests/graph-tests/graph_tests.rs

@@ -331,13 +331,16 @@ mod small {
             .metadata(&package_id(json::METADATA_PROC_MACRO1_MACRO))
             .expect("valid package ID");
         assert!(package.is_proc_macro(), "is proc macro");
-        assert!(matches!(
-            package
-                .build_target(&BuildTargetId::Library)
-                .expect("library package is present")
-                .kind(),
-            BuildTargetKind::ProcMacro
-        ));
+
+        let build_target_kind = package
+            .build_target(&BuildTargetId::Library)
+            .expect("library package is present")
+            .kind();
+        assert_eq!(
+            build_target_kind,
+            BuildTargetKind::ProcMacro,
+            "build target kind matches"
+        );
     }
 
     // No need for proptests because this is a really simple test.

guppy/tests/graph-tests/invalid_tests.rs

@@ -109,12 +109,16 @@ fn proc_macro_mixed_kinds() {
 
 fn assert_invalid(json: &str, search_str: &str) {
     let err = PackageGraph::from_json(json).expect_err("expected error for invalid metadata");
+    let Error::PackageGraphConstructError(s) = err else {
+        panic!(
+            "expected PackageGraphConstructError, got: {} ({:?}",
+            err, err
+        );
+    };
     assert!(
-        matches!(
-            err,
-            Error::PackageGraphConstructError(ref s) if s.contains(search_str),
-        ),
-        "actual error is: {}",
-        err,
+        s.contains(search_str),
+        "expected error to contain '{}', got: {}",
+        search_str,
+        s
     );
 }

tools/cargo-hakari/src/command.rs

@@ -306,7 +306,14 @@ impl CommandWithBuilder {
                         // 102 is picked pretty arbitrarily because regular errors exit with 101.
                         return Ok(102);
                     }
-                    Err(err) => Err(err).with_context(|| "error generating new hakari.toml")?,
+                    Err(
+                        err @ TomlOutError::Platform(_)
+                        | err @ TomlOutError::Toml { .. }
+                        | err @ TomlOutError::FmtWrite(_)
+                        | err @ TomlOutError::UnrecognizedExternal { .. }
+                        | err @ TomlOutError::PathWithoutHakari { .. }
+                        | err,
+                    ) => Err(err).with_context(|| "error generating new hakari.toml")?,
                 };
 
                 let existing_toml = hakari

tools/hakari/Cargo.toml

@@ -21,6 +21,9 @@ rust-version.workspace = true
 all-features = true
 rustdoc-args = ["--cfg=doc_cfg"]
 
+[lints]
+workspace = true
+
 [dependencies]
 ahash = "0.8.11"
 atomicwrites = "0.4.4"

tools/hakari/src/cli_ops/initialize.rs

@@ -60,6 +60,7 @@ impl<'g, 'a> HakariInit<'g, 'a> {
                 // The path exists.
                 return Err(InitError::WorkspacePathExists { abs_path });
             }
+            #[cfg_attr(guppy_nightly, expect(non_exhaustive_omitted_patterns))]
             Err(err) => match err.kind() {
                 io::ErrorKind::NotFound => {}
                 _ => {