lintcheck: use clap's derive interface

This makes the code shorter and clearer.

The only incompatible change is that an explicit command-line argument
`--crates-toml=` will take precedence over the `LINTCHECK_TOML`
environment variable.

2 files changed, 44 insertions, 102 deletions

diff --git a/lintcheck/Cargo.toml b/lintcheck/Cargo.toml
index 653121af54d..dbfeb8dd1d1 100644
--- a/lintcheck/Cargo.toml
+++ b/lintcheck/Cargo.toml
@@ -11,7 +11,7 @@ publish = false
 
 [dependencies]
 cargo_metadata = "0.15.3"
-clap = "4.1.4"
+clap = { version = "4.1.8", features = ["derive", "env"] }
 crossbeam-channel = "0.5.6"
 flate2 = "1.0"
 rayon = "1.5.1"
diff --git a/lintcheck/src/config.rs b/lintcheck/src/config.rs
index f87b902b92d..e1836c19aa2 100644
--- a/lintcheck/src/config.rs
+++ b/lintcheck/src/config.rs
@@ -1,128 +1,70 @@
-use clap::{Arg, ArgAction, ArgMatches, Command};
-use std::env;
+use clap::Parser;
 use std::path::PathBuf;
 
-fn get_clap_config() -> ArgMatches {
-    Command::new("lintcheck")
-        .about("run clippy on a set of crates and check output")
-        .args([
-            Arg::new("only")
-                .action(ArgAction::Set)
-                .value_name("CRATE")
-                .long("only")
-                .help("Only process a single crate of the list"),
-            Arg::new("crates-toml")
-                .action(ArgAction::Set)
-                .value_name("CRATES-SOURCES-TOML-PATH")
-                .long("crates-toml")
-                .help("Set the path for a crates.toml where lintcheck should read the sources from"),
-            Arg::new("threads")
-                .action(ArgAction::Set)
-                .value_name("N")
-                .value_parser(clap::value_parser!(usize))
-                .short('j')
-                .long("jobs")
-                .help("Number of threads to use, 0 automatic choice"),
-            Arg::new("fix")
-                .long("fix")
-                .help("Runs cargo clippy --fix and checks if all suggestions apply"),
-            Arg::new("filter")
-                .long("filter")
-                .action(ArgAction::Append)
-                .value_name("clippy_lint_name")
-                .help("Apply a filter to only collect specified lints, this also overrides `allow` attributes"),
-            Arg::new("markdown")
-                .long("markdown")
-                .help("Change the reports table to use markdown links"),
-            Arg::new("recursive")
-                .long("recursive")
-                .help("Run clippy on the dependencies of crates specified in crates-toml")
-                .conflicts_with("threads")
-                .conflicts_with("fix"),
-        ])
-        .get_matches()
-}
-
-#[derive(Debug, Clone)]
+#[derive(Clone, Debug, Parser)]
 pub(crate) struct LintcheckConfig {
-    /// max number of jobs to spawn (default 1)
+    /// Number of threads to use, 0 automatic choice
+    #[clap(long = "jobs", short = 'j', value_name = "N", default_value_t = 1)]
     pub max_jobs: usize,
-    /// we read the sources to check from here
+    /// Set the path for a crates.toml where lintcheck should read the sources from
+    #[clap(
+        long = "crates-toml",
+        value_name = "CRATES-SOURCES-TOML-PATH",
+        default_value = "lintcheck/lintcheck_crates.toml",
+        hide_default_value = true,
+        env = "LINTCHECK_TOML",
+        hide_env = true
+    )]
     pub sources_toml_path: PathBuf,
-    /// we save the clippy lint results here
-    pub lintcheck_results_path: PathBuf,
-    /// Check only a specified package
+    /// File to save the clippy lint results here
+    #[clap(skip = "")]
+    pub lintcheck_results_path: PathBuf, // Overridden in new()
+    /// Only process a single crate on the list
+    #[clap(long, value_name = "CRATE")]
     pub only: Option<String>,
-    /// whether to just run --fix and not collect all the warnings
+    /// Runs cargo clippy --fix and checks if all suggestions apply
+    #[clap(long, conflicts_with("max_jobs"))]
     pub fix: bool,
-    /// A list of lints that this lintcheck run should focus on
+    /// Apply a filter to only collect specified lints, this also overrides `allow` attributes
+    #[clap(long = "filter", value_name = "clippy_lint_name", use_value_delimiter = true)]
     pub lint_filter: Vec<String>,
-    /// Indicate if the output should support markdown syntax
+    /// Change the reports table to use markdown links
+    #[clap(long)]
     pub markdown: bool,
-    /// Run clippy on the dependencies of crates
+    /// Run clippy on the dependencies of crates specified in crates-toml
+    #[clap(long, conflicts_with("max_jobs"))]
     pub recursive: bool,
 }
 
 impl LintcheckConfig {
     pub fn new() -> Self {
-        let clap_config = get_clap_config();
-
-        // first, check if we got anything passed via the LINTCHECK_TOML env var,
-        // if not, ask clap if we got any value for --crates-toml  <foo>
-        // if not, use the default "lintcheck/lintcheck_crates.toml"
-        let sources_toml = env::var("LINTCHECK_TOML").unwrap_or_else(|_| {
-            clap_config
-                .get_one::<String>("crates-toml")
-                .map_or("lintcheck/lintcheck_crates.toml", |s| &**s)
-                .into()
-        });
-
-        let markdown = clap_config.contains_id("markdown");
-        let sources_toml_path = PathBuf::from(sources_toml);
+        let mut config = LintcheckConfig::parse();
 
         // for the path where we save the lint results, get the filename without extension (so for
         // wasd.toml, use "wasd"...)
-        let filename: PathBuf = sources_toml_path.file_stem().unwrap().into();
-        let lintcheck_results_path = PathBuf::from(format!(
+        let filename: PathBuf = config.sources_toml_path.file_stem().unwrap().into();
+        config.lintcheck_results_path = PathBuf::from(format!(
             "lintcheck-logs/{}_logs.{}",
             filename.display(),
-            if markdown { "md" } else { "txt" }
+            if config.markdown { "md" } else { "txt" }
         ));
 
         // look at the --threads arg, if 0 is passed, use the threads count
-        let max_jobs = match clap_config.get_one::<usize>("threads") {
-            Some(&0) => {
-                // automatic choice
-                std::thread::available_parallelism().map(|n| n.get()).unwrap_or(1)
-            },
-            Some(&threads) => threads,
-            // no -j passed, use a single thread
-            None => 1,
+        if config.max_jobs == 0 {
+            // automatic choice
+            config.max_jobs = std::thread::available_parallelism().map_or(1, |n| n.get());
         };
 
-        let lint_filter: Vec<String> = clap_config
-            .get_many::<String>("filter")
-            .map(|iter| {
-                iter.map(|lint_name| {
-                    let mut filter = lint_name.replace('_', "-");
-                    if !filter.starts_with("clippy::") {
-                        filter.insert_str(0, "clippy::");
-                    }
-                    filter
-                })
-                .collect()
-            })
-            .unwrap_or_default();
-
-        LintcheckConfig {
-            max_jobs,
-            sources_toml_path,
-            lintcheck_results_path,
-            only: clap_config.get_one::<String>("only").map(String::from),
-            fix: clap_config.contains_id("fix"),
-            lint_filter,
-            markdown,
-            recursive: clap_config.contains_id("recursive"),
+        for lint_name in &mut config.lint_filter {
+            *lint_name = format!(
+                "clippy::{}",
+                lint_name
+                    .strip_prefix("clippy::")
+                    .unwrap_or(lint_name)
+                    .replace('_', "-")
+            );
         }
+
+        config
     }
 }