Generate manpage as part of build (sirwart#83)

* Generate manpage via `clap_mangen`

* Cleanup CLI docstrings

Cargo.toml

@@ -30,3 +30,6 @@ criterion = { version = "0.3", features = ["html_reports"] }
 name = "find_secrets"
 harness = false
 
+[build-dependencies]
+clap = { version = "4.2.5", features = ["derive"] }
+clap_mangen = "0.2.15"

build.rs

@@ -0,0 +1,21 @@
+include!("src/args.rs");
+
+fn main() -> std::io::Result<()> {
+    // Tell Cargo that if the given file changes, to rerun this build script.
+    println!("cargo:rerun-if-changed=src/args.rs");
+
+    let out_dir =
+        std::path::PathBuf::from(std::env::var_os("OUT_DIR").ok_or(std::io::ErrorKind::NotFound)?);
+
+    let cmd = <Args as clap::CommandFactory>::command();
+
+    let man = clap_mangen::Man::new(cmd);
+    let mut buffer: Vec<u8> = Default::default();
+    man.render(&mut buffer)?;
+
+    println!("{:?}", buffer);
+
+    std::fs::write(out_dir.join("ripsecrets.1"), buffer)?;
+
+    Ok(())
+}

src/args.rs

@@ -0,0 +1,41 @@
+use clap::Parser;
+use std::path::PathBuf;
+
+/// Prevent committing secret keys into your source code.
+#[derive(Parser, Debug)]
+#[clap(
+    version,
+    about,
+    name = "ripsecrets",
+    long_about = "ripsecrets searches files and directories recursively for secret API keys.
+It's primarily designed to be used as a pre-commit to prevent committing
+secrets into version control."
+)]
+struct Args {
+    /// Install `ripsecrets` as a pre-commit hook automatically in git directory provided.
+    #[clap(long = "install-pre-commit")]
+    install_pre_commit: bool,
+
+    /// If you pass a path as an argument that's ignored by .secretsignore it
+    /// will be scanned by default. --strict-ignore will override this
+    /// behavior and not search the paths passed as arguments that are excluded
+    /// by the .secretsignore file. This is useful when invoking secrets as a
+    /// pre-commit.
+    #[clap(long = "strict-ignore")]
+    strict_ignore: bool,
+
+    /// Print only the matched (non-empty) parts of a matching line, with each such
+    /// part on a separate output line.
+    #[clap(long = "only-matching")]
+    only_matching: bool,
+
+    /// Additional regex patterns used to find secrets. If there is a matching
+    /// group in the regex the matched group will be tested for randomness before
+    /// being reported as a secret.
+    #[clap(long = "additional-pattern")]
+    additional_patterns: Vec<String>,
+
+    /// Source files. Can be files or directories. Defaults to '.'
+    #[clap(name = "Source files")]
+    paths: Vec<PathBuf>,
+}

src/main.rs

@@ -1,60 +1,20 @@
 #![allow(clippy::needless_return)]
 
-use clap::Parser;
 use ripsecrets::find_secrets;
-use std::path::PathBuf;
 use std::process;
 use termcolor::{BufferWriter, ColorChoice};
 
 mod pre_commit;
 
+include!("args.rs");
+
 #[derive(Debug)]
 pub enum UsageError {
     PreCommit,
     Version,
     Help,
 }
 
-/// Prevent committing secret keys into your source code
-#[derive(Parser, Debug)]
-#[clap(
-    version,
-    about,
-    name = "ripsecrets",
-    long_about = "ripsecrets searches files and directories recursively for secret API keys.
-It's primarily designed to be used as a pre-commit to prevent committing
-secrets into version control."
-)]
-struct Args {
-    /// Install `ripsecrets` as a pre-commit hook automatically in git directory provided. Defaults to
-    /// '.'
-    #[clap(long = "install-pre-commit")]
-    install_pre_commit: bool,
-
-    /// If you pass a path as an argument that's ignored by .secretsignore it
-    /// will be scanned by default. --strict-ignore will override this
-    /// behavior and not search the paths passed as arguments that are excluded
-    /// by the .secretsignore file. This is useful when invoking secrets as a
-    /// pre-commit.
-    #[clap(long = "strict-ignore")]
-    strict_ignore: bool,
-
-    /// Print only the matched (non-empty) parts of a matching line, with each such
-    /// part on a separate output line.
-    #[clap(long = "only-matching")]
-    only_matching: bool,
-
-    /// Additional regex patterns used to find secrets. If there is a matching
-    /// group in the regex the matched group will be tested for randomness before
-    /// being reported as a secret.
-    #[clap(long = "additional-pattern")]
-    additional_patterns: Vec<String>,
-
-    /// Source files. Can be files or directories. Defaults to '.'
-    #[clap(name = "Source files")]
-    paths: Vec<PathBuf>,
-}
-
 enum RunResult {
     PreCommitInstallSuccessful,
     NoSecretsFound,