puts logging behind log feature

- use log and env_logger crates
- removes --debug CLI flag

Cargo.toml

@@ -13,11 +13,16 @@ categories = ["command-line-utilities", "filesystem"]
 edition = "2021"
 rust-version = "1.74"
 
+[features]
+log = ["dep:log", "dep:env_logger"]
+
 [dependencies]
 anyhow = "1"
 bstr = "1"
 bytesize = "1"
+env_logger = { version = "0.11", optional = true }
 libc = "0.2"
+log = { version = "0.4", optional = true }
 pwd-grp = "0.1"
 tempfile = "3"
 

src/cli.rs

@@ -45,12 +45,6 @@ pub fn build() -> Command {
  directories are read from standard input.",
         );
 
-    let debug = Arg::new("debug")
-        .long("debug")
-        .action(ArgAction::SetTrue)
-        .hide_short_help(true)
-        .long_help("Print debug messages while running.");
-
     let max_depth = Arg::new("max-depth")
         .short('d')
         .long("max-depth")
@@ -108,7 +102,6 @@ pub fn build() -> Command {
         .arg(max_depth)
         .arg(count_links)
         .arg(kb_allocated)
-        .arg(debug)
         .arg(help)
         .arg(version)
         .after_help(

src/config.rs

@@ -31,7 +31,6 @@ use libc::{gid_t, uid_t};
 
 #[derive(Debug)]
 pub struct Config {
-    pub debug: bool,
     pub filter: Filter,
     pub count_links: bool,
     pub max_depth: Option<usize>,
@@ -46,8 +45,6 @@ impl TryFrom<&ArgMatches> for Config {
     type Error = anyhow::Error;
 
     fn try_from(args: &ArgMatches) -> Result<Self> {
-        let debug = args.get_one::<bool>("debug").copied().unwrap_or_default();
-
         let filter = Filter::try_from(args)?;
 
         let count_links = args.get_flag("count-links");
@@ -74,7 +71,6 @@ impl TryFrom<&ArgMatches> for Config {
         let count_mode = CountMode::from(args);
 
         Ok(Self {
-            debug,
             filter,
             count_links,
             max_depth,

src/main.rs

@@ -30,7 +30,6 @@
 
 mod cli;
 mod config;
-mod log;
 mod output;
 mod policy;
 mod usage;
@@ -43,11 +42,15 @@ use anyhow::Result;
 use crate::config::Config;
 
 fn main() -> Result<()> {
-    let cli = crate::cli::build();
-    let args = cli.get_matches();
+    #[cfg(feature = "log")]
+    env_logger::init();
 
+    let cli = cli::build();
+    let args = cli.get_matches();
     let config = Config::try_from(&args)?;
-    log::debug(format!("{config:#?}"), config.debug);
+
+    #[cfg(feature = "log")]
+    log::debug!("{config:#?}");
 
     // ALLOW if let is easier to comprehend
     #[allow(clippy::option_if_let_else)]
@@ -59,12 +62,12 @@ fn main() -> Result<()> {
         let interactive = std::io::stdin().is_terminal();
 
         if interactive {
-            log::warning("input is read from terminal");
-            log::warning("only experts do this on purpose");
-            log::warning("you may have forgotten to either");
-            log::warning("- specify directories on the command line or");
-            log::warning("- pipe data into this tool");
-            log::warning("press CTRL-D or CTRL-C to exit");
+            eprintln!("input is read from terminal");
+            eprintln!("only experts do this on purpose");
+            eprintln!("you may have forgotten to either");
+            eprintln!("- specify directories on the command line or");
+            eprintln!("- pipe data into this tool");
+            eprintln!("press CTRL-D or CTRL-C to exit");
         }
 
         let lines = io::stdin().lines();
@@ -78,9 +81,16 @@ fn main() -> Result<()> {
 }
 
 fn run(dir: &Path, config: &Config) {
-    log::debug(format!("running {} ...", dir.display()), config.debug);
+    #[cfg(feature = "log")]
+    log::debug!("running with directory {} ...", dir.display());
+
     if let Err(error) = usage::run(dir, config) {
         let dir = dir.display();
-        log::error(format!("skipping directory {dir}: {error:#}"));
+
+        #[cfg(not(feature = "log"))]
+        eprintln!("{}: skipping {dir}: {error:?}", clap::crate_name!());
+
+        #[cfg(feature = "log")]
+        log::warn!("skipping directory {dir}: {error:#}");
     }
 }

src/usage.rs

@@ -36,7 +36,6 @@ use clap::crate_name;
 use tempfile::{tempdir, tempdir_in};
 
 use crate::config::Config;
-use crate::log;
 use crate::output::output;
 use crate::policy::{self, Entry};
 
@@ -77,7 +76,8 @@ pub fn run(dir: &Path, config: &Config) -> Result<()> {
         command.arg("-g").arg(global_work_dir);
     };
 
-    log::debug(format!("command: {command:?}"), config.debug);
+    #[cfg(feature = "log")]
+    log::debug!("command: {command:?}");
 
     let mut child = command
         .stdout(Stdio::null())
@@ -115,8 +115,7 @@ fn sum(dir: &Path, report: &Path, config: &Config) -> Result<()> {
     })?;
 
     if let Some(depth) = config.max_depth {
-        let sizes =
-            sum_depth(dir, depth, report, config.count_links, config.debug)?;
+        let sizes = sum_depth(dir, depth, report, config.count_links)?;
 
         for (dir, Acc { inodes, bytes }) in sizes {
             output(&dir, inodes, bytes, config);
@@ -134,7 +133,6 @@ fn sum_depth(
     depth: usize,
     report: impl Read,
     count_links: bool,
-    debug: bool,
 ) -> Result<BTreeMap<PathBuf, Acc>> {
     let report = BufReader::new(report);
 
@@ -154,14 +152,10 @@ fn sum_depth(
         let path_depth = path.iter().count();
         let path_suffix_depth = path_depth - prefix_depth;
 
-        log::debug(format!("path: {path:?}"), debug);
-
         for depth in 0..=depth.min(path_suffix_depth) {
             let prefix: PathBuf =
                 path.iter().take(prefix_depth + depth).collect();
 
-            log::debug(format!("prefix: {prefix:?}"), debug);
-
             if count_links || nlink == "1" {
                 sums.entry(prefix)
                     .and_modify(|v| v.acc += bytes)
@@ -321,14 +315,9 @@ mod test {
         once.insert("/data/test/a".into(), Acc::from((2, 5120)));
         once.insert("/data/test/b".into(), Acc::from((3, 6144)));
 
-        let result = sum_depth(
-            Path::new("/data/test"),
-            1,
-            source.as_bytes(),
-            false,
-            false,
-        )
-        .unwrap();
+        let result =
+            sum_depth(Path::new("/data/test"), 1, source.as_bytes(), false)
+                .unwrap();
 
         assert_eq!(once, result);
 
@@ -337,14 +326,9 @@ mod test {
         many.insert("/data/test/a".into(), Acc::from((3, 6144)));
         many.insert("/data/test/b".into(), Acc::from((3, 6144)));
 
-        let result = sum_depth(
-            Path::new("/data/test"),
-            1,
-            source.as_bytes(),
-            true,
-            false,
-        )
-        .unwrap();
+        let result =
+            sum_depth(Path::new("/data/test"), 1, source.as_bytes(), true)
+                .unwrap();
 
         assert_eq!(many, result);
     }