add optional tracing feature, trace which logic

Cargo.toml

@@ -12,9 +12,14 @@ readme = "README.md"
 categories = ["os", "filesystem"]
 keywords = ["which", "which-rs", "unix", "command"]
 
+[features]
+regex = ["dep:regex"]
+tracing = ["dep:tracing"]
+
 [dependencies]
 either = "1.9.0"
 regex = { version = "1.10.2", optional = true }
+tracing = { version = "0.1.40", optional = true }
 
 [target.'cfg(any(windows, unix, target_os = "redox"))'.dependencies]
 home = "0.5.9"

src/checker.rs

@@ -14,7 +14,10 @@ impl Checker for ExecutableChecker {
     #[cfg(any(unix, target_os = "wasi", target_os = "redox"))]
     fn is_valid(&self, path: &Path) -> bool {
         use rustix::fs as rfs;
-        rfs::access(path, rfs::Access::EXEC_OK).is_ok()
+        let ret = rfs::access(path, rfs::Access::EXEC_OK).is_ok();
+        #[cfg(feature = "tracing")]
+        tracing::trace!("{} EXEC_OK = {ret}", path.display());
+        ret
     }
 
     #[cfg(windows)]
@@ -34,26 +37,37 @@ impl ExistedChecker {
 impl Checker for ExistedChecker {
     #[cfg(target_os = "windows")]
     fn is_valid(&self, path: &Path) -> bool {
-        fs::symlink_metadata(path)
+        let ret = fs::symlink_metadata(path)
             .map(|metadata| {
                 let file_type = metadata.file_type();
+                #[cfg(feature = "tracing")]
+                tracing::trace!("{} is_file() = {}, is_symlink() = {}", new_path.display(), file_type.is_file(), file_type.is_symlink());
                 file_type.is_file() || file_type.is_symlink()
             })
             .unwrap_or(false)
-            && (path.extension().is_some() || matches_arch(path))
+            && (path.extension().is_some() || matches_arch(path));
+        #[cfg(feature = "tracing")]
+        tracing::trace!("{} has_extension = {}, ExistedChecker::is_valid() = {ret}", path.display(), path.extension().is_some());
+        ret
     }
 
     #[cfg(not(target_os = "windows"))]
     fn is_valid(&self, path: &Path) -> bool {
-        fs::metadata(path)
+        let ret = fs::metadata(path)
             .map(|metadata| metadata.is_file())
-            .unwrap_or(false)
+            .unwrap_or(false);
+        #[cfg(feature = "tracing")]
+        tracing::trace!("{} is_file() = {ret}", path.display());
+        ret
     }
 }
 
 #[cfg(target_os = "windows")]
 fn matches_arch(path: &Path) -> bool {
-    winsafe::GetBinaryType(&path.display().to_string()).is_ok()
+    let ret = winsafe::GetBinaryType(&path.display().to_string()).is_ok();
+    #[cfg(feature = "tracing")]
+    tracing::trace!("{} matches_arch() = {ret}", path.display());
+    ret
 }
 
 pub struct CompositeChecker {

src/finder.rs

@@ -78,10 +78,17 @@ impl Finder {
 
         let binary_path_candidates = match cwd {
             Some(cwd) if path.has_separator() => {
+                #[cfg(feature = "tracing")]
+                tracing::trace!(
+                    "{} has a path seperator, so only CWD will be searched.",
+                    path.display()
+                );
                 // Search binary in cwd if the path have a path separator.
                 Either::Left(Self::cwd_search_candidates(path, cwd).into_iter())
             }
             _ => {
+                #[cfg(feature = "tracing")]
+                tracing::trace!("{} has no path seperators, so only paths in PATH environment variable will be searched.", path.display());
                 // Search binary in PATHs(defined in environment variable).
                 let paths =
                     env::split_paths(&paths.ok_or(Error::CannotGetCurrentDirAndPathListEmpty)?)
@@ -201,8 +208,18 @@ impl Finder {
                 });
                 // Check if path already have executable extension
                 if has_executable_extension(&p, path_extensions) {
+                    #[cfg(feature = "tracing")]
+                    tracing::trace!(
+                        "{} already has an executable extension, not modifying it further",
+                        p.display()
+                    );
                     Box::new(iter::once(p))
                 } else {
+                    #[cfg(feature = "tracing")]
+                    tracing::trace!(
+                        "{} has no extension, using PATHEXT environment variable to infer one",
+                        p.display()
+                    );
                     // Appended paths with windows executable extensions.
                     // e.g. path `c:/windows/bin[.ext]` will expand to:
                     // [c:/windows/bin.ext]
@@ -215,7 +232,8 @@ impl Finder {
                             // Append the extension.
                             let mut p = p.clone().into_os_string();
                             p.push(e);
-
+                            #[cfg(feature = "tracing")]
+                            tracing::trace!("possible extension: {}", p.display());
                             PathBuf::from(p)
                         })),
                     )
@@ -230,6 +248,11 @@ fn tilde_expansion(p: &PathBuf) -> Cow<'_, PathBuf> {
         if o == "~" {
             let mut new_path = home_dir().unwrap_or_default();
             new_path.extend(component_iter);
+            #[cfg(feature = "tracing")]
+            tracing::trace!(
+                "found tilde, substituting in user's home directory to get {}",
+                new_path.display()
+            );
             Cow::Owned(new_path)
         } else {
             Cow::Borrowed(p)