clippy: fix used_underscore_binding lint

https://rust-lang.github.io/rust-clippy/master/index.html#used_underscore_binding

Author: xtqqczze

Cargo.toml

@@ -657,7 +657,6 @@ ignored_unit_patterns = "allow"              # 21
 similar_names = "allow"                      # 20
 large_stack_arrays = "allow"                 # 20
 wildcard_imports = "allow"                   # 18
-used_underscore_binding = "allow"            # 18
 needless_pass_by_value = "allow"             # 16
 float_cmp = "allow"                          # 12
 items_after_statements = "allow"             # 11

src/uu/df/src/filesystem.rs

@@ -121,7 +121,7 @@ where
 impl Filesystem {
     // TODO: resolve uuid in `mount_info.dev_name` if exists
     pub(crate) fn new(mount_info: MountInfo, file: Option<OsString>) -> Option<Self> {
-        let _stat_path = if mount_info.mount_dir.is_empty() {
+        let stat_path = if mount_info.mount_dir.is_empty() {
             #[cfg(unix)]
             {
                 mount_info.dev_name.clone().into()
@@ -135,9 +135,9 @@ impl Filesystem {
             mount_info.mount_dir.clone()
         };
         #[cfg(unix)]
-        let usage = FsUsage::new(statfs(&_stat_path).ok()?);
+        let usage = FsUsage::new(statfs(&stat_path).ok()?);
         #[cfg(windows)]
-        let usage = FsUsage::new(Path::new(&_stat_path)).ok()?;
+        let usage = FsUsage::new(Path::new(&stat_path)).ok()?;
         Some(Self {
             file,
             mount_info,

src/uu/env/src/env.rs

@@ -755,20 +755,18 @@ impl EnvAppData {
         let arg0 = prog.clone();
         let args = &opts.program[1..];
 
-        if let Some(_argv0) = opts.argv0 {
-            #[cfg(unix)]
-            {
-                arg0 = Cow::Borrowed(_argv0);
+        if let Some(argv0) = opts.argv0 {
+            if cfg!(unix) {
+                arg0 = Cow::Borrowed(argv0);
                 if do_debug_printing {
                     eprintln!("argv0:     {}", arg0.quote());
                 }
+            } else {
+                return Err(USimpleError::new(
+                    2,
+                    translate!("env-error-argv0-not-supported"),
+                ));
             }
-
-            #[cfg(not(unix))]
-            return Err(USimpleError::new(
-                2,
-                translate!("env-error-argv0-not-supported"),
-            ));
         }
 
         if do_debug_printing {

src/uu/split/src/platform/unix.rs

@@ -43,9 +43,9 @@ impl Write for FilterWriter {
 /// Have an environment variable set at a value during this lifetime
 struct WithEnvVarSet {
     /// Env var key
-    _previous_var_key: String,
+    previous_var_key: String,
     /// Previous value set to this key
-    _previous_var_value: std::result::Result<String, env::VarError>,
+    previous_var_value: std::result::Result<String, env::VarError>,
 }
 impl WithEnvVarSet {
     /// Save previous value assigned to key, set key=value
@@ -55,22 +55,22 @@ impl WithEnvVarSet {
             env::set_var(key, value);
         }
         Self {
-            _previous_var_key: String::from(key),
-            _previous_var_value: previous_env_value,
+            previous_var_key: String::from(key),
+            previous_var_value: previous_env_value,
         }
     }
 }
 
 impl Drop for WithEnvVarSet {
     /// Restore previous value now that this is being dropped by context
     fn drop(&mut self) {
-        if let Ok(ref prev_value) = self._previous_var_value {
+        if let Ok(ref prev_value) = self.previous_var_value {
             unsafe {
-                env::set_var(&self._previous_var_key, prev_value);
+                env::set_var(&self.previous_var_key, prev_value);
             }
         } else {
             unsafe {
-                env::remove_var(&self._previous_var_key);
+                env::remove_var(&self.previous_var_key);
             }
         }
     }

src/uu/stat/src/stat.rs

@@ -1004,7 +1004,8 @@ impl Stater {
         file: &OsString,
         file_type: &FileType,
         from_user: bool,
-        _follow_symbolic_links: bool,
+        #[cfg(feature = "selinux")] follow_symbolic_links: bool,
+        #[cfg(not(feature = "selinux"))] _: bool,
     ) -> Result<(), i32> {
         match *t {
             Token::Byte(byte) => write_raw_byte(byte),
@@ -1035,7 +1036,7 @@ impl Stater {
                             if uucore::selinux::is_selinux_enabled() {
                                 match uucore::selinux::get_selinux_security_context(
                                     Path::new(file),
-                                    _follow_symbolic_links,
+                                    follow_symbolic_links,
                                 ) {
                                     Ok(ctx) => OutputType::Str(ctx),
                                     Err(_) => OutputType::Str(translate!(

src/uu/tail/src/paths.rs

@@ -179,10 +179,10 @@ impl MetadataExtTail for Metadata {
         Ok(other.len() < self.len() && other.modified()? != self.modified()?)
     }
 
-    fn file_id_eq(&self, _other: &Metadata) -> bool {
+    fn file_id_eq(&self, #[cfg(unix)] other: &Metadata, #[cfg(not(unix))] _: &Metadata) -> bool {
         #[cfg(unix)]
         {
-            self.ino().eq(&_other.ino())
+            self.ino().eq(&other.ino())
         }
         #[cfg(windows)]
         {

src/uucore/src/lib/features/fs.rs

@@ -765,13 +765,16 @@ pub mod sane_blksize {
     ///
     /// If the metadata contain invalid values a meaningful adaption
     /// of that value is done.
-    pub fn sane_blksize_from_metadata(_metadata: &std::fs::Metadata) -> u64 {
-        #[cfg(not(target_os = "windows"))]
+    pub fn sane_blksize_from_metadata(
+        #[cfg(unix)] metadata: &std::fs::Metadata,
+        #[cfg(not(unix))] _: &std::fs::Metadata,
+    ) -> u64 {
+        #[cfg(unix)]
         {
-            sane_blksize(_metadata.blksize())
+            sane_blksize(metadata.blksize())
         }
 
-        #[cfg(target_os = "windows")]
+        #[cfg(not(unix))]
         {
             DEFAULT
         }

src/uucore/src/lib/features/sum.rs

@@ -284,8 +284,8 @@ impl Digest for Bsd {
     }
 
     fn result(&mut self) -> DigestOutput {
-        let mut _out = [0; 2];
-        self.hash_finalize(&mut _out);
+        let mut out = [0; 2];
+        self.hash_finalize(&mut out);
         DigestOutput::U16(self.state)
     }
 
@@ -319,8 +319,8 @@ impl Digest for SysV {
     }
 
     fn result(&mut self) -> DigestOutput {
-        let mut _out = [0; 2];
-        self.hash_finalize(&mut _out);
+        let mut out = [0; 2];
+        self.hash_finalize(&mut out);
         DigestOutput::U16((self.state & (u16::MAX as u32)) as u16)
     }