Use drop instead of the toilet closure |_| ()

src/libstd/sys/windows/fs.rs

@@ -923,6 +923,6 @@ fn symlink_junction_inner(target: &Path, junction: &Path) -> io::Result<()> {
             &mut ret,
             ptr::null_mut(),
         ))
-        .map(|_| ())
+        .map(drop)
     }
 }

src/libstd/sys/windows/handle.rs

@@ -156,7 +156,7 @@ impl RawHandle {
     }
 
     pub fn cancel_io(&self) -> io::Result<()> {
-        unsafe { cvt(c::CancelIo(self.raw())).map(|_| ()) }
+        unsafe { cvt(c::CancelIo(self.raw())).map(drop) }
     }
 
     pub fn write(&self, buf: &[u8]) -> io::Result<usize> {

src/libstd/sys/windows/net.rs

@@ -355,7 +355,7 @@ impl Socket {
     #[cfg(not(target_vendor = "uwp"))]
     fn set_no_inherit(&self) -> io::Result<()> {
         sys::cvt(unsafe { c::SetHandleInformation(self.0 as c::HANDLE, c::HANDLE_FLAG_INHERIT, 0) })
-            .map(|_| ())
+            .map(drop)
     }
 
     #[cfg(target_vendor = "uwp")]

src/libstd/sys/windows/os.rs

@@ -247,7 +247,7 @@ pub fn chdir(p: &path::Path) -> io::Result<()> {
     let mut p = p.encode_wide().collect::<Vec<_>>();
     p.push(0);
 
-    cvt(unsafe { c::SetCurrentDirectoryW(p.as_ptr()) }).map(|_| ())
+    cvt(unsafe { c::SetCurrentDirectoryW(p.as_ptr()) }).map(drop)
 }
 
 pub fn getenv(k: &OsStr) -> io::Result<Option<OsString>> {
@@ -272,12 +272,12 @@ pub fn setenv(k: &OsStr, v: &OsStr) -> io::Result<()> {
     let k = to_u16s(k)?;
     let v = to_u16s(v)?;
 
-    cvt(unsafe { c::SetEnvironmentVariableW(k.as_ptr(), v.as_ptr()) }).map(|_| ())
+    cvt(unsafe { c::SetEnvironmentVariableW(k.as_ptr(), v.as_ptr()) }).map(drop)
 }
 
 pub fn unsetenv(n: &OsStr) -> io::Result<()> {
     let v = to_u16s(n)?;
-    cvt(unsafe { c::SetEnvironmentVariableW(v.as_ptr(), ptr::null()) }).map(|_| ())
+    cvt(unsafe { c::SetEnvironmentVariableW(v.as_ptr(), ptr::null()) }).map(drop)
 }
 
 pub fn temp_dir() -> PathBuf {