Prefer `map(drop)` to `map(|_| ())`

I previously advocated for the latter syntax on stylistic grounds.  But
it generates less efficient code, because it creates a new lambda
function for each usage.  The optimizer does not combine them.  This
change saves about 6KB of code.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/sys/signalfd.rs b/src/sys/signalfd.rs
index 52027d36..65c09ea4 100644
--- a/src/sys/signalfd.rs
+++ b/src/sys/signalfd.rs
@@ -94,7 +94,7 @@ impl SignalFd {
     }
 
     pub fn set_mask(&mut self, mask: &SigSet) -> Result<()> {
-        signalfd(self.0, mask, SfdFlags::empty()).map(|_| ())
+        signalfd(self.0, mask, SfdFlags::empty()).map(drop)
     }
 
     pub fn read_signal(&mut self) -> Result<Option<siginfo>> {