From cdf730ca3cdc5ce7dfb284986d39398ac23187b2 Mon Sep 17 00:00:00 2001
From: Alan Somers <asomers@gmail.com>
Date: Wed, 28 Nov 2018 10:47:12 -0700
Subject: 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.
---
 src/sys/termios.rs | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

(limited to 'src/sys/termios.rs')

diff --git a/src/sys/termios.rs b/src/sys/termios.rs
index 11cacd7c..8621cf0c 100644
--- a/src/sys/termios.rs
+++ b/src/sys/termios.rs
@@ -929,7 +929,7 @@ cfg_if!{
             let inner_termios = unsafe { termios.get_libc_termios_mut() };
             let res = unsafe { libc::cfsetispeed(inner_termios, baud.into() as libc::speed_t) };
             termios.update_wrapper();
-            Errno::result(res).map(|_| ())
+            Errno::result(res).map(drop)
         }
 
         /// Set output baud rate (see
@@ -940,7 +940,7 @@ cfg_if!{
             let inner_termios = unsafe { termios.get_libc_termios_mut() };
             let res = unsafe { libc::cfsetospeed(inner_termios, baud.into() as libc::speed_t) };
             termios.update_wrapper();
-            Errno::result(res).map(|_| ())
+            Errno::result(res).map(drop)
         }
 
         /// Set both the input and output baud rates (see
@@ -952,7 +952,7 @@ cfg_if!{
             let inner_termios = unsafe { termios.get_libc_termios_mut() };
             let res = unsafe { libc::cfsetspeed(inner_termios, baud.into() as libc::speed_t) };
             termios.update_wrapper();
-            Errno::result(res).map(|_| ())
+            Errno::result(res).map(drop)
         }
     } else {
         /// Get input baud rate (see
@@ -981,7 +981,7 @@ cfg_if!{
             let inner_termios = unsafe { termios.get_libc_termios_mut() };
             let res = unsafe { libc::cfsetispeed(inner_termios, baud as libc::speed_t) };
             termios.update_wrapper();
-            Errno::result(res).map(|_| ())
+            Errno::result(res).map(drop)
         }
 
         /// Set output baud rate (see
@@ -992,7 +992,7 @@ cfg_if!{
             let inner_termios = unsafe { termios.get_libc_termios_mut() };
             let res = unsafe { libc::cfsetospeed(inner_termios, baud as libc::speed_t) };
             termios.update_wrapper();
-            Errno::result(res).map(|_| ())
+            Errno::result(res).map(drop)
         }
 
         /// Set both the input and output baud rates (see
@@ -1004,7 +1004,7 @@ cfg_if!{
             let inner_termios = unsafe { termios.get_libc_termios_mut() };
             let res = unsafe { libc::cfsetspeed(inner_termios, baud as libc::speed_t) };
             termios.update_wrapper();
-            Errno::result(res).map(|_| ())
+            Errno::result(res).map(drop)
         }
     }
 }
@@ -1060,13 +1060,13 @@ pub fn tcgetattr(fd: RawFd) -> Result<Termios> {
 /// *any* of the parameters were successfully set, not only if all were set successfully.
 pub fn tcsetattr(fd: RawFd, actions: SetArg, termios: &Termios) -> Result<()> {
     let inner_termios = termios.get_libc_termios();
-    Errno::result(unsafe { libc::tcsetattr(fd, actions as c_int, &*inner_termios) }).map(|_| ())
+    Errno::result(unsafe { libc::tcsetattr(fd, actions as c_int, &*inner_termios) }).map(drop)
 }
 
 /// Block until all output data is written (see
 /// [tcdrain(3p)](http://pubs.opengroup.org/onlinepubs/9699919799/functions/tcdrain.html)).
 pub fn tcdrain(fd: RawFd) -> Result<()> {
-    Errno::result(unsafe { libc::tcdrain(fd) }).map(|_| ())
+    Errno::result(unsafe { libc::tcdrain(fd) }).map(drop)
 }
 
 /// Suspend or resume the transmission or reception of data (see
@@ -1075,7 +1075,7 @@ pub fn tcdrain(fd: RawFd) -> Result<()> {
 /// `tcflow()` suspends of resumes the transmission or reception of data for the given port
 /// depending on the value of `action`.
 pub fn tcflow(fd: RawFd, action: FlowArg) -> Result<()> {
-    Errno::result(unsafe { libc::tcflow(fd, action as c_int) }).map(|_| ())
+    Errno::result(unsafe { libc::tcflow(fd, action as c_int) }).map(drop)
 }
 
 /// Discard data in the output or input queue (see
@@ -1084,7 +1084,7 @@ pub fn tcflow(fd: RawFd, action: FlowArg) -> Result<()> {
 /// `tcflush()` will discard data for a terminal port in the input queue, output queue, or both
 /// depending on the value of `action`.
 pub fn tcflush(fd: RawFd, action: FlushArg) -> Result<()> {
-    Errno::result(unsafe { libc::tcflush(fd, action as c_int) }).map(|_| ())
+    Errno::result(unsafe { libc::tcflush(fd, action as c_int) }).map(drop)
 }
 
 /// Send a break for a specific duration (see
@@ -1093,7 +1093,7 @@ pub fn tcflush(fd: RawFd, action: FlushArg) -> Result<()> {
 /// When using asynchronous data transmission `tcsendbreak()` will transmit a continuous stream
 /// of zero-valued bits for an implementation-defined duration.
 pub fn tcsendbreak(fd: RawFd, duration: c_int) -> Result<()> {
-    Errno::result(unsafe { libc::tcsendbreak(fd, duration) }).map(|_| ())
+    Errno::result(unsafe { libc::tcsendbreak(fd, duration) }).map(drop)
 }
 
 /// Get the session controlled by the given terminal (see
-- 
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