Rollup merge of #114194 - thomcc:flushinline, r=cuviper

Inline trivial (noop) flush calls

At work I noticed that `writer.flush()?` didn't get optimized away in cases where the flush is obviously a no-op, which I had expected (well, desired).

I went through and added `#[inline]` to a bunch of cases that were obviously noops, or delegated to ones that were obviously noops. I omitted platforms I don't have access to (some tier3). I didn't do this very scientifically, in cases where it was non-obvious I left `#[inline]` off.

8 files changed, 13 insertions, 0 deletions

diff --git a/library/std/src/fs.rs b/library/std/src/fs.rs
index 0f79e74f555..a7e65305386 100644
--- a/library/std/src/fs.rs
+++ b/library/std/src/fs.rs
@@ -791,6 +791,7 @@ impl Write for &File {
         self.inner.is_write_vectored()
     }
 
+    #[inline]
     fn flush(&mut self) -> io::Result<()> {
         self.inner.flush()
     }
@@ -836,6 +837,7 @@ impl Write for File {
     fn is_write_vectored(&self) -> bool {
         (&&*self).is_write_vectored()
     }
+    #[inline]
     fn flush(&mut self) -> io::Result<()> {
         (&*self).flush()
     }
@@ -881,6 +883,7 @@ impl Write for Arc<File> {
     fn is_write_vectored(&self) -> bool {
         (&**self).is_write_vectored()
     }
+    #[inline]
     fn flush(&mut self) -> io::Result<()> {
         (&**self).flush()
     }
diff --git a/library/std/src/io/readbuf.rs b/library/std/src/io/readbuf.rs
index 1f3f80b9618..034ddd8df9a 100644
--- a/library/std/src/io/readbuf.rs
+++ b/library/std/src/io/readbuf.rs
@@ -310,6 +310,7 @@ impl<'a> Write for BorrowedCursor<'a> {
         Ok(buf.len())
     }
 
+    #[inline]
     fn flush(&mut self) -> Result<()> {
         Ok(())
     }
diff --git a/library/std/src/net/tcp.rs b/library/std/src/net/tcp.rs
index 141a18a42dd..32fd54c8e75 100644
--- a/library/std/src/net/tcp.rs
+++ b/library/std/src/net/tcp.rs
@@ -647,6 +647,7 @@ impl Write for TcpStream {
         self.0.is_write_vectored()
     }
 
+    #[inline]
     fn flush(&mut self) -> io::Result<()> {
         Ok(())
     }
@@ -685,6 +686,7 @@ impl Write for &TcpStream {
         self.0.is_write_vectored()
     }
 
+    #[inline]
     fn flush(&mut self) -> io::Result<()> {
         Ok(())
     }
diff --git a/library/std/src/os/unix/net/stream.rs b/library/std/src/os/unix/net/stream.rs
index e20170873bb..41290e0017a 100644
--- a/library/std/src/os/unix/net/stream.rs
+++ b/library/std/src/os/unix/net/stream.rs
@@ -712,6 +712,7 @@ impl<'a> io::Write for &'a UnixStream {
         self.0.is_write_vectored()
     }
 
+    #[inline]
     fn flush(&mut self) -> io::Result<()> {
         Ok(())
     }
diff --git a/library/std/src/process.rs b/library/std/src/process.rs
index f1305dee146..f25ad2ece71 100644
--- a/library/std/src/process.rs
+++ b/library/std/src/process.rs
@@ -280,6 +280,7 @@ impl Write for ChildStdin {
         io::Write::is_write_vectored(&&*self)
     }
 
+    #[inline]
     fn flush(&mut self) -> io::Result<()> {
         (&*self).flush()
     }
@@ -299,6 +300,7 @@ impl Write for &ChildStdin {
         self.inner.is_write_vectored()
     }
 
+    #[inline]
     fn flush(&mut self) -> io::Result<()> {
         Ok(())
     }
diff --git a/library/std/src/sys/hermit/fs.rs b/library/std/src/sys/hermit/fs.rs
index 4bb735668d2..6aa4ea7f5b4 100644
--- a/library/std/src/sys/hermit/fs.rs
+++ b/library/std/src/sys/hermit/fs.rs
@@ -335,6 +335,7 @@ impl File {
         false
     }
 
+    #[inline]
     pub fn flush(&self) -> io::Result<()> {
         Ok(())
     }
diff --git a/library/std/src/sys/unix/fs.rs b/library/std/src/sys/unix/fs.rs
index 7dc809a038b..a5604c92a80 100644
--- a/library/std/src/sys/unix/fs.rs
+++ b/library/std/src/sys/unix/fs.rs
@@ -1204,6 +1204,7 @@ impl File {
         self.0.write_vectored_at(bufs, offset)
     }
 
+    #[inline]
     pub fn flush(&self) -> io::Result<()> {
         Ok(())
     }
diff --git a/library/std/src/sys/unix/stdio.rs b/library/std/src/sys/unix/stdio.rs
index a26f20795a1..97e75f1b5b6 100644
--- a/library/std/src/sys/unix/stdio.rs
+++ b/library/std/src/sys/unix/stdio.rs
@@ -54,6 +54,7 @@ impl io::Write for Stdout {
         true
     }
 
+    #[inline]
     fn flush(&mut self) -> io::Result<()> {
         Ok(())
     }
@@ -81,6 +82,7 @@ impl io::Write for Stderr {
         true
     }
 
+    #[inline]
     fn flush(&mut self) -> io::Result<()> {
         Ok(())
     }