Rollup merge of #83353 - m-ou-se:io-error-avoid-alloc, r=nagisa

Add internal io::Error::new_const to avoid allocations.

This makes it possible to have a io::Error containing a message with zero allocations, and uses that everywhere to avoid the *three* allocations involved in `io::Error::new(kind, "message")`.

The function signature isn't perfect, because it needs a reference to the `&str`. So for now, this is just a `pub(crate)` function. Later, we'll be able to use `fn new_const<MSG: &'static str>(kind: ErrorKind)` to make that a bit better. (Then we'll also be able to use some ZST trickery if that would result in more efficient code.)

See https://github.com/rust-lang/rust/issues/83352

1 files changed, 6 insertions, 6 deletions

diff --git a/library/std/src/sys/sgx/net.rs b/library/std/src/sys/sgx/net.rs
index 3dd8267921e..c0c5d55548c 100644
--- a/library/std/src/sys/sgx/net.rs
+++ b/library/std/src/sys/sgx/net.rs
@@ -97,9 +97,9 @@ impl TcpStream {
 
     pub fn connect_timeout(addr: &SocketAddr, dur: Duration) -> io::Result<TcpStream> {
         if dur == Duration::default() {
-            return Err(io::Error::new(
+            return Err(io::Error::new_const(
                 io::ErrorKind::InvalidInput,
-                "cannot set a 0 duration timeout",
+                &"cannot set a 0 duration timeout",
             ));
         }
         Self::connect(Ok(addr)) // FIXME: ignoring timeout
@@ -108,9 +108,9 @@ impl TcpStream {
     pub fn set_read_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
         match dur {
             Some(dur) if dur == Duration::default() => {
-                return Err(io::Error::new(
+                return Err(io::Error::new_const(
                     io::ErrorKind::InvalidInput,
-                    "cannot set a 0 duration timeout",
+                    &"cannot set a 0 duration timeout",
                 ));
             }
             _ => sgx_ineffective(()),
@@ -120,9 +120,9 @@ impl TcpStream {
     pub fn set_write_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
         match dur {
             Some(dur) if dur == Duration::default() => {
-                return Err(io::Error::new(
+                return Err(io::Error::new_const(
                     io::ErrorKind::InvalidInput,
-                    "cannot set a 0 duration timeout",
+                    &"cannot set a 0 duration timeout",
                 ));
             }
             _ => sgx_ineffective(()),