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/unix/ext/net/addr.rs b/library/std/src/sys/unix/ext/net/addr.rs
index 1f9036242eb..6e7d1f1678a 100644
--- a/library/std/src/sys/unix/ext/net/addr.rs
+++ b/library/std/src/sys/unix/ext/net/addr.rs
@@ -29,16 +29,16 @@ pub(super) unsafe fn sockaddr_un(path: &Path) -> io::Result<(libc::sockaddr_un,
     let bytes = path.as_os_str().as_bytes();
 
     if bytes.contains(&0) {
-        return Err(io::Error::new(
+        return Err(io::Error::new_const(
             io::ErrorKind::InvalidInput,
-            "paths may not contain interior null bytes",
+            &"paths may not contain interior null bytes",
         ));
     }
 
     if bytes.len() >= addr.sun_path.len() {
-        return Err(io::Error::new(
+        return Err(io::Error::new_const(
             io::ErrorKind::InvalidInput,
-            "path must be shorter than SUN_LEN",
+            &"path must be shorter than SUN_LEN",
         ));
     }
     for (dst, src) in addr.sun_path.iter_mut().zip(bytes.iter()) {
@@ -118,9 +118,9 @@ impl SocketAddr {
             // linux returns zero bytes of address
             len = sun_path_offset(&addr) as libc::socklen_t; // i.e., zero-length address
         } else if addr.sun_family != libc::AF_UNIX as libc::sa_family_t {
-            return Err(io::Error::new(
+            return Err(io::Error::new_const(
                 io::ErrorKind::InvalidInput,
-                "file descriptor did not correspond to a Unix socket",
+                &"file descriptor did not correspond to a Unix socket",
             ));
         }