From 0842f2c65c766301be488256a18d89e90c3b6304 Mon Sep 17 00:00:00 2001
From: Thalia Archibald <thalia@archibald.dev>
Date: Wed, 5 Feb 2025 19:37:27 -0800
Subject: [PATCH 1/2] Add fast path for displaying pre-validated Wtf8Buf
---
library/std/src/sys/os_str/wtf8.rs | 4 ++--
library/std/src/sys_common/wtf8.rs | 24 ++++++++++++++++++++++++
2 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/library/std/src/sys/os_str/wtf8.rs b/library/std/src/sys/os_str/wtf8.rs
index 19728d33990ac..8acec6f949fc5 100644
--- a/library/std/src/sys/os_str/wtf8.rs
+++ b/library/std/src/sys/os_str/wtf8.rs
@@ -41,13 +41,13 @@ impl AsInner<Wtf8> for Buf {
impl fmt::Debug for Buf {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
- fmt::Debug::fmt(self.as_slice(), f)
+ fmt::Debug::fmt(&self.inner, f)
}
}
impl fmt::Display for Buf {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
- fmt::Display::fmt(self.as_slice(), f)
+ fmt::Display::fmt(&self.inner, f)
}
}
diff --git a/library/std/src/sys_common/wtf8.rs b/library/std/src/sys_common/wtf8.rs
index 952c39132b056..01cbb3e24ff8a 100644
--- a/library/std/src/sys_common/wtf8.rs
+++ b/library/std/src/sys_common/wtf8.rs
@@ -169,6 +169,18 @@ impl fmt::Debug for Wtf8Buf {
}
}
+/// Formats the string with unpaired surrogates substituted with the replacement
+/// character, U+FFFD.
+impl fmt::Display for Wtf8Buf {
+ fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+ if let Some(s) = self.as_known_utf8() {
+ fmt::Display::fmt(s, formatter)
+ } else {
+ fmt::Display::fmt(&**self, formatter)
+ }
+ }
+}
+
impl Wtf8Buf {
/// Creates a new, empty WTF-8 string.
#[inline]
@@ -262,6 +274,18 @@ impl Wtf8Buf {
unsafe { Wtf8::from_mut_bytes_unchecked(&mut self.bytes) }
}
+ /// Converts the string to UTF-8 without validation, if it was created from
+ /// valid UTF-8.
+ #[inline]
+ fn as_known_utf8(&self) -> Option<&str> {
+ if self.is_known_utf8 {
+ // SAFETY: The buffer is known to be valid UTF-8.
+ Some(unsafe { str::from_utf8_unchecked(self.as_bytes()) })
+ } else {
+ None
+ }
+ }
+
/// Reserves capacity for at least `additional` more bytes to be inserted
/// in the given `Wtf8Buf`.
/// The collection may reserve more space to avoid frequent reallocations.
From eb14652770451022d424a1c301a4416514464932 Mon Sep 17 00:00:00 2001
From: Thalia Archibald <thalia@archibald.dev>
Date: Fri, 7 Feb 2025 11:54:02 -0800
Subject: [PATCH 2/2] Skip scanning for surrogates when not known valid
---
library/std/src/sys_common/wtf8.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/library/std/src/sys_common/wtf8.rs b/library/std/src/sys_common/wtf8.rs
index 01cbb3e24ff8a..f9ec112b19747 100644
--- a/library/std/src/sys_common/wtf8.rs
+++ b/library/std/src/sys_common/wtf8.rs
@@ -388,7 +388,7 @@ impl Wtf8Buf {
_ => {
// If we'll be pushing a string containing a surrogate, we may
// no longer have UTF-8.
- if other.next_surrogate(0).is_some() {
+ if self.is_known_utf8 && other.next_surrogate(0).is_some() {
self.is_known_utf8 = false;
}