Skip scanning for surrogates when not known valid

thaliaarchi · thaliaarchi · commit c5b3cb5522a4 · 2025-02-16T15:18:31.000-08:00
diff --git a/library/std/src/sys_common/wtf8.rs b/library/std/src/sys_common/wtf8.rs
@@ -383,7 +383,7 @@ 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;
                 }
 

Original file line number	Diff line number	Diff line change
`@@ -383,7 +383,7 @@ impl Wtf8Buf {`
`383`	`383`	`_ => {`
`384`	`384`	`// If we'll be pushing a string containing a surrogate, we may`
`385`	`385`	`// no longer have UTF-8.`
`386`		`- if other.next_surrogate(0).is_some() {`
	`386`	`+ if self.is_known_utf8 && other.next_surrogate(0).is_some() {`
`387`	`387`	`self.is_known_utf8 = false;`
`388`	`388`	`}`
`389`	`389`