Auto merge of #69004 - jonas-schievink:rollup-z2ymler, r=jonas-schievink

Rollup of 5 pull requests

Successful merges:

 - #68738 (Derive Clone + Eq for std::string::FromUtf8Error)
 - #68742 (implement AsMut<str> for String)
 - #68881 (rustc_codegen_llvm: always set AlwaysPreserve on all debuginfo variables)
 - #68911 (Speed up the inherent impl overlap check)
 - #68913 (Pretty-print generic params and where clauses on associated types)

Failed merges:

r? @ghost

2 files changed, 13 insertions, 1 deletions

diff --git a/src/liballoc/string.rs b/src/liballoc/string.rs
index 96f871d8897..3cb1f259a0b 100644
--- a/src/liballoc/string.rs
+++ b/src/liballoc/string.rs
@@ -319,7 +319,7 @@ pub struct String {
 /// assert_eq!(vec![0, 159], value.unwrap_err().into_bytes());
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
-#[derive(Debug)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct FromUtf8Error {
     bytes: Vec<u8>,
     error: Utf8Error,
@@ -2208,6 +2208,14 @@ impl AsRef<str> for String {
     }
 }
 
+#[stable(feature = "string_as_mut", since = "1.43.0")]
+impl AsMut<str> for String {
+    #[inline]
+    fn as_mut(&mut self) -> &mut str {
+        self
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl AsRef<[u8]> for String {
     #[inline]
diff --git a/src/liballoc/tests/string.rs b/src/liballoc/tests/string.rs
index dd444958459..08859b2b24b 100644
--- a/src/liballoc/tests/string.rs
+++ b/src/liballoc/tests/string.rs
@@ -50,7 +50,11 @@ fn test_from_utf8() {
 
     let xs = b"hello\xFF".to_vec();
     let err = String::from_utf8(xs).unwrap_err();
+    assert_eq!(err.as_bytes(), b"hello\xff");
+    let err_clone = err.clone();
+    assert_eq!(err, err_clone);
     assert_eq!(err.into_bytes(), b"hello\xff".to_vec());
+    assert_eq!(err_clone.utf8_error().valid_up_to(), 5);
 }
 
 #[test]