Rollup merge of rust-lang#137101 - GrigorenkoPV:str-inherent-lint, r=Urgau

`invalid_from_utf8[_unchecked]`: also lint inherent methods

Addressing rust-lang#131114 (comment)

Also corrected a typo: "_an_ invalid literal", not "_a_ invalid literal".

Author: matthiaskrgr

core/src/str/mod.rs

@@ -238,6 +238,7 @@ impl str {
     /// assert_eq!("💖", sparkle_heart);
     /// ```
     #[unstable(feature = "inherent_str_constructors", issue = "131114")]
+    #[rustc_diagnostic_item = "str_inherent_from_utf8"]
     pub const fn from_utf8(v: &[u8]) -> Result<&str, Utf8Error> {
         converts::from_utf8(v)
     }
@@ -274,6 +275,7 @@ impl str {
     /// errors that can be returned.
     #[unstable(feature = "inherent_str_constructors", issue = "131114")]
     #[rustc_const_unstable(feature = "const_str_from_utf8", issue = "91006")]
+    #[rustc_diagnostic_item = "str_inherent_from_utf8_mut"]
     pub const fn from_utf8_mut(v: &mut [u8]) -> Result<&mut str, Utf8Error> {
         converts::from_utf8_mut(v)
     }
@@ -306,6 +308,7 @@ impl str {
     #[inline]
     #[must_use]
     #[unstable(feature = "inherent_str_constructors", issue = "131114")]
+    #[rustc_diagnostic_item = "str_inherent_from_utf8_unchecked"]
     pub const unsafe fn from_utf8_unchecked(v: &[u8]) -> &str {
         // SAFETY: converts::from_utf8_unchecked has the same safety requirements as this function.
         unsafe { converts::from_utf8_unchecked(v) }
@@ -331,6 +334,7 @@ impl str {
     #[inline]
     #[must_use]
     #[unstable(feature = "inherent_str_constructors", issue = "131114")]
+    #[rustc_diagnostic_item = "str_inherent_from_utf8_unchecked_mut"]
     pub const unsafe fn from_utf8_unchecked_mut(v: &mut [u8]) -> &mut str {
         // SAFETY: converts::from_utf8_unchecked_mut has the same safety requirements as this function.
         unsafe { converts::from_utf8_unchecked_mut(v) }