Rollup merge of #130608 - YohDeadfall:cstr-from-into-str, r=workingjubilee

Implemented `FromStr` for `CString` and `TryFrom<CString>` for `String`

The motivation of this change is making it possible to use `CString` in generic methods with `FromStr` and `TryInto<String>` trait bounds. The same traits are already implemented for `OsString` which is an FFI type too.

library/alloc/src/ffi/c_str.rs

@@ -7,7 +7,7 @@
 use core::ffi::{CStr, c_char};
 use core::num::NonZero;
 use core::slice::memchr;
-use core::str::{self, Utf8Error};
+use core::str::{self, FromStr, Utf8Error};
 use core::{fmt, mem, ops, ptr, slice};
 
 use crate::borrow::{Cow, ToOwned};
@@ -817,6 +817,30 @@ fn from(v: Vec<NonZero<u8>>) -> CString {
     }
 }
 
+impl FromStr for CString {
+    type Err = NulError;
+
+    /// Converts a string `s` into a [`CString`].
+    ///
+    /// This method is equivalent to [`CString::new`].
+    #[inline]
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Self::new(s)
+    }
+}
+
+impl TryFrom<CString> for String {
+    type Error = IntoStringError;
+
+    /// Converts a [`CString`] into a [`String`] if it contains valid UTF-8 data.
+    ///
+    /// This method is equivalent to [`CString::into_string`].
+    #[inline]
+    fn try_from(value: CString) -> Result<Self, Self::Error> {
+        value.into_string()
+    }
+}
+
 #[cfg(not(test))]
 #[stable(feature = "more_box_slice_clone", since = "1.29.0")]
 impl Clone for Box<CStr> {