Rollup merge of #69937 - TyPR124:osstr_ascii, r=dtolnay

ASCII methods on OsStr

Would close #69566

I don't know enough about encodings to know if this is a valid change, however the comment on the issue suggests it could be.

This does two things:

1. Makes ASCII methods available on OsStr

2. Makes it possible to obtain a `&mut OsStr`. This is necessary to actually use `OsStr::make_ascii_*case` methods since they modify the underlying value. As far as I can tell, the only way to modify a `&mut OsStr` is via the methods I just added.

My original hope was to have these methods on `OsStrExt` for Windows, since the standard library already assumes `make_ascii_uppercase` is valid in Windows (see the change I made to windows/process.rs). If it is found these are not valid changes on non-Windows platforms, I can move the methods to the ext trait instead.

src/libstd/ffi/os_str.rs

@@ -698,6 +698,147 @@ impl OsStr {
     fn bytes(&self) -> &[u8] {
         unsafe { &*(&self.inner as *const _ as *const [u8]) }
     }
+
+    /// Converts this string to its ASCII lower case equivalent in-place.
+    ///
+    /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
+    /// but non-ASCII letters are unchanged.
+    ///
+    /// To return a new lowercased value without modifying the existing one, use
+    /// [`to_ascii_lowercase`].
+    ///
+    /// [`to_ascii_lowercase`]: #method.to_ascii_lowercase
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(osstring_ascii)]
+    /// use std::ffi::OsString;
+    ///
+    /// let mut s = OsString::from("GRÜßE, JÜRGEN ❤");
+    ///
+    /// s.make_ascii_lowercase();
+    ///
+    /// assert_eq!("grÜße, jÜrgen ❤", s);
+    /// ```
+    #[unstable(feature = "osstring_ascii", issue = "70516")]
+    pub fn make_ascii_lowercase(&mut self) {
+        self.inner.make_ascii_lowercase()
+    }
+
+    /// Converts this string to its ASCII upper case equivalent in-place.
+    ///
+    /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
+    /// but non-ASCII letters are unchanged.
+    ///
+    /// To return a new uppercased value without modifying the existing one, use
+    /// [`to_ascii_uppercase`].
+    ///
+    /// [`to_ascii_uppercase`]: #method.to_ascii_uppercase
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(osstring_ascii)]
+    /// use std::ffi::OsString;
+    ///
+    /// let mut s = OsString::from("Grüße, Jürgen ❤");
+    ///
+    /// s.make_ascii_uppercase();
+    ///
+    /// assert_eq!("GRüßE, JüRGEN ❤", s);
+    /// ```
+    #[unstable(feature = "osstring_ascii", issue = "70516")]
+    pub fn make_ascii_uppercase(&mut self) {
+        self.inner.make_ascii_uppercase()
+    }
+
+    /// Returns a copy of this string where each character is mapped to its
+    /// ASCII lower case equivalent.
+    ///
+    /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
+    /// but non-ASCII letters are unchanged.
+    ///
+    /// To lowercase the value in-place, use [`make_ascii_lowercase`].
+    ///
+    /// [`make_ascii_lowercase`]: #method.make_ascii_lowercase
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(osstring_ascii)]
+    /// use std::ffi::OsString;
+    /// let s = OsString::from("Grüße, Jürgen ❤");
+    ///
+    /// assert_eq!("grüße, jürgen ❤", s.to_ascii_lowercase());
+    /// ```
+    #[unstable(feature = "osstring_ascii", issue = "70516")]
+    pub fn to_ascii_lowercase(&self) -> OsString {
+        OsString::from_inner(self.inner.to_ascii_lowercase())
+    }
+
+    /// Returns a copy of this string where each character is mapped to its
+    /// ASCII upper case equivalent.
+    ///
+    /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
+    /// but non-ASCII letters are unchanged.
+    ///
+    /// To uppercase the value in-place, use [`make_ascii_uppercase`].
+    ///
+    /// [`make_ascii_uppercase`]: #method.make_ascii_uppercase
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(osstring_ascii)]
+    /// use std::ffi::OsString;
+    /// let s = OsString::from("Grüße, Jürgen ❤");
+    ///
+    /// assert_eq!("GRüßE, JüRGEN ❤", s.to_ascii_uppercase());
+    /// ```
+    #[unstable(feature = "osstring_ascii", issue = "70516")]
+    pub fn to_ascii_uppercase(&self) -> OsString {
+        OsString::from_inner(self.inner.to_ascii_uppercase())
+    }
+
+    /// Checks if all characters in this string are within the ASCII range.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(osstring_ascii)]
+    /// use std::ffi::OsString;
+    ///
+    /// let ascii = OsString::from("hello!\n");
+    /// let non_ascii = OsString::from("Grüße, Jürgen ❤");
+    ///
+    /// assert!(ascii.is_ascii());
+    /// assert!(!non_ascii.is_ascii());
+    /// ```
+    #[unstable(feature = "osstring_ascii", issue = "70516")]
+    pub fn is_ascii(&self) -> bool {
+        self.inner.is_ascii()
+    }
+
+    /// Checks that two strings are an ASCII case-insensitive match.
+    ///
+    /// Same as `to_ascii_lowercase(a) == to_ascii_lowercase(b)`,
+    /// but without allocating and copying temporaries.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(osstring_ascii)]
+    /// use std::ffi::OsString;
+    ///
+    /// assert!(OsString::from("Ferris").eq_ignore_ascii_case("FERRIS"));
+    /// assert!(OsString::from("Ferrös").eq_ignore_ascii_case("FERRöS"));
+    /// assert!(!OsString::from("Ferrös").eq_ignore_ascii_case("FERRÖS"));
+    /// ```
+    #[unstable(feature = "osstring_ascii", issue = "70516")]
+    pub fn eq_ignore_ascii_case<S: ?Sized + AsRef<OsStr>>(&self, other: &S) -> bool {
+        self.inner.eq_ignore_ascii_case(&other.as_ref().inner)
+    }
 }
 
 #[stable(feature = "box_from_os_str", since = "1.17.0")]

src/libstd/sys/windows/os_str.rs

@@ -179,4 +179,34 @@ impl Slice {
         let rc = self.inner.into_rc();
         unsafe { Rc::from_raw(Rc::into_raw(rc) as *const Slice) }
     }
+
+    #[inline]
+    pub fn make_ascii_lowercase(&mut self) {
+        self.inner.make_ascii_lowercase()
+    }
+
+    #[inline]
+    pub fn make_ascii_uppercase(&mut self) {
+        self.inner.make_ascii_uppercase()
+    }
+
+    #[inline]
+    pub fn to_ascii_lowercase(&self) -> Buf {
+        Buf { inner: self.inner.to_ascii_lowercase() }
+    }
+
+    #[inline]
+    pub fn to_ascii_uppercase(&self) -> Buf {
+        Buf { inner: self.inner.to_ascii_uppercase() }
+    }
+
+    #[inline]
+    pub fn is_ascii(&self) -> bool {
+        self.inner.is_ascii()
+    }
+
+    #[inline]
+    pub fn eq_ignore_ascii_case(&self, other: &Self) -> bool {
+        self.inner.eq_ignore_ascii_case(&other.inner)
+    }
 }

src/libstd/sys/windows/process.rs

@@ -20,7 +20,7 @@ use crate::sys::mutex::Mutex;
 use crate::sys::pipe::{self, AnonPipe};
 use crate::sys::stdio;
 use crate::sys_common::process::CommandEnv;
-use crate::sys_common::{AsInner, FromInner, IntoInner};
+use crate::sys_common::AsInner;
 
 use libc::{c_void, EXIT_FAILURE, EXIT_SUCCESS};
 
@@ -33,10 +33,9 @@ use libc::{c_void, EXIT_FAILURE, EXIT_SUCCESS};
 pub struct EnvKey(OsString);
 
 impl From<OsString> for EnvKey {
-    fn from(k: OsString) -> Self {
-        let mut buf = k.into_inner().into_inner();
-        buf.make_ascii_uppercase();
-        EnvKey(FromInner::from_inner(FromInner::from_inner(buf)))
+    fn from(mut k: OsString) -> Self {
+        k.make_ascii_uppercase();
+        EnvKey(k)
     }
 }
 

src/libstd/sys_common/os_str_bytes.rs

@@ -195,6 +195,36 @@ impl Slice {
         let rc: Rc<[u8]> = Rc::from(&self.inner);
         unsafe { Rc::from_raw(Rc::into_raw(rc) as *const Slice) }
     }
+
+    #[inline]
+    pub fn make_ascii_lowercase(&mut self) {
+        self.inner.make_ascii_lowercase()
+    }
+
+    #[inline]
+    pub fn make_ascii_uppercase(&mut self) {
+        self.inner.make_ascii_uppercase()
+    }
+
+    #[inline]
+    pub fn to_ascii_lowercase(&self) -> Buf {
+        Buf { inner: self.inner.to_ascii_lowercase() }
+    }
+
+    #[inline]
+    pub fn to_ascii_uppercase(&self) -> Buf {
+        Buf { inner: self.inner.to_ascii_uppercase() }
+    }
+
+    #[inline]
+    pub fn is_ascii(&self) -> bool {
+        self.inner.is_ascii()
+    }
+
+    #[inline]
+    pub fn eq_ignore_ascii_case(&self, other: &Self) -> bool {
+        self.inner.eq_ignore_ascii_case(&other.inner)
+    }
 }
 
 /// Platform-specific extensions to [`OsString`].

src/libstd/sys_common/wtf8.rs

@@ -637,6 +637,36 @@ impl Wtf8 {
         let rc: Rc<[u8]> = Rc::from(&self.bytes);
         unsafe { Rc::from_raw(Rc::into_raw(rc) as *const Wtf8) }
     }
+
+    #[inline]
+    pub fn make_ascii_lowercase(&mut self) {
+        self.bytes.make_ascii_lowercase()
+    }
+
+    #[inline]
+    pub fn make_ascii_uppercase(&mut self) {
+        self.bytes.make_ascii_uppercase()
+    }
+
+    #[inline]
+    pub fn to_ascii_lowercase(&self) -> Wtf8Buf {
+        Wtf8Buf { bytes: self.bytes.to_ascii_lowercase() }
+    }
+
+    #[inline]
+    pub fn to_ascii_uppercase(&self) -> Wtf8Buf {
+        Wtf8Buf { bytes: self.bytes.to_ascii_uppercase() }
+    }
+
+    #[inline]
+    pub fn is_ascii(&self) -> bool {
+        self.bytes.is_ascii()
+    }
+
+    #[inline]
+    pub fn eq_ignore_ascii_case(&self, other: &Self) -> bool {
+        self.bytes.eq_ignore_ascii_case(&other.bytes)
+    }
 }
 
 /// Returns a slice of the given string for the byte range [`begin`..`end`).
@@ -837,12 +867,6 @@ impl Hash for Wtf8 {
     }
 }
 
-impl Wtf8 {
-    pub fn make_ascii_uppercase(&mut self) {
-        self.bytes.make_ascii_uppercase()
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;