Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 780 insertions, 0 deletions

diff --git a/third_party/rust/clap_lex/src/ext.rs b/third_party/rust/clap_lex/src/ext.rs
new file mode 100644
index 0000000000..a2de707e2b
--- /dev/null
+++ b/third_party/rust/clap_lex/src/ext.rs
@@ -0,0 +1,312 @@
+use std::ffi::OsStr;
+
+pub trait OsStrExt: private::Sealed {
+    /// Converts to a string slice.
+    fn try_str(&self) -> Result<&str, std::str::Utf8Error>;
+    /// Returns `true` if the given pattern matches a sub-slice of
+    /// this string slice.
+    ///
+    /// Returns `false` if it does not.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use clap_lex::OsStrExt as _;
+    /// let bananas = std::ffi::OsStr::new("bananas");
+    ///
+    /// assert!(bananas.contains("nana"));
+    /// assert!(!bananas.contains("apples"));
+    /// ```
+    fn contains(&self, needle: &str) -> bool;
+    /// Returns the byte index of the first character of this string slice that
+    /// matches the pattern.
+    ///
+    /// Returns [`None`] if the pattern doesn't match.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use clap_lex::OsStrExt as _;
+    /// let s = std::ffi::OsStr::new("Löwe 老虎 Léopard Gepardi");
+    ///
+    /// assert_eq!(s.find("L"), Some(0));
+    /// assert_eq!(s.find("é"), Some(14));
+    /// assert_eq!(s.find("par"), Some(17));
+    /// ```
+    ///
+    /// Not finding the pattern:
+    ///
+    /// ```rust
+    /// use clap_lex::OsStrExt as _;
+    /// let s = std::ffi::OsStr::new("Löwe 老虎 Léopard");
+    ///
+    /// assert_eq!(s.find("1"), None);
+    /// ```
+    fn find(&self, needle: &str) -> Option<usize>;
+    /// Returns a string slice with the prefix removed.
+    ///
+    /// If the string starts with the pattern `prefix`, returns substring after the prefix, wrapped
+    /// in `Some`.
+    ///
+    /// If the string does not start with `prefix`, returns `None`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::ffi::OsStr;
+    /// use clap_lex::OsStrExt as _;
+    /// assert_eq!(OsStr::new("foo:bar").strip_prefix("foo:"), Some(OsStr::new("bar")));
+    /// assert_eq!(OsStr::new("foo:bar").strip_prefix("bar"), None);
+    /// assert_eq!(OsStr::new("foofoo").strip_prefix("foo"), Some(OsStr::new("foo")));
+    /// ```
+    fn strip_prefix(&self, prefix: &str) -> Option<&OsStr>;
+    /// Returns `true` if the given pattern matches a prefix of this
+    /// string slice.
+    ///
+    /// Returns `false` if it does not.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use clap_lex::OsStrExt as _;
+    /// let bananas = std::ffi::OsStr::new("bananas");
+    ///
+    /// assert!(bananas.starts_with("bana"));
+    /// assert!(!bananas.starts_with("nana"));
+    /// ```
+    fn starts_with(&self, prefix: &str) -> bool;
+    /// An iterator over substrings of this string slice, separated by
+    /// characters matched by a pattern.
+    ///
+    /// # Examples
+    ///
+    /// Simple patterns:
+    ///
+    /// ```
+    /// use std::ffi::OsStr;
+    /// use clap_lex::OsStrExt as _;
+    /// let v: Vec<_> = OsStr::new("Mary had a little lamb").split(" ").collect();
+    /// assert_eq!(v, [OsStr::new("Mary"), OsStr::new("had"), OsStr::new("a"), OsStr::new("little"), OsStr::new("lamb")]);
+    ///
+    /// let v: Vec<_> = OsStr::new("").split("X").collect();
+    /// assert_eq!(v, [OsStr::new("")]);
+    ///
+    /// let v: Vec<_> = OsStr::new("lionXXtigerXleopard").split("X").collect();
+    /// assert_eq!(v, [OsStr::new("lion"), OsStr::new(""), OsStr::new("tiger"), OsStr::new("leopard")]);
+    ///
+    /// let v: Vec<_> = OsStr::new("lion::tiger::leopard").split("::").collect();
+    /// assert_eq!(v, [OsStr::new("lion"), OsStr::new("tiger"), OsStr::new("leopard")]);
+    /// ```
+    ///
+    /// If a string contains multiple contiguous separators, you will end up
+    /// with empty strings in the output:
+    ///
+    /// ```
+    /// use std::ffi::OsStr;
+    /// use clap_lex::OsStrExt as _;
+    /// let x = OsStr::new("||||a||b|c");
+    /// let d: Vec<_> = x.split("|").collect();
+    ///
+    /// assert_eq!(d, &[OsStr::new(""), OsStr::new(""), OsStr::new(""), OsStr::new(""), OsStr::new("a"), OsStr::new(""), OsStr::new("b"), OsStr::new("c")]);
+    /// ```
+    ///
+    /// Contiguous separators are separated by the empty string.
+    ///
+    /// ```
+    /// use std::ffi::OsStr;
+    /// use clap_lex::OsStrExt as _;
+    /// let x = OsStr::new("(///)");
+    /// let d: Vec<_> = x.split("/").collect();
+    ///
+    /// assert_eq!(d, &[OsStr::new("("), OsStr::new(""), OsStr::new(""), OsStr::new(")")]);
+    /// ```
+    ///
+    /// Separators at the start or end of a string are neighbored
+    /// by empty strings.
+    ///
+    /// ```
+    /// use std::ffi::OsStr;
+    /// use clap_lex::OsStrExt as _;
+    /// let d: Vec<_> = OsStr::new("010").split("0").collect();
+    /// assert_eq!(d, &[OsStr::new(""), OsStr::new("1"), OsStr::new("")]);
+    /// ```
+    ///
+    /// When the empty string is used as a separator, it panics
+    ///
+    /// ```should_panic
+    /// use std::ffi::OsStr;
+    /// use clap_lex::OsStrExt as _;
+    /// let f: Vec<_> = OsStr::new("rust").split("").collect();
+    /// assert_eq!(f, &[OsStr::new(""), OsStr::new("r"), OsStr::new("u"), OsStr::new("s"), OsStr::new("t"), OsStr::new("")]);
+    /// ```
+    ///
+    /// Contiguous separators can lead to possibly surprising behavior
+    /// when whitespace is used as the separator. This code is correct:
+    ///
+    /// ```
+    /// use std::ffi::OsStr;
+    /// use clap_lex::OsStrExt as _;
+    /// let x = OsStr::new("    a  b c");
+    /// let d: Vec<_> = x.split(" ").collect();
+    ///
+    /// assert_eq!(d, &[OsStr::new(""), OsStr::new(""), OsStr::new(""), OsStr::new(""), OsStr::new("a"), OsStr::new(""), OsStr::new("b"), OsStr::new("c")]);
+    /// ```
+    ///
+    /// It does _not_ give you:
+    ///
+    /// ```,ignore
+    /// assert_eq!(d, &[OsStr::new("a"), OsStr::new("b"), OsStr::new("c")]);
+    /// ```
+    ///
+    /// Use [`split_whitespace`] for this behavior.
+    ///
+    /// [`split_whitespace`]: str::split_whitespace
+    fn split<'s, 'n>(&'s self, needle: &'n str) -> Split<'s, 'n>;
+    /// Splits the string on the first occurrence of the specified delimiter and
+    /// returns prefix before delimiter and suffix after delimiter.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::ffi::OsStr;
+    /// use clap_lex::OsStrExt as _;
+    /// assert_eq!(OsStr::new("cfg").split_once("="), None);
+    /// assert_eq!(OsStr::new("cfg=").split_once("="), Some((OsStr::new("cfg"), OsStr::new(""))));
+    /// assert_eq!(OsStr::new("cfg=foo").split_once("="), Some((OsStr::new("cfg"), OsStr::new("foo"))));
+    /// assert_eq!(OsStr::new("cfg=foo=bar").split_once("="), Some((OsStr::new("cfg"), OsStr::new("foo=bar"))));
+    /// ```
+    fn split_once(&self, needle: &'_ str) -> Option<(&OsStr, &OsStr)>;
+}
+
+impl OsStrExt for OsStr {
+    fn try_str(&self) -> Result<&str, std::str::Utf8Error> {
+        let bytes = to_bytes(self);
+        std::str::from_utf8(bytes)
+    }
+
+    fn contains(&self, needle: &str) -> bool {
+        self.find(needle).is_some()
+    }
+
+    fn find(&self, needle: &str) -> Option<usize> {
+        let bytes = to_bytes(self);
+        (0..=self.len().checked_sub(needle.len())?)
+            .find(|&x| bytes[x..].starts_with(needle.as_bytes()))
+    }
+
+    fn strip_prefix(&self, prefix: &str) -> Option<&OsStr> {
+        let bytes = to_bytes(self);
+        bytes.strip_prefix(prefix.as_bytes()).map(|s| {
+            // SAFETY:
+            // - This came from `to_bytes`
+            // - Since `prefix` is `&str`, any split will be along UTF-8 boundarie
+            unsafe { to_os_str_unchecked(s) }
+        })
+    }
+    fn starts_with(&self, prefix: &str) -> bool {
+        let bytes = to_bytes(self);
+        bytes.starts_with(prefix.as_bytes())
+    }
+
+    fn split<'s, 'n>(&'s self, needle: &'n str) -> Split<'s, 'n> {
+        assert_ne!(needle, "");
+        Split {
+            haystack: Some(self),
+            needle,
+        }
+    }
+
+    fn split_once(&self, needle: &'_ str) -> Option<(&OsStr, &OsStr)> {
+        let start = self.find(needle)?;
+        let end = start + needle.len();
+        let haystack = to_bytes(self);
+        let first = &haystack[0..start];
+        let second = &haystack[end..];
+        // SAFETY:
+        // - This came from `to_bytes`
+        // - Since `needle` is `&str`, any split will be along UTF-8 boundarie
+        unsafe { Some((to_os_str_unchecked(first), to_os_str_unchecked(second))) }
+    }
+}
+
+mod private {
+    pub trait Sealed {}
+
+    impl Sealed for std::ffi::OsStr {}
+}
+
+/// Allow access to raw bytes
+///
+/// As the non-UTF8 encoding is not defined, the bytes only make sense when compared with
+/// 7-bit ASCII or `&str`
+///
+/// # Compatibility
+///
+/// There is no guarantee how non-UTF8 bytes will be encoded, even within versions of this crate
+/// (since its dependent on rustc)
+fn to_bytes(s: &OsStr) -> &[u8] {
+    // SAFETY:
+    // - Lifetimes are the same
+    // - Types are compatible (`OsStr` is effectively a transparent wrapper for `[u8]`)
+    // - The primary contract is that the encoding for invalid surrogate code points is not
+    //   guaranteed which isn't a problem here
+    //
+    // There is a proposal to support this natively (https://github.com/rust-lang/rust/pull/95290)
+    // but its in limbo
+    unsafe { std::mem::transmute(s) }
+}
+
+/// Restore raw bytes as `OsStr`
+///
+/// # Safety
+///
+/// - `&[u8]` must either by a `&str` or originated with `to_bytes` within the same binary
+/// - Any splits of the original `&[u8]` must be done along UTF-8 boundaries
+unsafe fn to_os_str_unchecked(s: &[u8]) -> &OsStr {
+    // SAFETY:
+    // - Lifetimes are the same
+    // - Types are compatible (`OsStr` is effectively a transparent wrapper for `[u8]`)
+    // - The primary contract is that the encoding for invalid surrogate code points is not
+    //   guaranteed which isn't a problem here
+    //
+    // There is a proposal to support this natively (https://github.com/rust-lang/rust/pull/95290)
+    // but its in limbo
+    std::mem::transmute(s)
+}
+
+pub struct Split<'s, 'n> {
+    haystack: Option<&'s OsStr>,
+    needle: &'n str,
+}
+
+impl<'s, 'n> Iterator for Split<'s, 'n> {
+    type Item = &'s OsStr;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let haystack = self.haystack?;
+        match haystack.split_once(self.needle) {
+            Some((first, second)) => {
+                if !haystack.is_empty() {
+                    debug_assert_ne!(haystack, second);
+                }
+                self.haystack = Some(second);
+                Some(first)
+            }
+            None => {
+                self.haystack = None;
+                Some(haystack)
+            }
+        }
+    }
+}
+
+/// Split an `OsStr`
+///
+/// # Safety
+///
+/// `index` must be at a valid UTF-8 boundary
+pub(crate) unsafe fn split_at(os: &OsStr, index: usize) -> (&OsStr, &OsStr) {
+    let bytes = to_bytes(os);
+    let (first, second) = bytes.split_at(index);
+    (to_os_str_unchecked(first), to_os_str_unchecked(second))
+}
diff --git a/third_party/rust/clap_lex/src/lib.rs b/third_party/rust/clap_lex/src/lib.rs
new file mode 100644
index 0000000000..d519a10c56
--- /dev/null
+++ b/third_party/rust/clap_lex/src/lib.rs
@@ -0,0 +1,468 @@
+//! Minimal, flexible command-line parser
+//!
+//! As opposed to a declarative parser, this processes arguments as a stream of tokens.  As lexing
+//! a command-line is not context-free, we rely on the caller to decide how to interpret the
+//! arguments.
+//!
+//! # Examples
+//!
+//! ```rust
+//! use std::path::PathBuf;
+//! use std::ffi::OsStr;
+//!
+//! type BoxedError = Box<dyn std::error::Error + Send + Sync>;
+//!
+//! #[derive(Debug)]
+//! struct Args {
+//!     paths: Vec<PathBuf>,
+//!     color: Color,
+//!     verbosity: usize,
+//! }
+//!
+//! #[derive(Debug)]
+//! enum Color {
+//!     Always,
+//!     Auto,
+//!     Never,
+//! }
+//!
+//! impl Color {
+//!     fn parse(s: Option<&OsStr>) -> Result<Self, BoxedError> {
+//!         let s = s.map(|s| s.to_str().ok_or(s));
+//!         match s {
+//!             Some(Ok("always")) | Some(Ok("")) | None => {
+//!                 Ok(Color::Always)
+//!             }
+//!             Some(Ok("auto")) => {
+//!                 Ok(Color::Auto)
+//!             }
+//!             Some(Ok("never")) => {
+//!                 Ok(Color::Never)
+//!             }
+//!             Some(invalid) => {
+//!                 Err(format!("Invalid value for `--color`, {invalid:?}").into())
+//!             }
+//!         }
+//!     }
+//! }
+//!
+//! fn parse_args(
+//!     raw: impl IntoIterator<Item=impl Into<std::ffi::OsString>>
+//! ) -> Result<Args, BoxedError> {
+//!     let mut args = Args {
+//!         paths: Vec::new(),
+//!         color: Color::Auto,
+//!         verbosity: 0,
+//!     };
+//!
+//!     let raw = clap_lex::RawArgs::new(raw);
+//!     let mut cursor = raw.cursor();
+//!     raw.next(&mut cursor);  // Skip the bin
+//!     while let Some(arg) = raw.next(&mut cursor) {
+//!         if arg.is_escape() {
+//!             args.paths.extend(raw.remaining(&mut cursor).map(PathBuf::from));
+//!         } else if arg.is_stdio() {
+//!             args.paths.push(PathBuf::from("-"));
+//!         } else if let Some((long, value)) = arg.to_long() {
+//!             match long {
+//!                 Ok("verbose") => {
+//!                     if let Some(value) = value {
+//!                         return Err(format!("`--verbose` does not take a value, got `{value:?}`").into());
+//!                     }
+//!                     args.verbosity += 1;
+//!                 }
+//!                 Ok("color") => {
+//!                     args.color = Color::parse(value)?;
+//!                 }
+//!                 _ => {
+//!                     return Err(
+//!                         format!("Unexpected flag: --{}", arg.display()).into()
+//!                     );
+//!                 }
+//!             }
+//!         } else if let Some(mut shorts) = arg.to_short() {
+//!             while let Some(short) = shorts.next_flag() {
+//!                 match short {
+//!                     Ok('v') => {
+//!                         args.verbosity += 1;
+//!                     }
+//!                     Ok('c') => {
+//!                         let value = shorts.next_value_os();
+//!                         args.color = Color::parse(value)?;
+//!                     }
+//!                     Ok(c) => {
+//!                         return Err(format!("Unexpected flag: -{c}").into());
+//!                     }
+//!                     Err(e) => {
+//!                         return Err(format!("Unexpected flag: -{}", e.to_string_lossy()).into());
+//!                     }
+//!                 }
+//!             }
+//!         } else {
+//!             args.paths.push(PathBuf::from(arg.to_value_os().to_owned()));
+//!         }
+//!     }
+//!
+//!     Ok(args)
+//! }
+//!
+//! let args = parse_args(["bin", "--hello", "world"]);
+//! println!("{args:?}");
+//! ```
+
+mod ext;
+
+use std::ffi::OsStr;
+use std::ffi::OsString;
+
+pub use std::io::SeekFrom;
+
+pub use ext::OsStrExt;
+
+/// Command-line arguments
+#[derive(Default, Clone, Debug, PartialEq, Eq)]
+pub struct RawArgs {
+    items: Vec<OsString>,
+}
+
+impl RawArgs {
+    //// Create an argument list to parse
+    ///
+    /// **NOTE:** The argument returned will be the current binary.
+    ///
+    /// # Example
+    ///
+    /// ```rust,no_run
+    /// # use std::path::PathBuf;
+    /// let raw = clap_lex::RawArgs::from_args();
+    /// let mut cursor = raw.cursor();
+    /// let _bin = raw.next_os(&mut cursor);
+    ///
+    /// let mut paths = raw.remaining(&mut cursor).map(PathBuf::from).collect::<Vec<_>>();
+    /// println!("{paths:?}");
+    /// ```
+    pub fn from_args() -> Self {
+        Self::new(std::env::args_os())
+    }
+
+    //// Create an argument list to parse
+    ///
+    /// # Example
+    ///
+    /// ```rust,no_run
+    /// # use std::path::PathBuf;
+    /// let raw = clap_lex::RawArgs::new(["bin", "foo.txt"]);
+    /// let mut cursor = raw.cursor();
+    /// let _bin = raw.next_os(&mut cursor);
+    ///
+    /// let mut paths = raw.remaining(&mut cursor).map(PathBuf::from).collect::<Vec<_>>();
+    /// println!("{paths:?}");
+    /// ```
+    pub fn new(iter: impl IntoIterator<Item = impl Into<std::ffi::OsString>>) -> Self {
+        let iter = iter.into_iter();
+        Self::from(iter)
+    }
+
+    /// Create a cursor for walking the arguments
+    ///
+    /// # Example
+    ///
+    /// ```rust,no_run
+    /// # use std::path::PathBuf;
+    /// let raw = clap_lex::RawArgs::new(["bin", "foo.txt"]);
+    /// let mut cursor = raw.cursor();
+    /// let _bin = raw.next_os(&mut cursor);
+    ///
+    /// let mut paths = raw.remaining(&mut cursor).map(PathBuf::from).collect::<Vec<_>>();
+    /// println!("{paths:?}");
+    /// ```
+    pub fn cursor(&self) -> ArgCursor {
+        ArgCursor::new()
+    }
+
+    /// Advance the cursor, returning the next [`ParsedArg`]
+    pub fn next(&self, cursor: &mut ArgCursor) -> Option<ParsedArg<'_>> {
+        self.next_os(cursor).map(ParsedArg::new)
+    }
+
+    /// Advance the cursor, returning a raw argument value.
+    pub fn next_os(&self, cursor: &mut ArgCursor) -> Option<&OsStr> {
+        let next = self.items.get(cursor.cursor).map(|s| s.as_os_str());
+        cursor.cursor = cursor.cursor.saturating_add(1);
+        next
+    }
+
+    /// Return the next [`ParsedArg`]
+    pub fn peek(&self, cursor: &ArgCursor) -> Option<ParsedArg<'_>> {
+        self.peek_os(cursor).map(ParsedArg::new)
+    }
+
+    /// Return a raw argument value.
+    pub fn peek_os(&self, cursor: &ArgCursor) -> Option<&OsStr> {
+        self.items.get(cursor.cursor).map(|s| s.as_os_str())
+    }
+
+    /// Return all remaining raw arguments, advancing the cursor to the end
+    ///
+    /// # Example
+    ///
+    /// ```rust,no_run
+    /// # use std::path::PathBuf;
+    /// let raw = clap_lex::RawArgs::new(["bin", "foo.txt"]);
+    /// let mut cursor = raw.cursor();
+    /// let _bin = raw.next_os(&mut cursor);
+    ///
+    /// let mut paths = raw.remaining(&mut cursor).map(PathBuf::from).collect::<Vec<_>>();
+    /// println!("{paths:?}");
+    /// ```
+    pub fn remaining(&self, cursor: &mut ArgCursor) -> impl Iterator<Item = &OsStr> {
+        let remaining = self.items[cursor.cursor..].iter().map(|s| s.as_os_str());
+        cursor.cursor = self.items.len();
+        remaining
+    }
+
+    /// Adjust the cursor's position
+    pub fn seek(&self, cursor: &mut ArgCursor, pos: SeekFrom) {
+        let pos = match pos {
+            SeekFrom::Start(pos) => pos,
+            SeekFrom::End(pos) => (self.items.len() as i64).saturating_add(pos).max(0) as u64,
+            SeekFrom::Current(pos) => (cursor.cursor as i64).saturating_add(pos).max(0) as u64,
+        };
+        let pos = (pos as usize).min(self.items.len());
+        cursor.cursor = pos;
+    }
+
+    /// Inject arguments before the [`RawArgs::next`]
+    pub fn insert(
+        &mut self,
+        cursor: &ArgCursor,
+        insert_items: impl IntoIterator<Item = impl Into<OsString>>,
+    ) {
+        self.items.splice(
+            cursor.cursor..cursor.cursor,
+            insert_items.into_iter().map(Into::into),
+        );
+    }
+
+    /// Any remaining args?
+    pub fn is_end(&self, cursor: &ArgCursor) -> bool {
+        self.peek_os(cursor).is_none()
+    }
+}
+
+impl<I, T> From<I> for RawArgs
+where
+    I: Iterator<Item = T>,
+    T: Into<OsString>,
+{
+    fn from(val: I) -> Self {
+        Self {
+            items: val.map(|x| x.into()).collect(),
+        }
+    }
+}
+
+/// Position within [`RawArgs`]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct ArgCursor {
+    cursor: usize,
+}
+
+impl ArgCursor {
+    fn new() -> Self {
+        Self { cursor: 0 }
+    }
+}
+
+/// Command-line Argument
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ParsedArg<'s> {
+    inner: &'s OsStr,
+}
+
+impl<'s> ParsedArg<'s> {
+    fn new(inner: &'s OsStr) -> Self {
+        Self { inner }
+    }
+
+    /// Argument is length of 0
+    pub fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+
+    /// Does the argument look like a stdio argument (`-`)
+    pub fn is_stdio(&self) -> bool {
+        self.inner == "-"
+    }
+
+    /// Does the argument look like an argument escape (`--`)
+    pub fn is_escape(&self) -> bool {
+        self.inner == "--"
+    }
+
+    /// Does the argument look like a number
+    pub fn is_number(&self) -> bool {
+        self.to_value()
+            .map(|s| s.parse::<f64>().is_ok())
+            .unwrap_or_default()
+    }
+
+    /// Treat as a long-flag
+    pub fn to_long(&self) -> Option<(Result<&str, &OsStr>, Option<&OsStr>)> {
+        let raw = self.inner;
+        let remainder = raw.strip_prefix("--")?;
+        if remainder.is_empty() {
+            debug_assert!(self.is_escape());
+            return None;
+        }
+
+        let (flag, value) = if let Some((p0, p1)) = remainder.split_once("=") {
+            (p0, Some(p1))
+        } else {
+            (remainder, None)
+        };
+        let flag = flag.to_str().ok_or(flag);
+        Some((flag, value))
+    }
+
+    /// Can treat as a long-flag
+    pub fn is_long(&self) -> bool {
+        self.inner.starts_with("--") && !self.is_escape()
+    }
+
+    /// Treat as a short-flag
+    pub fn to_short(&self) -> Option<ShortFlags<'_>> {
+        if let Some(remainder_os) = self.inner.strip_prefix("-") {
+            if remainder_os.starts_with("-") {
+                None
+            } else if remainder_os.is_empty() {
+                debug_assert!(self.is_stdio());
+                None
+            } else {
+                Some(ShortFlags::new(remainder_os))
+            }
+        } else {
+            None
+        }
+    }
+
+    /// Can treat as a short-flag
+    pub fn is_short(&self) -> bool {
+        self.inner.starts_with("-") && !self.is_stdio() && !self.inner.starts_with("--")
+    }
+
+    /// Treat as a value
+    ///
+    /// **NOTE:** May return a flag or an escape.
+    pub fn to_value_os(&self) -> &OsStr {
+        self.inner
+    }
+
+    /// Treat as a value
+    ///
+    /// **NOTE:** May return a flag or an escape.
+    pub fn to_value(&self) -> Result<&str, &OsStr> {
+        self.inner.to_str().ok_or(self.inner)
+    }
+
+    /// Safely print an argument that may contain non-UTF8 content
+    ///
+    /// This may perform lossy conversion, depending on the platform. If you would like an implementation which escapes the path please use Debug instead.
+    pub fn display(&self) -> impl std::fmt::Display + '_ {
+        self.inner.to_string_lossy()
+    }
+}
+
+/// Walk through short flags within a [`ParsedArg`]
+#[derive(Clone, Debug)]
+pub struct ShortFlags<'s> {
+    inner: &'s OsStr,
+    utf8_prefix: std::str::CharIndices<'s>,
+    invalid_suffix: Option<&'s OsStr>,
+}
+
+impl<'s> ShortFlags<'s> {
+    fn new(inner: &'s OsStr) -> Self {
+        let (utf8_prefix, invalid_suffix) = split_nonutf8_once(inner);
+        let utf8_prefix = utf8_prefix.char_indices();
+        Self {
+            inner,
+            utf8_prefix,
+            invalid_suffix,
+        }
+    }
+
+    /// Move the iterator forward by `n` short flags
+    pub fn advance_by(&mut self, n: usize) -> Result<(), usize> {
+        for i in 0..n {
+            self.next().ok_or(i)?.map_err(|_| i)?;
+        }
+        Ok(())
+    }
+
+    /// No short flags left
+    pub fn is_empty(&self) -> bool {
+        self.invalid_suffix.is_none() && self.utf8_prefix.as_str().is_empty()
+    }
+
+    /// Does the short flag look like a number
+    ///
+    /// Ideally call this before doing any iterator
+    pub fn is_number(&self) -> bool {
+        self.invalid_suffix.is_none() && self.utf8_prefix.as_str().parse::<f64>().is_ok()
+    }
+
+    /// Advance the iterator, returning the next short flag on success
+    ///
+    /// On error, returns the invalid-UTF8 value
+    pub fn next_flag(&mut self) -> Option<Result<char, &'s OsStr>> {
+        if let Some((_, flag)) = self.utf8_prefix.next() {
+            return Some(Ok(flag));
+        }
+
+        if let Some(suffix) = self.invalid_suffix {
+            self.invalid_suffix = None;
+            return Some(Err(suffix));
+        }
+
+        None
+    }
+
+    /// Advance the iterator, returning everything left as a value
+    pub fn next_value_os(&mut self) -> Option<&'s OsStr> {
+        if let Some((index, _)) = self.utf8_prefix.next() {
+            self.utf8_prefix = "".char_indices();
+            self.invalid_suffix = None;
+            // SAFETY: `char_indices` ensures `index` is at a valid UTF-8 boundary
+            let remainder = unsafe { ext::split_at(self.inner, index).1 };
+            return Some(remainder);
+        }
+
+        if let Some(suffix) = self.invalid_suffix {
+            self.invalid_suffix = None;
+            return Some(suffix);
+        }
+
+        None
+    }
+}
+
+impl<'s> Iterator for ShortFlags<'s> {
+    type Item = Result<char, &'s OsStr>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.next_flag()
+    }
+}
+
+fn split_nonutf8_once(b: &OsStr) -> (&str, Option<&OsStr>) {
+    match b.try_str() {
+        Ok(s) => (s, None),
+        Err(err) => {
+            // SAFETY: `char_indices` ensures `index` is at a valid UTF-8 boundary
+            let (valid, after_valid) = unsafe { ext::split_at(b, err.valid_up_to()) };
+            let valid = valid.try_str().unwrap();
+            (valid, Some(after_valid))
+        }
+    }
+}