Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 1143 insertions, 0 deletions

diff --git a/vendor/proc-macro2/src/fallback.rs b/vendor/proc-macro2/src/fallback.rs
new file mode 100644
index 0000000..7b40427
--- /dev/null
+++ b/vendor/proc-macro2/src/fallback.rs
@@ -0,0 +1,1143 @@
+#[cfg(span_locations)]
+use crate::location::LineColumn;
+use crate::parse::{self, Cursor};
+use crate::rcvec::{RcVec, RcVecBuilder, RcVecIntoIter, RcVecMut};
+use crate::{Delimiter, Spacing, TokenTree};
+#[cfg(all(span_locations, not(fuzzing)))]
+use alloc::collections::BTreeMap;
+#[cfg(all(span_locations, not(fuzzing)))]
+use core::cell::RefCell;
+#[cfg(span_locations)]
+use core::cmp;
+use core::fmt::{self, Debug, Display, Write};
+use core::mem::ManuallyDrop;
+use core::ops::RangeBounds;
+use core::ptr;
+use core::str::FromStr;
+use std::path::PathBuf;
+
+/// Force use of proc-macro2's fallback implementation of the API for now, even
+/// if the compiler's implementation is available.
+pub fn force() {
+    #[cfg(wrap_proc_macro)]
+    crate::detection::force_fallback();
+}
+
+/// Resume using the compiler's implementation of the proc macro API if it is
+/// available.
+pub fn unforce() {
+    #[cfg(wrap_proc_macro)]
+    crate::detection::unforce_fallback();
+}
+
+#[derive(Clone)]
+pub(crate) struct TokenStream {
+    inner: RcVec<TokenTree>,
+}
+
+#[derive(Debug)]
+pub(crate) struct LexError {
+    pub(crate) span: Span,
+}
+
+impl LexError {
+    pub(crate) fn span(&self) -> Span {
+        self.span
+    }
+
+    pub(crate) fn call_site() -> Self {
+        LexError {
+            span: Span::call_site(),
+        }
+    }
+}
+
+impl TokenStream {
+    pub fn new() -> Self {
+        TokenStream {
+            inner: RcVecBuilder::new().build(),
+        }
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.inner.len() == 0
+    }
+
+    fn take_inner(self) -> RcVecBuilder<TokenTree> {
+        let nodrop = ManuallyDrop::new(self);
+        unsafe { ptr::read(&nodrop.inner) }.make_owned()
+    }
+}
+
+fn push_token_from_proc_macro(mut vec: RcVecMut<TokenTree>, token: TokenTree) {
+    // https://github.com/dtolnay/proc-macro2/issues/235
+    match token {
+        TokenTree::Literal(crate::Literal {
+            #[cfg(wrap_proc_macro)]
+                inner: crate::imp::Literal::Fallback(literal),
+            #[cfg(not(wrap_proc_macro))]
+                inner: literal,
+            ..
+        }) if literal.repr.starts_with('-') => {
+            push_negative_literal(vec, literal);
+        }
+        _ => vec.push(token),
+    }
+
+    #[cold]
+    fn push_negative_literal(mut vec: RcVecMut<TokenTree>, mut literal: Literal) {
+        literal.repr.remove(0);
+        let mut punct = crate::Punct::new('-', Spacing::Alone);
+        punct.set_span(crate::Span::_new_fallback(literal.span));
+        vec.push(TokenTree::Punct(punct));
+        vec.push(TokenTree::Literal(crate::Literal::_new_fallback(literal)));
+    }
+}
+
+// Nonrecursive to prevent stack overflow.
+impl Drop for TokenStream {
+    fn drop(&mut self) {
+        let mut inner = match self.inner.get_mut() {
+            Some(inner) => inner,
+            None => return,
+        };
+        while let Some(token) = inner.pop() {
+            let group = match token {
+                TokenTree::Group(group) => group.inner,
+                _ => continue,
+            };
+            #[cfg(wrap_proc_macro)]
+            let group = match group {
+                crate::imp::Group::Fallback(group) => group,
+                crate::imp::Group::Compiler(_) => continue,
+            };
+            inner.extend(group.stream.take_inner());
+        }
+    }
+}
+
+pub(crate) struct TokenStreamBuilder {
+    inner: RcVecBuilder<TokenTree>,
+}
+
+impl TokenStreamBuilder {
+    pub fn new() -> Self {
+        TokenStreamBuilder {
+            inner: RcVecBuilder::new(),
+        }
+    }
+
+    pub fn with_capacity(cap: usize) -> Self {
+        TokenStreamBuilder {
+            inner: RcVecBuilder::with_capacity(cap),
+        }
+    }
+
+    pub fn push_token_from_parser(&mut self, tt: TokenTree) {
+        self.inner.push(tt);
+    }
+
+    pub fn build(self) -> TokenStream {
+        TokenStream {
+            inner: self.inner.build(),
+        }
+    }
+}
+
+#[cfg(span_locations)]
+fn get_cursor(src: &str) -> Cursor {
+    #[cfg(fuzzing)]
+    return Cursor { rest: src, off: 1 };
+
+    // Create a dummy file & add it to the source map
+    #[cfg(not(fuzzing))]
+    SOURCE_MAP.with(|cm| {
+        let mut cm = cm.borrow_mut();
+        let span = cm.add_file(src);
+        Cursor {
+            rest: src,
+            off: span.lo,
+        }
+    })
+}
+
+#[cfg(not(span_locations))]
+fn get_cursor(src: &str) -> Cursor {
+    Cursor { rest: src }
+}
+
+impl FromStr for TokenStream {
+    type Err = LexError;
+
+    fn from_str(src: &str) -> Result<TokenStream, LexError> {
+        // Create a dummy file & add it to the source map
+        let mut cursor = get_cursor(src);
+
+        // Strip a byte order mark if present
+        const BYTE_ORDER_MARK: &str = "\u{feff}";
+        if cursor.starts_with(BYTE_ORDER_MARK) {
+            cursor = cursor.advance(BYTE_ORDER_MARK.len());
+        }
+
+        parse::token_stream(cursor)
+    }
+}
+
+impl Display for LexError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("cannot parse string into token stream")
+    }
+}
+
+impl Display for TokenStream {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut joint = false;
+        for (i, tt) in self.inner.iter().enumerate() {
+            if i != 0 && !joint {
+                write!(f, " ")?;
+            }
+            joint = false;
+            match tt {
+                TokenTree::Group(tt) => Display::fmt(tt, f),
+                TokenTree::Ident(tt) => Display::fmt(tt, f),
+                TokenTree::Punct(tt) => {
+                    joint = tt.spacing() == Spacing::Joint;
+                    Display::fmt(tt, f)
+                }
+                TokenTree::Literal(tt) => Display::fmt(tt, f),
+            }?;
+        }
+
+        Ok(())
+    }
+}
+
+impl Debug for TokenStream {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("TokenStream ")?;
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+#[cfg(feature = "proc-macro")]
+impl From<proc_macro::TokenStream> for TokenStream {
+    fn from(inner: proc_macro::TokenStream) -> Self {
+        inner
+            .to_string()
+            .parse()
+            .expect("compiler token stream parse failed")
+    }
+}
+
+#[cfg(feature = "proc-macro")]
+impl From<TokenStream> for proc_macro::TokenStream {
+    fn from(inner: TokenStream) -> Self {
+        inner
+            .to_string()
+            .parse()
+            .expect("failed to parse to compiler tokens")
+    }
+}
+
+impl From<TokenTree> for TokenStream {
+    fn from(tree: TokenTree) -> Self {
+        let mut stream = RcVecBuilder::new();
+        push_token_from_proc_macro(stream.as_mut(), tree);
+        TokenStream {
+            inner: stream.build(),
+        }
+    }
+}
+
+impl FromIterator<TokenTree> for TokenStream {
+    fn from_iter<I: IntoIterator<Item = TokenTree>>(tokens: I) -> Self {
+        let mut stream = TokenStream::new();
+        stream.extend(tokens);
+        stream
+    }
+}
+
+impl FromIterator<TokenStream> for TokenStream {
+    fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
+        let mut v = RcVecBuilder::new();
+
+        for stream in streams {
+            v.extend(stream.take_inner());
+        }
+
+        TokenStream { inner: v.build() }
+    }
+}
+
+impl Extend<TokenTree> for TokenStream {
+    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, tokens: I) {
+        let mut vec = self.inner.make_mut();
+        tokens
+            .into_iter()
+            .for_each(|token| push_token_from_proc_macro(vec.as_mut(), token));
+    }
+}
+
+impl Extend<TokenStream> for TokenStream {
+    fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
+        self.inner.make_mut().extend(streams.into_iter().flatten());
+    }
+}
+
+pub(crate) type TokenTreeIter = RcVecIntoIter<TokenTree>;
+
+impl IntoIterator for TokenStream {
+    type Item = TokenTree;
+    type IntoIter = TokenTreeIter;
+
+    fn into_iter(self) -> TokenTreeIter {
+        self.take_inner().into_iter()
+    }
+}
+
+#[derive(Clone, PartialEq, Eq)]
+pub(crate) struct SourceFile {
+    path: PathBuf,
+}
+
+impl SourceFile {
+    /// Get the path to this source file as a string.
+    pub fn path(&self) -> PathBuf {
+        self.path.clone()
+    }
+
+    pub fn is_real(&self) -> bool {
+        false
+    }
+}
+
+impl Debug for SourceFile {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("SourceFile")
+            .field("path", &self.path())
+            .field("is_real", &self.is_real())
+            .finish()
+    }
+}
+
+#[cfg(all(span_locations, not(fuzzing)))]
+thread_local! {
+    static SOURCE_MAP: RefCell<SourceMap> = RefCell::new(SourceMap {
+        // Start with a single dummy file which all call_site() and def_site()
+        // spans reference.
+        files: vec![FileInfo {
+            source_text: String::new(),
+            span: Span { lo: 0, hi: 0 },
+            lines: vec![0],
+            char_index_to_byte_offset: BTreeMap::new(),
+        }],
+    });
+}
+
+#[cfg(all(span_locations, not(fuzzing)))]
+struct FileInfo {
+    source_text: String,
+    span: Span,
+    lines: Vec<usize>,
+    char_index_to_byte_offset: BTreeMap<usize, usize>,
+}
+
+#[cfg(all(span_locations, not(fuzzing)))]
+impl FileInfo {
+    fn offset_line_column(&self, offset: usize) -> LineColumn {
+        assert!(self.span_within(Span {
+            lo: offset as u32,
+            hi: offset as u32,
+        }));
+        let offset = offset - self.span.lo as usize;
+        match self.lines.binary_search(&offset) {
+            Ok(found) => LineColumn {
+                line: found + 1,
+                column: 0,
+            },
+            Err(idx) => LineColumn {
+                line: idx,
+                column: offset - self.lines[idx - 1],
+            },
+        }
+    }
+
+    fn span_within(&self, span: Span) -> bool {
+        span.lo >= self.span.lo && span.hi <= self.span.hi
+    }
+
+    fn source_text(&mut self, span: Span) -> String {
+        let lo_char = (span.lo - self.span.lo) as usize;
+
+        // Look up offset of the largest already-computed char index that is
+        // less than or equal to the current requested one. We resume counting
+        // chars from that point.
+        let (&last_char_index, &last_byte_offset) = self
+            .char_index_to_byte_offset
+            .range(..=lo_char)
+            .next_back()
+            .unwrap_or((&0, &0));
+
+        let lo_byte = if last_char_index == lo_char {
+            last_byte_offset
+        } else {
+            let total_byte_offset = match self.source_text[last_byte_offset..]
+                .char_indices()
+                .nth(lo_char - last_char_index)
+            {
+                Some((additional_offset, _ch)) => last_byte_offset + additional_offset,
+                None => self.source_text.len(),
+            };
+            self.char_index_to_byte_offset
+                .insert(lo_char, total_byte_offset);
+            total_byte_offset
+        };
+
+        let trunc_lo = &self.source_text[lo_byte..];
+        let char_len = (span.hi - span.lo) as usize;
+        let source_text = match trunc_lo.char_indices().nth(char_len) {
+            Some((offset, _ch)) => &trunc_lo[..offset],
+            None => trunc_lo,
+        };
+        source_text.to_owned()
+    }
+}
+
+/// Computes the offsets of each line in the given source string
+/// and the total number of characters
+#[cfg(all(span_locations, not(fuzzing)))]
+fn lines_offsets(s: &str) -> (usize, Vec<usize>) {
+    let mut lines = vec![0];
+    let mut total = 0;
+
+    for ch in s.chars() {
+        total += 1;
+        if ch == '\n' {
+            lines.push(total);
+        }
+    }
+
+    (total, lines)
+}
+
+#[cfg(all(span_locations, not(fuzzing)))]
+struct SourceMap {
+    files: Vec<FileInfo>,
+}
+
+#[cfg(all(span_locations, not(fuzzing)))]
+impl SourceMap {
+    fn next_start_pos(&self) -> u32 {
+        // Add 1 so there's always space between files.
+        //
+        // We'll always have at least 1 file, as we initialize our files list
+        // with a dummy file.
+        self.files.last().unwrap().span.hi + 1
+    }
+
+    fn add_file(&mut self, src: &str) -> Span {
+        let (len, lines) = lines_offsets(src);
+        let lo = self.next_start_pos();
+        let span = Span {
+            lo,
+            hi: lo + (len as u32),
+        };
+
+        self.files.push(FileInfo {
+            source_text: src.to_owned(),
+            span,
+            lines,
+            // Populated lazily by source_text().
+            char_index_to_byte_offset: BTreeMap::new(),
+        });
+
+        span
+    }
+
+    #[cfg(procmacro2_semver_exempt)]
+    fn filepath(&self, span: Span) -> PathBuf {
+        for (i, file) in self.files.iter().enumerate() {
+            if file.span_within(span) {
+                return PathBuf::from(if i == 0 {
+                    "<unspecified>".to_owned()
+                } else {
+                    format!("<parsed string {}>", i)
+                });
+            }
+        }
+        unreachable!("Invalid span with no related FileInfo!");
+    }
+
+    fn fileinfo(&self, span: Span) -> &FileInfo {
+        for file in &self.files {
+            if file.span_within(span) {
+                return file;
+            }
+        }
+        unreachable!("Invalid span with no related FileInfo!");
+    }
+
+    fn fileinfo_mut(&mut self, span: Span) -> &mut FileInfo {
+        for file in &mut self.files {
+            if file.span_within(span) {
+                return file;
+            }
+        }
+        unreachable!("Invalid span with no related FileInfo!");
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub(crate) struct Span {
+    #[cfg(span_locations)]
+    pub(crate) lo: u32,
+    #[cfg(span_locations)]
+    pub(crate) hi: u32,
+}
+
+impl Span {
+    #[cfg(not(span_locations))]
+    pub fn call_site() -> Self {
+        Span {}
+    }
+
+    #[cfg(span_locations)]
+    pub fn call_site() -> Self {
+        Span { lo: 0, hi: 0 }
+    }
+
+    pub fn mixed_site() -> Self {
+        Span::call_site()
+    }
+
+    #[cfg(procmacro2_semver_exempt)]
+    pub fn def_site() -> Self {
+        Span::call_site()
+    }
+
+    pub fn resolved_at(&self, _other: Span) -> Span {
+        // Stable spans consist only of line/column information, so
+        // `resolved_at` and `located_at` only select which span the
+        // caller wants line/column information from.
+        *self
+    }
+
+    pub fn located_at(&self, other: Span) -> Span {
+        other
+    }
+
+    #[cfg(procmacro2_semver_exempt)]
+    pub fn source_file(&self) -> SourceFile {
+        #[cfg(fuzzing)]
+        return SourceFile {
+            path: PathBuf::from("<unspecified>"),
+        };
+
+        #[cfg(not(fuzzing))]
+        SOURCE_MAP.with(|cm| {
+            let cm = cm.borrow();
+            let path = cm.filepath(*self);
+            SourceFile { path }
+        })
+    }
+
+    #[cfg(span_locations)]
+    pub fn start(&self) -> LineColumn {
+        #[cfg(fuzzing)]
+        return LineColumn { line: 0, column: 0 };
+
+        #[cfg(not(fuzzing))]
+        SOURCE_MAP.with(|cm| {
+            let cm = cm.borrow();
+            let fi = cm.fileinfo(*self);
+            fi.offset_line_column(self.lo as usize)
+        })
+    }
+
+    #[cfg(span_locations)]
+    pub fn end(&self) -> LineColumn {
+        #[cfg(fuzzing)]
+        return LineColumn { line: 0, column: 0 };
+
+        #[cfg(not(fuzzing))]
+        SOURCE_MAP.with(|cm| {
+            let cm = cm.borrow();
+            let fi = cm.fileinfo(*self);
+            fi.offset_line_column(self.hi as usize)
+        })
+    }
+
+    #[cfg(not(span_locations))]
+    pub fn join(&self, _other: Span) -> Option<Span> {
+        Some(Span {})
+    }
+
+    #[cfg(span_locations)]
+    pub fn join(&self, other: Span) -> Option<Span> {
+        #[cfg(fuzzing)]
+        return {
+            let _ = other;
+            None
+        };
+
+        #[cfg(not(fuzzing))]
+        SOURCE_MAP.with(|cm| {
+            let cm = cm.borrow();
+            // If `other` is not within the same FileInfo as us, return None.
+            if !cm.fileinfo(*self).span_within(other) {
+                return None;
+            }
+            Some(Span {
+                lo: cmp::min(self.lo, other.lo),
+                hi: cmp::max(self.hi, other.hi),
+            })
+        })
+    }
+
+    #[cfg(not(span_locations))]
+    pub fn source_text(&self) -> Option<String> {
+        None
+    }
+
+    #[cfg(span_locations)]
+    pub fn source_text(&self) -> Option<String> {
+        #[cfg(fuzzing)]
+        return None;
+
+        #[cfg(not(fuzzing))]
+        {
+            if self.is_call_site() {
+                None
+            } else {
+                Some(SOURCE_MAP.with(|cm| cm.borrow_mut().fileinfo_mut(*self).source_text(*self)))
+            }
+        }
+    }
+
+    #[cfg(not(span_locations))]
+    pub(crate) fn first_byte(self) -> Self {
+        self
+    }
+
+    #[cfg(span_locations)]
+    pub(crate) fn first_byte(self) -> Self {
+        Span {
+            lo: self.lo,
+            hi: cmp::min(self.lo.saturating_add(1), self.hi),
+        }
+    }
+
+    #[cfg(not(span_locations))]
+    pub(crate) fn last_byte(self) -> Self {
+        self
+    }
+
+    #[cfg(span_locations)]
+    pub(crate) fn last_byte(self) -> Self {
+        Span {
+            lo: cmp::max(self.hi.saturating_sub(1), self.lo),
+            hi: self.hi,
+        }
+    }
+
+    #[cfg(span_locations)]
+    fn is_call_site(&self) -> bool {
+        self.lo == 0 && self.hi == 0
+    }
+}
+
+impl Debug for Span {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        #[cfg(span_locations)]
+        return write!(f, "bytes({}..{})", self.lo, self.hi);
+
+        #[cfg(not(span_locations))]
+        write!(f, "Span")
+    }
+}
+
+pub(crate) fn debug_span_field_if_nontrivial(debug: &mut fmt::DebugStruct, span: Span) {
+    #[cfg(span_locations)]
+    {
+        if span.is_call_site() {
+            return;
+        }
+    }
+
+    if cfg!(span_locations) {
+        debug.field("span", &span);
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct Group {
+    delimiter: Delimiter,
+    stream: TokenStream,
+    span: Span,
+}
+
+impl Group {
+    pub fn new(delimiter: Delimiter, stream: TokenStream) -> Self {
+        Group {
+            delimiter,
+            stream,
+            span: Span::call_site(),
+        }
+    }
+
+    pub fn delimiter(&self) -> Delimiter {
+        self.delimiter
+    }
+
+    pub fn stream(&self) -> TokenStream {
+        self.stream.clone()
+    }
+
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    pub fn span_open(&self) -> Span {
+        self.span.first_byte()
+    }
+
+    pub fn span_close(&self) -> Span {
+        self.span.last_byte()
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.span = span;
+    }
+}
+
+impl Display for Group {
+    // We attempt to match libproc_macro's formatting.
+    // Empty parens: ()
+    // Nonempty parens: (...)
+    // Empty brackets: []
+    // Nonempty brackets: [...]
+    // Empty braces: { }
+    // Nonempty braces: { ... }
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let (open, close) = match self.delimiter {
+            Delimiter::Parenthesis => ("(", ")"),
+            Delimiter::Brace => ("{ ", "}"),
+            Delimiter::Bracket => ("[", "]"),
+            Delimiter::None => ("", ""),
+        };
+
+        f.write_str(open)?;
+        Display::fmt(&self.stream, f)?;
+        if self.delimiter == Delimiter::Brace && !self.stream.inner.is_empty() {
+            f.write_str(" ")?;
+        }
+        f.write_str(close)?;
+
+        Ok(())
+    }
+}
+
+impl Debug for Group {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = fmt.debug_struct("Group");
+        debug.field("delimiter", &self.delimiter);
+        debug.field("stream", &self.stream);
+        debug_span_field_if_nontrivial(&mut debug, self.span);
+        debug.finish()
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct Ident {
+    sym: String,
+    span: Span,
+    raw: bool,
+}
+
+impl Ident {
+    #[track_caller]
+    pub fn new_checked(string: &str, span: Span) -> Self {
+        validate_ident(string);
+        Ident::new_unchecked(string, span)
+    }
+
+    pub fn new_unchecked(string: &str, span: Span) -> Self {
+        Ident {
+            sym: string.to_owned(),
+            span,
+            raw: false,
+        }
+    }
+
+    #[track_caller]
+    pub fn new_raw_checked(string: &str, span: Span) -> Self {
+        validate_ident_raw(string);
+        Ident::new_raw_unchecked(string, span)
+    }
+
+    pub fn new_raw_unchecked(string: &str, span: Span) -> Self {
+        Ident {
+            sym: string.to_owned(),
+            span,
+            raw: true,
+        }
+    }
+
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.span = span;
+    }
+}
+
+pub(crate) fn is_ident_start(c: char) -> bool {
+    c == '_' || unicode_ident::is_xid_start(c)
+}
+
+pub(crate) fn is_ident_continue(c: char) -> bool {
+    unicode_ident::is_xid_continue(c)
+}
+
+#[track_caller]
+fn validate_ident(string: &str) {
+    if string.is_empty() {
+        panic!("Ident is not allowed to be empty; use Option<Ident>");
+    }
+
+    if string.bytes().all(|digit| b'0' <= digit && digit <= b'9') {
+        panic!("Ident cannot be a number; use Literal instead");
+    }
+
+    fn ident_ok(string: &str) -> bool {
+        let mut chars = string.chars();
+        let first = chars.next().unwrap();
+        if !is_ident_start(first) {
+            return false;
+        }
+        for ch in chars {
+            if !is_ident_continue(ch) {
+                return false;
+            }
+        }
+        true
+    }
+
+    if !ident_ok(string) {
+        panic!("{:?} is not a valid Ident", string);
+    }
+}
+
+#[track_caller]
+fn validate_ident_raw(string: &str) {
+    validate_ident(string);
+
+    match string {
+        "_" | "super" | "self" | "Self" | "crate" => {
+            panic!("`r#{}` cannot be a raw identifier", string);
+        }
+        _ => {}
+    }
+}
+
+impl PartialEq for Ident {
+    fn eq(&self, other: &Ident) -> bool {
+        self.sym == other.sym && self.raw == other.raw
+    }
+}
+
+impl<T> PartialEq<T> for Ident
+where
+    T: ?Sized + AsRef<str>,
+{
+    fn eq(&self, other: &T) -> bool {
+        let other = other.as_ref();
+        if self.raw {
+            other.starts_with("r#") && self.sym == other[2..]
+        } else {
+            self.sym == other
+        }
+    }
+}
+
+impl Display for Ident {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.raw {
+            f.write_str("r#")?;
+        }
+        Display::fmt(&self.sym, f)
+    }
+}
+
+#[allow(clippy::missing_fields_in_debug)]
+impl Debug for Ident {
+    // Ident(proc_macro), Ident(r#union)
+    #[cfg(not(span_locations))]
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = f.debug_tuple("Ident");
+        debug.field(&format_args!("{}", self));
+        debug.finish()
+    }
+
+    // Ident {
+    //     sym: proc_macro,
+    //     span: bytes(128..138)
+    // }
+    #[cfg(span_locations)]
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = f.debug_struct("Ident");
+        debug.field("sym", &format_args!("{}", self));
+        debug_span_field_if_nontrivial(&mut debug, self.span);
+        debug.finish()
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct Literal {
+    repr: String,
+    span: Span,
+}
+
+macro_rules! suffixed_numbers {
+    ($($name:ident => $kind:ident,)*) => ($(
+        pub fn $name(n: $kind) -> Literal {
+            Literal::_new(format!(concat!("{}", stringify!($kind)), n))
+        }
+    )*)
+}
+
+macro_rules! unsuffixed_numbers {
+    ($($name:ident => $kind:ident,)*) => ($(
+        pub fn $name(n: $kind) -> Literal {
+            Literal::_new(n.to_string())
+        }
+    )*)
+}
+
+impl Literal {
+    pub(crate) fn _new(repr: String) -> Self {
+        Literal {
+            repr,
+            span: Span::call_site(),
+        }
+    }
+
+    pub(crate) unsafe fn from_str_unchecked(repr: &str) -> Self {
+        Literal::_new(repr.to_owned())
+    }
+
+    suffixed_numbers! {
+        u8_suffixed => u8,
+        u16_suffixed => u16,
+        u32_suffixed => u32,
+        u64_suffixed => u64,
+        u128_suffixed => u128,
+        usize_suffixed => usize,
+        i8_suffixed => i8,
+        i16_suffixed => i16,
+        i32_suffixed => i32,
+        i64_suffixed => i64,
+        i128_suffixed => i128,
+        isize_suffixed => isize,
+
+        f32_suffixed => f32,
+        f64_suffixed => f64,
+    }
+
+    unsuffixed_numbers! {
+        u8_unsuffixed => u8,
+        u16_unsuffixed => u16,
+        u32_unsuffixed => u32,
+        u64_unsuffixed => u64,
+        u128_unsuffixed => u128,
+        usize_unsuffixed => usize,
+        i8_unsuffixed => i8,
+        i16_unsuffixed => i16,
+        i32_unsuffixed => i32,
+        i64_unsuffixed => i64,
+        i128_unsuffixed => i128,
+        isize_unsuffixed => isize,
+    }
+
+    pub fn f32_unsuffixed(f: f32) -> Literal {
+        let mut s = f.to_string();
+        if !s.contains('.') {
+            s.push_str(".0");
+        }
+        Literal::_new(s)
+    }
+
+    pub fn f64_unsuffixed(f: f64) -> Literal {
+        let mut s = f.to_string();
+        if !s.contains('.') {
+            s.push_str(".0");
+        }
+        Literal::_new(s)
+    }
+
+    pub fn string(t: &str) -> Literal {
+        let mut repr = String::with_capacity(t.len() + 2);
+        repr.push('"');
+        let mut chars = t.chars();
+        while let Some(ch) = chars.next() {
+            if ch == '\0' {
+                repr.push_str(
+                    if chars
+                        .as_str()
+                        .starts_with(|next| '0' <= next && next <= '7')
+                    {
+                        // circumvent clippy::octal_escapes lint
+                        "\\x00"
+                    } else {
+                        "\\0"
+                    },
+                );
+            } else if ch == '\'' {
+                // escape_debug turns this into "\'" which is unnecessary.
+                repr.push(ch);
+            } else {
+                repr.extend(ch.escape_debug());
+            }
+        }
+        repr.push('"');
+        Literal::_new(repr)
+    }
+
+    pub fn character(t: char) -> Literal {
+        let mut repr = String::new();
+        repr.push('\'');
+        if t == '"' {
+            // escape_debug turns this into '\"' which is unnecessary.
+            repr.push(t);
+        } else {
+            repr.extend(t.escape_debug());
+        }
+        repr.push('\'');
+        Literal::_new(repr)
+    }
+
+    pub fn byte_string(bytes: &[u8]) -> Literal {
+        let mut escaped = "b\"".to_string();
+        let mut bytes = bytes.iter();
+        while let Some(&b) = bytes.next() {
+            #[allow(clippy::match_overlapping_arm)]
+            match b {
+                b'\0' => escaped.push_str(match bytes.as_slice().first() {
+                    // circumvent clippy::octal_escapes lint
+                    Some(b'0'..=b'7') => r"\x00",
+                    _ => r"\0",
+                }),
+                b'\t' => escaped.push_str(r"\t"),
+                b'\n' => escaped.push_str(r"\n"),
+                b'\r' => escaped.push_str(r"\r"),
+                b'"' => escaped.push_str("\\\""),
+                b'\\' => escaped.push_str("\\\\"),
+                b'\x20'..=b'\x7E' => escaped.push(b as char),
+                _ => {
+                    let _ = write!(escaped, "\\x{:02X}", b);
+                }
+            }
+        }
+        escaped.push('"');
+        Literal::_new(escaped)
+    }
+
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.span = span;
+    }
+
+    pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
+        #[cfg(not(span_locations))]
+        {
+            let _ = range;
+            None
+        }
+
+        #[cfg(span_locations)]
+        {
+            use core::ops::Bound;
+
+            let lo = match range.start_bound() {
+                Bound::Included(start) => {
+                    let start = u32::try_from(*start).ok()?;
+                    self.span.lo.checked_add(start)?
+                }
+                Bound::Excluded(start) => {
+                    let start = u32::try_from(*start).ok()?;
+                    self.span.lo.checked_add(start)?.checked_add(1)?
+                }
+                Bound::Unbounded => self.span.lo,
+            };
+            let hi = match range.end_bound() {
+                Bound::Included(end) => {
+                    let end = u32::try_from(*end).ok()?;
+                    self.span.lo.checked_add(end)?.checked_add(1)?
+                }
+                Bound::Excluded(end) => {
+                    let end = u32::try_from(*end).ok()?;
+                    self.span.lo.checked_add(end)?
+                }
+                Bound::Unbounded => self.span.hi,
+            };
+            if lo <= hi && hi <= self.span.hi {
+                Some(Span { lo, hi })
+            } else {
+                None
+            }
+        }
+    }
+}
+
+impl FromStr for Literal {
+    type Err = LexError;
+
+    fn from_str(repr: &str) -> Result<Self, Self::Err> {
+        let mut cursor = get_cursor(repr);
+        #[cfg(span_locations)]
+        let lo = cursor.off;
+
+        let negative = cursor.starts_with_char('-');
+        if negative {
+            cursor = cursor.advance(1);
+            if !cursor.starts_with_fn(|ch| ch.is_ascii_digit()) {
+                return Err(LexError::call_site());
+            }
+        }
+
+        if let Ok((rest, mut literal)) = parse::literal(cursor) {
+            if rest.is_empty() {
+                if negative {
+                    literal.repr.insert(0, '-');
+                }
+                literal.span = Span {
+                    #[cfg(span_locations)]
+                    lo,
+                    #[cfg(span_locations)]
+                    hi: rest.off,
+                };
+                return Ok(literal);
+            }
+        }
+        Err(LexError::call_site())
+    }
+}
+
+impl Display for Literal {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.repr, f)
+    }
+}
+
+impl Debug for Literal {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = fmt.debug_struct("Literal");
+        debug.field("lit", &format_args!("{}", self.repr));
+        debug_span_field_if_nontrivial(&mut debug, self.span);
+        debug.finish()
+    }
+}