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use core::convert::TryFrom;
use core::{char, fmt, iter, mem, str};
#[allow(unused_macros)]
macro_rules! write {
($($ignored:tt)*) => {
compile_error!(
"use `self.print(value)` or `fmt::Trait::fmt(&value, self.out)`, \
instead of `write!(self.out, \"{...}\", value)`"
)
};
}
// Maximum recursion depth when parsing symbols before we just bail out saying
// "this symbol is invalid"
const MAX_DEPTH: u32 = 500;
/// Representation of a demangled symbol name.
pub struct Demangle<'a> {
inner: &'a str,
}
#[derive(PartialEq, Eq, Debug)]
pub enum ParseError {
/// Symbol doesn't match the expected `v0` grammar.
Invalid,
/// Parsing the symbol crossed the recursion limit (see `MAX_DEPTH`).
RecursedTooDeep,
}
/// De-mangles a Rust symbol into a more readable version
///
/// This function will take a **mangled** symbol and return a value. When printed,
/// the de-mangled version will be written. If the symbol does not look like
/// a mangled symbol, the original value will be written instead.
pub fn demangle(s: &str) -> Result<(Demangle, &str), ParseError> {
// First validate the symbol. If it doesn't look like anything we're
// expecting, we just print it literally. Note that we must handle non-Rust
// symbols because we could have any function in the backtrace.
let inner;
if s.len() > 2 && s.starts_with("_R") {
inner = &s[2..];
} else if s.len() > 1 && s.starts_with('R') {
// On Windows, dbghelp strips leading underscores, so we accept "R..."
// form too.
inner = &s[1..];
} else if s.len() > 3 && s.starts_with("__R") {
// On OSX, symbols are prefixed with an extra _
inner = &s[3..];
} else {
return Err(ParseError::Invalid);
}
// Paths always start with uppercase characters.
match inner.as_bytes()[0] {
b'A'..=b'Z' => {}
_ => return Err(ParseError::Invalid),
}
// only work with ascii text
if inner.bytes().any(|c| c & 0x80 != 0) {
return Err(ParseError::Invalid);
}
// Verify that the symbol is indeed a valid path.
let try_parse_path = |parser| {
let mut dummy_printer = Printer {
parser: Ok(parser),
out: None,
bound_lifetime_depth: 0,
};
dummy_printer
.print_path(false)
.expect("`fmt::Error`s should be impossible without a `fmt::Formatter`");
dummy_printer.parser
};
let mut parser = Parser {
sym: inner,
next: 0,
depth: 0,
};
parser = try_parse_path(parser)?;
// Instantiating crate (paths always start with uppercase characters).
if let Some(&(b'A'..=b'Z')) = parser.sym.as_bytes().get(parser.next) {
parser = try_parse_path(parser)?;
}
Ok((Demangle { inner }, &parser.sym[parser.next..]))
}
impl<'s> fmt::Display for Demangle<'s> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let mut printer = Printer {
parser: Ok(Parser {
sym: self.inner,
next: 0,
depth: 0,
}),
out: Some(f),
bound_lifetime_depth: 0,
};
printer.print_path(true)
}
}
struct Ident<'s> {
/// ASCII part of the identifier.
ascii: &'s str,
/// Punycode insertion codes for Unicode codepoints, if any.
punycode: &'s str,
}
const SMALL_PUNYCODE_LEN: usize = 128;
impl<'s> Ident<'s> {
/// Attempt to decode punycode on the stack (allocation-free),
/// and pass the char slice to the closure, if successful.
/// This supports up to `SMALL_PUNYCODE_LEN` characters.
fn try_small_punycode_decode<F: FnOnce(&[char]) -> R, R>(&self, f: F) -> Option<R> {
let mut out = ['\0'; SMALL_PUNYCODE_LEN];
let mut out_len = 0;
let r = self.punycode_decode(|i, c| {
// Check there's space left for another character.
out.get(out_len).ok_or(())?;
// Move the characters after the insert position.
let mut j = out_len;
out_len += 1;
while j > i {
out[j] = out[j - 1];
j -= 1;
}
// Insert the new character.
out[i] = c;
Ok(())
});
if r.is_ok() {
Some(f(&out[..out_len]))
} else {
None
}
}
/// Decode punycode as insertion positions and characters
/// and pass them to the closure, which can return `Err(())`
/// to stop the decoding process.
fn punycode_decode<F: FnMut(usize, char) -> Result<(), ()>>(
&self,
mut insert: F,
) -> Result<(), ()> {
let mut punycode_bytes = self.punycode.bytes().peekable();
if punycode_bytes.peek().is_none() {
return Err(());
}
let mut len = 0;
// Populate initial output from ASCII fragment.
for c in self.ascii.chars() {
insert(len, c)?;
len += 1;
}
// Punycode parameters and initial state.
let base = 36;
let t_min = 1;
let t_max = 26;
let skew = 38;
let mut damp = 700;
let mut bias = 72;
let mut i: usize = 0;
let mut n: usize = 0x80;
loop {
// Read one delta value.
let mut delta: usize = 0;
let mut w = 1;
let mut k: usize = 0;
loop {
use core::cmp::{max, min};
k += base;
let t = min(max(k.saturating_sub(bias), t_min), t_max);
let d = match punycode_bytes.next() {
Some(d @ b'a'..=b'z') => d - b'a',
Some(d @ b'0'..=b'9') => 26 + (d - b'0'),
_ => return Err(()),
};
let d = d as usize;
delta = delta.checked_add(d.checked_mul(w).ok_or(())?).ok_or(())?;
if d < t {
break;
}
w = w.checked_mul(base - t).ok_or(())?;
}
// Compute the new insert position and character.
len += 1;
i = i.checked_add(delta).ok_or(())?;
n = n.checked_add(i / len).ok_or(())?;
i %= len;
let n_u32 = n as u32;
let c = if n_u32 as usize == n {
char::from_u32(n_u32).ok_or(())?
} else {
return Err(());
};
// Insert the new character and increment the insert position.
insert(i, c)?;
i += 1;
// If there are no more deltas, decoding is complete.
if punycode_bytes.peek().is_none() {
return Ok(());
}
// Perform bias adaptation.
delta /= damp;
damp = 2;
delta += delta / len;
let mut k = 0;
while delta > ((base - t_min) * t_max) / 2 {
delta /= base - t_min;
k += base;
}
bias = k + ((base - t_min + 1) * delta) / (delta + skew);
}
}
}
impl<'s> fmt::Display for Ident<'s> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.try_small_punycode_decode(|chars| {
for &c in chars {
c.fmt(f)?;
}
Ok(())
})
.unwrap_or_else(|| {
if !self.punycode.is_empty() {
f.write_str("punycode{")?;
// Reconstruct a standard Punycode encoding,
// by using `-` as the separator.
if !self.ascii.is_empty() {
f.write_str(self.ascii)?;
f.write_str("-")?;
}
f.write_str(self.punycode)?;
f.write_str("}")
} else {
f.write_str(self.ascii)
}
})
}
}
/// Sequence of lowercase hexadecimal nibbles (`0-9a-f`), used by leaf consts.
struct HexNibbles<'s> {
nibbles: &'s str,
}
impl<'s> HexNibbles<'s> {
/// Decode an integer value (with the "most significant nibble" first),
/// returning `None` if it can't fit in an `u64`.
// FIXME(eddyb) should this "just" use `u128` instead?
fn try_parse_uint(&self) -> Option<u64> {
let nibbles = self.nibbles.trim_start_matches("0");
if nibbles.len() > 16 {
return None;
}
let mut v = 0;
for nibble in nibbles.chars() {
v = (v << 4) | (nibble.to_digit(16).unwrap() as u64);
}
Some(v)
}
/// Decode a UTF-8 byte sequence (with each byte using a pair of nibbles)
/// into individual `char`s, returning `None` for invalid UTF-8.
fn try_parse_str_chars(&self) -> Option<impl Iterator<Item = char> + 's> {
if self.nibbles.len() % 2 != 0 {
return None;
}
// FIXME(eddyb) use `array_chunks` instead, when that becomes stable.
let mut bytes = self
.nibbles
.as_bytes()
.chunks_exact(2)
.map(|slice| match slice {
[a, b] => [a, b],
_ => unreachable!(),
})
.map(|[&hi, &lo]| {
let half = |nibble: u8| (nibble as char).to_digit(16).unwrap() as u8;
(half(hi) << 4) | half(lo)
});
let chars = iter::from_fn(move || {
// As long as there are any bytes left, there's at least one more
// UTF-8-encoded `char` to decode (or the possibility of error).
bytes.next().map(|first_byte| -> Result<char, ()> {
// FIXME(eddyb) this `enum` and `fn` should be somewhere in `core`.
enum Utf8FirstByteError {
ContinuationByte,
TooLong,
}
fn utf8_len_from_first_byte(byte: u8) -> Result<usize, Utf8FirstByteError> {
match byte {
0x00..=0x7f => Ok(1),
0x80..=0xbf => Err(Utf8FirstByteError::ContinuationByte),
0xc0..=0xdf => Ok(2),
0xe0..=0xef => Ok(3),
0xf0..=0xf7 => Ok(4),
0xf8..=0xff => Err(Utf8FirstByteError::TooLong),
}
}
// Collect the appropriate amount of bytes (up to 4), according
// to the UTF-8 length implied by the first byte.
let utf8_len = utf8_len_from_first_byte(first_byte).map_err(|_| ())?;
let utf8 = &mut [first_byte, 0, 0, 0][..utf8_len];
for i in 1..utf8_len {
utf8[i] = bytes.next().ok_or(())?;
}
// Fully validate the UTF-8 sequence.
let s = str::from_utf8(utf8).map_err(|_| ())?;
// Since we included exactly one UTF-8 sequence, and validation
// succeeded, `str::chars` should return exactly one `char`.
let mut chars = s.chars();
match (chars.next(), chars.next()) {
(Some(c), None) => Ok(c),
_ => unreachable!(
"str::from_utf8({:?}) = {:?} was expected to have 1 char, \
but {} chars were found",
utf8,
s,
s.chars().count()
),
}
})
});
// HACK(eddyb) doing a separate validation iteration like this might be
// wasteful, but it's easier to avoid starting to print a string literal
// in the first place, than to abort it mid-string.
if chars.clone().any(|r| r.is_err()) {
None
} else {
Some(chars.map(Result::unwrap))
}
}
}
fn basic_type(tag: u8) -> Option<&'static str> {
Some(match tag {
b'b' => "bool",
b'c' => "char",
b'e' => "str",
b'u' => "()",
b'a' => "i8",
b's' => "i16",
b'l' => "i32",
b'x' => "i64",
b'n' => "i128",
b'i' => "isize",
b'h' => "u8",
b't' => "u16",
b'm' => "u32",
b'y' => "u64",
b'o' => "u128",
b'j' => "usize",
b'f' => "f32",
b'd' => "f64",
b'z' => "!",
b'p' => "_",
b'v' => "...",
_ => return None,
})
}
struct Parser<'s> {
sym: &'s str,
next: usize,
depth: u32,
}
impl<'s> Parser<'s> {
fn push_depth(&mut self) -> Result<(), ParseError> {
self.depth += 1;
if self.depth > MAX_DEPTH {
Err(ParseError::RecursedTooDeep)
} else {
Ok(())
}
}
fn pop_depth(&mut self) {
self.depth -= 1;
}
fn peek(&self) -> Option<u8> {
self.sym.as_bytes().get(self.next).cloned()
}
fn eat(&mut self, b: u8) -> bool {
if self.peek() == Some(b) {
self.next += 1;
true
} else {
false
}
}
fn next(&mut self) -> Result<u8, ParseError> {
let b = self.peek().ok_or(ParseError::Invalid)?;
self.next += 1;
Ok(b)
}
fn hex_nibbles(&mut self) -> Result<HexNibbles<'s>, ParseError> {
let start = self.next;
loop {
match self.next()? {
b'0'..=b'9' | b'a'..=b'f' => {}
b'_' => break,
_ => return Err(ParseError::Invalid),
}
}
Ok(HexNibbles {
nibbles: &self.sym[start..self.next - 1],
})
}
fn digit_10(&mut self) -> Result<u8, ParseError> {
let d = match self.peek() {
Some(d @ b'0'..=b'9') => d - b'0',
_ => return Err(ParseError::Invalid),
};
self.next += 1;
Ok(d)
}
fn digit_62(&mut self) -> Result<u8, ParseError> {
let d = match self.peek() {
Some(d @ b'0'..=b'9') => d - b'0',
Some(d @ b'a'..=b'z') => 10 + (d - b'a'),
Some(d @ b'A'..=b'Z') => 10 + 26 + (d - b'A'),
_ => return Err(ParseError::Invalid),
};
self.next += 1;
Ok(d)
}
fn integer_62(&mut self) -> Result<u64, ParseError> {
if self.eat(b'_') {
return Ok(0);
}
let mut x: u64 = 0;
while !self.eat(b'_') {
let d = self.digit_62()? as u64;
x = x.checked_mul(62).ok_or(ParseError::Invalid)?;
x = x.checked_add(d).ok_or(ParseError::Invalid)?;
}
x.checked_add(1).ok_or(ParseError::Invalid)
}
fn opt_integer_62(&mut self, tag: u8) -> Result<u64, ParseError> {
if !self.eat(tag) {
return Ok(0);
}
self.integer_62()?.checked_add(1).ok_or(ParseError::Invalid)
}
fn disambiguator(&mut self) -> Result<u64, ParseError> {
self.opt_integer_62(b's')
}
fn namespace(&mut self) -> Result<Option<char>, ParseError> {
match self.next()? {
// Special namespaces, like closures and shims.
ns @ b'A'..=b'Z' => Ok(Some(ns as char)),
// Implementation-specific/unspecified namespaces.
b'a'..=b'z' => Ok(None),
_ => Err(ParseError::Invalid),
}
}
fn backref(&mut self) -> Result<Parser<'s>, ParseError> {
let s_start = self.next - 1;
let i = self.integer_62()?;
if i >= s_start as u64 {
return Err(ParseError::Invalid);
}
let mut new_parser = Parser {
sym: self.sym,
next: i as usize,
depth: self.depth,
};
new_parser.push_depth()?;
Ok(new_parser)
}
fn ident(&mut self) -> Result<Ident<'s>, ParseError> {
let is_punycode = self.eat(b'u');
let mut len = self.digit_10()? as usize;
if len != 0 {
while let Ok(d) = self.digit_10() {
len = len.checked_mul(10).ok_or(ParseError::Invalid)?;
len = len.checked_add(d as usize).ok_or(ParseError::Invalid)?;
}
}
// Skip past the optional `_` separator.
self.eat(b'_');
let start = self.next;
self.next = self.next.checked_add(len).ok_or(ParseError::Invalid)?;
if self.next > self.sym.len() {
return Err(ParseError::Invalid);
}
let ident = &self.sym[start..self.next];
if is_punycode {
let ident = match ident.bytes().rposition(|b| b == b'_') {
Some(i) => Ident {
ascii: &ident[..i],
punycode: &ident[i + 1..],
},
None => Ident {
ascii: "",
punycode: ident,
},
};
if ident.punycode.is_empty() {
return Err(ParseError::Invalid);
}
Ok(ident)
} else {
Ok(Ident {
ascii: ident,
punycode: "",
})
}
}
}
struct Printer<'a, 'b: 'a, 's> {
/// The input parser to demangle from, or `Err` if any (parse) error was
/// encountered (in order to disallow further likely-incorrect demangling).
///
/// See also the documentation on the `invalid!` and `parse!` macros below.
parser: Result<Parser<'s>, ParseError>,
/// The output formatter to demangle to, or `None` while skipping printing.
out: Option<&'a mut fmt::Formatter<'b>>,
/// Cumulative number of lifetimes bound by `for<...>` binders ('G'),
/// anywhere "around" the current entity (e.g. type) being demangled.
/// This value is not tracked while skipping printing, as it'd be unused.
///
/// See also the documentation on the `Printer::in_binder` method.
bound_lifetime_depth: u32,
}
impl ParseError {
/// Snippet to print when the error is initially encountered.
fn message(&self) -> &str {
match self {
ParseError::Invalid => "{invalid syntax}",
ParseError::RecursedTooDeep => "{recursion limit reached}",
}
}
}
/// Mark the parser as errored (with `ParseError::Invalid`), print the
/// appropriate message (see `ParseError::message`) and return early.
macro_rules! invalid {
($printer:ident) => {{
let err = ParseError::Invalid;
$printer.print(err.message())?;
$printer.parser = Err(err);
return Ok(());
}};
}
/// Call a parser method (if the parser hasn't errored yet),
/// and mark the parser as errored if it returns `Err`.
///
/// If the parser errored, before or now, this returns early,
/// from the current function, after printing either:
/// * for a new error, the appropriate message (see `ParseError::message`)
/// * for an earlier error, only `?` - this allows callers to keep printing
/// the approximate syntax of the path/type/const, despite having errors,
/// e.g. `Vec<[(A, ?); ?]>` instead of `Vec<[(A, ?`
macro_rules! parse {
($printer:ident, $method:ident $(($($arg:expr),*))*) => {
match $printer.parser {
Ok(ref mut parser) => match parser.$method($($($arg),*)*) {
Ok(x) => x,
Err(err) => {
$printer.print(err.message())?;
$printer.parser = Err(err);
return Ok(());
}
}
Err(_) => return $printer.print("?"),
}
};
}
impl<'a, 'b, 's> Printer<'a, 'b, 's> {
/// Eat the given character from the parser,
/// returning `false` if the parser errored.
fn eat(&mut self, b: u8) -> bool {
self.parser.as_mut().map(|p| p.eat(b)) == Ok(true)
}
/// Skip printing (i.e. `self.out` will be `None`) for the duration of the
/// given closure. This should not change parsing behavior, only disable the
/// output, but there may be optimizations (such as not traversing backrefs).
fn skipping_printing<F>(&mut self, f: F)
where
F: FnOnce(&mut Self) -> fmt::Result,
{
let orig_out = self.out.take();
f(self).expect("`fmt::Error`s should be impossible without a `fmt::Formatter`");
self.out = orig_out;
}
/// Print the target of a backref, using the given closure.
/// When printing is being skipped, the backref will only be parsed,
/// ignoring the backref's target completely.
fn print_backref<F>(&mut self, f: F) -> fmt::Result
where
F: FnOnce(&mut Self) -> fmt::Result,
{
let backref_parser = parse!(self, backref);
if self.out.is_none() {
return Ok(());
}
let orig_parser = mem::replace(&mut self.parser, Ok(backref_parser));
let r = f(self);
self.parser = orig_parser;
r
}
fn pop_depth(&mut self) {
if let Ok(ref mut parser) = self.parser {
parser.pop_depth();
}
}
/// Output the given value to `self.out` (using `fmt::Display` formatting),
/// if printing isn't being skipped.
fn print(&mut self, x: impl fmt::Display) -> fmt::Result {
if let Some(out) = &mut self.out {
fmt::Display::fmt(&x, out)?;
}
Ok(())
}
/// Output the given `char`s (escaped using `char::escape_debug`), with the
/// whole sequence wrapped in quotes, for either a `char` or `&str` literal,
/// if printing isn't being skipped.
fn print_quoted_escaped_chars(
&mut self,
quote: char,
chars: impl Iterator<Item = char>,
) -> fmt::Result {
if let Some(out) = &mut self.out {
use core::fmt::Write;
out.write_char(quote)?;
for c in chars {
// Special-case not escaping a single/double quote, when
// inside the opposite kind of quote.
if matches!((quote, c), ('\'', '"') | ('"', '\'')) {
out.write_char(c)?;
continue;
}
for escaped in c.escape_debug() {
out.write_char(escaped)?;
}
}
out.write_char(quote)?;
}
Ok(())
}
/// Print the lifetime according to the previously decoded index.
/// An index of `0` always refers to `'_`, but starting with `1`,
/// indices refer to late-bound lifetimes introduced by a binder.
fn print_lifetime_from_index(&mut self, lt: u64) -> fmt::Result {
// Bound lifetimes aren't tracked when skipping printing.
if self.out.is_none() {
return Ok(());
}
self.print("'")?;
if lt == 0 {
return self.print("_");
}
match (self.bound_lifetime_depth as u64).checked_sub(lt) {
Some(depth) => {
// Try to print lifetimes alphabetically first.
if depth < 26 {
let c = (b'a' + depth as u8) as char;
self.print(c)
} else {
// Use `'_123` after running out of letters.
self.print("_")?;
self.print(depth)
}
}
None => invalid!(self),
}
}
/// Optionally enter a binder ('G') for late-bound lifetimes,
/// printing e.g. `for<'a, 'b> ` before calling the closure,
/// and make those lifetimes visible to it (via depth level).
fn in_binder<F>(&mut self, f: F) -> fmt::Result
where
F: FnOnce(&mut Self) -> fmt::Result,
{
let bound_lifetimes = parse!(self, opt_integer_62(b'G'));
// Don't track bound lifetimes when skipping printing.
if self.out.is_none() {
return f(self);
}
if bound_lifetimes > 0 {
self.print("for<")?;
for i in 0..bound_lifetimes {
if i > 0 {
self.print(", ")?;
}
self.bound_lifetime_depth += 1;
self.print_lifetime_from_index(1)?;
}
self.print("> ")?;
}
let r = f(self);
// Restore `bound_lifetime_depth` to the previous value.
self.bound_lifetime_depth -= bound_lifetimes as u32;
r
}
/// Print list elements using the given closure and separator,
/// until the end of the list ('E') is found, or the parser errors.
/// Returns the number of elements printed.
fn print_sep_list<F>(&mut self, f: F, sep: &str) -> Result<usize, fmt::Error>
where
F: Fn(&mut Self) -> fmt::Result,
{
let mut i = 0;
while self.parser.is_ok() && !self.eat(b'E') {
if i > 0 {
self.print(sep)?;
}
f(self)?;
i += 1;
}
Ok(i)
}
fn print_path(&mut self, in_value: bool) -> fmt::Result {
parse!(self, push_depth);
let tag = parse!(self, next);
match tag {
b'C' => {
let dis = parse!(self, disambiguator);
let name = parse!(self, ident);
self.print(name)?;
if let Some(out) = &mut self.out {
if !out.alternate() {
out.write_str("[")?;
fmt::LowerHex::fmt(&dis, out)?;
out.write_str("]")?;
}
}
}
b'N' => {
let ns = parse!(self, namespace);
self.print_path(in_value)?;
// HACK(eddyb) if the parser is already marked as having errored,
// `parse!` below will print a `?` without its preceding `::`
// (because printing the `::` is skipped in certain conditions,
// i.e. a lowercase namespace with an empty identifier),
// so in order to get `::?`, the `::` has to be printed here.
if self.parser.is_err() {
self.print("::")?;
}
let dis = parse!(self, disambiguator);
let name = parse!(self, ident);
match ns {
// Special namespaces, like closures and shims.
Some(ns) => {
self.print("::{")?;
match ns {
'C' => self.print("closure")?,
'S' => self.print("shim")?,
_ => self.print(ns)?,
}
if !name.ascii.is_empty() || !name.punycode.is_empty() {
self.print(":")?;
self.print(name)?;
}
self.print("#")?;
self.print(dis)?;
self.print("}")?;
}
// Implementation-specific/unspecified namespaces.
None => {
if !name.ascii.is_empty() || !name.punycode.is_empty() {
self.print("::")?;
self.print(name)?;
}
}
}
}
b'M' | b'X' | b'Y' => {
if tag != b'Y' {
// Ignore the `impl`'s own path.
parse!(self, disambiguator);
self.skipping_printing(|this| this.print_path(false));
}
self.print("<")?;
self.print_type()?;
if tag != b'M' {
self.print(" as ")?;
self.print_path(false)?;
}
self.print(">")?;
}
b'I' => {
self.print_path(in_value)?;
if in_value {
self.print("::")?;
}
self.print("<")?;
self.print_sep_list(Self::print_generic_arg, ", ")?;
self.print(">")?;
}
b'B' => {
self.print_backref(|this| this.print_path(in_value))?;
}
_ => invalid!(self),
}
self.pop_depth();
Ok(())
}
fn print_generic_arg(&mut self) -> fmt::Result {
if self.eat(b'L') {
let lt = parse!(self, integer_62);
self.print_lifetime_from_index(lt)
} else if self.eat(b'K') {
self.print_const(false)
} else {
self.print_type()
}
}
fn print_type(&mut self) -> fmt::Result {
let tag = parse!(self, next);
if let Some(ty) = basic_type(tag) {
return self.print(ty);
}
parse!(self, push_depth);
match tag {
b'R' | b'Q' => {
self.print("&")?;
if self.eat(b'L') {
let lt = parse!(self, integer_62);
if lt != 0 {
self.print_lifetime_from_index(lt)?;
self.print(" ")?;
}
}
if tag != b'R' {
self.print("mut ")?;
}
self.print_type()?;
}
b'P' | b'O' => {
self.print("*")?;
if tag != b'P' {
self.print("mut ")?;
} else {
self.print("const ")?;
}
self.print_type()?;
}
b'A' | b'S' => {
self.print("[")?;
self.print_type()?;
if tag == b'A' {
self.print("; ")?;
self.print_const(true)?;
}
self.print("]")?;
}
b'T' => {
self.print("(")?;
let count = self.print_sep_list(Self::print_type, ", ")?;
if count == 1 {
self.print(",")?;
}
self.print(")")?;
}
b'F' => self.in_binder(|this| {
let is_unsafe = this.eat(b'U');
let abi = if this.eat(b'K') {
if this.eat(b'C') {
Some("C")
} else {
let abi = parse!(this, ident);
if abi.ascii.is_empty() || !abi.punycode.is_empty() {
invalid!(this);
}
Some(abi.ascii)
}
} else {
None
};
if is_unsafe {
this.print("unsafe ")?;
}
if let Some(abi) = abi {
this.print("extern \"")?;
// If the ABI had any `-`, they were replaced with `_`,
// so the parts between `_` have to be re-joined with `-`.
let mut parts = abi.split('_');
this.print(parts.next().unwrap())?;
for part in parts {
this.print("-")?;
this.print(part)?;
}
this.print("\" ")?;
}
this.print("fn(")?;
this.print_sep_list(Self::print_type, ", ")?;
this.print(")")?;
if this.eat(b'u') {
// Skip printing the return type if it's 'u', i.e. `()`.
} else {
this.print(" -> ")?;
this.print_type()?;
}
Ok(())
})?,
b'D' => {
self.print("dyn ")?;
self.in_binder(|this| {
this.print_sep_list(Self::print_dyn_trait, " + ")?;
Ok(())
})?;
if !self.eat(b'L') {
invalid!(self);
}
let lt = parse!(self, integer_62);
if lt != 0 {
self.print(" + ")?;
self.print_lifetime_from_index(lt)?;
}
}
b'B' => {
self.print_backref(Self::print_type)?;
}
_ => {
// Go back to the tag, so `print_path` also sees it.
let _ = self.parser.as_mut().map(|p| p.next -= 1);
self.print_path(false)?;
}
}
self.pop_depth();
Ok(())
}
/// A trait in a trait object may have some "existential projections"
/// (i.e. associated type bindings) after it, which should be printed
/// in the `<...>` of the trait, e.g. `dyn Trait<T, U, Assoc=X>`.
/// To this end, this method will keep the `<...>` of an 'I' path
/// open, by omitting the `>`, and return `Ok(true)` in that case.
fn print_path_maybe_open_generics(&mut self) -> Result<bool, fmt::Error> {
if self.eat(b'B') {
// NOTE(eddyb) the closure may not run if printing is being skipped,
// but in that case the returned boolean doesn't matter.
let mut open = false;
self.print_backref(|this| {
open = this.print_path_maybe_open_generics()?;
Ok(())
})?;
Ok(open)
} else if self.eat(b'I') {
self.print_path(false)?;
self.print("<")?;
self.print_sep_list(Self::print_generic_arg, ", ")?;
Ok(true)
} else {
self.print_path(false)?;
Ok(false)
}
}
fn print_dyn_trait(&mut self) -> fmt::Result {
let mut open = self.print_path_maybe_open_generics()?;
while self.eat(b'p') {
if !open {
self.print("<")?;
open = true;
} else {
self.print(", ")?;
}
let name = parse!(self, ident);
self.print(name)?;
self.print(" = ")?;
self.print_type()?;
}
if open {
self.print(">")?;
}
Ok(())
}
fn print_const(&mut self, in_value: bool) -> fmt::Result {
let tag = parse!(self, next);
parse!(self, push_depth);
// Only literals (and the names of `const` generic parameters, but they
// don't get mangled at all), can appear in generic argument position
// without any disambiguation, all other expressions require braces.
// To avoid duplicating the mapping between `tag` and what syntax gets
// used (especially any special-casing), every case that needs braces
// has to call `open_brace(self)?` (and the closing brace is automatic).
let mut opened_brace = false;
let mut open_brace_if_outside_expr = |this: &mut Self| {
// If this expression is nested in another, braces aren't required.
if in_value {
return Ok(());
}
opened_brace = true;
this.print("{")
};
match tag {
b'p' => self.print("_")?,
// Primitive leaves with hex-encoded values (see `basic_type`).
b'h' | b't' | b'm' | b'y' | b'o' | b'j' => self.print_const_uint(tag)?,
b'a' | b's' | b'l' | b'x' | b'n' | b'i' => {
if self.eat(b'n') {
self.print("-")?;
}
self.print_const_uint(tag)?;
}
b'b' => match parse!(self, hex_nibbles).try_parse_uint() {
Some(0) => self.print("false")?,
Some(1) => self.print("true")?,
_ => invalid!(self),
},
b'c' => {
let valid_char = parse!(self, hex_nibbles)
.try_parse_uint()
.and_then(|v| u32::try_from(v).ok())
.and_then(char::from_u32);
match valid_char {
Some(c) => self.print_quoted_escaped_chars('\'', iter::once(c))?,
None => invalid!(self),
}
}
b'e' => {
// NOTE(eddyb) a string literal `"..."` has type `&str`, so
// to get back the type `str`, `*"..."` syntax is needed
// (even if that may not be valid in Rust itself).
open_brace_if_outside_expr(self)?;
self.print("*")?;
self.print_const_str_literal()?;
}
b'R' | b'Q' => {
// NOTE(eddyb) this prints `"..."` instead of `&*"..."`, which
// is what `Re..._` would imply (see comment for `str` above).
if tag == b'R' && self.eat(b'e') {
self.print_const_str_literal()?;
} else {
open_brace_if_outside_expr(self)?;
self.print("&")?;
if tag != b'R' {
self.print("mut ")?;
}
self.print_const(true)?;
}
}
b'A' => {
open_brace_if_outside_expr(self)?;
self.print("[")?;
self.print_sep_list(|this| this.print_const(true), ", ")?;
self.print("]")?;
}
b'T' => {
open_brace_if_outside_expr(self)?;
self.print("(")?;
let count = self.print_sep_list(|this| this.print_const(true), ", ")?;
if count == 1 {
self.print(",")?;
}
self.print(")")?;
}
b'V' => {
open_brace_if_outside_expr(self)?;
self.print_path(true)?;
match parse!(self, next) {
b'U' => {}
b'T' => {
self.print("(")?;
self.print_sep_list(|this| this.print_const(true), ", ")?;
self.print(")")?;
}
b'S' => {
self.print(" { ")?;
self.print_sep_list(
|this| {
parse!(this, disambiguator);
let name = parse!(this, ident);
this.print(name)?;
this.print(": ")?;
this.print_const(true)
},
", ",
)?;
self.print(" }")?;
}
_ => invalid!(self),
}
}
b'B' => {
self.print_backref(|this| this.print_const(in_value))?;
}
_ => invalid!(self),
}
if opened_brace {
self.print("}")?;
}
self.pop_depth();
Ok(())
}
fn print_const_uint(&mut self, ty_tag: u8) -> fmt::Result {
let hex = parse!(self, hex_nibbles);
match hex.try_parse_uint() {
Some(v) => self.print(v)?,
// Print anything that doesn't fit in `u64` verbatim.
None => {
self.print("0x")?;
self.print(hex.nibbles)?;
}
}
if let Some(out) = &mut self.out {
if !out.alternate() {
let ty = basic_type(ty_tag).unwrap();
self.print(ty)?;
}
}
Ok(())
}
fn print_const_str_literal(&mut self) -> fmt::Result {
match parse!(self, hex_nibbles).try_parse_str_chars() {
Some(chars) => self.print_quoted_escaped_chars('"', chars),
None => invalid!(self),
}
}
}
#[cfg(test)]
mod tests {
use std::prelude::v1::*;
macro_rules! t {
($a:expr, $b:expr) => {{
assert_eq!(format!("{}", ::demangle($a)), $b);
}};
}
macro_rules! t_nohash {
($a:expr, $b:expr) => {{
assert_eq!(format!("{:#}", ::demangle($a)), $b);
}};
}
macro_rules! t_nohash_type {
($a:expr, $b:expr) => {
t_nohash!(concat!("_RMC0", $a), concat!("<", $b, ">"))
};
}
macro_rules! t_const {
($mangled:expr, $value:expr) => {
t_nohash!(
concat!("_RIC0K", $mangled, "E"),
concat!("::<", $value, ">")
)
};
}
macro_rules! t_const_suffixed {
($mangled:expr, $value:expr, $value_ty_suffix:expr) => {{
t_const!($mangled, $value);
t!(
concat!("_RIC0K", $mangled, "E"),
concat!("[0]::<", $value, $value_ty_suffix, ">")
);
}};
}
#[test]
fn demangle_crate_with_leading_digit() {
t_nohash!("_RNvC6_123foo3bar", "123foo::bar");
}
#[test]
fn demangle_utf8_idents() {
t_nohash!(
"_RNqCs4fqI2P2rA04_11utf8_identsu30____7hkackfecea1cbdathfdh9hlq6y",
"utf8_idents::საჭმელად_გემრიელი_სადილი"
);
}
#[test]
fn demangle_closure() {
t_nohash!(
"_RNCNCNgCs6DXkGYLi8lr_2cc5spawn00B5_",
"cc::spawn::{closure#0}::{closure#0}"
);
t_nohash!(
"_RNCINkXs25_NgCsbmNqQUJIY6D_4core5sliceINyB9_4IterhENuNgNoBb_4iter8iterator8Iterator9rpositionNCNgNpB9_6memchr7memrchrs_0E0Bb_",
"<core::slice::Iter<u8> as core::iter::iterator::Iterator>::rposition::<core::slice::memchr::memrchr::{closure#1}>::{closure#0}"
);
}
#[test]
fn demangle_dyn_trait() {
t_nohash!(
"_RINbNbCskIICzLVDPPb_5alloc5alloc8box_freeDINbNiB4_5boxed5FnBoxuEp6OutputuEL_ECs1iopQbuBiw2_3std",
"alloc::alloc::box_free::<dyn alloc::boxed::FnBox<(), Output = ()>>"
);
}
#[test]
fn demangle_const_generics_preview() {
// NOTE(eddyb) this was hand-written, before rustc had working
// const generics support (but the mangling format did include them).
t_nohash_type!(
"INtC8arrayvec8ArrayVechKj7b_E",
"arrayvec::ArrayVec<u8, 123>"
);
t_const_suffixed!("j7b_", "123", "usize");
}
#[test]
fn demangle_min_const_generics() {
t_const!("p", "_");
t_const_suffixed!("hb_", "11", "u8");
t_const_suffixed!("off00ff00ff00ff00ff_", "0xff00ff00ff00ff00ff", "u128");
t_const_suffixed!("s98_", "152", "i16");
t_const_suffixed!("anb_", "-11", "i8");
t_const!("b0_", "false");
t_const!("b1_", "true");
t_const!("c76_", "'v'");
t_const!("c22_", r#"'"'"#);
t_const!("ca_", "'\\n'");
t_const!("c2202_", "'∂'");
}
#[test]
fn demangle_const_str() {
t_const!("e616263_", "{*\"abc\"}");
t_const!("e27_", r#"{*"'"}"#);
t_const!("e090a_", "{*\"\\t\\n\"}");
t_const!("ee28882c3bc_", "{*\"∂ü\"}");
t_const!(
"ee183a1e18390e183ade1839be18394e1839ae18390e183935fe18392e18394e1839b\
e183a0e18398e18394e1839ae183985fe183a1e18390e18393e18398e1839ae18398_",
"{*\"საჭმელად_გემრიელი_სადილი\"}"
);
t_const!(
"ef09f908af09fa688f09fa686f09f90ae20c2a720f09f90b6f09f9192e298\
95f09f94a520c2a720f09fa7a1f09f929bf09f929af09f9299f09f929c_",
"{*\"🐊🦈🦆🐮 § 🐶👒☕🔥 § 🧡💛💚💙💜\"}"
);
}
// NOTE(eddyb) this uses the same strings as `demangle_const_str` and should
// be kept in sync with it - while a macro could be used to generate both
// `str` and `&str` tests, from a single list of strings, this seems clearer.
#[test]
fn demangle_const_ref_str() {
t_const!("Re616263_", "\"abc\"");
t_const!("Re27_", r#""'""#);
t_const!("Re090a_", "\"\\t\\n\"");
t_const!("Ree28882c3bc_", "\"∂ü\"");
t_const!(
"Ree183a1e18390e183ade1839be18394e1839ae18390e183935fe18392e18394e1839b\
e183a0e18398e18394e1839ae183985fe183a1e18390e18393e18398e1839ae18398_",
"\"საჭმელად_გემრიელი_სადილი\""
);
t_const!(
"Ref09f908af09fa688f09fa686f09f90ae20c2a720f09f90b6f09f9192e298\
95f09f94a520c2a720f09fa7a1f09f929bf09f929af09f9299f09f929c_",
"\"🐊🦈🦆🐮 § 🐶👒☕🔥 § 🧡💛💚💙💜\""
);
}
#[test]
fn demangle_const_ref() {
t_const!("Rp", "{&_}");
t_const!("Rh7b_", "{&123}");
t_const!("Rb0_", "{&false}");
t_const!("Rc58_", "{&'X'}");
t_const!("RRRh0_", "{&&&0}");
t_const!("RRRe_", "{&&\"\"}");
t_const!("QAE", "{&mut []}");
}
#[test]
fn demangle_const_array() {
t_const!("AE", "{[]}");
t_const!("Aj0_E", "{[0]}");
t_const!("Ah1_h2_h3_E", "{[1, 2, 3]}");
t_const!("ARe61_Re62_Re63_E", "{[\"a\", \"b\", \"c\"]}");
t_const!("AAh1_h2_EAh3_h4_EE", "{[[1, 2], [3, 4]]}");
}
#[test]
fn demangle_const_tuple() {
t_const!("TE", "{()}");
t_const!("Tj0_E", "{(0,)}");
t_const!("Th1_b0_E", "{(1, false)}");
t_const!(
"TRe616263_c78_RAh1_h2_h3_EE",
"{(\"abc\", 'x', &[1, 2, 3])}"
);
}
#[test]
fn demangle_const_adt() {
t_const!(
"VNvINtNtC4core6option6OptionjE4NoneU",
"{core::option::Option::<usize>::None}"
);
t_const!(
"VNvINtNtC4core6option6OptionjE4SomeTj0_E",
"{core::option::Option::<usize>::Some(0)}"
);
t_const!(
"VNtC3foo3BarS1sRe616263_2chc78_5sliceRAh1_h2_h3_EE",
"{foo::Bar { s: \"abc\", ch: 'x', slice: &[1, 2, 3] }}"
);
}
#[test]
fn demangle_exponential_explosion() {
// NOTE(eddyb) because of the prefix added by `t_nohash_type!` is
// 3 bytes long, `B2_` refers to the start of the type, not `B_`.
// 6 backrefs (`B8_E` through `B3_E`) result in 2^6 = 64 copies of `_`.
// Also, because the `p` (`_`) type is after all of the starts of the
// backrefs, it can be replaced with any other type, independently.
t_nohash_type!(
concat!("TTTTTT", "p", "B8_E", "B7_E", "B6_E", "B5_E", "B4_E", "B3_E"),
"((((((_, _), (_, _)), ((_, _), (_, _))), (((_, _), (_, _)), ((_, _), (_, _)))), \
((((_, _), (_, _)), ((_, _), (_, _))), (((_, _), (_, _)), ((_, _), (_, _))))), \
(((((_, _), (_, _)), ((_, _), (_, _))), (((_, _), (_, _)), ((_, _), (_, _)))), \
((((_, _), (_, _)), ((_, _), (_, _))), (((_, _), (_, _)), ((_, _), (_, _))))))"
);
}
#[test]
fn demangle_thinlto() {
t_nohash!("_RC3foo.llvm.9D1C9369", "foo");
t_nohash!("_RC3foo.llvm.9D1C9369@@16", "foo");
t_nohash!("_RNvC9backtrace3foo.llvm.A5310EB9", "backtrace::foo");
}
#[test]
fn demangle_extra_suffix() {
// From alexcrichton/rustc-demangle#27:
t_nohash!(
"_RNvNtNtNtNtCs92dm3009vxr_4rand4rngs7adapter9reseeding4fork23FORK_HANDLER_REGISTERED.0.0",
"rand::rngs::adapter::reseeding::fork::FORK_HANDLER_REGISTERED.0.0"
);
}
#[test]
fn demangling_limits() {
// Stress tests found via fuzzing.
for sym in include_str!("v0-large-test-symbols/early-recursion-limit")
.lines()
.filter(|line| !line.is_empty() && !line.starts_with('#'))
{
assert_eq!(
super::demangle(sym).map(|_| ()),
Err(super::ParseError::RecursedTooDeep)
);
}
assert_contains!(
::demangle(
"RIC20tRYIMYNRYFG05_EB5_B_B6_RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR\
RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRB_E",
)
.to_string(),
"{recursion limit reached}"
);
}
#[test]
fn recursion_limit_leaks() {
// NOTE(eddyb) this test checks that both paths and types support the
// recursion limit correctly, i.e. matching `push_depth` and `pop_depth`,
// and don't leak "recursion levels" and trip the limit.
// The test inputs are generated on the fly, using a repeated pattern,
// as hardcoding the actual strings would be too verbose.
// Also, `MAX_DEPTH` can be directly used, instead of assuming its value.
for &(sym_leaf, expected_leaf) in &[("p", "_"), ("Rp", "&_"), ("C1x", "x")] {
let mut sym = format!("_RIC0p");
let mut expected = format!("::<_");
for _ in 0..(super::MAX_DEPTH * 2) {
sym.push_str(sym_leaf);
expected.push_str(", ");
expected.push_str(expected_leaf);
}
sym.push('E');
expected.push('>');
t_nohash!(&sym, expected);
}
}
#[test]
fn recursion_limit_backref_free_bypass() {
// NOTE(eddyb) this test checks that long symbols cannot bypass the
// recursion limit by not using backrefs, and cause a stack overflow.
// This value was chosen to be high enough that stack overflows were
// observed even with `cargo test --release`.
let depth = 100_000;
// In order to hide the long mangling from the initial "shallow" parse,
// it's nested in an identifier (crate name), preceding its use.
let mut sym = format!("_RIC{}", depth);
let backref_start = sym.len() - 2;
for _ in 0..depth {
sym.push('R');
}
// Write a backref to just after the length of the identifier.
sym.push('B');
sym.push(char::from_digit((backref_start - 1) as u32, 36).unwrap());
sym.push('_');
// Close the `I` at the start.
sym.push('E');
assert_contains!(::demangle(&sym).to_string(), "{recursion limit reached}");
}
}