//! Demangle Rust compiler symbol names.
//!
//! This crate provides a `demangle` function which will return a `Demangle`
//! sentinel value that can be used to learn about the demangled version of a
//! symbol name. The demangled representation will be the same as the original
//! if it doesn't look like a mangled symbol name.
//!
//! `Demangle` can be formatted with the `Display` trait. The alternate
//! modifier (`#`) can be used to format the symbol name without the
//! trailing hash value.
//!
//! # Examples
//!
//! ```
//! use rustc_demangle::demangle;
//!
//! assert_eq!(demangle("_ZN4testE").to_string(), "test");
//! assert_eq!(demangle("_ZN3foo3barE").to_string(), "foo::bar");
//! assert_eq!(demangle("foo").to_string(), "foo");
//! // With hash
//! assert_eq!(format!("{}", demangle("_ZN3foo17h05af221e174051e9E")), "foo::h05af221e174051e9");
//! // Without hash
//! assert_eq!(format!("{:#}", demangle("_ZN3foo17h05af221e174051e9E")), "foo");
//! ```
#![no_std]
#![deny(missing_docs)]
#![cfg_attr(docsrs, feature(doc_cfg))]
#[cfg(any(test, feature = "std"))]
#[macro_use]
extern crate std;
// HACK(eddyb) helper macros for tests.
#[cfg(test)]
macro_rules! assert_contains {
($s:expr, $needle:expr) => {{
let (s, needle) = ($s, $needle);
assert!(
s.contains(needle),
"{:?} should've contained {:?}",
s,
needle
);
}};
}
#[cfg(test)]
macro_rules! assert_ends_with {
($s:expr, $suffix:expr) => {{
let (s, suffix) = ($s, $suffix);
assert!(
s.ends_with(suffix),
"{:?} should've ended in {:?}",
s,
suffix
);
}};
}
mod legacy;
mod v0;
use core::fmt::{self, Write as _};
/// Representation of a demangled symbol name.
pub struct Demangle<'a> {
style: Option<DemangleStyle<'a>>,
original: &'a str,
suffix: &'a str,
}
enum DemangleStyle<'a> {
Legacy(legacy::Demangle<'a>),
V0(v0::Demangle<'a>),
}
/// 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.
///
/// # Examples
///
/// ```
/// use rustc_demangle::demangle;
///
/// assert_eq!(demangle("_ZN4testE").to_string(), "test");
/// assert_eq!(demangle("_ZN3foo3barE").to_string(), "foo::bar");
/// assert_eq!(demangle("foo").to_string(), "foo");
/// ```
pub fn demangle(mut s: &str) -> Demangle {
// During ThinLTO LLVM may import and rename internal symbols, so strip out
// those endings first as they're one of the last manglings applied to symbol
// names.
let llvm = ".llvm.";
if let Some(i) = s.find(llvm) {
let candidate = &s[i + llvm.len()..];
let all_hex = candidate.chars().all(|c| match c {
'A'..='F' | '0'..='9' | '@' => true,
_ => false,
});
if all_hex {
s = &s[..i];
}
}
let mut suffix = "";
let mut style = match legacy::demangle(s) {
Ok((d, s)) => {
suffix = s;
Some(DemangleStyle::Legacy(d))
}
Err(()) => match v0::demangle(s) {
Ok((d, s)) => {
suffix = s;
Some(DemangleStyle::V0(d))
}
// FIXME(eddyb) would it make sense to treat an unknown-validity
// symbol (e.g. one that errored with `RecursedTooDeep`) as
// v0-mangled, and have the error show up in the demangling?
// (that error already gets past this initial check, and therefore
// will show up in the demangling, if hidden behind a backref)
Err(v0::ParseError::Invalid) | Err(v0::ParseError::RecursedTooDeep) => None,
},
};
// Output like LLVM IR adds extra period-delimited words. See if
// we are in that case and save the trailing words if so.
if !suffix.is_empty() {
if suffix.starts_with('.') && is_symbol_like(suffix) {
// Keep the suffix.
} else {
// Reset the suffix and invalidate the demangling.
suffix = "";
style = None;
}
}
Demangle {
style,
original: s,
suffix,
}
}
#[cfg(feature = "std")]
fn demangle_line(
line: &str,
output: &mut impl std::io::Write,
include_hash: bool,
) -> std::io::Result<()> {
let mut head = 0;
while head < line.len() {
// Move to the next potential match
let next_head = match (line[head..].find("_ZN"), line[head..].find("_R")) {
(Some(idx), None) | (None, Some(idx)) => head + idx,
(Some(idx1), Some(idx2)) => head + idx1.min(idx2),
(None, None) => {
// No more matches...
line.len()
}
};
output.write_all(line[head..next_head].as_bytes())?;
head = next_head;
// Find the non-matching character.
//
// If we do not find a character, then until the end of the line is the
// thing to demangle.
let match_end = line[head..]
.find(|ch: char| !(ch == '$' || ch == '.' || ch == '_' || ch.is_ascii_alphanumeric()))
.map(|idx| head + idx)
.unwrap_or(line.len());
let mangled = &line[head..match_end];
head = head + mangled.len();
if let Ok(demangled) = try_demangle(mangled) {
if include_hash {
write!(output, "{}", demangled)?;
} else {
write!(output, "{:#}", demangled)?;
}
} else {
output.write_all(mangled.as_bytes())?;
}
}
Ok(())
}
/// Process a stream of data from `input` into the provided `output`, demangling any symbols found
/// within.
///
/// Note that the underlying implementation will perform many relatively small writes to the
/// output. If the output is expensive to write to (e.g., requires syscalls), consider using
/// `std::io::BufWriter`.
#[cfg(feature = "std")]
#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
pub fn demangle_stream<R: std::io::BufRead, W: std::io::Write>(
input: &mut R,
output: &mut W,
include_hash: bool,
) -> std::io::Result<()> {
let mut buf = std::string::String::new();
// We read in lines to reduce the memory usage at any time.
//
// demangle_line is also more efficient with relatively small buffers as it will copy around
// trailing data during demangling. In the future we might directly stream to the output but at
// least right now that seems to be less efficient.
while input.read_line(&mut buf)? > 0 {
demangle_line(&buf, output, include_hash)?;
buf.clear();
}
Ok(())
}
/// Error returned from the `try_demangle` function below when demangling fails.
#[derive(Debug, Clone)]
pub struct TryDemangleError {
_priv: (),
}
/// The same as `demangle`, except return an `Err` if the string does not appear
/// to be a Rust symbol, rather than "demangling" the given string as a no-op.
///
/// ```
/// extern crate rustc_demangle;
///
/// let not_a_rust_symbol = "la la la";
///
/// // The `try_demangle` function will reject strings which are not Rust symbols.
/// assert!(rustc_demangle::try_demangle(not_a_rust_symbol).is_err());
///
/// // While `demangle` will just pass the non-symbol through as a no-op.
/// assert_eq!(rustc_demangle::demangle(not_a_rust_symbol).as_str(), not_a_rust_symbol);
/// ```
pub fn try_demangle(s: &str) -> Result<Demangle, TryDemangleError> {
let sym = demangle(s);
if sym.style.is_some() {
Ok(sym)
} else {
Err(TryDemangleError { _priv: () })
}
}
impl<'a> Demangle<'a> {
/// Returns the underlying string that's being demangled.
pub fn as_str(&self) -> &'a str {
self.original
}
}
fn is_symbol_like(s: &str) -> bool {
s.chars().all(|c| {
// Once `char::is_ascii_punctuation` and `char::is_ascii_alphanumeric`
// have been stable for long enough, use those instead for clarity
is_ascii_alphanumeric(c) || is_ascii_punctuation(c)
})
}
// Copied from the documentation of `char::is_ascii_alphanumeric`
fn is_ascii_alphanumeric(c: char) -> bool {
match c {
'\u{0041}'..='\u{005A}' | '\u{0061}'..='\u{007A}' | '\u{0030}'..='\u{0039}' => true,
_ => false,
}
}
// Copied from the documentation of `char::is_ascii_punctuation`
fn is_ascii_punctuation(c: char) -> bool {
match c {
'\u{0021}'..='\u{002F}'
| '\u{003A}'..='\u{0040}'
| '\u{005B}'..='\u{0060}'
| '\u{007B}'..='\u{007E}' => true,
_ => false,
}
}
impl<'a> fmt::Display for DemangleStyle<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
DemangleStyle::Legacy(ref d) => fmt::Display::fmt(d, f),
DemangleStyle::V0(ref d) => fmt::Display::fmt(d, f),
}
}
}
// Maximum size of the symbol that we'll print.
const MAX_SIZE: usize = 1_000_000;
#[derive(Copy, Clone, Debug)]
struct SizeLimitExhausted;
struct SizeLimitedFmtAdapter<F> {
remaining: Result<usize, SizeLimitExhausted>,
inner: F,
}
impl<F: fmt::Write> fmt::Write for SizeLimitedFmtAdapter<F> {
fn write_str(&mut self, s: &str) -> fmt::Result {
self.remaining = self
.remaining
.and_then(|r| r.checked_sub(s.len()).ok_or(SizeLimitExhausted));
match self.remaining {
Ok(_) => self.inner.write_str(s),
Err(SizeLimitExhausted) => Err(fmt::Error),
}
}
}
impl<'a> fmt::Display for Demangle<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self.style {
None => f.write_str(self.original)?,
Some(ref d) => {
let alternate = f.alternate();
let mut size_limited_fmt = SizeLimitedFmtAdapter {
remaining: Ok(MAX_SIZE),
inner: &mut *f,
};
let fmt_result = if alternate {
write!(size_limited_fmt, "{:#}", d)
} else {
write!(size_limited_fmt, "{}", d)
};
let size_limit_result = size_limited_fmt.remaining.map(|_| ());
// Translate a `fmt::Error` generated by `SizeLimitedFmtAdapter`
// into an error message, instead of propagating it upwards
// (which could cause panicking from inside e.g. `std::io::print`).
match (fmt_result, size_limit_result) {
(Err(_), Err(SizeLimitExhausted)) => f.write_str("{size limit reached}")?,
_ => {
fmt_result?;
size_limit_result
.expect("`fmt::Error` from `SizeLimitedFmtAdapter` was discarded");
}
}
}
}
f.write_str(self.suffix)
}
}
impl<'a> fmt::Debug for Demangle<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Display::fmt(self, f)
}
}
#[cfg(test)]
mod tests {
use std::prelude::v1::*;
macro_rules! t {
($a:expr, $b:expr) => {
assert!(ok($a, $b))
};
}
macro_rules! t_err {
($a:expr) => {
assert!(ok_err($a))
};
}
macro_rules! t_nohash {
($a:expr, $b:expr) => {{
assert_eq!(format!("{:#}", super::demangle($a)), $b);
}};
}
fn ok(sym: &str, expected: &str) -> bool {
match super::try_demangle(sym) {
Ok(s) => {
if s.to_string() == expected {
true
} else {
println!("\n{}\n!=\n{}\n", s, expected);
false
}
}
Err(_) => {
println!("error demangling");
false
}
}
}
fn ok_err(sym: &str) -> bool {
match super::try_demangle(sym) {
Ok(_) => {
println!("succeeded in demangling");
false
}
Err(_) => super::demangle(sym).to_string() == sym,
}
}
#[test]
fn demangle() {
t_err!("test");
t!("_ZN4testE", "test");
t_err!("_ZN4test");
t!("_ZN4test1a2bcE", "test::a::bc");
}
#[test]
fn demangle_dollars() {
t!("_ZN4$RP$E", ")");
t!("_ZN8$RF$testE", "&test");
t!("_ZN8$BP$test4foobE", "*test::foob");
t!("_ZN9$u20$test4foobE", " test::foob");
t!("_ZN35Bar$LT$$u5b$u32$u3b$$u20$4$u5d$$GT$E", "Bar<[u32; 4]>");
}
#[test]
fn demangle_many_dollars() {
t!("_ZN13test$u20$test4foobE", "test test::foob");
t!("_ZN12test$BP$test4foobE", "test*test::foob");
}
#[test]
fn demangle_osx() {
t!(
"__ZN5alloc9allocator6Layout9for_value17h02a996811f781011E",
"alloc::allocator::Layout::for_value::h02a996811f781011"
);
t!("__ZN38_$LT$core..option..Option$LT$T$GT$$GT$6unwrap18_MSG_FILE_LINE_COL17haf7cb8d5824ee659E", "<core::option::Option<T>>::unwrap::_MSG_FILE_LINE_COL::haf7cb8d5824ee659");
t!("__ZN4core5slice89_$LT$impl$u20$core..iter..traits..IntoIterator$u20$for$u20$$RF$$u27$a$u20$$u5b$T$u5d$$GT$9into_iter17h450e234d27262170E", "core::slice::<impl core::iter::traits::IntoIterator for &'a [T]>::into_iter::h450e234d27262170");
}
#[test]
fn demangle_windows() {
t!("ZN4testE", "test");
t!("ZN13test$u20$test4foobE", "test test::foob");
t!("ZN12test$RF$test4foobE", "test&test::foob");
}
#[test]
fn demangle_elements_beginning_with_underscore() {
t!("_ZN13_$LT$test$GT$E", "<test>");
t!("_ZN28_$u7b$$u7b$closure$u7d$$u7d$E", "{{closure}}");
t!("_ZN15__STATIC_FMTSTRE", "__STATIC_FMTSTR");
}
#[test]
fn demangle_trait_impls() {
t!(
"_ZN71_$LT$Test$u20$$u2b$$u20$$u27$static$u20$as$u20$foo..Bar$LT$Test$GT$$GT$3barE",
"<Test + 'static as foo::Bar<Test>>::bar"
);
}
#[test]
fn demangle_without_hash() {
let s = "_ZN3foo17h05af221e174051e9E";
t!(s, "foo::h05af221e174051e9");
t_nohash!(s, "foo");
}
#[test]
fn demangle_without_hash_edgecases() {
// One element, no hash.
t_nohash!("_ZN3fooE", "foo");
// Two elements, no hash.
t_nohash!("_ZN3foo3barE", "foo::bar");
// Longer-than-normal hash.
t_nohash!("_ZN3foo20h05af221e174051e9abcE", "foo");
// Shorter-than-normal hash.
t_nohash!("_ZN3foo5h05afE", "foo");
// Valid hash, but not at the end.
t_nohash!("_ZN17h05af221e174051e93fooE", "h05af221e174051e9::foo");
// Not a valid hash, missing the 'h'.
t_nohash!("_ZN3foo16ffaf221e174051e9E", "foo::ffaf221e174051e9");
// Not a valid hash, has a non-hex-digit.
t_nohash!("_ZN3foo17hg5af221e174051e9E", "foo::hg5af221e174051e9");
}
#[test]
fn demangle_thinlto() {
// One element, no hash.
t!("_ZN3fooE.llvm.9D1C9369", "foo");
t!("_ZN3fooE.llvm.9D1C9369@@16", "foo");
t_nohash!(
"_ZN9backtrace3foo17hbb467fcdaea5d79bE.llvm.A5310EB9",
"backtrace::foo"
);
}
#[test]
fn demangle_llvm_ir_branch_labels() {
t!("_ZN4core5slice77_$LT$impl$u20$core..ops..index..IndexMut$LT$I$GT$$u20$for$u20$$u5b$T$u5d$$GT$9index_mut17haf9727c2edfbc47bE.exit.i.i", "core::slice::<impl core::ops::index::IndexMut<I> for [T]>::index_mut::haf9727c2edfbc47b.exit.i.i");
t_nohash!("_ZN4core5slice77_$LT$impl$u20$core..ops..index..IndexMut$LT$I$GT$$u20$for$u20$$u5b$T$u5d$$GT$9index_mut17haf9727c2edfbc47bE.exit.i.i", "core::slice::<impl core::ops::index::IndexMut<I> for [T]>::index_mut.exit.i.i");
}
#[test]
fn demangle_ignores_suffix_that_doesnt_look_like_a_symbol() {
t_err!("_ZN3fooE.llvm moocow");
}
#[test]
fn dont_panic() {
super::demangle("_ZN2222222222222222222222EE").to_string();
super::demangle("_ZN5*70527e27.ll34csaғE").to_string();
super::demangle("_ZN5*70527a54.ll34_$b.1E").to_string();
super::demangle(
"\
_ZN5~saäb4e\n\
2734cOsbE\n\
5usage20h)3\0\0\0\0\0\0\07e2734cOsbE\
",
)
.to_string();
}
#[test]
fn invalid_no_chop() {
t_err!("_ZNfooE");
}
#[test]
fn handle_assoc_types() {
t!("_ZN151_$LT$alloc..boxed..Box$LT$alloc..boxed..FnBox$LT$A$C$$u20$Output$u3d$R$GT$$u20$$u2b$$u20$$u27$a$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$9call_once17h69e8f44b3723e1caE", "<alloc::boxed::Box<alloc::boxed::FnBox<A, Output=R> + 'a> as core::ops::function::FnOnce<A>>::call_once::h69e8f44b3723e1ca");
}
#[test]
fn handle_bang() {
t!(
"_ZN88_$LT$core..result..Result$LT$$u21$$C$$u20$E$GT$$u20$as$u20$std..process..Termination$GT$6report17hfc41d0da4a40b3e8E",
"<core::result::Result<!, E> as std::process::Termination>::report::hfc41d0da4a40b3e8"
);
}
#[test]
fn limit_recursion() {
assert_contains!(
super::demangle("_RNvB_1a").to_string(),
"{recursion limit reached}"
);
assert_contains!(
super::demangle("_RMC0RB2_").to_string(),
"{recursion limit reached}"
);
}
#[test]
fn limit_output() {
assert_ends_with!(
super::demangle("RYFG_FGyyEvRYFF_EvRYFFEvERLB_B_B_ERLRjB_B_B_").to_string(),
"{size limit reached}"
);
// NOTE(eddyb) somewhat reduced version of the above, effectively
// `<for<...> fn()>` with a larger number of lifetimes in `...`.
assert_ends_with!(
super::demangle("_RMC0FGZZZ_Eu").to_string(),
"{size limit reached}"
);
}
#[cfg(feature = "std")]
fn demangle_str(input: &str) -> String {
let mut output = Vec::new();
super::demangle_line(input, &mut output, false);
String::from_utf8(output).unwrap()
}
#[test]
#[cfg(feature = "std")]
fn find_multiple() {
assert_eq!(
demangle_str("_ZN3fooE.llvm moocow _ZN3fooE.llvm"),
"foo.llvm moocow foo.llvm"
);
}
#[test]
#[cfg(feature = "std")]
fn interleaved_new_legacy() {
assert_eq!(
demangle_str("_ZN3fooE.llvm moocow _RNvMNtNtNtNtCs8a2262Dv4r_3mio3sys4unix8selector5epollNtB2_8Selector6select _ZN3fooE.llvm"),
"foo.llvm moocow <mio::sys::unix::selector::epoll::Selector>::select foo.llvm"
);
}
}
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