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use rustc::hir;
use rustc::hir::def_id::{CrateNum, DefId};
use rustc::hir::map::{DefPathData, DisambiguatedDefPathData};
use rustc::ty::{self, Ty, TyCtxt, TypeFoldable, Instance};
use rustc::ty::print::{Printer, Print};
use rustc::ty::subst::{Kind, Subst, UnpackedKind};
use rustc_data_structures::base_n;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_target::spec::abi::Abi;
use syntax::ast::{IntTy, UintTy, FloatTy};
use std::fmt::Write;
use std::ops::Range;
pub(super) fn mangle(
tcx: TyCtxt<'tcx>,
instance: Instance<'tcx>,
instantiating_crate: Option<CrateNum>,
) -> String {
let def_id = instance.def_id();
// FIXME(eddyb) this should ideally not be needed.
let substs =
tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), instance.substs);
let prefix = "_R";
let mut cx = SymbolMangler {
tcx,
compress: Some(Box::new(CompressionCaches {
start_offset: prefix.len(),
paths: FxHashMap::default(),
types: FxHashMap::default(),
consts: FxHashMap::default(),
})),
binders: vec![],
out: String::from(prefix),
};
cx = if instance.is_vtable_shim() {
cx.path_append_ns(
|cx| cx.print_def_path(def_id, substs),
'S',
0,
"",
).unwrap()
} else {
cx.print_def_path(def_id, substs).unwrap()
};
if let Some(instantiating_crate) = instantiating_crate {
cx = cx.print_def_path(instantiating_crate.as_def_id(), &[]).unwrap();
}
cx.out
}
struct CompressionCaches<'tcx> {
// The length of the prefix in `out` (e.g. 2 for `_R`).
start_offset: usize,
// The values are start positions in `out`, in bytes.
paths: FxHashMap<(DefId, &'tcx [Kind<'tcx>]), usize>,
types: FxHashMap<Ty<'tcx>, usize>,
consts: FxHashMap<&'tcx ty::Const<'tcx>, usize>,
}
struct BinderLevel {
/// The range of distances from the root of what's
/// being printed, to the lifetimes in a binder.
/// Specifically, a `BrAnon(i)` lifetime has depth
/// `lifetime_depths.start + i`, going away from the
/// the root and towards its use site, as `i` increases.
/// This is used to flatten rustc's pairing of `BrAnon`
/// (intra-binder disambiguation) with a `DebruijnIndex`
/// (binder addressing), to "true" de Bruijn indices,
/// by subtracting the depth of a certain lifetime, from
/// the innermost depth at its use site.
lifetime_depths: Range<u32>,
}
struct SymbolMangler<'tcx> {
tcx: TyCtxt<'tcx>,
compress: Option<Box<CompressionCaches<'tcx>>>,
binders: Vec<BinderLevel>,
out: String,
}
impl SymbolMangler<'tcx> {
fn push(&mut self, s: &str) {
self.out.push_str(s);
}
/// Push a `_`-terminated base 62 integer, using the format
/// specified in the RFC as `<base-62-number>`, that is:
/// * `x = 0` is encoded as just the `"_"` terminator
/// * `x > 0` is encoded as `x - 1` in base 62, followed by `"_"`,
/// e.g. `1` becomes `"0_"`, `62` becomes `"Z_"`, etc.
fn push_integer_62(&mut self, x: u64) {
if let Some(x) = x.checked_sub(1) {
base_n::push_str(x as u128, 62, &mut self.out);
}
self.push("_");
}
/// Push a `tag`-prefixed base 62 integer, when larger than `0`, that is:
/// * `x = 0` is encoded as `""` (nothing)
/// * `x > 0` is encoded as the `tag` followed by `push_integer_62(x - 1)`
/// e.g. `1` becomes `tag + "_"`, `2` becomes `tag + "0_"`, etc.
fn push_opt_integer_62(&mut self, tag: &str, x: u64) {
if let Some(x) = x.checked_sub(1) {
self.push(tag);
self.push_integer_62(x);
}
}
fn push_disambiguator(&mut self, dis: u64) {
self.push_opt_integer_62("s", dis);
}
fn push_ident(&mut self, ident: &str) {
let mut use_punycode = false;
for b in ident.bytes() {
match b {
b'_' | b'a'..=b'z' | b'A'..=b'Z' | b'0'..=b'9' => {}
0x80..=0xff => use_punycode = true,
_ => bug!("symbol_names: bad byte {} in ident {:?}", b, ident),
}
}
let punycode_string;
let ident = if use_punycode {
self.push("u");
// FIXME(eddyb) we should probably roll our own punycode implementation.
let mut punycode_bytes = match ::punycode::encode(ident) {
Ok(s) => s.into_bytes(),
Err(()) => bug!("symbol_names: punycode encoding failed for ident {:?}", ident),
};
// Replace `-` with `_`.
if let Some(c) = punycode_bytes.iter_mut().rfind(|&&mut c| c == b'-') {
*c = b'_';
}
// FIXME(eddyb) avoid rechecking UTF-8 validity.
punycode_string = String::from_utf8(punycode_bytes).unwrap();
&punycode_string
} else {
ident
};
let _ = write!(self.out, "{}", ident.len());
// Write a separating `_` if necessary (leading digit or `_`).
match ident.chars().next() {
Some('_') | Some('0'..='9') => {
self.push("_");
}
_ => {}
}
self.push(ident);
}
fn path_append_ns(
mut self,
print_prefix: impl FnOnce(Self) -> Result<Self, !>,
ns: char,
disambiguator: u64,
name: &str,
) -> Result<Self, !> {
self.push("N");
self.out.push(ns);
self = print_prefix(self)?;
self.push_disambiguator(disambiguator as u64);
self.push_ident(name);
Ok(self)
}
fn print_backref(mut self, i: usize) -> Result<Self, !> {
self.push("B");
self.push_integer_62((i - self.compress.as_ref().unwrap().start_offset) as u64);
Ok(self)
}
fn in_binder<T>(
mut self,
value: &ty::Binder<T>,
print_value: impl FnOnce(Self, &T) -> Result<Self, !>
) -> Result<Self, !>
where T: TypeFoldable<'tcx>
{
let regions = if value.has_late_bound_regions() {
self.tcx.collect_referenced_late_bound_regions(value)
} else {
FxHashSet::default()
};
let mut lifetime_depths =
self.binders.last().map(|b| b.lifetime_depths.end).map_or(0..0, |i| i..i);
let lifetimes = regions.into_iter().map(|br| {
match br {
ty::BrAnon(i) => i + 1,
_ => bug!("symbol_names: non-anonymized region `{:?}` in `{:?}`", br, value),
}
}).max().unwrap_or(0);
self.push_opt_integer_62("G", lifetimes as u64);
lifetime_depths.end += lifetimes;
self.binders.push(BinderLevel { lifetime_depths });
self = print_value(self, value.skip_binder())?;
self.binders.pop();
Ok(self)
}
}
impl Printer<'tcx> for SymbolMangler<'tcx> {
type Error = !;
type Path = Self;
type Region = Self;
type Type = Self;
type DynExistential = Self;
type Const = Self;
fn tcx(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn print_def_path(
mut self,
def_id: DefId,
substs: &'tcx [Kind<'tcx>],
) -> Result<Self::Path, Self::Error> {
if let Some(&i) = self.compress.as_ref().and_then(|c| c.paths.get(&(def_id, substs))) {
return self.print_backref(i);
}
let start = self.out.len();
self = self.default_print_def_path(def_id, substs)?;
// Only cache paths that do not refer to an enclosing
// binder (which would change depending on context).
if !substs.iter().any(|k| k.has_escaping_bound_vars()) {
if let Some(c) = &mut self.compress {
c.paths.insert((def_id, substs), start);
}
}
Ok(self)
}
fn print_impl_path(
self,
impl_def_id: DefId,
substs: &'tcx [Kind<'tcx>],
mut self_ty: Ty<'tcx>,
mut impl_trait_ref: Option<ty::TraitRef<'tcx>>,
) -> Result<Self::Path, Self::Error> {
let key = self.tcx.def_key(impl_def_id);
let parent_def_id = DefId { index: key.parent.unwrap(), ..impl_def_id };
let mut param_env = self.tcx.param_env(impl_def_id)
.with_reveal_all();
if !substs.is_empty() {
param_env = param_env.subst(self.tcx, substs);
}
match &mut impl_trait_ref {
Some(impl_trait_ref) => {
assert_eq!(impl_trait_ref.self_ty(), self_ty);
*impl_trait_ref =
self.tcx.normalize_erasing_regions(param_env, *impl_trait_ref);
self_ty = impl_trait_ref.self_ty();
}
None => {
self_ty = self.tcx.normalize_erasing_regions(param_env, self_ty);
}
}
self.path_append_impl(
|cx| cx.print_def_path(parent_def_id, &[]),
&key.disambiguated_data,
self_ty,
impl_trait_ref,
)
}
fn print_region(
mut self,
region: ty::Region<'_>,
) -> Result<Self::Region, Self::Error> {
let i = match *region {
// Erased lifetimes use the index 0, for a
// shorter mangling of `L_`.
ty::ReErased => 0,
// Late-bound lifetimes use indices starting at 1,
// see `BinderLevel` for more details.
ty::ReLateBound(debruijn, ty::BrAnon(i)) => {
let binder = &self.binders[self.binders.len() - 1 - debruijn.index()];
let depth = binder.lifetime_depths.start + i;
1 + (self.binders.last().unwrap().lifetime_depths.end - 1 - depth)
}
_ => bug!("symbol_names: non-erased region `{:?}`", region),
};
self.push("L");
self.push_integer_62(i as u64);
Ok(self)
}
fn print_type(
mut self,
ty: Ty<'tcx>,
) -> Result<Self::Type, Self::Error> {
// Basic types, never cached (single-character).
let basic_type = match ty.sty {
ty::Bool => "b",
ty::Char => "c",
ty::Str => "e",
ty::Tuple(_) if ty.is_unit() => "u",
ty::Int(IntTy::I8) => "a",
ty::Int(IntTy::I16) => "s",
ty::Int(IntTy::I32) => "l",
ty::Int(IntTy::I64) => "x",
ty::Int(IntTy::I128) => "n",
ty::Int(IntTy::Isize) => "i",
ty::Uint(UintTy::U8) => "h",
ty::Uint(UintTy::U16) => "t",
ty::Uint(UintTy::U32) => "m",
ty::Uint(UintTy::U64) => "y",
ty::Uint(UintTy::U128) => "o",
ty::Uint(UintTy::Usize) => "j",
ty::Float(FloatTy::F32) => "f",
ty::Float(FloatTy::F64) => "d",
ty::Never => "z",
// Placeholders (should be demangled as `_`).
ty::Param(_) | ty::Bound(..) | ty::Placeholder(_) |
ty::Infer(_) | ty::Error => "p",
_ => "",
};
if !basic_type.is_empty() {
self.push(basic_type);
return Ok(self);
}
if let Some(&i) = self.compress.as_ref().and_then(|c| c.types.get(&ty)) {
return self.print_backref(i);
}
let start = self.out.len();
match ty.sty {
// Basic types, handled above.
ty::Bool | ty::Char | ty::Str |
ty::Int(_) | ty::Uint(_) | ty::Float(_) |
ty::Never => unreachable!(),
ty::Tuple(_) if ty.is_unit() => unreachable!(),
// Placeholders, also handled as part of basic types.
ty::Param(_) | ty::Bound(..) | ty::Placeholder(_) |
ty::Infer(_) | ty::Error => unreachable!(),
ty::Ref(r, ty, mutbl) => {
self.push(match mutbl {
hir::MutImmutable => "R",
hir::MutMutable => "Q",
});
if *r != ty::ReErased {
self = r.print(self)?;
}
self = ty.print(self)?;
}
ty::RawPtr(mt) => {
self.push(match mt.mutbl {
hir::MutImmutable => "P",
hir::MutMutable => "O",
});
self = mt.ty.print(self)?;
}
ty::Array(ty, len) => {
self.push("A");
self = ty.print(self)?;
self = self.print_const(len)?;
}
ty::Slice(ty) => {
self.push("S");
self = ty.print(self)?;
}
ty::Tuple(tys) => {
self.push("T");
for ty in tys.iter().map(|k| k.expect_ty()) {
self = ty.print(self)?;
}
self.push("E");
}
// Mangle all nominal types as paths.
ty::Adt(&ty::AdtDef { did: def_id, .. }, substs) |
ty::FnDef(def_id, substs) |
ty::Opaque(def_id, substs) |
ty::Projection(ty::ProjectionTy { item_def_id: def_id, substs }) |
ty::UnnormalizedProjection(ty::ProjectionTy { item_def_id: def_id, substs }) |
ty::Closure(def_id, ty::ClosureSubsts { substs }) |
ty::Generator(def_id, ty::GeneratorSubsts { substs }, _) => {
self = self.print_def_path(def_id, substs)?;
}
ty::Foreign(def_id) => {
self = self.print_def_path(def_id, &[])?;
}
ty::FnPtr(sig) => {
self.push("F");
self = self.in_binder(&sig, |mut cx, sig| {
if sig.unsafety == hir::Unsafety::Unsafe {
cx.push("U");
}
match sig.abi {
Abi::Rust => {}
Abi::C => cx.push("KC"),
abi => {
cx.push("K");
let name = abi.name();
if name.contains('-') {
cx.push_ident(&name.replace('-', "_"));
} else {
cx.push_ident(name);
}
}
}
for &ty in sig.inputs() {
cx = ty.print(cx)?;
}
if sig.c_variadic {
cx.push("v");
}
cx.push("E");
sig.output().print(cx)
})?;
}
ty::Dynamic(predicates, r) => {
self.push("D");
self = self.in_binder(&predicates, |cx, predicates| {
cx.print_dyn_existential(predicates)
})?;
self = r.print(self)?;
}
ty::GeneratorWitness(_) => {
bug!("symbol_names: unexpected `GeneratorWitness`")
}
}
// Only cache types that do not refer to an enclosing
// binder (which would change depending on context).
if !ty.has_escaping_bound_vars() {
if let Some(c) = &mut self.compress {
c.types.insert(ty, start);
}
}
Ok(self)
}
fn print_dyn_existential(
mut self,
predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>,
) -> Result<Self::DynExistential, Self::Error> {
for predicate in predicates {
match *predicate {
ty::ExistentialPredicate::Trait(trait_ref) => {
// Use a type that can't appear in defaults of type parameters.
let dummy_self = self.tcx.mk_ty_infer(ty::FreshTy(0));
let trait_ref = trait_ref.with_self_ty(self.tcx, dummy_self);
self = self.print_def_path(trait_ref.def_id, trait_ref.substs)?;
}
ty::ExistentialPredicate::Projection(projection) => {
let name = self.tcx.associated_item(projection.item_def_id).ident;
self.push("p");
self.push_ident(&name.as_str());
self = projection.ty.print(self)?;
}
ty::ExistentialPredicate::AutoTrait(def_id) => {
self = self.print_def_path(def_id, &[])?;
}
}
}
self.push("E");
Ok(self)
}
fn print_const(
mut self,
ct: &'tcx ty::Const<'tcx>,
) -> Result<Self::Const, Self::Error> {
if let Some(&i) = self.compress.as_ref().and_then(|c| c.consts.get(&ct)) {
return self.print_backref(i);
}
let start = self.out.len();
match ct.ty.sty {
ty::Uint(_) => {}
_ => {
bug!("symbol_names: unsupported constant of type `{}` ({:?})",
ct.ty, ct);
}
}
self = ct.ty.print(self)?;
if let Some(bits) = ct.assert_bits(self.tcx, ty::ParamEnv::empty().and(ct.ty)) {
let _ = write!(self.out, "{:x}_", bits);
} else {
// NOTE(eddyb) despite having the path, we need to
// encode a placeholder, as the path could refer
// back to e.g. an `impl` using the constant.
self.push("p");
}
// Only cache consts that do not refer to an enclosing
// binder (which would change depending on context).
if !ct.has_escaping_bound_vars() {
if let Some(c) = &mut self.compress {
c.consts.insert(ct, start);
}
}
Ok(self)
}
fn path_crate(
mut self,
cnum: CrateNum,
) -> Result<Self::Path, Self::Error> {
self.push("C");
let fingerprint = self.tcx.crate_disambiguator(cnum).to_fingerprint();
self.push_disambiguator(fingerprint.to_smaller_hash());
let name = self.tcx.original_crate_name(cnum).as_str();
self.push_ident(&name);
Ok(self)
}
fn path_qualified(
mut self,
self_ty: Ty<'tcx>,
trait_ref: Option<ty::TraitRef<'tcx>>,
) -> Result<Self::Path, Self::Error> {
assert!(trait_ref.is_some());
let trait_ref = trait_ref.unwrap();
self.push("Y");
self = self_ty.print(self)?;
self.print_def_path(trait_ref.def_id, trait_ref.substs)
}
fn path_append_impl(
mut self,
print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
disambiguated_data: &DisambiguatedDefPathData,
self_ty: Ty<'tcx>,
trait_ref: Option<ty::TraitRef<'tcx>>,
) -> Result<Self::Path, Self::Error> {
self.push(match trait_ref {
Some(_) => "X",
None => "M",
});
self.push_disambiguator(disambiguated_data.disambiguator as u64);
self = print_prefix(self)?;
self = self_ty.print(self)?;
if let Some(trait_ref) = trait_ref {
self = self.print_def_path(trait_ref.def_id, trait_ref.substs)?;
}
Ok(self)
}
fn path_append(
self,
print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
disambiguated_data: &DisambiguatedDefPathData,
) -> Result<Self::Path, Self::Error> {
let ns = match disambiguated_data.data {
// Uppercase categories are more stable than lowercase ones.
DefPathData::TypeNs(_) => 't',
DefPathData::ValueNs(_) => 'v',
DefPathData::ClosureExpr => 'C',
DefPathData::Ctor => 'c',
DefPathData::AnonConst => 'k',
DefPathData::ImplTrait => 'i',
// These should never show up as `path_append` arguments.
DefPathData::CrateRoot
| DefPathData::Misc
| DefPathData::Impl
| DefPathData::MacroNs(_)
| DefPathData::LifetimeNs(_)
| DefPathData::GlobalMetaData(_) => {
bug!("symbol_names: unexpected DefPathData: {:?}", disambiguated_data.data)
}
};
let name = disambiguated_data.data.get_opt_name().map(|s| s.as_str());
self.path_append_ns(
print_prefix,
ns,
disambiguated_data.disambiguator as u64,
name.as_ref().map_or("", |s| &s[..])
)
}
fn path_generic_args(
mut self,
print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
args: &[Kind<'tcx>],
) -> Result<Self::Path, Self::Error> {
// Don't print any regions if they're all erased.
let print_regions = args.iter().any(|arg| {
match arg.unpack() {
UnpackedKind::Lifetime(r) => *r != ty::ReErased,
_ => false,
}
});
let args = args.iter().cloned().filter(|arg| {
match arg.unpack() {
UnpackedKind::Lifetime(_) => print_regions,
_ => true,
}
});
if args.clone().next().is_none() {
return print_prefix(self);
}
self.push("I");
self = print_prefix(self)?;
for arg in args {
match arg.unpack() {
UnpackedKind::Lifetime(lt) => {
self = lt.print(self)?;
}
UnpackedKind::Type(ty) => {
self = ty.print(self)?;
}
UnpackedKind::Const(c) => {
self.push("K");
// FIXME(const_generics) implement `ty::print::Print` on `ty::Const`.
// self = c.print(self)?;
self = self.print_const(c)?;
}
}
}
self.push("E");
Ok(self)
}
}
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