1 use rustc_ast::{FloatTy, IntTy, UintTy};
2 use rustc_data_structures::base_n;
3 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
5 use rustc_hir::def_id::{CrateNum, DefId};
6 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
7 use rustc_middle::ty::print::{Print, Printer};
8 use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst};
9 use rustc_middle::ty::{self, Instance, Ty, TyCtxt, TypeFoldable};
10 use rustc_target::spec::abi::Abi;
17 instance: Instance<'tcx>,
18 instantiating_crate: Option<CrateNum>,
20 let def_id = instance.def_id();
21 // FIXME(eddyb) this should ideally not be needed.
22 let substs = tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), instance.substs);
25 let mut cx = SymbolMangler {
27 compress: Some(Box::new(CompressionCaches {
28 start_offset: prefix.len(),
30 paths: FxHashMap::default(),
31 types: FxHashMap::default(),
32 consts: FxHashMap::default(),
35 out: String::from(prefix),
38 // Append `::{shim:...#0}` to shims that can coexist with a non-shim instance.
39 let shim_kind = match instance.def {
40 ty::InstanceDef::VtableShim(_) => Some("vtable"),
41 ty::InstanceDef::ReifyShim(_) => Some("reify"),
46 cx = if let Some(shim_kind) = shim_kind {
47 cx.path_append_ns(|cx| cx.print_def_path(def_id, substs), 'S', 0, shim_kind).unwrap()
49 cx.print_def_path(def_id, substs).unwrap()
51 if let Some(instantiating_crate) = instantiating_crate {
52 cx = cx.print_def_path(instantiating_crate.as_def_id(), &[]).unwrap();
57 struct CompressionCaches<'tcx> {
58 // The length of the prefix in `out` (e.g. 2 for `_R`).
61 // The values are start positions in `out`, in bytes.
62 paths: FxHashMap<(DefId, &'tcx [GenericArg<'tcx>]), usize>,
63 types: FxHashMap<Ty<'tcx>, usize>,
64 consts: FxHashMap<&'tcx ty::Const<'tcx>, usize>,
68 /// The range of distances from the root of what's
69 /// being printed, to the lifetimes in a binder.
70 /// Specifically, a `BrAnon(i)` lifetime has depth
71 /// `lifetime_depths.start + i`, going away from the
72 /// the root and towards its use site, as `i` increases.
73 /// This is used to flatten rustc's pairing of `BrAnon`
74 /// (intra-binder disambiguation) with a `DebruijnIndex`
75 /// (binder addressing), to "true" de Bruijn indices,
76 /// by subtracting the depth of a certain lifetime, from
77 /// the innermost depth at its use site.
78 lifetime_depths: Range<u32>,
81 struct SymbolMangler<'tcx> {
83 compress: Option<Box<CompressionCaches<'tcx>>>,
84 binders: Vec<BinderLevel>,
88 impl SymbolMangler<'tcx> {
89 fn push(&mut self, s: &str) {
93 /// Push a `_`-terminated base 62 integer, using the format
94 /// specified in the RFC as `<base-62-number>`, that is:
95 /// * `x = 0` is encoded as just the `"_"` terminator
96 /// * `x > 0` is encoded as `x - 1` in base 62, followed by `"_"`,
97 /// e.g. `1` becomes `"0_"`, `62` becomes `"Z_"`, etc.
98 fn push_integer_62(&mut self, x: u64) {
99 if let Some(x) = x.checked_sub(1) {
100 base_n::push_str(x as u128, 62, &mut self.out);
105 /// Push a `tag`-prefixed base 62 integer, when larger than `0`, that is:
106 /// * `x = 0` is encoded as `""` (nothing)
107 /// * `x > 0` is encoded as the `tag` followed by `push_integer_62(x - 1)`
108 /// e.g. `1` becomes `tag + "_"`, `2` becomes `tag + "0_"`, etc.
109 fn push_opt_integer_62(&mut self, tag: &str, x: u64) {
110 if let Some(x) = x.checked_sub(1) {
112 self.push_integer_62(x);
116 fn push_disambiguator(&mut self, dis: u64) {
117 self.push_opt_integer_62("s", dis);
120 fn push_ident(&mut self, ident: &str) {
121 let mut use_punycode = false;
122 for b in ident.bytes() {
124 b'_' | b'a'..=b'z' | b'A'..=b'Z' | b'0'..=b'9' => {}
125 0x80..=0xff => use_punycode = true,
126 _ => bug!("symbol_names: bad byte {} in ident {:?}", b, ident),
131 let ident = if use_punycode {
134 // FIXME(eddyb) we should probably roll our own punycode implementation.
135 let mut punycode_bytes = match punycode::encode(ident) {
136 Ok(s) => s.into_bytes(),
137 Err(()) => bug!("symbol_names: punycode encoding failed for ident {:?}", ident),
140 // Replace `-` with `_`.
141 if let Some(c) = punycode_bytes.iter_mut().rfind(|&&mut c| c == b'-') {
145 // FIXME(eddyb) avoid rechecking UTF-8 validity.
146 punycode_string = String::from_utf8(punycode_bytes).unwrap();
152 let _ = write!(self.out, "{}", ident.len());
154 // Write a separating `_` if necessary (leading digit or `_`).
155 if let Some('_' | '0'..='9') = ident.chars().next() {
164 print_prefix: impl FnOnce(Self) -> Result<Self, !>,
168 ) -> Result<Self, !> {
171 self = print_prefix(self)?;
172 self.push_disambiguator(disambiguator as u64);
173 self.push_ident(name);
177 fn print_backref(mut self, i: usize) -> Result<Self, !> {
179 self.push_integer_62((i - self.compress.as_ref().unwrap().start_offset) as u64);
185 value: &ty::Binder<T>,
186 print_value: impl FnOnce(Self, &T) -> Result<Self, !>,
189 T: TypeFoldable<'tcx>,
191 let regions = if value.has_late_bound_regions() {
192 self.tcx.collect_referenced_late_bound_regions(value)
197 let mut lifetime_depths =
198 self.binders.last().map(|b| b.lifetime_depths.end).map_or(0..0, |i| i..i);
200 let lifetimes = regions
204 _ => bug!("symbol_names: non-anonymized region `{:?}` in `{:?}`", br, value),
207 .map_or(0, |max| max + 1);
209 self.push_opt_integer_62("G", lifetimes as u64);
210 lifetime_depths.end += lifetimes;
212 self.binders.push(BinderLevel { lifetime_depths });
213 self = print_value(self, value.as_ref().skip_binder())?;
220 impl Printer<'tcx> for SymbolMangler<'tcx> {
226 type DynExistential = Self;
229 fn tcx(&self) -> TyCtxt<'tcx> {
236 substs: &'tcx [GenericArg<'tcx>],
237 ) -> Result<Self::Path, Self::Error> {
238 if let Some(&i) = self.compress.as_ref().and_then(|c| c.paths.get(&(def_id, substs))) {
239 return self.print_backref(i);
241 let start = self.out.len();
243 self = self.default_print_def_path(def_id, substs)?;
245 // Only cache paths that do not refer to an enclosing
246 // binder (which would change depending on context).
247 if !substs.iter().any(|k| k.has_escaping_bound_vars()) {
248 if let Some(c) = &mut self.compress {
249 c.paths.insert((def_id, substs), start);
258 substs: &'tcx [GenericArg<'tcx>],
259 mut self_ty: Ty<'tcx>,
260 mut impl_trait_ref: Option<ty::TraitRef<'tcx>>,
261 ) -> Result<Self::Path, Self::Error> {
262 let key = self.tcx.def_key(impl_def_id);
263 let parent_def_id = DefId { index: key.parent.unwrap(), ..impl_def_id };
265 let mut param_env = self.tcx.param_env_reveal_all_normalized(impl_def_id);
266 if !substs.is_empty() {
267 param_env = param_env.subst(self.tcx, substs);
270 match &mut impl_trait_ref {
271 Some(impl_trait_ref) => {
272 assert_eq!(impl_trait_ref.self_ty(), self_ty);
273 *impl_trait_ref = self.tcx.normalize_erasing_regions(param_env, *impl_trait_ref);
274 self_ty = impl_trait_ref.self_ty();
277 self_ty = self.tcx.normalize_erasing_regions(param_env, self_ty);
281 self.push(match impl_trait_ref {
286 // Encode impl generic params if the substitutions contain parameters (implying
287 // polymorphization is enabled) and this isn't an inherent impl.
288 if impl_trait_ref.is_some() && substs.iter().any(|a| a.has_param_types_or_consts()) {
289 self = self.path_generic_args(
292 |cx| cx.print_def_path(parent_def_id, &[]),
294 key.disambiguated_data.disambiguator as u64,
301 self.push_disambiguator(key.disambiguated_data.disambiguator as u64);
302 self = self.print_def_path(parent_def_id, &[])?;
305 self = self_ty.print(self)?;
307 if let Some(trait_ref) = impl_trait_ref {
308 self = self.print_def_path(trait_ref.def_id, trait_ref.substs)?;
314 fn print_region(mut self, region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
315 let i = match *region {
316 // Erased lifetimes use the index 0, for a
317 // shorter mangling of `L_`.
320 // Late-bound lifetimes use indices starting at 1,
321 // see `BinderLevel` for more details.
322 ty::ReLateBound(debruijn, ty::BoundRegion { kind: ty::BrAnon(i) }) => {
323 let binder = &self.binders[self.binders.len() - 1 - debruijn.index()];
324 let depth = binder.lifetime_depths.start + i;
326 1 + (self.binders.last().unwrap().lifetime_depths.end - 1 - depth)
329 _ => bug!("symbol_names: non-erased region `{:?}`", region),
332 self.push_integer_62(i as u64);
336 fn print_type(mut self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
337 // Basic types, never cached (single-character).
338 let basic_type = match ty.kind() {
342 ty::Tuple(_) if ty.is_unit() => "u",
343 ty::Int(IntTy::I8) => "a",
344 ty::Int(IntTy::I16) => "s",
345 ty::Int(IntTy::I32) => "l",
346 ty::Int(IntTy::I64) => "x",
347 ty::Int(IntTy::I128) => "n",
348 ty::Int(IntTy::Isize) => "i",
349 ty::Uint(UintTy::U8) => "h",
350 ty::Uint(UintTy::U16) => "t",
351 ty::Uint(UintTy::U32) => "m",
352 ty::Uint(UintTy::U64) => "y",
353 ty::Uint(UintTy::U128) => "o",
354 ty::Uint(UintTy::Usize) => "j",
355 ty::Float(FloatTy::F32) => "f",
356 ty::Float(FloatTy::F64) => "d",
359 // Placeholders (should be demangled as `_`).
360 ty::Param(_) | ty::Bound(..) | ty::Placeholder(_) | ty::Infer(_) | ty::Error(_) => "p",
364 if !basic_type.is_empty() {
365 self.push(basic_type);
369 if let Some(&i) = self.compress.as_ref().and_then(|c| c.types.get(&ty)) {
370 return self.print_backref(i);
372 let start = self.out.len();
375 // Basic types, handled above.
376 ty::Bool | ty::Char | ty::Str | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Never => {
379 ty::Tuple(_) if ty.is_unit() => unreachable!(),
381 // Placeholders, also handled as part of basic types.
382 ty::Param(_) | ty::Bound(..) | ty::Placeholder(_) | ty::Infer(_) | ty::Error(_) => {
386 ty::Ref(r, ty, mutbl) => {
387 self.push(match mutbl {
388 hir::Mutability::Not => "R",
389 hir::Mutability::Mut => "Q",
391 if *r != ty::ReErased {
392 self = r.print(self)?;
394 self = ty.print(self)?;
398 self.push(match mt.mutbl {
399 hir::Mutability::Not => "P",
400 hir::Mutability::Mut => "O",
402 self = mt.ty.print(self)?;
405 ty::Array(ty, len) => {
407 self = ty.print(self)?;
408 self = self.print_const(len)?;
412 self = ty.print(self)?;
417 for ty in tys.iter().map(|k| k.expect_ty()) {
418 self = ty.print(self)?;
423 // Mangle all nominal types as paths.
424 ty::Adt(&ty::AdtDef { did: def_id, .. }, substs)
425 | ty::FnDef(def_id, substs)
426 | ty::Opaque(def_id, substs)
427 | ty::Projection(ty::ProjectionTy { item_def_id: def_id, substs })
428 | ty::Closure(def_id, substs)
429 | ty::Generator(def_id, substs, _) => {
430 self = self.print_def_path(def_id, substs)?;
432 ty::Foreign(def_id) => {
433 self = self.print_def_path(def_id, &[])?;
438 self = self.in_binder(&sig, |mut cx, sig| {
439 if sig.unsafety == hir::Unsafety::Unsafe {
444 Abi::C => cx.push("KC"),
447 let name = abi.name();
448 if name.contains('-') {
449 cx.push_ident(&name.replace('-', "_"));
455 for &ty in sig.inputs() {
462 sig.output().print(cx)
466 ty::Dynamic(predicates, r) => {
468 self = self.print_dyn_existential(predicates)?;
469 self = r.print(self)?;
472 ty::GeneratorWitness(_) => bug!("symbol_names: unexpected `GeneratorWitness`"),
475 // Only cache types that do not refer to an enclosing
476 // binder (which would change depending on context).
477 if !ty.has_escaping_bound_vars() {
478 if let Some(c) = &mut self.compress {
479 c.types.insert(ty, start);
485 fn print_dyn_existential(
487 predicates: &'tcx ty::List<ty::Binder<ty::ExistentialPredicate<'tcx>>>,
488 ) -> Result<Self::DynExistential, Self::Error> {
489 for predicate in predicates {
490 self = self.in_binder(&predicate, |mut cx, predicate| {
492 ty::ExistentialPredicate::Trait(trait_ref) => {
493 // Use a type that can't appear in defaults of type parameters.
494 let dummy_self = cx.tcx.mk_ty_infer(ty::FreshTy(0));
495 let trait_ref = trait_ref.with_self_ty(cx.tcx, dummy_self);
496 cx = cx.print_def_path(trait_ref.def_id, trait_ref.substs)?;
498 ty::ExistentialPredicate::Projection(projection) => {
499 let name = cx.tcx.associated_item(projection.item_def_id).ident;
501 cx.push_ident(&name.as_str());
502 cx = projection.ty.print(cx)?;
504 ty::ExistentialPredicate::AutoTrait(def_id) => {
505 cx = cx.print_def_path(*def_id, &[])?;
515 fn print_const(mut self, ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
516 if let Some(&i) = self.compress.as_ref().and_then(|c| c.consts.get(&ct)) {
517 return self.print_backref(i);
519 let start = self.out.len();
522 let val = match ct.ty.kind() {
523 ty::Uint(_) | ty::Bool | ty::Char => {
524 ct.try_eval_bits(self.tcx, ty::ParamEnv::reveal_all(), ct.ty)
527 let param_env = ty::ParamEnv::reveal_all();
528 ct.try_eval_bits(self.tcx, param_env, ct.ty).and_then(|b| {
529 let sz = self.tcx.layout_of(param_env.and(ct.ty)).ok()?.size;
530 let val = sz.sign_extend(b) as i128;
534 Some(val.wrapping_abs() as u128)
538 bug!("symbol_names: unsupported constant of type `{}` ({:?})", ct.ty, ct);
542 if let Some(bits) = val {
543 // We only print the type if the const can be evaluated.
544 self = ct.ty.print(self)?;
545 let _ = write!(self.out, "{}{:x}_", if neg { "n" } else { "" }, bits);
547 // NOTE(eddyb) despite having the path, we need to
548 // encode a placeholder, as the path could refer
549 // back to e.g. an `impl` using the constant.
553 // Only cache consts that do not refer to an enclosing
554 // binder (which would change depending on context).
555 if !ct.has_escaping_bound_vars() {
556 if let Some(c) = &mut self.compress {
557 c.consts.insert(ct, start);
563 fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
565 let fingerprint = self.tcx.crate_disambiguator(cnum).to_fingerprint();
566 self.push_disambiguator(fingerprint.to_smaller_hash());
567 let name = self.tcx.original_crate_name(cnum).as_str();
568 self.push_ident(&name);
575 trait_ref: Option<ty::TraitRef<'tcx>>,
576 ) -> Result<Self::Path, Self::Error> {
577 assert!(trait_ref.is_some());
578 let trait_ref = trait_ref.unwrap();
581 self = self_ty.print(self)?;
582 self.print_def_path(trait_ref.def_id, trait_ref.substs)
587 _: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
588 _: &DisambiguatedDefPathData,
590 _: Option<ty::TraitRef<'tcx>>,
591 ) -> Result<Self::Path, Self::Error> {
592 // Inlined into `print_impl_path`
598 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
599 disambiguated_data: &DisambiguatedDefPathData,
600 ) -> Result<Self::Path, Self::Error> {
601 let ns = match disambiguated_data.data {
602 // Uppercase categories are more stable than lowercase ones.
603 DefPathData::TypeNs(_) => 't',
604 DefPathData::ValueNs(_) => 'v',
605 DefPathData::ClosureExpr => 'C',
606 DefPathData::Ctor => 'c',
607 DefPathData::AnonConst => 'k',
608 DefPathData::ImplTrait => 'i',
610 // These should never show up as `path_append` arguments.
611 DefPathData::CrateRoot
614 | DefPathData::MacroNs(_)
615 | DefPathData::LifetimeNs(_) => {
616 bug!("symbol_names: unexpected DefPathData: {:?}", disambiguated_data.data)
620 let name = disambiguated_data.data.get_opt_name().map(|s| s.as_str());
625 disambiguated_data.disambiguator as u64,
626 name.as_ref().map_or("", |s| &s[..]),
630 fn path_generic_args(
632 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
633 args: &[GenericArg<'tcx>],
634 ) -> Result<Self::Path, Self::Error> {
635 // Don't print any regions if they're all erased.
636 let print_regions = args.iter().any(|arg| match arg.unpack() {
637 GenericArgKind::Lifetime(r) => *r != ty::ReErased,
640 let args = args.iter().cloned().filter(|arg| match arg.unpack() {
641 GenericArgKind::Lifetime(_) => print_regions,
645 if args.clone().next().is_none() {
646 return print_prefix(self);
650 self = print_prefix(self)?;
653 GenericArgKind::Lifetime(lt) => {
654 self = lt.print(self)?;
656 GenericArgKind::Type(ty) => {
657 self = ty.print(self)?;
659 GenericArgKind::Const(c) => {
661 self = c.print(self)?;