compiler/rustc_middle/src/ty/print/pretty.rs

   1 use crate::mir::interpret::{AllocRange, GlobalAlloc, Pointer, Provenance, Scalar};
   2 use crate::ty::{
   3     self, ConstInt, DefIdTree, ParamConst, ScalarInt, Term, TermKind, Ty, TyCtxt, TypeFoldable,
   4     TypeSuperFoldable, TypeSuperVisitable, TypeVisitable,
   5 };
   6 use crate::ty::{GenericArg, GenericArgKind};
   7 use rustc_apfloat::ieee::{Double, Single};
   8 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
   9 use rustc_data_structures::sso::SsoHashSet;
  10 use rustc_hir as hir;
  11 use rustc_hir::def::{self, CtorKind, DefKind, Namespace};
  12 use rustc_hir::def_id::{DefId, DefIdSet, CRATE_DEF_ID, LOCAL_CRATE};
  13 use rustc_hir::definitions::{DefPathData, DefPathDataName, DisambiguatedDefPathData};
  14 use rustc_hir::LangItem;
  15 use rustc_session::config::TrimmedDefPaths;
  16 use rustc_session::cstore::{ExternCrate, ExternCrateSource};
  17 use rustc_session::Limit;
  18 use rustc_span::symbol::{kw, Ident, Symbol};
  19 use rustc_target::abi::Size;
  20 use rustc_target::spec::abi::Abi;
  21 use smallvec::SmallVec;
  22
  23 use std::cell::Cell;
  24 use std::char;
  25 use std::collections::BTreeMap;
  26 use std::convert::TryFrom;
  27 use std::fmt::{self, Write as _};
  28 use std::iter;
  29 use std::ops::{ControlFlow, Deref, DerefMut};
  30
  31 // `pretty` is a separate module only for organization.
  32 use super::*;
  33
  34 macro_rules! p {
  35     (@$lit:literal) => {
  36         write!(scoped_cx!(), $lit)?
  37     };
  38     (@write($($data:expr),+)) => {
  39         write!(scoped_cx!(), $($data),+)?
  40     };
  41     (@print($x:expr)) => {
  42         scoped_cx!() = $x.print(scoped_cx!())?
  43     };
  44     (@$method:ident($($arg:expr),*)) => {
  45         scoped_cx!() = scoped_cx!().$method($($arg),*)?
  46     };
  47     ($($elem:tt $(($($args:tt)*))?),+) => {{
  48         $(p!(@ $elem $(($($args)*))?);)+
  49     }};
  50 }
  51 macro_rules! define_scoped_cx {
  52     ($cx:ident) => {
  53         #[allow(unused_macros)]
  54         macro_rules! scoped_cx {
  55             () => {
  56                 $cx
  57             };
  58         }
  59     };
  60 }
  61
  62 thread_local! {
  63     static FORCE_IMPL_FILENAME_LINE: Cell<bool> = const { Cell::new(false) };
  64     static SHOULD_PREFIX_WITH_CRATE: Cell<bool> = const { Cell::new(false) };
  65     static NO_TRIMMED_PATH: Cell<bool> = const { Cell::new(false) };
  66     static NO_QUERIES: Cell<bool> = const { Cell::new(false) };
  67     static NO_VISIBLE_PATH: Cell<bool> = const { Cell::new(false) };
  68 }
  69
  70 macro_rules! define_helper {
  71     ($($(#[$a:meta])* fn $name:ident($helper:ident, $tl:ident);)+) => {
  72         $(
  73             #[must_use]
  74             pub struct $helper(bool);
  75
  76             impl $helper {
  77                 pub fn new() -> $helper {
  78                     $helper($tl.with(|c| c.replace(true)))
  79                 }
  80             }
  81
  82             $(#[$a])*
  83             pub macro $name($e:expr) {
  84                 {
  85                     let _guard = $helper::new();
  86                     $e
  87                 }
  88             }
  89
  90             impl Drop for $helper {
  91                 fn drop(&mut self) {
  92                     $tl.with(|c| c.set(self.0))
  93                 }
  94             }
  95         )+
  96     }
  97 }
  98
  99 define_helper!(
 100     /// Avoids running any queries during any prints that occur
 101     /// during the closure. This may alter the appearance of some
 102     /// types (e.g. forcing verbose printing for opaque types).
 103     /// This method is used during some queries (e.g. `explicit_item_bounds`
 104     /// for opaque types), to ensure that any debug printing that
 105     /// occurs during the query computation does not end up recursively
 106     /// calling the same query.
 107     fn with_no_queries(NoQueriesGuard, NO_QUERIES);
 108     /// Force us to name impls with just the filename/line number. We
 109     /// normally try to use types. But at some points, notably while printing
 110     /// cycle errors, this can result in extra or suboptimal error output,
 111     /// so this variable disables that check.
 112     fn with_forced_impl_filename_line(ForcedImplGuard, FORCE_IMPL_FILENAME_LINE);
 113     /// Adds the `crate::` prefix to paths where appropriate.
 114     fn with_crate_prefix(CratePrefixGuard, SHOULD_PREFIX_WITH_CRATE);
 115     /// Prevent path trimming if it is turned on. Path trimming affects `Display` impl
 116     /// of various rustc types, for example `std::vec::Vec` would be trimmed to `Vec`,
 117     /// if no other `Vec` is found.
 118     fn with_no_trimmed_paths(NoTrimmedGuard, NO_TRIMMED_PATH);
 119     /// Prevent selection of visible paths. `Display` impl of DefId will prefer
 120     /// visible (public) reexports of types as paths.
 121     fn with_no_visible_paths(NoVisibleGuard, NO_VISIBLE_PATH);
 122 );
 123
 124 /// The "region highlights" are used to control region printing during
 125 /// specific error messages. When a "region highlight" is enabled, it
 126 /// gives an alternate way to print specific regions. For now, we
 127 /// always print those regions using a number, so something like "`'0`".
 128 ///
 129 /// Regions not selected by the region highlight mode are presently
 130 /// unaffected.
 131 #[derive(Copy, Clone)]
 132 pub struct RegionHighlightMode<'tcx> {
 133     tcx: TyCtxt<'tcx>,
 134
 135     /// If enabled, when we see the selected region, use "`'N`"
 136     /// instead of the ordinary behavior.
 137     highlight_regions: [Option<(ty::Region<'tcx>, usize)>; 3],
 138
 139     /// If enabled, when printing a "free region" that originated from
 140     /// the given `ty::BoundRegionKind`, print it as "`'1`". Free regions that would ordinarily
 141     /// have names print as normal.
 142     ///
 143     /// This is used when you have a signature like `fn foo(x: &u32,
 144     /// y: &'a u32)` and we want to give a name to the region of the
 145     /// reference `x`.
 146     highlight_bound_region: Option<(ty::BoundRegionKind, usize)>,
 147 }
 148
 149 impl<'tcx> RegionHighlightMode<'tcx> {
 150     pub fn new(tcx: TyCtxt<'tcx>) -> Self {
 151         Self {
 152             tcx,
 153             highlight_regions: Default::default(),
 154             highlight_bound_region: Default::default(),
 155         }
 156     }
 157
 158     /// If `region` and `number` are both `Some`, invokes
 159     /// `highlighting_region`.
 160     pub fn maybe_highlighting_region(
 161         &mut self,
 162         region: Option<ty::Region<'tcx>>,
 163         number: Option<usize>,
 164     ) {
 165         if let Some(k) = region {
 166             if let Some(n) = number {
 167                 self.highlighting_region(k, n);
 168             }
 169         }
 170     }
 171
 172     /// Highlights the region inference variable `vid` as `'N`.
 173     pub fn highlighting_region(&mut self, region: ty::Region<'tcx>, number: usize) {
 174         let num_slots = self.highlight_regions.len();
 175         let first_avail_slot =
 176             self.highlight_regions.iter_mut().find(|s| s.is_none()).unwrap_or_else(|| {
 177                 bug!("can only highlight {} placeholders at a time", num_slots,)
 178             });
 179         *first_avail_slot = Some((region, number));
 180     }
 181
 182     /// Convenience wrapper for `highlighting_region`.
 183     pub fn highlighting_region_vid(&mut self, vid: ty::RegionVid, number: usize) {
 184         self.highlighting_region(self.tcx.mk_region(ty::ReVar(vid)), number)
 185     }
 186
 187     /// Returns `Some(n)` with the number to use for the given region, if any.
 188     fn region_highlighted(&self, region: ty::Region<'tcx>) -> Option<usize> {
 189         self.highlight_regions.iter().find_map(|h| match h {
 190             Some((r, n)) if *r == region => Some(*n),
 191             _ => None,
 192         })
 193     }
 194
 195     /// Highlight the given bound region.
 196     /// We can only highlight one bound region at a time. See
 197     /// the field `highlight_bound_region` for more detailed notes.
 198     pub fn highlighting_bound_region(&mut self, br: ty::BoundRegionKind, number: usize) {
 199         assert!(self.highlight_bound_region.is_none());
 200         self.highlight_bound_region = Some((br, number));
 201     }
 202 }
 203
 204 /// Trait for printers that pretty-print using `fmt::Write` to the printer.
 205 pub trait PrettyPrinter<'tcx>:
 206     Printer<
 207         'tcx,
 208         Error = fmt::Error,
 209         Path = Self,
 210         Region = Self,
 211         Type = Self,
 212         DynExistential = Self,
 213         Const = Self,
 214     > + fmt::Write
 215 {
 216     /// Like `print_def_path` but for value paths.
 217     fn print_value_path(
 218         self,
 219         def_id: DefId,
 220         substs: &'tcx [GenericArg<'tcx>],
 221     ) -> Result<Self::Path, Self::Error> {
 222         self.print_def_path(def_id, substs)
 223     }
 224
 225     fn in_binder<T>(self, value: &ty::Binder<'tcx, T>) -> Result<Self, Self::Error>
 226     where
 227         T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>,
 228     {
 229         value.as_ref().skip_binder().print(self)
 230     }
 231
 232     fn wrap_binder<T, F: FnOnce(&T, Self) -> Result<Self, fmt::Error>>(
 233         self,
 234         value: &ty::Binder<'tcx, T>,
 235         f: F,
 236     ) -> Result<Self, Self::Error>
 237     where
 238         T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>,
 239     {
 240         f(value.as_ref().skip_binder(), self)
 241     }
 242
 243     /// Prints comma-separated elements.
 244     fn comma_sep<T>(mut self, mut elems: impl Iterator<Item = T>) -> Result<Self, Self::Error>
 245     where
 246         T: Print<'tcx, Self, Output = Self, Error = Self::Error>,
 247     {
 248         if let Some(first) = elems.next() {
 249             self = first.print(self)?;
 250             for elem in elems {
 251                 self.write_str(", ")?;
 252                 self = elem.print(self)?;
 253             }
 254         }
 255         Ok(self)
 256     }
 257
 258     /// Prints `{f: t}` or `{f as t}` depending on the `cast` argument
 259     fn typed_value(
 260         mut self,
 261         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
 262         t: impl FnOnce(Self) -> Result<Self, Self::Error>,
 263         conversion: &str,
 264     ) -> Result<Self::Const, Self::Error> {
 265         self.write_str("{")?;
 266         self = f(self)?;
 267         self.write_str(conversion)?;
 268         self = t(self)?;
 269         self.write_str("}")?;
 270         Ok(self)
 271     }
 272
 273     /// Prints `<...>` around what `f` prints.
 274     fn generic_delimiters(
 275         self,
 276         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
 277     ) -> Result<Self, Self::Error>;
 278
 279     /// Returns `true` if the region should be printed in
 280     /// optional positions, e.g., `&'a T` or `dyn Tr + 'b`.
 281     /// This is typically the case for all non-`'_` regions.
 282     fn should_print_region(&self, region: ty::Region<'tcx>) -> bool;
 283
 284     // Defaults (should not be overridden):
 285
 286     /// If possible, this returns a global path resolving to `def_id` that is visible
 287     /// from at least one local module, and returns `true`. If the crate defining `def_id` is
 288     /// declared with an `extern crate`, the path is guaranteed to use the `extern crate`.
 289     fn try_print_visible_def_path(self, def_id: DefId) -> Result<(Self, bool), Self::Error> {
 290         if NO_VISIBLE_PATH.with(|flag| flag.get()) {
 291             return Ok((self, false));
 292         }
 293
 294         let mut callers = Vec::new();
 295         self.try_print_visible_def_path_recur(def_id, &mut callers)
 296     }
 297
 298     /// Try to see if this path can be trimmed to a unique symbol name.
 299     fn try_print_trimmed_def_path(
 300         mut self,
 301         def_id: DefId,
 302     ) -> Result<(Self::Path, bool), Self::Error> {
 303         if !self.tcx().sess.opts.unstable_opts.trim_diagnostic_paths
 304             || matches!(self.tcx().sess.opts.trimmed_def_paths, TrimmedDefPaths::Never)
 305             || NO_TRIMMED_PATH.with(|flag| flag.get())
 306             || SHOULD_PREFIX_WITH_CRATE.with(|flag| flag.get())
 307         {
 308             return Ok((self, false));
 309         }
 310
 311         match self.tcx().trimmed_def_paths(()).get(&def_id) {
 312             None => Ok((self, false)),
 313             Some(symbol) => {
 314                 self.write_str(symbol.as_str())?;
 315                 Ok((self, true))
 316             }
 317         }
 318     }
 319
 320     /// Does the work of `try_print_visible_def_path`, building the
 321     /// full definition path recursively before attempting to
 322     /// post-process it into the valid and visible version that
 323     /// accounts for re-exports.
 324     ///
 325     /// This method should only be called by itself or
 326     /// `try_print_visible_def_path`.
 327     ///
 328     /// `callers` is a chain of visible_parent's leading to `def_id`,
 329     /// to support cycle detection during recursion.
 330     ///
 331     /// This method returns false if we can't print the visible path, so
 332     /// `print_def_path` can fall back on the item's real definition path.
 333     fn try_print_visible_def_path_recur(
 334         mut self,
 335         def_id: DefId,
 336         callers: &mut Vec<DefId>,
 337     ) -> Result<(Self, bool), Self::Error> {
 338         define_scoped_cx!(self);
 339
 340         debug!("try_print_visible_def_path: def_id={:?}", def_id);
 341
 342         // If `def_id` is a direct or injected extern crate, return the
 343         // path to the crate followed by the path to the item within the crate.
 344         if let Some(cnum) = def_id.as_crate_root() {
 345             if cnum == LOCAL_CRATE {
 346                 return Ok((self.path_crate(cnum)?, true));
 347             }
 348
 349             // In local mode, when we encounter a crate other than
 350             // LOCAL_CRATE, execution proceeds in one of two ways:
 351             //
 352             // 1. For a direct dependency, where user added an
 353             //    `extern crate` manually, we put the `extern
 354             //    crate` as the parent. So you wind up with
 355             //    something relative to the current crate.
 356             // 2. For an extern inferred from a path or an indirect crate,
 357             //    where there is no explicit `extern crate`, we just prepend
 358             //    the crate name.
 359             match self.tcx().extern_crate(def_id) {
 360                 Some(&ExternCrate { src, dependency_of, span, .. }) => match (src, dependency_of) {
 361                     (ExternCrateSource::Extern(def_id), LOCAL_CRATE) => {
 362                         // NOTE(eddyb) the only reason `span` might be dummy,
 363                         // that we're aware of, is that it's the `std`/`core`
 364                         // `extern crate` injected by default.
 365                         // FIXME(eddyb) find something better to key this on,
 366                         // or avoid ending up with `ExternCrateSource::Extern`,
 367                         // for the injected `std`/`core`.
 368                         if span.is_dummy() {
 369                             return Ok((self.path_crate(cnum)?, true));
 370                         }
 371
 372                         // Disable `try_print_trimmed_def_path` behavior within
 373                         // the `print_def_path` call, to avoid infinite recursion
 374                         // in cases where the `extern crate foo` has non-trivial
 375                         // parents, e.g. it's nested in `impl foo::Trait for Bar`
 376                         // (see also issues #55779 and #87932).
 377                         self = with_no_visible_paths!(self.print_def_path(def_id, &[])?);
 378
 379                         return Ok((self, true));
 380                     }
 381                     (ExternCrateSource::Path, LOCAL_CRATE) => {
 382                         return Ok((self.path_crate(cnum)?, true));
 383                     }
 384                     _ => {}
 385                 },
 386                 None => {
 387                     return Ok((self.path_crate(cnum)?, true));
 388                 }
 389             }
 390         }
 391
 392         if def_id.is_local() {
 393             return Ok((self, false));
 394         }
 395
 396         let visible_parent_map = self.tcx().visible_parent_map(());
 397
 398         let mut cur_def_key = self.tcx().def_key(def_id);
 399         debug!("try_print_visible_def_path: cur_def_key={:?}", cur_def_key);
 400
 401         // For a constructor, we want the name of its parent rather than <unnamed>.
 402         if let DefPathData::Ctor = cur_def_key.disambiguated_data.data {
 403             let parent = DefId {
 404                 krate: def_id.krate,
 405                 index: cur_def_key
 406                     .parent
 407                     .expect("`DefPathData::Ctor` / `VariantData` missing a parent"),
 408             };
 409
 410             cur_def_key = self.tcx().def_key(parent);
 411         }
 412
 413         let Some(visible_parent) = visible_parent_map.get(&def_id).cloned() else {
 414             return Ok((self, false));
 415         };
 416
 417         let actual_parent = self.tcx().opt_parent(def_id);
 418         debug!(
 419             "try_print_visible_def_path: visible_parent={:?} actual_parent={:?}",
 420             visible_parent, actual_parent,
 421         );
 422
 423         let mut data = cur_def_key.disambiguated_data.data;
 424         debug!(
 425             "try_print_visible_def_path: data={:?} visible_parent={:?} actual_parent={:?}",
 426             data, visible_parent, actual_parent,
 427         );
 428
 429         match data {
 430             // In order to output a path that could actually be imported (valid and visible),
 431             // we need to handle re-exports correctly.
 432             //
 433             // For example, take `std::os::unix::process::CommandExt`, this trait is actually
 434             // defined at `std::sys::unix::ext::process::CommandExt` (at time of writing).
 435             //
 436             // `std::os::unix` reexports the contents of `std::sys::unix::ext`. `std::sys` is
 437             // private so the "true" path to `CommandExt` isn't accessible.
 438             //
 439             // In this case, the `visible_parent_map` will look something like this:
 440             //
 441             // (child) -> (parent)
 442             // `std::sys::unix::ext::process::CommandExt` -> `std::sys::unix::ext::process`
 443             // `std::sys::unix::ext::process` -> `std::sys::unix::ext`
 444             // `std::sys::unix::ext` -> `std::os`
 445             //
 446             // This is correct, as the visible parent of `std::sys::unix::ext` is in fact
 447             // `std::os`.
 448             //
 449             // When printing the path to `CommandExt` and looking at the `cur_def_key` that
 450             // corresponds to `std::sys::unix::ext`, we would normally print `ext` and then go
 451             // to the parent - resulting in a mangled path like
 452             // `std::os::ext::process::CommandExt`.
 453             //
 454             // Instead, we must detect that there was a re-export and instead print `unix`
 455             // (which is the name `std::sys::unix::ext` was re-exported as in `std::os`). To
 456             // do this, we compare the parent of `std::sys::unix::ext` (`std::sys::unix`) with
 457             // the visible parent (`std::os`). If these do not match, then we iterate over
 458             // the children of the visible parent (as was done when computing
 459             // `visible_parent_map`), looking for the specific child we currently have and then
 460             // have access to the re-exported name.
 461             DefPathData::TypeNs(ref mut name) if Some(visible_parent) != actual_parent => {
 462                 // Item might be re-exported several times, but filter for the one
 463                 // that's public and whose identifier isn't `_`.
 464                 let reexport = self
 465                     .tcx()
 466                     .module_children(visible_parent)
 467                     .iter()
 468                     .filter(|child| child.res.opt_def_id() == Some(def_id))
 469                     .find(|child| child.vis.is_public() && child.ident.name != kw::Underscore)
 470                     .map(|child| child.ident.name);
 471
 472                 if let Some(new_name) = reexport {
 473                     *name = new_name;
 474                 } else {
 475                     // There is no name that is public and isn't `_`, so bail.
 476                     return Ok((self, false));
 477                 }
 478             }
 479             // Re-exported `extern crate` (#43189).
 480             DefPathData::CrateRoot => {
 481                 data = DefPathData::TypeNs(self.tcx().crate_name(def_id.krate));
 482             }
 483             _ => {}
 484         }
 485         debug!("try_print_visible_def_path: data={:?}", data);
 486
 487         if callers.contains(&visible_parent) {
 488             return Ok((self, false));
 489         }
 490         callers.push(visible_parent);
 491         // HACK(eddyb) this bypasses `path_append`'s prefix printing to avoid
 492         // knowing ahead of time whether the entire path will succeed or not.
 493         // To support printers that do not implement `PrettyPrinter`, a `Vec` or
 494         // linked list on the stack would need to be built, before any printing.
 495         match self.try_print_visible_def_path_recur(visible_parent, callers)? {
 496             (cx, false) => return Ok((cx, false)),
 497             (cx, true) => self = cx,
 498         }
 499         callers.pop();
 500
 501         Ok((self.path_append(Ok, &DisambiguatedDefPathData { data, disambiguator: 0 })?, true))
 502     }
 503
 504     fn pretty_path_qualified(
 505         self,
 506         self_ty: Ty<'tcx>,
 507         trait_ref: Option<ty::TraitRef<'tcx>>,
 508     ) -> Result<Self::Path, Self::Error> {
 509         if trait_ref.is_none() {
 510             // Inherent impls. Try to print `Foo::bar` for an inherent
 511             // impl on `Foo`, but fallback to `<Foo>::bar` if self-type is
 512             // anything other than a simple path.
 513             match self_ty.kind() {
 514                 ty::Adt(..)
 515                 | ty::Foreign(_)
 516                 | ty::Bool
 517                 | ty::Char
 518                 | ty::Str
 519                 | ty::Int(_)
 520                 | ty::Uint(_)
 521                 | ty::Float(_) => {
 522                     return self_ty.print(self);
 523                 }
 524
 525                 _ => {}
 526             }
 527         }
 528
 529         self.generic_delimiters(|mut cx| {
 530             define_scoped_cx!(cx);
 531
 532             p!(print(self_ty));
 533             if let Some(trait_ref) = trait_ref {
 534                 p!(" as ", print(trait_ref.print_only_trait_path()));
 535             }
 536             Ok(cx)
 537         })
 538     }
 539
 540     fn pretty_path_append_impl(
 541         mut self,
 542         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 543         self_ty: Ty<'tcx>,
 544         trait_ref: Option<ty::TraitRef<'tcx>>,
 545     ) -> Result<Self::Path, Self::Error> {
 546         self = print_prefix(self)?;
 547
 548         self.generic_delimiters(|mut cx| {
 549             define_scoped_cx!(cx);
 550
 551             p!("impl ");
 552             if let Some(trait_ref) = trait_ref {
 553                 p!(print(trait_ref.print_only_trait_path()), " for ");
 554             }
 555             p!(print(self_ty));
 556
 557             Ok(cx)
 558         })
 559     }
 560
 561     fn pretty_print_type(mut self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
 562         define_scoped_cx!(self);
 563
 564         match *ty.kind() {
 565             ty::Bool => p!("bool"),
 566             ty::Char => p!("char"),
 567             ty::Int(t) => p!(write("{}", t.name_str())),
 568             ty::Uint(t) => p!(write("{}", t.name_str())),
 569             ty::Float(t) => p!(write("{}", t.name_str())),
 570             ty::RawPtr(ref tm) => {
 571                 p!(write(
 572                     "*{} ",
 573                     match tm.mutbl {
 574                         hir::Mutability::Mut => "mut",
 575                         hir::Mutability::Not => "const",
 576                     }
 577                 ));
 578                 p!(print(tm.ty))
 579             }
 580             ty::Ref(r, ty, mutbl) => {
 581                 p!("&");
 582                 if self.should_print_region(r) {
 583                     p!(print(r), " ");
 584                 }
 585                 p!(print(ty::TypeAndMut { ty, mutbl }))
 586             }
 587             ty::Never => p!("!"),
 588             ty::Tuple(ref tys) => {
 589                 p!("(", comma_sep(tys.iter()));
 590                 if tys.len() == 1 {
 591                     p!(",");
 592                 }
 593                 p!(")")
 594             }
 595             ty::FnDef(def_id, substs) => {
 596                 let sig = self.tcx().bound_fn_sig(def_id).subst(self.tcx(), substs);
 597                 p!(print(sig), " {{", print_value_path(def_id, substs), "}}");
 598             }
 599             ty::FnPtr(ref bare_fn) => p!(print(bare_fn)),
 600             ty::Infer(infer_ty) => {
 601                 let verbose = self.should_print_verbose();
 602                 if let ty::TyVar(ty_vid) = infer_ty {
 603                     if let Some(name) = self.ty_infer_name(ty_vid) {
 604                         p!(write("{}", name))
 605                     } else {
 606                         if verbose {
 607                             p!(write("{:?}", infer_ty))
 608                         } else {
 609                             p!(write("{}", infer_ty))
 610                         }
 611                     }
 612                 } else {
 613                     if verbose { p!(write("{:?}", infer_ty)) } else { p!(write("{}", infer_ty)) }
 614                 }
 615             }
 616             ty::Error(_) => p!("[type error]"),
 617             ty::Param(ref param_ty) => p!(print(param_ty)),
 618             ty::Bound(debruijn, bound_ty) => match bound_ty.kind {
 619                 ty::BoundTyKind::Anon => self.pretty_print_bound_var(debruijn, bound_ty.var)?,
 620                 ty::BoundTyKind::Param(p) => p!(write("{}", p)),
 621             },
 622             ty::Adt(def, substs) => {
 623                 p!(print_def_path(def.did(), substs));
 624             }
 625             ty::Dynamic(data, r, repr) => {
 626                 let print_r = self.should_print_region(r);
 627                 if print_r {
 628                     p!("(");
 629                 }
 630                 match repr {
 631                     ty::Dyn => p!("dyn "),
 632                     ty::DynStar => p!("dyn* "),
 633                 }
 634                 p!(print(data));
 635                 if print_r {
 636                     p!(" + ", print(r), ")");
 637                 }
 638             }
 639             ty::Foreign(def_id) => {
 640                 p!(print_def_path(def_id, &[]));
 641             }
 642             ty::Projection(ref data) => {
 643                 if !(self.should_print_verbose() || NO_QUERIES.with(|q| q.get()))
 644                     && self.tcx().def_kind(data.item_def_id) == DefKind::ImplTraitPlaceholder
 645                 {
 646                     return self.pretty_print_opaque_impl_type(data.item_def_id, data.substs);
 647                 } else {
 648                     p!(print(data))
 649                 }
 650             }
 651             ty::Placeholder(placeholder) => p!(write("Placeholder({:?})", placeholder)),
 652             ty::Opaque(def_id, substs) => {
 653                 // FIXME(eddyb) print this with `print_def_path`.
 654                 // We use verbose printing in 'NO_QUERIES' mode, to
 655                 // avoid needing to call `predicates_of`. This should
 656                 // only affect certain debug messages (e.g. messages printed
 657                 // from `rustc_middle::ty` during the computation of `tcx.predicates_of`),
 658                 // and should have no effect on any compiler output.
 659                 if self.should_print_verbose() || NO_QUERIES.with(|q| q.get()) {
 660                     p!(write("Opaque({:?}, {:?})", def_id, substs));
 661                     return Ok(self);
 662                 }
 663
 664                 let parent = self.tcx().parent(def_id);
 665                 match self.tcx().def_kind(parent) {
 666                     DefKind::TyAlias | DefKind::AssocTy => {
 667                         if let ty::Opaque(d, _) = *self.tcx().type_of(parent).kind() {
 668                             if d == def_id {
 669                                 // If the type alias directly starts with the `impl` of the
 670                                 // opaque type we're printing, then skip the `::{opaque#1}`.
 671                                 p!(print_def_path(parent, substs));
 672                                 return Ok(self);
 673                             }
 674                         }
 675                         // Complex opaque type, e.g. `type Foo = (i32, impl Debug);`
 676                         p!(print_def_path(def_id, substs));
 677                         return Ok(self);
 678                     }
 679                     _ => return self.pretty_print_opaque_impl_type(def_id, substs),
 680                 }
 681             }
 682             ty::Str => p!("str"),
 683             ty::Generator(did, substs, movability) => {
 684                 p!(write("["));
 685                 let generator_kind = self.tcx().generator_kind(did).unwrap();
 686                 let should_print_movability =
 687                     self.should_print_verbose() || generator_kind == hir::GeneratorKind::Gen;
 688
 689                 if should_print_movability {
 690                     match movability {
 691                         hir::Movability::Movable => {}
 692                         hir::Movability::Static => p!("static "),
 693                     }
 694                 }
 695
 696                 if !self.should_print_verbose() {
 697                     p!(write("{}", generator_kind));
 698                     // FIXME(eddyb) should use `def_span`.
 699                     if let Some(did) = did.as_local() {
 700                         let span = self.tcx().def_span(did);
 701                         p!(write(
 702                             "@{}",
 703                             // This may end up in stderr diagnostics but it may also be emitted
 704                             // into MIR. Hence we use the remapped path if available
 705                             self.tcx().sess.source_map().span_to_embeddable_string(span)
 706                         ));
 707                     } else {
 708                         p!(write("@"), print_def_path(did, substs));
 709                     }
 710                 } else {
 711                     p!(print_def_path(did, substs));
 712                     p!(" upvar_tys=(");
 713                     if !substs.as_generator().is_valid() {
 714                         p!("unavailable");
 715                     } else {
 716                         self = self.comma_sep(substs.as_generator().upvar_tys())?;
 717                     }
 718                     p!(")");
 719
 720                     if substs.as_generator().is_valid() {
 721                         p!(" ", print(substs.as_generator().witness()));
 722                     }
 723                 }
 724
 725                 p!("]")
 726             }
 727             ty::GeneratorWitness(types) => {
 728                 p!(in_binder(&types));
 729             }
 730             ty::Closure(did, substs) => {
 731                 p!(write("["));
 732                 if !self.should_print_verbose() {
 733                     p!(write("closure"));
 734                     // FIXME(eddyb) should use `def_span`.
 735                     if let Some(did) = did.as_local() {
 736                         if self.tcx().sess.opts.unstable_opts.span_free_formats {
 737                             p!("@", print_def_path(did.to_def_id(), substs));
 738                         } else {
 739                             let span = self.tcx().def_span(did);
 740                             p!(write(
 741                                 "@{}",
 742                                 // This may end up in stderr diagnostics but it may also be emitted
 743                                 // into MIR. Hence we use the remapped path if available
 744                                 self.tcx().sess.source_map().span_to_embeddable_string(span)
 745                             ));
 746                         }
 747                     } else {
 748                         p!(write("@"), print_def_path(did, substs));
 749                     }
 750                 } else {
 751                     p!(print_def_path(did, substs));
 752                     if !substs.as_closure().is_valid() {
 753                         p!(" closure_substs=(unavailable)");
 754                         p!(write(" substs={:?}", substs));
 755                     } else {
 756                         p!(" closure_kind_ty=", print(substs.as_closure().kind_ty()));
 757                         p!(
 758                             " closure_sig_as_fn_ptr_ty=",
 759                             print(substs.as_closure().sig_as_fn_ptr_ty())
 760                         );
 761                         p!(" upvar_tys=(");
 762                         self = self.comma_sep(substs.as_closure().upvar_tys())?;
 763                         p!(")");
 764                     }
 765                 }
 766                 p!("]");
 767             }
 768             ty::Array(ty, sz) => {
 769                 p!("[", print(ty), "; ");
 770                 if self.should_print_verbose() {
 771                     p!(write("{:?}", sz));
 772                 } else if let ty::ConstKind::Unevaluated(..) = sz.kind() {
 773                     // Do not try to evaluate unevaluated constants. If we are const evaluating an
 774                     // array length anon const, rustc will (with debug assertions) print the
 775                     // constant's path. Which will end up here again.
 776                     p!("_");
 777                 } else if let Some(n) = sz.kind().try_to_bits(self.tcx().data_layout.pointer_size) {
 778                     p!(write("{}", n));
 779                 } else if let ty::ConstKind::Param(param) = sz.kind() {
 780                     p!(print(param));
 781                 } else {
 782                     p!("_");
 783                 }
 784                 p!("]")
 785             }
 786             ty::Slice(ty) => p!("[", print(ty), "]"),
 787         }
 788
 789         Ok(self)
 790     }
 791
 792     fn pretty_print_opaque_impl_type(
 793         mut self,
 794         def_id: DefId,
 795         substs: &'tcx ty::List<ty::GenericArg<'tcx>>,
 796     ) -> Result<Self::Type, Self::Error> {
 797         let tcx = self.tcx();
 798
 799         // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
 800         // by looking up the projections associated with the def_id.
 801         let bounds = tcx.bound_explicit_item_bounds(def_id);
 802
 803         let mut traits = FxIndexMap::default();
 804         let mut fn_traits = FxIndexMap::default();
 805         let mut is_sized = false;
 806         let mut lifetimes = SmallVec::<[ty::Region<'tcx>; 1]>::new();
 807
 808         for (predicate, _) in bounds.subst_iter_copied(tcx, substs) {
 809             let bound_predicate = predicate.kind();
 810
 811             match bound_predicate.skip_binder() {
 812                 ty::PredicateKind::Clause(ty::Clause::Trait(pred)) => {
 813                     let trait_ref = bound_predicate.rebind(pred.trait_ref);
 814
 815                     // Don't print + Sized, but rather + ?Sized if absent.
 816                     if Some(trait_ref.def_id()) == tcx.lang_items().sized_trait() {
 817                         is_sized = true;
 818                         continue;
 819                     }
 820
 821                     self.insert_trait_and_projection(trait_ref, None, &mut traits, &mut fn_traits);
 822                 }
 823                 ty::PredicateKind::Clause(ty::Clause::Projection(pred)) => {
 824                     let proj_ref = bound_predicate.rebind(pred);
 825                     let trait_ref = proj_ref.required_poly_trait_ref(tcx);
 826
 827                     // Projection type entry -- the def-id for naming, and the ty.
 828                     let proj_ty = (proj_ref.projection_def_id(), proj_ref.term());
 829
 830                     self.insert_trait_and_projection(
 831                         trait_ref,
 832                         Some(proj_ty),
 833                         &mut traits,
 834                         &mut fn_traits,
 835                     );
 836                 }
 837                 ty::PredicateKind::Clause(ty::Clause::TypeOutlives(outlives)) => {
 838                     lifetimes.push(outlives.1);
 839                 }
 840                 _ => {}
 841             }
 842         }
 843
 844         write!(self, "impl ")?;
 845
 846         let mut first = true;
 847         // Insert parenthesis around (Fn(A, B) -> C) if the opaque ty has more than one other trait
 848         let paren_needed = fn_traits.len() > 1 || traits.len() > 0 || !is_sized;
 849
 850         for (fn_once_trait_ref, entry) in fn_traits {
 851             write!(self, "{}", if first { "" } else { " + " })?;
 852             write!(self, "{}", if paren_needed { "(" } else { "" })?;
 853
 854             self = self.wrap_binder(&fn_once_trait_ref, |trait_ref, mut cx| {
 855                 define_scoped_cx!(cx);
 856                 // Get the (single) generic ty (the args) of this FnOnce trait ref.
 857                 let generics = tcx.generics_of(trait_ref.def_id);
 858                 let args = generics.own_substs_no_defaults(tcx, trait_ref.substs);
 859
 860                 match (entry.return_ty, args[0].expect_ty()) {
 861                     // We can only print `impl Fn() -> ()` if we have a tuple of args and we recorded
 862                     // a return type.
 863                     (Some(return_ty), arg_tys) if matches!(arg_tys.kind(), ty::Tuple(_)) => {
 864                         let name = if entry.fn_trait_ref.is_some() {
 865                             "Fn"
 866                         } else if entry.fn_mut_trait_ref.is_some() {
 867                             "FnMut"
 868                         } else {
 869                             "FnOnce"
 870                         };
 871
 872                         p!(write("{}(", name));
 873
 874                         for (idx, ty) in arg_tys.tuple_fields().iter().enumerate() {
 875                             if idx > 0 {
 876                                 p!(", ");
 877                             }
 878                             p!(print(ty));
 879                         }
 880
 881                         p!(")");
 882                         if let Some(ty) = return_ty.skip_binder().ty() {
 883                             if !ty.is_unit() {
 884                                 p!(" -> ", print(return_ty));
 885                             }
 886                         }
 887                         p!(write("{}", if paren_needed { ")" } else { "" }));
 888
 889                         first = false;
 890                     }
 891                     // If we got here, we can't print as a `impl Fn(A, B) -> C`. Just record the
 892                     // trait_refs we collected in the OpaqueFnEntry as normal trait refs.
 893                     _ => {
 894                         if entry.has_fn_once {
 895                             traits.entry(fn_once_trait_ref).or_default().extend(
 896                                 // Group the return ty with its def id, if we had one.
 897                                 entry
 898                                     .return_ty
 899                                     .map(|ty| (tcx.require_lang_item(LangItem::FnOnce, None), ty)),
 900                             );
 901                         }
 902                         if let Some(trait_ref) = entry.fn_mut_trait_ref {
 903                             traits.entry(trait_ref).or_default();
 904                         }
 905                         if let Some(trait_ref) = entry.fn_trait_ref {
 906                             traits.entry(trait_ref).or_default();
 907                         }
 908                     }
 909                 }
 910
 911                 Ok(cx)
 912             })?;
 913         }
 914
 915         // Print the rest of the trait types (that aren't Fn* family of traits)
 916         for (trait_ref, assoc_items) in traits {
 917             write!(self, "{}", if first { "" } else { " + " })?;
 918
 919             self = self.wrap_binder(&trait_ref, |trait_ref, mut cx| {
 920                 define_scoped_cx!(cx);
 921                 p!(print(trait_ref.print_only_trait_name()));
 922
 923                 let generics = tcx.generics_of(trait_ref.def_id);
 924                 let args = generics.own_substs_no_defaults(tcx, trait_ref.substs);
 925
 926                 if !args.is_empty() || !assoc_items.is_empty() {
 927                     let mut first = true;
 928
 929                     for ty in args {
 930                         if first {
 931                             p!("<");
 932                             first = false;
 933                         } else {
 934                             p!(", ");
 935                         }
 936                         p!(print(ty));
 937                     }
 938
 939                     for (assoc_item_def_id, term) in assoc_items {
 940                         // Skip printing `<[generator@] as Generator<_>>::Return` from async blocks,
 941                         // unless we can find out what generator return type it comes from.
 942                         let term = if let Some(ty) = term.skip_binder().ty()
 943                             && let ty::Projection(proj) = ty.kind()
 944                             && let Some(assoc) = tcx.opt_associated_item(proj.item_def_id)
 945                             && assoc.trait_container(tcx) == tcx.lang_items().gen_trait()
 946                             && assoc.name == rustc_span::sym::Return
 947                         {
 948                             if let ty::Generator(_, substs, _) = substs.type_at(0).kind() {
 949                                 let return_ty = substs.as_generator().return_ty();
 950                                 if !return_ty.is_ty_var() {
 951                                     return_ty.into()
 952                                 } else {
 953                                     continue;
 954                                 }
 955                             } else {
 956                                 continue;
 957                             }
 958                         } else {
 959                             term.skip_binder()
 960                         };
 961
 962                         if first {
 963                             p!("<");
 964                             first = false;
 965                         } else {
 966                             p!(", ");
 967                         }
 968
 969                         p!(write("{} = ", tcx.associated_item(assoc_item_def_id).name));
 970
 971                         match term.unpack() {
 972                             TermKind::Ty(ty) => p!(print(ty)),
 973                             TermKind::Const(c) => p!(print(c)),
 974                         };
 975                     }
 976
 977                     if !first {
 978                         p!(">");
 979                     }
 980                 }
 981
 982                 first = false;
 983                 Ok(cx)
 984             })?;
 985         }
 986
 987         if !is_sized {
 988             write!(self, "{}?Sized", if first { "" } else { " + " })?;
 989         } else if first {
 990             write!(self, "Sized")?;
 991         }
 992
 993         for re in lifetimes {
 994             write!(self, " + ")?;
 995             self = self.print_region(re)?;
 996         }
 997
 998         Ok(self)
 999     }
1000
1001     /// Insert the trait ref and optionally a projection type associated with it into either the
1002     /// traits map or fn_traits map, depending on if the trait is in the Fn* family of traits.
1003     fn insert_trait_and_projection(
1004         &mut self,
1005         trait_ref: ty::PolyTraitRef<'tcx>,
1006         proj_ty: Option<(DefId, ty::Binder<'tcx, Term<'tcx>>)>,
1007         traits: &mut FxIndexMap<
1008             ty::PolyTraitRef<'tcx>,
1009             FxIndexMap<DefId, ty::Binder<'tcx, Term<'tcx>>>,
1010         >,
1011         fn_traits: &mut FxIndexMap<ty::PolyTraitRef<'tcx>, OpaqueFnEntry<'tcx>>,
1012     ) {
1013         let trait_def_id = trait_ref.def_id();
1014
1015         // If our trait_ref is FnOnce or any of its children, project it onto the parent FnOnce
1016         // super-trait ref and record it there.
1017         if let Some(fn_once_trait) = self.tcx().lang_items().fn_once_trait() {
1018             // If we have a FnOnce, then insert it into
1019             if trait_def_id == fn_once_trait {
1020                 let entry = fn_traits.entry(trait_ref).or_default();
1021                 // Optionally insert the return_ty as well.
1022                 if let Some((_, ty)) = proj_ty {
1023                     entry.return_ty = Some(ty);
1024                 }
1025                 entry.has_fn_once = true;
1026                 return;
1027             } else if Some(trait_def_id) == self.tcx().lang_items().fn_mut_trait() {
1028                 let super_trait_ref = crate::traits::util::supertraits(self.tcx(), trait_ref)
1029                     .find(|super_trait_ref| super_trait_ref.def_id() == fn_once_trait)
1030                     .unwrap();
1031
1032                 fn_traits.entry(super_trait_ref).or_default().fn_mut_trait_ref = Some(trait_ref);
1033                 return;
1034             } else if Some(trait_def_id) == self.tcx().lang_items().fn_trait() {
1035                 let super_trait_ref = crate::traits::util::supertraits(self.tcx(), trait_ref)
1036                     .find(|super_trait_ref| super_trait_ref.def_id() == fn_once_trait)
1037                     .unwrap();
1038
1039                 fn_traits.entry(super_trait_ref).or_default().fn_trait_ref = Some(trait_ref);
1040                 return;
1041             }
1042         }
1043
1044         // Otherwise, just group our traits and projection types.
1045         traits.entry(trait_ref).or_default().extend(proj_ty);
1046     }
1047
1048     fn pretty_print_bound_var(
1049         &mut self,
1050         debruijn: ty::DebruijnIndex,
1051         var: ty::BoundVar,
1052     ) -> Result<(), Self::Error> {
1053         if debruijn == ty::INNERMOST {
1054             write!(self, "^{}", var.index())
1055         } else {
1056             write!(self, "^{}_{}", debruijn.index(), var.index())
1057         }
1058     }
1059
1060     fn ty_infer_name(&self, _: ty::TyVid) -> Option<Symbol> {
1061         None
1062     }
1063
1064     fn const_infer_name(&self, _: ty::ConstVid<'tcx>) -> Option<Symbol> {
1065         None
1066     }
1067
1068     fn pretty_print_dyn_existential(
1069         mut self,
1070         predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
1071     ) -> Result<Self::DynExistential, Self::Error> {
1072         // Generate the main trait ref, including associated types.
1073         let mut first = true;
1074
1075         if let Some(principal) = predicates.principal() {
1076             self = self.wrap_binder(&principal, |principal, mut cx| {
1077                 define_scoped_cx!(cx);
1078                 p!(print_def_path(principal.def_id, &[]));
1079
1080                 let mut resugared = false;
1081
1082                 // Special-case `Fn(...) -> ...` and re-sugar it.
1083                 let fn_trait_kind = cx.tcx().fn_trait_kind_from_def_id(principal.def_id);
1084                 if !cx.should_print_verbose() && fn_trait_kind.is_some() {
1085                     if let ty::Tuple(tys) = principal.substs.type_at(0).kind() {
1086                         let mut projections = predicates.projection_bounds();
1087                         if let (Some(proj), None) = (projections.next(), projections.next()) {
1088                             p!(pretty_fn_sig(
1089                                 tys,
1090                                 false,
1091                                 proj.skip_binder().term.ty().expect("Return type was a const")
1092                             ));
1093                             resugared = true;
1094                         }
1095                     }
1096                 }
1097
1098                 // HACK(eddyb) this duplicates `FmtPrinter`'s `path_generic_args`,
1099                 // in order to place the projections inside the `<...>`.
1100                 if !resugared {
1101                     // Use a type that can't appear in defaults of type parameters.
1102                     let dummy_cx = cx.tcx().mk_ty_infer(ty::FreshTy(0));
1103                     let principal = principal.with_self_ty(cx.tcx(), dummy_cx);
1104
1105                     let args = cx
1106                         .tcx()
1107                         .generics_of(principal.def_id)
1108                         .own_substs_no_defaults(cx.tcx(), principal.substs);
1109
1110                     let mut projections = predicates.projection_bounds();
1111
1112                     let mut args = args.iter().cloned();
1113                     let arg0 = args.next();
1114                     let projection0 = projections.next();
1115                     if arg0.is_some() || projection0.is_some() {
1116                         let args = arg0.into_iter().chain(args);
1117                         let projections = projection0.into_iter().chain(projections);
1118
1119                         p!(generic_delimiters(|mut cx| {
1120                             cx = cx.comma_sep(args)?;
1121                             if arg0.is_some() && projection0.is_some() {
1122                                 write!(cx, ", ")?;
1123                             }
1124                             cx.comma_sep(projections)
1125                         }));
1126                     }
1127                 }
1128                 Ok(cx)
1129             })?;
1130
1131             first = false;
1132         }
1133
1134         define_scoped_cx!(self);
1135
1136         // Builtin bounds.
1137         // FIXME(eddyb) avoid printing twice (needed to ensure
1138         // that the auto traits are sorted *and* printed via cx).
1139         let mut auto_traits: Vec<_> = predicates.auto_traits().collect();
1140
1141         // The auto traits come ordered by `DefPathHash`. While
1142         // `DefPathHash` is *stable* in the sense that it depends on
1143         // neither the host nor the phase of the moon, it depends
1144         // "pseudorandomly" on the compiler version and the target.
1145         //
1146         // To avoid causing instabilities in compiletest
1147         // output, sort the auto-traits alphabetically.
1148         auto_traits.sort_by_cached_key(|did| with_no_trimmed_paths!(self.tcx().def_path_str(*did)));
1149
1150         for def_id in auto_traits {
1151             if !first {
1152                 p!(" + ");
1153             }
1154             first = false;
1155
1156             p!(print_def_path(def_id, &[]));
1157         }
1158
1159         Ok(self)
1160     }
1161
1162     fn pretty_fn_sig(
1163         mut self,
1164         inputs: &[Ty<'tcx>],
1165         c_variadic: bool,
1166         output: Ty<'tcx>,
1167     ) -> Result<Self, Self::Error> {
1168         define_scoped_cx!(self);
1169
1170         p!("(", comma_sep(inputs.iter().copied()));
1171         if c_variadic {
1172             if !inputs.is_empty() {
1173                 p!(", ");
1174             }
1175             p!("...");
1176         }
1177         p!(")");
1178         if !output.is_unit() {
1179             p!(" -> ", print(output));
1180         }
1181
1182         Ok(self)
1183     }
1184
1185     fn pretty_print_const(
1186         mut self,
1187         ct: ty::Const<'tcx>,
1188         print_ty: bool,
1189     ) -> Result<Self::Const, Self::Error> {
1190         define_scoped_cx!(self);
1191
1192         if self.should_print_verbose() {
1193             p!(write("Const({:?}: {:?})", ct.kind(), ct.ty()));
1194             return Ok(self);
1195         }
1196
1197         macro_rules! print_underscore {
1198             () => {{
1199                 if print_ty {
1200                     self = self.typed_value(
1201                         |mut this| {
1202                             write!(this, "_")?;
1203                             Ok(this)
1204                         },
1205                         |this| this.print_type(ct.ty()),
1206                         ": ",
1207                     )?;
1208                 } else {
1209                     write!(self, "_")?;
1210                 }
1211             }};
1212         }
1213
1214         match ct.kind() {
1215             ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, substs }) => {
1216                 match self.tcx().def_kind(def.did) {
1217                     DefKind::Static(..) | DefKind::Const | DefKind::AssocConst => {
1218                         p!(print_value_path(def.did, substs))
1219                     }
1220                     _ => {
1221                         if def.is_local() {
1222                             let span = self.tcx().def_span(def.did);
1223                             if let Ok(snip) = self.tcx().sess.source_map().span_to_snippet(span) {
1224                                 p!(write("{}", snip))
1225                             } else {
1226                                 print_underscore!()
1227                             }
1228                         } else {
1229                             print_underscore!()
1230                         }
1231                     }
1232                 }
1233             }
1234             ty::ConstKind::Infer(infer_ct) => {
1235                 match infer_ct {
1236                     ty::InferConst::Var(ct_vid)
1237                         if let Some(name) = self.const_infer_name(ct_vid) =>
1238                             p!(write("{}", name)),
1239                     _ => print_underscore!(),
1240                 }
1241             }
1242             ty::ConstKind::Param(ParamConst { name, .. }) => p!(write("{}", name)),
1243             ty::ConstKind::Value(value) => {
1244                 return self.pretty_print_const_valtree(value, ct.ty(), print_ty);
1245             }
1246
1247             ty::ConstKind::Bound(debruijn, bound_var) => {
1248                 self.pretty_print_bound_var(debruijn, bound_var)?
1249             }
1250             ty::ConstKind::Placeholder(placeholder) => p!(write("Placeholder({:?})", placeholder)),
1251             // FIXME(generic_const_exprs):
1252             // write out some legible representation of an abstract const?
1253             ty::ConstKind::Expr(_) => p!("[Const Expr]"),
1254             ty::ConstKind::Error(_) => p!("[const error]"),
1255         };
1256         Ok(self)
1257     }
1258
1259     fn pretty_print_const_scalar(
1260         self,
1261         scalar: Scalar,
1262         ty: Ty<'tcx>,
1263         print_ty: bool,
1264     ) -> Result<Self::Const, Self::Error> {
1265         match scalar {
1266             Scalar::Ptr(ptr, _size) => self.pretty_print_const_scalar_ptr(ptr, ty, print_ty),
1267             Scalar::Int(int) => self.pretty_print_const_scalar_int(int, ty, print_ty),
1268         }
1269     }
1270
1271     fn pretty_print_const_scalar_ptr(
1272         mut self,
1273         ptr: Pointer,
1274         ty: Ty<'tcx>,
1275         print_ty: bool,
1276     ) -> Result<Self::Const, Self::Error> {
1277         define_scoped_cx!(self);
1278
1279         let (alloc_id, offset) = ptr.into_parts();
1280         match ty.kind() {
1281             // Byte strings (&[u8; N])
1282             ty::Ref(_, inner, _) => {
1283                 if let ty::Array(elem, len) = inner.kind() {
1284                     if let ty::Uint(ty::UintTy::U8) = elem.kind() {
1285                         if let ty::ConstKind::Value(ty::ValTree::Leaf(int)) = len.kind() {
1286                             match self.tcx().try_get_global_alloc(alloc_id) {
1287                                 Some(GlobalAlloc::Memory(alloc)) => {
1288                                     let len = int.assert_bits(self.tcx().data_layout.pointer_size);
1289                                     let range =
1290                                         AllocRange { start: offset, size: Size::from_bytes(len) };
1291                                     if let Ok(byte_str) =
1292                                         alloc.inner().get_bytes_strip_provenance(&self.tcx(), range)
1293                                     {
1294                                         p!(pretty_print_byte_str(byte_str))
1295                                     } else {
1296                                         p!("<too short allocation>")
1297                                     }
1298                                 }
1299                                 // FIXME: for statics, vtables, and functions, we could in principle print more detail.
1300                                 Some(GlobalAlloc::Static(def_id)) => {
1301                                     p!(write("<static({:?})>", def_id))
1302                                 }
1303                                 Some(GlobalAlloc::Function(_)) => p!("<function>"),
1304                                 Some(GlobalAlloc::VTable(..)) => p!("<vtable>"),
1305                                 None => p!("<dangling pointer>"),
1306                             }
1307                             return Ok(self);
1308                         }
1309                     }
1310                 }
1311             }
1312             ty::FnPtr(_) => {
1313                 // FIXME: We should probably have a helper method to share code with the "Byte strings"
1314                 // printing above (which also has to handle pointers to all sorts of things).
1315                 if let Some(GlobalAlloc::Function(instance)) =
1316                     self.tcx().try_get_global_alloc(alloc_id)
1317                 {
1318                     self = self.typed_value(
1319                         |this| this.print_value_path(instance.def_id(), instance.substs),
1320                         |this| this.print_type(ty),
1321                         " as ",
1322                     )?;
1323                     return Ok(self);
1324                 }
1325             }
1326             _ => {}
1327         }
1328         // Any pointer values not covered by a branch above
1329         self = self.pretty_print_const_pointer(ptr, ty, print_ty)?;
1330         Ok(self)
1331     }
1332
1333     fn pretty_print_const_scalar_int(
1334         mut self,
1335         int: ScalarInt,
1336         ty: Ty<'tcx>,
1337         print_ty: bool,
1338     ) -> Result<Self::Const, Self::Error> {
1339         define_scoped_cx!(self);
1340
1341         match ty.kind() {
1342             // Bool
1343             ty::Bool if int == ScalarInt::FALSE => p!("false"),
1344             ty::Bool if int == ScalarInt::TRUE => p!("true"),
1345             // Float
1346             ty::Float(ty::FloatTy::F32) => {
1347                 p!(write("{}f32", Single::try_from(int).unwrap()))
1348             }
1349             ty::Float(ty::FloatTy::F64) => {
1350                 p!(write("{}f64", Double::try_from(int).unwrap()))
1351             }
1352             // Int
1353             ty::Uint(_) | ty::Int(_) => {
1354                 let int =
1355                     ConstInt::new(int, matches!(ty.kind(), ty::Int(_)), ty.is_ptr_sized_integral());
1356                 if print_ty { p!(write("{:#?}", int)) } else { p!(write("{:?}", int)) }
1357             }
1358             // Char
1359             ty::Char if char::try_from(int).is_ok() => {
1360                 p!(write("{:?}", char::try_from(int).unwrap()))
1361             }
1362             // Pointer types
1363             ty::Ref(..) | ty::RawPtr(_) | ty::FnPtr(_) => {
1364                 let data = int.assert_bits(self.tcx().data_layout.pointer_size);
1365                 self = self.typed_value(
1366                     |mut this| {
1367                         write!(this, "0x{:x}", data)?;
1368                         Ok(this)
1369                     },
1370                     |this| this.print_type(ty),
1371                     " as ",
1372                 )?;
1373             }
1374             // Nontrivial types with scalar bit representation
1375             _ => {
1376                 let print = |mut this: Self| {
1377                     if int.size() == Size::ZERO {
1378                         write!(this, "transmute(())")?;
1379                     } else {
1380                         write!(this, "transmute(0x{:x})", int)?;
1381                     }
1382                     Ok(this)
1383                 };
1384                 self = if print_ty {
1385                     self.typed_value(print, |this| this.print_type(ty), ": ")?
1386                 } else {
1387                     print(self)?
1388                 };
1389             }
1390         }
1391         Ok(self)
1392     }
1393
1394     /// This is overridden for MIR printing because we only want to hide alloc ids from users, not
1395     /// from MIR where it is actually useful.
1396     fn pretty_print_const_pointer<Prov: Provenance>(
1397         mut self,
1398         _: Pointer<Prov>,
1399         ty: Ty<'tcx>,
1400         print_ty: bool,
1401     ) -> Result<Self::Const, Self::Error> {
1402         if print_ty {
1403             self.typed_value(
1404                 |mut this| {
1405                     this.write_str("&_")?;
1406                     Ok(this)
1407                 },
1408                 |this| this.print_type(ty),
1409                 ": ",
1410             )
1411         } else {
1412             self.write_str("&_")?;
1413             Ok(self)
1414         }
1415     }
1416
1417     fn pretty_print_byte_str(mut self, byte_str: &'tcx [u8]) -> Result<Self::Const, Self::Error> {
1418         write!(self, "b\"{}\"", byte_str.escape_ascii())?;
1419         Ok(self)
1420     }
1421
1422     fn pretty_print_const_valtree(
1423         mut self,
1424         valtree: ty::ValTree<'tcx>,
1425         ty: Ty<'tcx>,
1426         print_ty: bool,
1427     ) -> Result<Self::Const, Self::Error> {
1428         define_scoped_cx!(self);
1429
1430         if self.should_print_verbose() {
1431             p!(write("ValTree({:?}: ", valtree), print(ty), ")");
1432             return Ok(self);
1433         }
1434
1435         let u8_type = self.tcx().types.u8;
1436         match (valtree, ty.kind()) {
1437             (ty::ValTree::Branch(_), ty::Ref(_, inner_ty, _)) => match inner_ty.kind() {
1438                 ty::Slice(t) if *t == u8_type => {
1439                     let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
1440                         bug!(
1441                             "expected to convert valtree {:?} to raw bytes for type {:?}",
1442                             valtree,
1443                             t
1444                         )
1445                     });
1446                     return self.pretty_print_byte_str(bytes);
1447                 }
1448                 ty::Str => {
1449                     let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
1450                         bug!("expected to convert valtree to raw bytes for type {:?}", ty)
1451                     });
1452                     p!(write("{:?}", String::from_utf8_lossy(bytes)));
1453                     return Ok(self);
1454                 }
1455                 _ => {
1456                     p!("&");
1457                     p!(pretty_print_const_valtree(valtree, *inner_ty, print_ty));
1458                     return Ok(self);
1459                 }
1460             },
1461             (ty::ValTree::Branch(_), ty::Array(t, _)) if *t == u8_type => {
1462                 let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
1463                     bug!("expected to convert valtree to raw bytes for type {:?}", t)
1464                 });
1465                 p!("*");
1466                 p!(pretty_print_byte_str(bytes));
1467                 return Ok(self);
1468             }
1469             // Aggregates, printed as array/tuple/struct/variant construction syntax.
1470             (ty::ValTree::Branch(_), ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) => {
1471                 let contents =
1472                     self.tcx().destructure_const(ty::Const::from_value(self.tcx(), valtree, ty));
1473                 let fields = contents.fields.iter().copied();
1474                 match *ty.kind() {
1475                     ty::Array(..) => {
1476                         p!("[", comma_sep(fields), "]");
1477                     }
1478                     ty::Tuple(..) => {
1479                         p!("(", comma_sep(fields));
1480                         if contents.fields.len() == 1 {
1481                             p!(",");
1482                         }
1483                         p!(")");
1484                     }
1485                     ty::Adt(def, _) if def.variants().is_empty() => {
1486                         self = self.typed_value(
1487                             |mut this| {
1488                                 write!(this, "unreachable()")?;
1489                                 Ok(this)
1490                             },
1491                             |this| this.print_type(ty),
1492                             ": ",
1493                         )?;
1494                     }
1495                     ty::Adt(def, substs) => {
1496                         let variant_idx =
1497                             contents.variant.expect("destructed const of adt without variant idx");
1498                         let variant_def = &def.variant(variant_idx);
1499                         p!(print_value_path(variant_def.def_id, substs));
1500                         match variant_def.ctor_kind() {
1501                             Some(CtorKind::Const) => {}
1502                             Some(CtorKind::Fn) => {
1503                                 p!("(", comma_sep(fields), ")");
1504                             }
1505                             None => {
1506                                 p!(" {{ ");
1507                                 let mut first = true;
1508                                 for (field_def, field) in iter::zip(&variant_def.fields, fields) {
1509                                     if !first {
1510                                         p!(", ");
1511                                     }
1512                                     p!(write("{}: ", field_def.name), print(field));
1513                                     first = false;
1514                                 }
1515                                 p!(" }}");
1516                             }
1517                         }
1518                     }
1519                     _ => unreachable!(),
1520                 }
1521                 return Ok(self);
1522             }
1523             (ty::ValTree::Leaf(leaf), ty::Ref(_, inner_ty, _)) => {
1524                 p!(write("&"));
1525                 return self.pretty_print_const_scalar_int(leaf, *inner_ty, print_ty);
1526             }
1527             (ty::ValTree::Leaf(leaf), _) => {
1528                 return self.pretty_print_const_scalar_int(leaf, ty, print_ty);
1529             }
1530             // FIXME(oli-obk): also pretty print arrays and other aggregate constants by reading
1531             // their fields instead of just dumping the memory.
1532             _ => {}
1533         }
1534
1535         // fallback
1536         if valtree == ty::ValTree::zst() {
1537             p!(write("<ZST>"));
1538         } else {
1539             p!(write("{:?}", valtree));
1540         }
1541         if print_ty {
1542             p!(": ", print(ty));
1543         }
1544         Ok(self)
1545     }
1546
1547     fn pretty_closure_as_impl(
1548         mut self,
1549         closure: ty::ClosureSubsts<'tcx>,
1550     ) -> Result<Self::Const, Self::Error> {
1551         let sig = closure.sig();
1552         let kind = closure.kind_ty().to_opt_closure_kind().unwrap_or(ty::ClosureKind::Fn);
1553
1554         write!(self, "impl ")?;
1555         self.wrap_binder(&sig, |sig, mut cx| {
1556             define_scoped_cx!(cx);
1557
1558             p!(print(kind), "(");
1559             for (i, arg) in sig.inputs()[0].tuple_fields().iter().enumerate() {
1560                 if i > 0 {
1561                     p!(", ");
1562                 }
1563                 p!(print(arg));
1564             }
1565             p!(")");
1566
1567             if !sig.output().is_unit() {
1568                 p!(" -> ", print(sig.output()));
1569             }
1570
1571             Ok(cx)
1572         })
1573     }
1574
1575     fn should_print_verbose(&self) -> bool {
1576         self.tcx().sess.verbose()
1577     }
1578 }
1579
1580 // HACK(eddyb) boxed to avoid moving around a large struct by-value.
1581 pub struct FmtPrinter<'a, 'tcx>(Box<FmtPrinterData<'a, 'tcx>>);
1582
1583 pub struct FmtPrinterData<'a, 'tcx> {
1584     tcx: TyCtxt<'tcx>,
1585     fmt: String,
1586
1587     empty_path: bool,
1588     in_value: bool,
1589     pub print_alloc_ids: bool,
1590
1591     // set of all named (non-anonymous) region names
1592     used_region_names: FxHashSet<Symbol>,
1593
1594     region_index: usize,
1595     binder_depth: usize,
1596     printed_type_count: usize,
1597     type_length_limit: Limit,
1598     truncated: bool,
1599
1600     pub region_highlight_mode: RegionHighlightMode<'tcx>,
1601
1602     pub ty_infer_name_resolver: Option<Box<dyn Fn(ty::TyVid) -> Option<Symbol> + 'a>>,
1603     pub const_infer_name_resolver: Option<Box<dyn Fn(ty::ConstVid<'tcx>) -> Option<Symbol> + 'a>>,
1604 }
1605
1606 impl<'a, 'tcx> Deref for FmtPrinter<'a, 'tcx> {
1607     type Target = FmtPrinterData<'a, 'tcx>;
1608     fn deref(&self) -> &Self::Target {
1609         &self.0
1610     }
1611 }
1612
1613 impl DerefMut for FmtPrinter<'_, '_> {
1614     fn deref_mut(&mut self) -> &mut Self::Target {
1615         &mut self.0
1616     }
1617 }
1618
1619 impl<'a, 'tcx> FmtPrinter<'a, 'tcx> {
1620     pub fn new(tcx: TyCtxt<'tcx>, ns: Namespace) -> Self {
1621         Self::new_with_limit(tcx, ns, tcx.type_length_limit())
1622     }
1623
1624     pub fn new_with_limit(tcx: TyCtxt<'tcx>, ns: Namespace, type_length_limit: Limit) -> Self {
1625         FmtPrinter(Box::new(FmtPrinterData {
1626             tcx,
1627             // Estimated reasonable capacity to allocate upfront based on a few
1628             // benchmarks.
1629             fmt: String::with_capacity(64),
1630             empty_path: false,
1631             in_value: ns == Namespace::ValueNS,
1632             print_alloc_ids: false,
1633             used_region_names: Default::default(),
1634             region_index: 0,
1635             binder_depth: 0,
1636             printed_type_count: 0,
1637             type_length_limit,
1638             truncated: false,
1639             region_highlight_mode: RegionHighlightMode::new(tcx),
1640             ty_infer_name_resolver: None,
1641             const_infer_name_resolver: None,
1642         }))
1643     }
1644
1645     pub fn into_buffer(self) -> String {
1646         self.0.fmt
1647     }
1648 }
1649
1650 // HACK(eddyb) get rid of `def_path_str` and/or pass `Namespace` explicitly always
1651 // (but also some things just print a `DefId` generally so maybe we need this?)
1652 fn guess_def_namespace(tcx: TyCtxt<'_>, def_id: DefId) -> Namespace {
1653     match tcx.def_key(def_id).disambiguated_data.data {
1654         DefPathData::TypeNs(..) | DefPathData::CrateRoot | DefPathData::ImplTrait => {
1655             Namespace::TypeNS
1656         }
1657
1658         DefPathData::ValueNs(..)
1659         | DefPathData::AnonConst
1660         | DefPathData::ClosureExpr
1661         | DefPathData::Ctor => Namespace::ValueNS,
1662
1663         DefPathData::MacroNs(..) => Namespace::MacroNS,
1664
1665         _ => Namespace::TypeNS,
1666     }
1667 }
1668
1669 impl<'t> TyCtxt<'t> {
1670     /// Returns a string identifying this `DefId`. This string is
1671     /// suitable for user output.
1672     pub fn def_path_str(self, def_id: DefId) -> String {
1673         self.def_path_str_with_substs(def_id, &[])
1674     }
1675
1676     pub fn def_path_str_with_substs(self, def_id: DefId, substs: &'t [GenericArg<'t>]) -> String {
1677         let ns = guess_def_namespace(self, def_id);
1678         debug!("def_path_str: def_id={:?}, ns={:?}", def_id, ns);
1679         FmtPrinter::new(self, ns).print_def_path(def_id, substs).unwrap().into_buffer()
1680     }
1681
1682     pub fn value_path_str_with_substs(self, def_id: DefId, substs: &'t [GenericArg<'t>]) -> String {
1683         let ns = guess_def_namespace(self, def_id);
1684         debug!("value_path_str: def_id={:?}, ns={:?}", def_id, ns);
1685         FmtPrinter::new(self, ns).print_value_path(def_id, substs).unwrap().into_buffer()
1686     }
1687 }
1688
1689 impl fmt::Write for FmtPrinter<'_, '_> {
1690     fn write_str(&mut self, s: &str) -> fmt::Result {
1691         self.fmt.push_str(s);
1692         Ok(())
1693     }
1694 }
1695
1696 impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
1697     type Error = fmt::Error;
1698
1699     type Path = Self;
1700     type Region = Self;
1701     type Type = Self;
1702     type DynExistential = Self;
1703     type Const = Self;
1704
1705     fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
1706         self.tcx
1707     }
1708
1709     fn print_def_path(
1710         mut self,
1711         def_id: DefId,
1712         substs: &'tcx [GenericArg<'tcx>],
1713     ) -> Result<Self::Path, Self::Error> {
1714         define_scoped_cx!(self);
1715
1716         if substs.is_empty() {
1717             match self.try_print_trimmed_def_path(def_id)? {
1718                 (cx, true) => return Ok(cx),
1719                 (cx, false) => self = cx,
1720             }
1721
1722             match self.try_print_visible_def_path(def_id)? {
1723                 (cx, true) => return Ok(cx),
1724                 (cx, false) => self = cx,
1725             }
1726         }
1727
1728         let key = self.tcx.def_key(def_id);
1729         if let DefPathData::Impl = key.disambiguated_data.data {
1730             // Always use types for non-local impls, where types are always
1731             // available, and filename/line-number is mostly uninteresting.
1732             let use_types = !def_id.is_local() || {
1733                 // Otherwise, use filename/line-number if forced.
1734                 let force_no_types = FORCE_IMPL_FILENAME_LINE.with(|f| f.get());
1735                 !force_no_types
1736             };
1737
1738             if !use_types {
1739                 // If no type info is available, fall back to
1740                 // pretty printing some span information. This should
1741                 // only occur very early in the compiler pipeline.
1742                 let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id };
1743                 let span = self.tcx.def_span(def_id);
1744
1745                 self = self.print_def_path(parent_def_id, &[])?;
1746
1747                 // HACK(eddyb) copy of `path_append` to avoid
1748                 // constructing a `DisambiguatedDefPathData`.
1749                 if !self.empty_path {
1750                     write!(self, "::")?;
1751                 }
1752                 write!(
1753                     self,
1754                     "<impl at {}>",
1755                     // This may end up in stderr diagnostics but it may also be emitted
1756                     // into MIR. Hence we use the remapped path if available
1757                     self.tcx.sess.source_map().span_to_embeddable_string(span)
1758                 )?;
1759                 self.empty_path = false;
1760
1761                 return Ok(self);
1762             }
1763         }
1764
1765         self.default_print_def_path(def_id, substs)
1766     }
1767
1768     fn print_region(self, region: ty::Region<'tcx>) -> Result<Self::Region, Self::Error> {
1769         self.pretty_print_region(region)
1770     }
1771
1772     fn print_type(mut self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
1773         if self.type_length_limit.value_within_limit(self.printed_type_count) {
1774             self.printed_type_count += 1;
1775             self.pretty_print_type(ty)
1776         } else {
1777             self.truncated = true;
1778             write!(self, "...")?;
1779             Ok(self)
1780         }
1781     }
1782
1783     fn print_dyn_existential(
1784         self,
1785         predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
1786     ) -> Result<Self::DynExistential, Self::Error> {
1787         self.pretty_print_dyn_existential(predicates)
1788     }
1789
1790     fn print_const(self, ct: ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
1791         self.pretty_print_const(ct, false)
1792     }
1793
1794     fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
1795         self.empty_path = true;
1796         if cnum == LOCAL_CRATE {
1797             if self.tcx.sess.rust_2018() {
1798                 // We add the `crate::` keyword on Rust 2018, only when desired.
1799                 if SHOULD_PREFIX_WITH_CRATE.with(|flag| flag.get()) {
1800                     write!(self, "{}", kw::Crate)?;
1801                     self.empty_path = false;
1802                 }
1803             }
1804         } else {
1805             write!(self, "{}", self.tcx.crate_name(cnum))?;
1806             self.empty_path = false;
1807         }
1808         Ok(self)
1809     }
1810
1811     fn path_qualified(
1812         mut self,
1813         self_ty: Ty<'tcx>,
1814         trait_ref: Option<ty::TraitRef<'tcx>>,
1815     ) -> Result<Self::Path, Self::Error> {
1816         self = self.pretty_path_qualified(self_ty, trait_ref)?;
1817         self.empty_path = false;
1818         Ok(self)
1819     }
1820
1821     fn path_append_impl(
1822         mut self,
1823         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1824         _disambiguated_data: &DisambiguatedDefPathData,
1825         self_ty: Ty<'tcx>,
1826         trait_ref: Option<ty::TraitRef<'tcx>>,
1827     ) -> Result<Self::Path, Self::Error> {
1828         self = self.pretty_path_append_impl(
1829             |mut cx| {
1830                 cx = print_prefix(cx)?;
1831                 if !cx.empty_path {
1832                     write!(cx, "::")?;
1833                 }
1834
1835                 Ok(cx)
1836             },
1837             self_ty,
1838             trait_ref,
1839         )?;
1840         self.empty_path = false;
1841         Ok(self)
1842     }
1843
1844     fn path_append(
1845         mut self,
1846         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1847         disambiguated_data: &DisambiguatedDefPathData,
1848     ) -> Result<Self::Path, Self::Error> {
1849         self = print_prefix(self)?;
1850
1851         // Skip `::{{extern}}` blocks and `::{{constructor}}` on tuple/unit structs.
1852         if let DefPathData::ForeignMod | DefPathData::Ctor = disambiguated_data.data {
1853             return Ok(self);
1854         }
1855
1856         let name = disambiguated_data.data.name();
1857         if !self.empty_path {
1858             write!(self, "::")?;
1859         }
1860
1861         if let DefPathDataName::Named(name) = name {
1862             if Ident::with_dummy_span(name).is_raw_guess() {
1863                 write!(self, "r#")?;
1864             }
1865         }
1866
1867         let verbose = self.should_print_verbose();
1868         disambiguated_data.fmt_maybe_verbose(&mut self, verbose)?;
1869
1870         self.empty_path = false;
1871
1872         Ok(self)
1873     }
1874
1875     fn path_generic_args(
1876         mut self,
1877         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1878         args: &[GenericArg<'tcx>],
1879     ) -> Result<Self::Path, Self::Error> {
1880         self = print_prefix(self)?;
1881
1882         if args.first().is_some() {
1883             if self.in_value {
1884                 write!(self, "::")?;
1885             }
1886             self.generic_delimiters(|cx| cx.comma_sep(args.iter().cloned()))
1887         } else {
1888             Ok(self)
1889         }
1890     }
1891 }
1892
1893 impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
1894     fn ty_infer_name(&self, id: ty::TyVid) -> Option<Symbol> {
1895         self.0.ty_infer_name_resolver.as_ref().and_then(|func| func(id))
1896     }
1897
1898     fn const_infer_name(&self, id: ty::ConstVid<'tcx>) -> Option<Symbol> {
1899         self.0.const_infer_name_resolver.as_ref().and_then(|func| func(id))
1900     }
1901
1902     fn print_value_path(
1903         mut self,
1904         def_id: DefId,
1905         substs: &'tcx [GenericArg<'tcx>],
1906     ) -> Result<Self::Path, Self::Error> {
1907         let was_in_value = std::mem::replace(&mut self.in_value, true);
1908         self = self.print_def_path(def_id, substs)?;
1909         self.in_value = was_in_value;
1910
1911         Ok(self)
1912     }
1913
1914     fn in_binder<T>(self, value: &ty::Binder<'tcx, T>) -> Result<Self, Self::Error>
1915     where
1916         T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>,
1917     {
1918         self.pretty_in_binder(value)
1919     }
1920
1921     fn wrap_binder<T, C: FnOnce(&T, Self) -> Result<Self, Self::Error>>(
1922         self,
1923         value: &ty::Binder<'tcx, T>,
1924         f: C,
1925     ) -> Result<Self, Self::Error>
1926     where
1927         T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>,
1928     {
1929         self.pretty_wrap_binder(value, f)
1930     }
1931
1932     fn typed_value(
1933         mut self,
1934         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
1935         t: impl FnOnce(Self) -> Result<Self, Self::Error>,
1936         conversion: &str,
1937     ) -> Result<Self::Const, Self::Error> {
1938         self.write_str("{")?;
1939         self = f(self)?;
1940         self.write_str(conversion)?;
1941         let was_in_value = std::mem::replace(&mut self.in_value, false);
1942         self = t(self)?;
1943         self.in_value = was_in_value;
1944         self.write_str("}")?;
1945         Ok(self)
1946     }
1947
1948     fn generic_delimiters(
1949         mut self,
1950         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
1951     ) -> Result<Self, Self::Error> {
1952         write!(self, "<")?;
1953
1954         let was_in_value = std::mem::replace(&mut self.in_value, false);
1955         let mut inner = f(self)?;
1956         inner.in_value = was_in_value;
1957
1958         write!(inner, ">")?;
1959         Ok(inner)
1960     }
1961
1962     fn should_print_region(&self, region: ty::Region<'tcx>) -> bool {
1963         let highlight = self.region_highlight_mode;
1964         if highlight.region_highlighted(region).is_some() {
1965             return true;
1966         }
1967
1968         if self.should_print_verbose() {
1969             return true;
1970         }
1971
1972         let identify_regions = self.tcx.sess.opts.unstable_opts.identify_regions;
1973
1974         match *region {
1975             ty::ReEarlyBound(ref data) => data.has_name(),
1976
1977             ty::ReLateBound(_, ty::BoundRegion { kind: br, .. })
1978             | ty::ReFree(ty::FreeRegion { bound_region: br, .. })
1979             | ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
1980                 if br.is_named() {
1981                     return true;
1982                 }
1983
1984                 if let Some((region, _)) = highlight.highlight_bound_region {
1985                     if br == region {
1986                         return true;
1987                     }
1988                 }
1989
1990                 false
1991             }
1992
1993             ty::ReVar(_) if identify_regions => true,
1994
1995             ty::ReVar(_) | ty::ReErased => false,
1996
1997             ty::ReStatic => true,
1998         }
1999     }
2000
2001     fn pretty_print_const_pointer<Prov: Provenance>(
2002         self,
2003         p: Pointer<Prov>,
2004         ty: Ty<'tcx>,
2005         print_ty: bool,
2006     ) -> Result<Self::Const, Self::Error> {
2007         let print = |mut this: Self| {
2008             define_scoped_cx!(this);
2009             if this.print_alloc_ids {
2010                 p!(write("{:?}", p));
2011             } else {
2012                 p!("&_");
2013             }
2014             Ok(this)
2015         };
2016         if print_ty {
2017             self.typed_value(print, |this| this.print_type(ty), ": ")
2018         } else {
2019             print(self)
2020         }
2021     }
2022 }
2023
2024 // HACK(eddyb) limited to `FmtPrinter` because of `region_highlight_mode`.
2025 impl<'tcx> FmtPrinter<'_, 'tcx> {
2026     pub fn pretty_print_region(mut self, region: ty::Region<'tcx>) -> Result<Self, fmt::Error> {
2027         define_scoped_cx!(self);
2028
2029         // Watch out for region highlights.
2030         let highlight = self.region_highlight_mode;
2031         if let Some(n) = highlight.region_highlighted(region) {
2032             p!(write("'{}", n));
2033             return Ok(self);
2034         }
2035
2036         if self.should_print_verbose() {
2037             p!(write("{:?}", region));
2038             return Ok(self);
2039         }
2040
2041         let identify_regions = self.tcx.sess.opts.unstable_opts.identify_regions;
2042
2043         // These printouts are concise.  They do not contain all the information
2044         // the user might want to diagnose an error, but there is basically no way
2045         // to fit that into a short string.  Hence the recommendation to use
2046         // `explain_region()` or `note_and_explain_region()`.
2047         match *region {
2048             ty::ReEarlyBound(ref data) => {
2049                 if data.name != kw::Empty {
2050                     p!(write("{}", data.name));
2051                     return Ok(self);
2052                 }
2053             }
2054             ty::ReLateBound(_, ty::BoundRegion { kind: br, .. })
2055             | ty::ReFree(ty::FreeRegion { bound_region: br, .. })
2056             | ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
2057                 if let ty::BrNamed(_, name) = br && br.is_named() {
2058                     p!(write("{}", name));
2059                     return Ok(self);
2060                 }
2061
2062                 if let Some((region, counter)) = highlight.highlight_bound_region {
2063                     if br == region {
2064                         p!(write("'{}", counter));
2065                         return Ok(self);
2066                     }
2067                 }
2068             }
2069             ty::ReVar(region_vid) if identify_regions => {
2070                 p!(write("{:?}", region_vid));
2071                 return Ok(self);
2072             }
2073             ty::ReVar(_) => {}
2074             ty::ReErased => {}
2075             ty::ReStatic => {
2076                 p!("'static");
2077                 return Ok(self);
2078             }
2079         }
2080
2081         p!("'_");
2082
2083         Ok(self)
2084     }
2085 }
2086
2087 /// Folds through bound vars and placeholders, naming them
2088 struct RegionFolder<'a, 'tcx> {
2089     tcx: TyCtxt<'tcx>,
2090     current_index: ty::DebruijnIndex,
2091     region_map: BTreeMap<ty::BoundRegion, ty::Region<'tcx>>,
2092     name: &'a mut (
2093                 dyn FnMut(
2094         Option<ty::DebruijnIndex>, // Debruijn index of the folded late-bound region
2095         ty::DebruijnIndex,         // Index corresponding to binder level
2096         ty::BoundRegion,
2097     ) -> ty::Region<'tcx>
2098                     + 'a
2099             ),
2100 }
2101
2102 impl<'a, 'tcx> ty::TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
2103     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
2104         self.tcx
2105     }
2106
2107     fn fold_binder<T: TypeFoldable<'tcx>>(
2108         &mut self,
2109         t: ty::Binder<'tcx, T>,
2110     ) -> ty::Binder<'tcx, T> {
2111         self.current_index.shift_in(1);
2112         let t = t.super_fold_with(self);
2113         self.current_index.shift_out(1);
2114         t
2115     }
2116
2117     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
2118         match *t.kind() {
2119             _ if t.has_vars_bound_at_or_above(self.current_index) || t.has_placeholders() => {
2120                 return t.super_fold_with(self);
2121             }
2122             _ => {}
2123         }
2124         t
2125     }
2126
2127     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
2128         let name = &mut self.name;
2129         let region = match *r {
2130             ty::ReLateBound(db, br) if db >= self.current_index => {
2131                 *self.region_map.entry(br).or_insert_with(|| name(Some(db), self.current_index, br))
2132             }
2133             ty::RePlaceholder(ty::PlaceholderRegion { name: kind, .. }) => {
2134                 // If this is an anonymous placeholder, don't rename. Otherwise, in some
2135                 // async fns, we get a `for<'r> Send` bound
2136                 match kind {
2137                     ty::BrAnon(..) | ty::BrEnv => r,
2138                     _ => {
2139                         // Index doesn't matter, since this is just for naming and these never get bound
2140                         let br = ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind };
2141                         *self
2142                             .region_map
2143                             .entry(br)
2144                             .or_insert_with(|| name(None, self.current_index, br))
2145                     }
2146                 }
2147             }
2148             _ => return r,
2149         };
2150         if let ty::ReLateBound(debruijn1, br) = *region {
2151             assert_eq!(debruijn1, ty::INNERMOST);
2152             self.tcx.mk_region(ty::ReLateBound(self.current_index, br))
2153         } else {
2154             region
2155         }
2156     }
2157 }
2158
2159 // HACK(eddyb) limited to `FmtPrinter` because of `binder_depth`,
2160 // `region_index` and `used_region_names`.
2161 impl<'tcx> FmtPrinter<'_, 'tcx> {
2162     pub fn name_all_regions<T>(
2163         mut self,
2164         value: &ty::Binder<'tcx, T>,
2165     ) -> Result<(Self, T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>), fmt::Error>
2166     where
2167         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
2168     {
2169         fn name_by_region_index(
2170             index: usize,
2171             available_names: &mut Vec<Symbol>,
2172             num_available: usize,
2173         ) -> Symbol {
2174             if let Some(name) = available_names.pop() {
2175                 name
2176             } else {
2177                 Symbol::intern(&format!("'z{}", index - num_available))
2178             }
2179         }
2180
2181         debug!("name_all_regions");
2182
2183         // Replace any anonymous late-bound regions with named
2184         // variants, using new unique identifiers, so that we can
2185         // clearly differentiate between named and unnamed regions in
2186         // the output. We'll probably want to tweak this over time to
2187         // decide just how much information to give.
2188         if self.binder_depth == 0 {
2189             self.prepare_region_info(value);
2190         }
2191
2192         debug!("self.used_region_names: {:?}", &self.used_region_names);
2193
2194         let mut empty = true;
2195         let mut start_or_continue = |cx: &mut Self, start: &str, cont: &str| {
2196             let w = if empty {
2197                 empty = false;
2198                 start
2199             } else {
2200                 cont
2201             };
2202             let _ = write!(cx, "{}", w);
2203         };
2204         let do_continue = |cx: &mut Self, cont: Symbol| {
2205             let _ = write!(cx, "{}", cont);
2206         };
2207
2208         define_scoped_cx!(self);
2209
2210         let possible_names = ('a'..='z').rev().map(|s| Symbol::intern(&format!("'{s}")));
2211
2212         let mut available_names = possible_names
2213             .filter(|name| !self.used_region_names.contains(&name))
2214             .collect::<Vec<_>>();
2215         debug!(?available_names);
2216         let num_available = available_names.len();
2217
2218         let mut region_index = self.region_index;
2219         let mut next_name = |this: &Self| {
2220             let mut name;
2221
2222             loop {
2223                 name = name_by_region_index(region_index, &mut available_names, num_available);
2224                 region_index += 1;
2225
2226                 if !this.used_region_names.contains(&name) {
2227                     break;
2228                 }
2229             }
2230
2231             name
2232         };
2233
2234         // If we want to print verbosely, then print *all* binders, even if they
2235         // aren't named. Eventually, we might just want this as the default, but
2236         // this is not *quite* right and changes the ordering of some output
2237         // anyways.
2238         let (new_value, map) = if self.should_print_verbose() {
2239             for var in value.bound_vars().iter() {
2240                 start_or_continue(&mut self, "for<", ", ");
2241                 write!(self, "{:?}", var)?;
2242             }
2243             start_or_continue(&mut self, "", "> ");
2244             (value.clone().skip_binder(), BTreeMap::default())
2245         } else {
2246             let tcx = self.tcx;
2247
2248             // Closure used in `RegionFolder` to create names for anonymous late-bound
2249             // regions. We use two `DebruijnIndex`es (one for the currently folded
2250             // late-bound region and the other for the binder level) to determine
2251             // whether a name has already been created for the currently folded region,
2252             // see issue #102392.
2253             let mut name = |lifetime_idx: Option<ty::DebruijnIndex>,
2254                             binder_level_idx: ty::DebruijnIndex,
2255                             br: ty::BoundRegion| {
2256                 let (name, kind) = match br.kind {
2257                     ty::BrAnon(..) | ty::BrEnv => {
2258                         let name = next_name(&self);
2259
2260                         if let Some(lt_idx) = lifetime_idx {
2261                             if lt_idx > binder_level_idx {
2262                                 let kind = ty::BrNamed(CRATE_DEF_ID.to_def_id(), name);
2263                                 return tcx.mk_region(ty::ReLateBound(
2264                                     ty::INNERMOST,
2265                                     ty::BoundRegion { var: br.var, kind },
2266                                 ));
2267                             }
2268                         }
2269
2270                         (name, ty::BrNamed(CRATE_DEF_ID.to_def_id(), name))
2271                     }
2272                     ty::BrNamed(def_id, kw::UnderscoreLifetime | kw::Empty) => {
2273                         let name = next_name(&self);
2274
2275                         if let Some(lt_idx) = lifetime_idx {
2276                             if lt_idx > binder_level_idx {
2277                                 let kind = ty::BrNamed(def_id, name);
2278                                 return tcx.mk_region(ty::ReLateBound(
2279                                     ty::INNERMOST,
2280                                     ty::BoundRegion { var: br.var, kind },
2281                                 ));
2282                             }
2283                         }
2284
2285                         (name, ty::BrNamed(def_id, name))
2286                     }
2287                     ty::BrNamed(_, name) => {
2288                         if let Some(lt_idx) = lifetime_idx {
2289                             if lt_idx > binder_level_idx {
2290                                 let kind = br.kind;
2291                                 return tcx.mk_region(ty::ReLateBound(
2292                                     ty::INNERMOST,
2293                                     ty::BoundRegion { var: br.var, kind },
2294                                 ));
2295                             }
2296                         }
2297
2298                         (name, br.kind)
2299                     }
2300                 };
2301
2302                 start_or_continue(&mut self, "for<", ", ");
2303                 do_continue(&mut self, name);
2304                 tcx.mk_region(ty::ReLateBound(ty::INNERMOST, ty::BoundRegion { var: br.var, kind }))
2305             };
2306             let mut folder = RegionFolder {
2307                 tcx,
2308                 current_index: ty::INNERMOST,
2309                 name: &mut name,
2310                 region_map: BTreeMap::new(),
2311             };
2312             let new_value = value.clone().skip_binder().fold_with(&mut folder);
2313             let region_map = folder.region_map;
2314             start_or_continue(&mut self, "", "> ");
2315             (new_value, region_map)
2316         };
2317
2318         self.binder_depth += 1;
2319         self.region_index = region_index;
2320         Ok((self, new_value, map))
2321     }
2322
2323     pub fn pretty_in_binder<T>(self, value: &ty::Binder<'tcx, T>) -> Result<Self, fmt::Error>
2324     where
2325         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
2326     {
2327         let old_region_index = self.region_index;
2328         let (new, new_value, _) = self.name_all_regions(value)?;
2329         let mut inner = new_value.print(new)?;
2330         inner.region_index = old_region_index;
2331         inner.binder_depth -= 1;
2332         Ok(inner)
2333     }
2334
2335     pub fn pretty_wrap_binder<T, C: FnOnce(&T, Self) -> Result<Self, fmt::Error>>(
2336         self,
2337         value: &ty::Binder<'tcx, T>,
2338         f: C,
2339     ) -> Result<Self, fmt::Error>
2340     where
2341         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
2342     {
2343         let old_region_index = self.region_index;
2344         let (new, new_value, _) = self.name_all_regions(value)?;
2345         let mut inner = f(&new_value, new)?;
2346         inner.region_index = old_region_index;
2347         inner.binder_depth -= 1;
2348         Ok(inner)
2349     }
2350
2351     fn prepare_region_info<T>(&mut self, value: &ty::Binder<'tcx, T>)
2352     where
2353         T: TypeVisitable<'tcx>,
2354     {
2355         struct RegionNameCollector<'tcx> {
2356             used_region_names: FxHashSet<Symbol>,
2357             type_collector: SsoHashSet<Ty<'tcx>>,
2358         }
2359
2360         impl<'tcx> RegionNameCollector<'tcx> {
2361             fn new() -> Self {
2362                 RegionNameCollector {
2363                     used_region_names: Default::default(),
2364                     type_collector: SsoHashSet::new(),
2365                 }
2366             }
2367         }
2368
2369         impl<'tcx> ty::visit::TypeVisitor<'tcx> for RegionNameCollector<'tcx> {
2370             type BreakTy = ();
2371
2372             fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
2373                 trace!("address: {:p}", r.0.0);
2374
2375                 // Collect all named lifetimes. These allow us to prevent duplication
2376                 // of already existing lifetime names when introducing names for
2377                 // anonymous late-bound regions.
2378                 if let Some(name) = r.get_name() {
2379                     self.used_region_names.insert(name);
2380                 }
2381
2382                 r.super_visit_with(self)
2383             }
2384
2385             // We collect types in order to prevent really large types from compiling for
2386             // a really long time. See issue #83150 for why this is necessary.
2387             fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
2388                 let not_previously_inserted = self.type_collector.insert(ty);
2389                 if not_previously_inserted {
2390                     ty.super_visit_with(self)
2391                 } else {
2392                     ControlFlow::CONTINUE
2393                 }
2394             }
2395         }
2396
2397         let mut collector = RegionNameCollector::new();
2398         value.visit_with(&mut collector);
2399         self.used_region_names = collector.used_region_names;
2400         self.region_index = 0;
2401     }
2402 }
2403
2404 impl<'tcx, T, P: PrettyPrinter<'tcx>> Print<'tcx, P> for ty::Binder<'tcx, T>
2405 where
2406     T: Print<'tcx, P, Output = P, Error = P::Error> + TypeFoldable<'tcx>,
2407 {
2408     type Output = P;
2409     type Error = P::Error;
2410
2411     fn print(&self, cx: P) -> Result<Self::Output, Self::Error> {
2412         cx.in_binder(self)
2413     }
2414 }
2415
2416 impl<'tcx, T, U, P: PrettyPrinter<'tcx>> Print<'tcx, P> for ty::OutlivesPredicate<T, U>
2417 where
2418     T: Print<'tcx, P, Output = P, Error = P::Error>,
2419     U: Print<'tcx, P, Output = P, Error = P::Error>,
2420 {
2421     type Output = P;
2422     type Error = P::Error;
2423     fn print(&self, mut cx: P) -> Result<Self::Output, Self::Error> {
2424         define_scoped_cx!(cx);
2425         p!(print(self.0), ": ", print(self.1));
2426         Ok(cx)
2427     }
2428 }
2429
2430 macro_rules! forward_display_to_print {
2431     ($($ty:ty),+) => {
2432         // Some of the $ty arguments may not actually use 'tcx
2433         $(#[allow(unused_lifetimes)] impl<'tcx> fmt::Display for $ty {
2434             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2435                 ty::tls::with(|tcx| {
2436                     let cx = tcx.lift(*self)
2437                         .expect("could not lift for printing")
2438                         .print(FmtPrinter::new(tcx, Namespace::TypeNS))?;
2439                     f.write_str(&cx.into_buffer())?;
2440                     Ok(())
2441                 })
2442             }
2443         })+
2444     };
2445 }
2446
2447 macro_rules! define_print_and_forward_display {
2448     (($self:ident, $cx:ident): $($ty:ty $print:block)+) => {
2449         $(impl<'tcx, P: PrettyPrinter<'tcx>> Print<'tcx, P> for $ty {
2450             type Output = P;
2451             type Error = fmt::Error;
2452             fn print(&$self, $cx: P) -> Result<Self::Output, Self::Error> {
2453                 #[allow(unused_mut)]
2454                 let mut $cx = $cx;
2455                 define_scoped_cx!($cx);
2456                 let _: () = $print;
2457                 #[allow(unreachable_code)]
2458                 Ok($cx)
2459             }
2460         })+
2461
2462         forward_display_to_print!($($ty),+);
2463     };
2464 }
2465
2466 /// Wrapper type for `ty::TraitRef` which opts-in to pretty printing only
2467 /// the trait path. That is, it will print `Trait<U>` instead of
2468 /// `<T as Trait<U>>`.
2469 #[derive(Copy, Clone, TypeFoldable, TypeVisitable, Lift)]
2470 pub struct TraitRefPrintOnlyTraitPath<'tcx>(ty::TraitRef<'tcx>);
2471
2472 impl<'tcx> fmt::Debug for TraitRefPrintOnlyTraitPath<'tcx> {
2473     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2474         fmt::Display::fmt(self, f)
2475     }
2476 }
2477
2478 /// Wrapper type for `ty::TraitRef` which opts-in to pretty printing only
2479 /// the trait name. That is, it will print `Trait` instead of
2480 /// `<T as Trait<U>>`.
2481 #[derive(Copy, Clone, TypeFoldable, TypeVisitable, Lift)]
2482 pub struct TraitRefPrintOnlyTraitName<'tcx>(ty::TraitRef<'tcx>);
2483
2484 impl<'tcx> fmt::Debug for TraitRefPrintOnlyTraitName<'tcx> {
2485     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2486         fmt::Display::fmt(self, f)
2487     }
2488 }
2489
2490 impl<'tcx> ty::TraitRef<'tcx> {
2491     pub fn print_only_trait_path(self) -> TraitRefPrintOnlyTraitPath<'tcx> {
2492         TraitRefPrintOnlyTraitPath(self)
2493     }
2494
2495     pub fn print_only_trait_name(self) -> TraitRefPrintOnlyTraitName<'tcx> {
2496         TraitRefPrintOnlyTraitName(self)
2497     }
2498 }
2499
2500 impl<'tcx> ty::Binder<'tcx, ty::TraitRef<'tcx>> {
2501     pub fn print_only_trait_path(self) -> ty::Binder<'tcx, TraitRefPrintOnlyTraitPath<'tcx>> {
2502         self.map_bound(|tr| tr.print_only_trait_path())
2503     }
2504 }
2505
2506 #[derive(Copy, Clone, TypeFoldable, TypeVisitable, Lift)]
2507 pub struct TraitPredPrintModifiersAndPath<'tcx>(ty::TraitPredicate<'tcx>);
2508
2509 impl<'tcx> fmt::Debug for TraitPredPrintModifiersAndPath<'tcx> {
2510     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2511         fmt::Display::fmt(self, f)
2512     }
2513 }
2514
2515 impl<'tcx> ty::TraitPredicate<'tcx> {
2516     pub fn print_modifiers_and_trait_path(self) -> TraitPredPrintModifiersAndPath<'tcx> {
2517         TraitPredPrintModifiersAndPath(self)
2518     }
2519 }
2520
2521 impl<'tcx> ty::PolyTraitPredicate<'tcx> {
2522     pub fn print_modifiers_and_trait_path(
2523         self,
2524     ) -> ty::Binder<'tcx, TraitPredPrintModifiersAndPath<'tcx>> {
2525         self.map_bound(TraitPredPrintModifiersAndPath)
2526     }
2527 }
2528
2529 #[derive(Debug, Copy, Clone, TypeFoldable, TypeVisitable, Lift)]
2530 pub struct PrintClosureAsImpl<'tcx> {
2531     pub closure: ty::ClosureSubsts<'tcx>,
2532 }
2533
2534 forward_display_to_print! {
2535     ty::Region<'tcx>,
2536     Ty<'tcx>,
2537     &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
2538     ty::Const<'tcx>,
2539
2540     // HACK(eddyb) these are exhaustive instead of generic,
2541     // because `for<'tcx>` isn't possible yet.
2542     ty::PolyExistentialPredicate<'tcx>,
2543     ty::Binder<'tcx, ty::TraitRef<'tcx>>,
2544     ty::Binder<'tcx, ty::ExistentialTraitRef<'tcx>>,
2545     ty::Binder<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
2546     ty::Binder<'tcx, TraitRefPrintOnlyTraitName<'tcx>>,
2547     ty::Binder<'tcx, ty::FnSig<'tcx>>,
2548     ty::Binder<'tcx, ty::TraitPredicate<'tcx>>,
2549     ty::Binder<'tcx, TraitPredPrintModifiersAndPath<'tcx>>,
2550     ty::Binder<'tcx, ty::SubtypePredicate<'tcx>>,
2551     ty::Binder<'tcx, ty::ProjectionPredicate<'tcx>>,
2552     ty::Binder<'tcx, ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>>,
2553     ty::Binder<'tcx, ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>>,
2554
2555     ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>,
2556     ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>
2557 }
2558
2559 define_print_and_forward_display! {
2560     (self, cx):
2561
2562     &'tcx ty::List<Ty<'tcx>> {
2563         p!("{{", comma_sep(self.iter()), "}}")
2564     }
2565
2566     ty::TypeAndMut<'tcx> {
2567         p!(write("{}", self.mutbl.prefix_str()), print(self.ty))
2568     }
2569
2570     ty::ExistentialTraitRef<'tcx> {
2571         // Use a type that can't appear in defaults of type parameters.
2572         let dummy_self = cx.tcx().mk_ty_infer(ty::FreshTy(0));
2573         let trait_ref = self.with_self_ty(cx.tcx(), dummy_self);
2574         p!(print(trait_ref.print_only_trait_path()))
2575     }
2576
2577     ty::ExistentialProjection<'tcx> {
2578         let name = cx.tcx().associated_item(self.item_def_id).name;
2579         p!(write("{} = ", name), print(self.term))
2580     }
2581
2582     ty::ExistentialPredicate<'tcx> {
2583         match *self {
2584             ty::ExistentialPredicate::Trait(x) => p!(print(x)),
2585             ty::ExistentialPredicate::Projection(x) => p!(print(x)),
2586             ty::ExistentialPredicate::AutoTrait(def_id) => {
2587                 p!(print_def_path(def_id, &[]));
2588             }
2589         }
2590     }
2591
2592     ty::FnSig<'tcx> {
2593         p!(write("{}", self.unsafety.prefix_str()));
2594
2595         if self.abi != Abi::Rust {
2596             p!(write("extern {} ", self.abi));
2597         }
2598
2599         p!("fn", pretty_fn_sig(self.inputs(), self.c_variadic, self.output()));
2600     }
2601
2602     ty::TraitRef<'tcx> {
2603         p!(write("<{} as {}>", self.self_ty(), self.print_only_trait_path()))
2604     }
2605
2606     TraitRefPrintOnlyTraitPath<'tcx> {
2607         p!(print_def_path(self.0.def_id, self.0.substs));
2608     }
2609
2610     TraitRefPrintOnlyTraitName<'tcx> {
2611         p!(print_def_path(self.0.def_id, &[]));
2612     }
2613
2614     TraitPredPrintModifiersAndPath<'tcx> {
2615         if let ty::BoundConstness::ConstIfConst = self.0.constness {
2616             p!("~const ")
2617         }
2618
2619         if let ty::ImplPolarity::Negative = self.0.polarity {
2620             p!("!")
2621         }
2622
2623         p!(print(self.0.trait_ref.print_only_trait_path()));
2624     }
2625
2626     PrintClosureAsImpl<'tcx> {
2627         p!(pretty_closure_as_impl(self.closure))
2628     }
2629
2630     ty::ParamTy {
2631         p!(write("{}", self.name))
2632     }
2633
2634     ty::ParamConst {
2635         p!(write("{}", self.name))
2636     }
2637
2638     ty::SubtypePredicate<'tcx> {
2639         p!(print(self.a), " <: ", print(self.b))
2640     }
2641
2642     ty::CoercePredicate<'tcx> {
2643         p!(print(self.a), " -> ", print(self.b))
2644     }
2645
2646     ty::TraitPredicate<'tcx> {
2647         p!(print(self.trait_ref.self_ty()), ": ");
2648         if let ty::BoundConstness::ConstIfConst = self.constness && cx.tcx().features().const_trait_impl {
2649             p!("~const ");
2650         }
2651         p!(print(self.trait_ref.print_only_trait_path()))
2652     }
2653
2654     ty::ProjectionPredicate<'tcx> {
2655         p!(print(self.projection_ty), " == ", print(self.term))
2656     }
2657
2658     ty::Term<'tcx> {
2659       match self.unpack() {
2660         ty::TermKind::Ty(ty) => p!(print(ty)),
2661         ty::TermKind::Const(c) => p!(print(c)),
2662       }
2663     }
2664
2665     ty::ProjectionTy<'tcx> {
2666         p!(print_def_path(self.item_def_id, self.substs));
2667     }
2668
2669     ty::ClosureKind {
2670         match *self {
2671             ty::ClosureKind::Fn => p!("Fn"),
2672             ty::ClosureKind::FnMut => p!("FnMut"),
2673             ty::ClosureKind::FnOnce => p!("FnOnce"),
2674         }
2675     }
2676
2677     ty::Predicate<'tcx> {
2678         let binder = self.kind();
2679         p!(print(binder))
2680     }
2681
2682     ty::PredicateKind<'tcx> {
2683         match *self {
2684             ty::PredicateKind::Clause(ty::Clause::Trait(ref data)) => {
2685                 p!(print(data))
2686             }
2687             ty::PredicateKind::Subtype(predicate) => p!(print(predicate)),
2688             ty::PredicateKind::Coerce(predicate) => p!(print(predicate)),
2689             ty::PredicateKind::Clause(ty::Clause::RegionOutlives(predicate)) => p!(print(predicate)),
2690             ty::PredicateKind::Clause(ty::Clause::TypeOutlives(predicate)) => p!(print(predicate)),
2691             ty::PredicateKind::Clause(ty::Clause::Projection(predicate)) => p!(print(predicate)),
2692             ty::PredicateKind::WellFormed(arg) => p!(print(arg), " well-formed"),
2693             ty::PredicateKind::ObjectSafe(trait_def_id) => {
2694                 p!("the trait `", print_def_path(trait_def_id, &[]), "` is object-safe")
2695             }
2696             ty::PredicateKind::ClosureKind(closure_def_id, _closure_substs, kind) => {
2697                 p!("the closure `",
2698                 print_value_path(closure_def_id, &[]),
2699                 write("` implements the trait `{}`", kind))
2700             }
2701             ty::PredicateKind::ConstEvaluatable(ct) => {
2702                 p!("the constant `", print(ct), "` can be evaluated")
2703             }
2704             ty::PredicateKind::ConstEquate(c1, c2) => {
2705                 p!("the constant `", print(c1), "` equals `", print(c2), "`")
2706             }
2707             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
2708                 p!("the type `", print(ty), "` is found in the environment")
2709             }
2710             ty::PredicateKind::Ambiguous => p!("ambiguous"),
2711         }
2712     }
2713
2714     GenericArg<'tcx> {
2715         match self.unpack() {
2716             GenericArgKind::Lifetime(lt) => p!(print(lt)),
2717             GenericArgKind::Type(ty) => p!(print(ty)),
2718             GenericArgKind::Const(ct) => p!(print(ct)),
2719         }
2720     }
2721 }
2722
2723 fn for_each_def(tcx: TyCtxt<'_>, mut collect_fn: impl for<'b> FnMut(&'b Ident, Namespace, DefId)) {
2724     // Iterate all local crate items no matter where they are defined.
2725     let hir = tcx.hir();
2726     for id in hir.items() {
2727         if matches!(tcx.def_kind(id.owner_id), DefKind::Use) {
2728             continue;
2729         }
2730
2731         let item = hir.item(id);
2732         if item.ident.name == kw::Empty {
2733             continue;
2734         }
2735
2736         let def_id = item.owner_id.to_def_id();
2737         let ns = tcx.def_kind(def_id).ns().unwrap_or(Namespace::TypeNS);
2738         collect_fn(&item.ident, ns, def_id);
2739     }
2740
2741     // Now take care of extern crate items.
2742     let queue = &mut Vec::new();
2743     let mut seen_defs: DefIdSet = Default::default();
2744
2745     for &cnum in tcx.crates(()).iter() {
2746         let def_id = cnum.as_def_id();
2747
2748         // Ignore crates that are not direct dependencies.
2749         match tcx.extern_crate(def_id) {
2750             None => continue,
2751             Some(extern_crate) => {
2752                 if !extern_crate.is_direct() {
2753                     continue;
2754                 }
2755             }
2756         }
2757
2758         queue.push(def_id);
2759     }
2760
2761     // Iterate external crate defs but be mindful about visibility
2762     while let Some(def) = queue.pop() {
2763         for child in tcx.module_children(def).iter() {
2764             if !child.vis.is_public() {
2765                 continue;
2766             }
2767
2768             match child.res {
2769                 def::Res::Def(DefKind::AssocTy, _) => {}
2770                 def::Res::Def(DefKind::TyAlias, _) => {}
2771                 def::Res::Def(defkind, def_id) => {
2772                     if let Some(ns) = defkind.ns() {
2773                         collect_fn(&child.ident, ns, def_id);
2774                     }
2775
2776                     if matches!(defkind, DefKind::Mod | DefKind::Enum | DefKind::Trait)
2777                         && seen_defs.insert(def_id)
2778                     {
2779                         queue.push(def_id);
2780                     }
2781                 }
2782                 _ => {}
2783             }
2784         }
2785     }
2786 }
2787
2788 /// The purpose of this function is to collect public symbols names that are unique across all
2789 /// crates in the build. Later, when printing about types we can use those names instead of the
2790 /// full exported path to them.
2791 ///
2792 /// So essentially, if a symbol name can only be imported from one place for a type, and as
2793 /// long as it was not glob-imported anywhere in the current crate, we can trim its printed
2794 /// path and print only the name.
2795 ///
2796 /// This has wide implications on error messages with types, for example, shortening
2797 /// `std::vec::Vec` to just `Vec`, as long as there is no other `Vec` importable anywhere.
2798 ///
2799 /// The implementation uses similar import discovery logic to that of 'use' suggestions.
2800 fn trimmed_def_paths(tcx: TyCtxt<'_>, (): ()) -> FxHashMap<DefId, Symbol> {
2801     let mut map: FxHashMap<DefId, Symbol> = FxHashMap::default();
2802
2803     if let TrimmedDefPaths::GoodPath = tcx.sess.opts.trimmed_def_paths {
2804         // For good paths causing this bug, the `rustc_middle::ty::print::with_no_trimmed_paths`
2805         // wrapper can be used to suppress this query, in exchange for full paths being formatted.
2806         tcx.sess.delay_good_path_bug("trimmed_def_paths constructed");
2807     }
2808
2809     let unique_symbols_rev: &mut FxHashMap<(Namespace, Symbol), Option<DefId>> =
2810         &mut FxHashMap::default();
2811
2812     for symbol_set in tcx.resolutions(()).glob_map.values() {
2813         for symbol in symbol_set {
2814             unique_symbols_rev.insert((Namespace::TypeNS, *symbol), None);
2815             unique_symbols_rev.insert((Namespace::ValueNS, *symbol), None);
2816             unique_symbols_rev.insert((Namespace::MacroNS, *symbol), None);
2817         }
2818     }
2819
2820     for_each_def(tcx, |ident, ns, def_id| {
2821         use std::collections::hash_map::Entry::{Occupied, Vacant};
2822
2823         match unique_symbols_rev.entry((ns, ident.name)) {
2824             Occupied(mut v) => match v.get() {
2825                 None => {}
2826                 Some(existing) => {
2827                     if *existing != def_id {
2828                         v.insert(None);
2829                     }
2830                 }
2831             },
2832             Vacant(v) => {
2833                 v.insert(Some(def_id));
2834             }
2835         }
2836     });
2837
2838     for ((_, symbol), opt_def_id) in unique_symbols_rev.drain() {
2839         use std::collections::hash_map::Entry::{Occupied, Vacant};
2840
2841         if let Some(def_id) = opt_def_id {
2842             match map.entry(def_id) {
2843                 Occupied(mut v) => {
2844                     // A single DefId can be known under multiple names (e.g.,
2845                     // with a `pub use ... as ...;`). We need to ensure that the
2846                     // name placed in this map is chosen deterministically, so
2847                     // if we find multiple names (`symbol`) resolving to the
2848                     // same `def_id`, we prefer the lexicographically smallest
2849                     // name.
2850                     //
2851                     // Any stable ordering would be fine here though.
2852                     if *v.get() != symbol {
2853                         if v.get().as_str() > symbol.as_str() {
2854                             v.insert(symbol);
2855                         }
2856                     }
2857                 }
2858                 Vacant(v) => {
2859                     v.insert(symbol);
2860                 }
2861             }
2862         }
2863     }
2864
2865     map
2866 }
2867
2868 pub fn provide(providers: &mut ty::query::Providers) {
2869     *providers = ty::query::Providers { trimmed_def_paths, ..*providers };
2870 }
2871
2872 #[derive(Default)]
2873 pub struct OpaqueFnEntry<'tcx> {
2874     // The trait ref is already stored as a key, so just track if we have it as a real predicate
2875     has_fn_once: bool,
2876     fn_mut_trait_ref: Option<ty::PolyTraitRef<'tcx>>,
2877     fn_trait_ref: Option<ty::PolyTraitRef<'tcx>>,
2878     return_ty: Option<ty::Binder<'tcx, Term<'tcx>>>,
2879 }