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

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