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,
   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: Fn(&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.debugging_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.debugging_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         define_scoped_cx!(self);
 777
 778         // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
 779         // by looking up the projections associated with the def_id.
 780         let bounds = self.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(self.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()) == self.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(self.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         let mut first = true;
 821         // Insert parenthesis around (Fn(A, B) -> C) if the opaque ty has more than one other trait
 822         let paren_needed = fn_traits.len() > 1 || traits.len() > 0 || !is_sized;
 823
 824         p!("impl");
 825
 826         for (fn_once_trait_ref, entry) in fn_traits {
 827             // Get the (single) generic ty (the args) of this FnOnce trait ref.
 828             let generics = self.tcx().generics_of(fn_once_trait_ref.def_id());
 829             let args =
 830                 generics.own_substs_no_defaults(self.tcx(), fn_once_trait_ref.skip_binder().substs);
 831
 832             match (entry.return_ty, args[0].expect_ty()) {
 833                 // We can only print `impl Fn() -> ()` if we have a tuple of args and we recorded
 834                 // a return type.
 835                 (Some(return_ty), arg_tys) if matches!(arg_tys.kind(), ty::Tuple(_)) => {
 836                     let name = if entry.fn_trait_ref.is_some() {
 837                         "Fn"
 838                     } else if entry.fn_mut_trait_ref.is_some() {
 839                         "FnMut"
 840                     } else {
 841                         "FnOnce"
 842                     };
 843
 844                     p!(
 845                         write("{}", if first { " " } else { " + " }),
 846                         write("{}{}(", if paren_needed { "(" } else { "" }, name)
 847                     );
 848
 849                     for (idx, ty) in arg_tys.tuple_fields().iter().enumerate() {
 850                         if idx > 0 {
 851                             p!(", ");
 852                         }
 853                         p!(print(ty));
 854                     }
 855
 856                     p!(")");
 857                     if let Term::Ty(ty) = return_ty.skip_binder() {
 858                         if !ty.is_unit() {
 859                             p!("-> ", print(return_ty));
 860                         }
 861                     }
 862                     p!(write("{}", if paren_needed { ")" } else { "" }));
 863
 864                     first = false;
 865                 }
 866                 // If we got here, we can't print as a `impl Fn(A, B) -> C`. Just record the
 867                 // trait_refs we collected in the OpaqueFnEntry as normal trait refs.
 868                 _ => {
 869                     if entry.has_fn_once {
 870                         traits.entry(fn_once_trait_ref).or_default().extend(
 871                             // Group the return ty with its def id, if we had one.
 872                             entry
 873                                 .return_ty
 874                                 .map(|ty| (self.tcx().lang_items().fn_once_output().unwrap(), ty)),
 875                         );
 876                     }
 877                     if let Some(trait_ref) = entry.fn_mut_trait_ref {
 878                         traits.entry(trait_ref).or_default();
 879                     }
 880                     if let Some(trait_ref) = entry.fn_trait_ref {
 881                         traits.entry(trait_ref).or_default();
 882                     }
 883                 }
 884             }
 885         }
 886
 887         // Print the rest of the trait types (that aren't Fn* family of traits)
 888         for (trait_ref, assoc_items) in traits {
 889             p!(
 890                 write("{}", if first { " " } else { " + " }),
 891                 print(trait_ref.skip_binder().print_only_trait_name())
 892             );
 893
 894             let generics = self.tcx().generics_of(trait_ref.def_id());
 895             let args = generics.own_substs_no_defaults(self.tcx(), trait_ref.skip_binder().substs);
 896
 897             if !args.is_empty() || !assoc_items.is_empty() {
 898                 let mut first = true;
 899
 900                 for ty in args {
 901                     if first {
 902                         p!("<");
 903                         first = false;
 904                     } else {
 905                         p!(", ");
 906                     }
 907                     p!(print(trait_ref.rebind(*ty)));
 908                 }
 909
 910                 for (assoc_item_def_id, term) in assoc_items {
 911                     // Skip printing `<[generator@] as Generator<_>>::Return` from async blocks,
 912                     // unless we can find out what generator return type it comes from.
 913                     let term = if let Some(ty) = term.skip_binder().ty()
 914                         && let ty::Projection(ty::ProjectionTy { item_def_id, substs }) = ty.kind()
 915                         && Some(*item_def_id) == self.tcx().lang_items().generator_return()
 916                     {
 917                         if let ty::Generator(_, substs, _) = substs.type_at(0).kind() {
 918                             let return_ty = substs.as_generator().return_ty();
 919                             if !return_ty.is_ty_infer() {
 920                                 return_ty.into()
 921                             } else {
 922                                 continue;
 923                             }
 924                         } else {
 925                             continue;
 926                         }
 927                     } else {
 928                         term.skip_binder()
 929                     };
 930
 931                     if first {
 932                         p!("<");
 933                         first = false;
 934                     } else {
 935                         p!(", ");
 936                     }
 937
 938                     p!(write("{} = ", self.tcx().associated_item(assoc_item_def_id).name));
 939
 940                     match term {
 941                         Term::Ty(ty) => {
 942                             p!(print(ty))
 943                         }
 944                         Term::Const(c) => {
 945                             p!(print(c));
 946                         }
 947                     };
 948                 }
 949
 950                 if !first {
 951                     p!(">");
 952                 }
 953             }
 954
 955             first = false;
 956         }
 957
 958         if !is_sized {
 959             p!(write("{}?Sized", if first { " " } else { " + " }));
 960         } else if first {
 961             p!(" Sized");
 962         }
 963
 964         Ok(self)
 965     }
 966
 967     /// Insert the trait ref and optionally a projection type associated with it into either the
 968     /// traits map or fn_traits map, depending on if the trait is in the Fn* family of traits.
 969     fn insert_trait_and_projection(
 970         &mut self,
 971         trait_ref: ty::PolyTraitRef<'tcx>,
 972         proj_ty: Option<(DefId, ty::Binder<'tcx, Term<'tcx>>)>,
 973         traits: &mut FxIndexMap<
 974             ty::PolyTraitRef<'tcx>,
 975             FxIndexMap<DefId, ty::Binder<'tcx, Term<'tcx>>>,
 976         >,
 977         fn_traits: &mut FxIndexMap<ty::PolyTraitRef<'tcx>, OpaqueFnEntry<'tcx>>,
 978     ) {
 979         let trait_def_id = trait_ref.def_id();
 980
 981         // If our trait_ref is FnOnce or any of its children, project it onto the parent FnOnce
 982         // super-trait ref and record it there.
 983         if let Some(fn_once_trait) = self.tcx().lang_items().fn_once_trait() {
 984             // If we have a FnOnce, then insert it into
 985             if trait_def_id == fn_once_trait {
 986                 let entry = fn_traits.entry(trait_ref).or_default();
 987                 // Optionally insert the return_ty as well.
 988                 if let Some((_, ty)) = proj_ty {
 989                     entry.return_ty = Some(ty);
 990                 }
 991                 entry.has_fn_once = true;
 992                 return;
 993             } else if Some(trait_def_id) == self.tcx().lang_items().fn_mut_trait() {
 994                 let super_trait_ref = crate::traits::util::supertraits(self.tcx(), trait_ref)
 995                     .find(|super_trait_ref| super_trait_ref.def_id() == fn_once_trait)
 996                     .unwrap();
 997
 998                 fn_traits.entry(super_trait_ref).or_default().fn_mut_trait_ref = Some(trait_ref);
 999                 return;
1000             } else if Some(trait_def_id) == self.tcx().lang_items().fn_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_trait_ref = Some(trait_ref);
1006                 return;
1007             }
1008         }
1009
1010         // Otherwise, just group our traits and projection types.
1011         traits.entry(trait_ref).or_default().extend(proj_ty);
1012     }
1013
1014     fn pretty_print_bound_var(
1015         &mut self,
1016         debruijn: ty::DebruijnIndex,
1017         var: ty::BoundVar,
1018     ) -> Result<(), Self::Error> {
1019         if debruijn == ty::INNERMOST {
1020             write!(self, "^{}", var.index())
1021         } else {
1022             write!(self, "^{}_{}", debruijn.index(), var.index())
1023         }
1024     }
1025
1026     fn ty_infer_name(&self, _: ty::TyVid) -> Option<String> {
1027         None
1028     }
1029
1030     fn const_infer_name(&self, _: ty::ConstVid<'tcx>) -> Option<String> {
1031         None
1032     }
1033
1034     fn pretty_print_dyn_existential(
1035         mut self,
1036         predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
1037     ) -> Result<Self::DynExistential, Self::Error> {
1038         // Generate the main trait ref, including associated types.
1039         let mut first = true;
1040
1041         if let Some(principal) = predicates.principal() {
1042             self = self.wrap_binder(&principal, |principal, mut cx| {
1043                 define_scoped_cx!(cx);
1044                 p!(print_def_path(principal.def_id, &[]));
1045
1046                 let mut resugared = false;
1047
1048                 // Special-case `Fn(...) -> ...` and re-sugar it.
1049                 let fn_trait_kind = cx.tcx().fn_trait_kind_from_lang_item(principal.def_id);
1050                 if !cx.tcx().sess.verbose() && fn_trait_kind.is_some() {
1051                     if let ty::Tuple(tys) = principal.substs.type_at(0).kind() {
1052                         let mut projections = predicates.projection_bounds();
1053                         if let (Some(proj), None) = (projections.next(), projections.next()) {
1054                             p!(pretty_fn_sig(
1055                                 tys,
1056                                 false,
1057                                 proj.skip_binder().term.ty().expect("Return type was a const")
1058                             ));
1059                             resugared = true;
1060                         }
1061                     }
1062                 }
1063
1064                 // HACK(eddyb) this duplicates `FmtPrinter`'s `path_generic_args`,
1065                 // in order to place the projections inside the `<...>`.
1066                 if !resugared {
1067                     // Use a type that can't appear in defaults of type parameters.
1068                     let dummy_cx = cx.tcx().mk_ty_infer(ty::FreshTy(0));
1069                     let principal = principal.with_self_ty(cx.tcx(), dummy_cx);
1070
1071                     let args = cx
1072                         .tcx()
1073                         .generics_of(principal.def_id)
1074                         .own_substs_no_defaults(cx.tcx(), principal.substs);
1075
1076                     // Don't print `'_` if there's no unerased regions.
1077                     let print_regions = args.iter().any(|arg| match arg.unpack() {
1078                         GenericArgKind::Lifetime(r) => !r.is_erased(),
1079                         _ => false,
1080                     });
1081                     let mut args = args.iter().cloned().filter(|arg| match arg.unpack() {
1082                         GenericArgKind::Lifetime(_) => print_regions,
1083                         _ => true,
1084                     });
1085                     let mut projections = predicates.projection_bounds();
1086
1087                     let arg0 = args.next();
1088                     let projection0 = projections.next();
1089                     if arg0.is_some() || projection0.is_some() {
1090                         let args = arg0.into_iter().chain(args);
1091                         let projections = projection0.into_iter().chain(projections);
1092
1093                         p!(generic_delimiters(|mut cx| {
1094                             cx = cx.comma_sep(args)?;
1095                             if arg0.is_some() && projection0.is_some() {
1096                                 write!(cx, ", ")?;
1097                             }
1098                             cx.comma_sep(projections)
1099                         }));
1100                     }
1101                 }
1102                 Ok(cx)
1103             })?;
1104
1105             first = false;
1106         }
1107
1108         define_scoped_cx!(self);
1109
1110         // Builtin bounds.
1111         // FIXME(eddyb) avoid printing twice (needed to ensure
1112         // that the auto traits are sorted *and* printed via cx).
1113         let mut auto_traits: Vec<_> = predicates.auto_traits().collect();
1114
1115         // The auto traits come ordered by `DefPathHash`. While
1116         // `DefPathHash` is *stable* in the sense that it depends on
1117         // neither the host nor the phase of the moon, it depends
1118         // "pseudorandomly" on the compiler version and the target.
1119         //
1120         // To avoid causing instabilities in compiletest
1121         // output, sort the auto-traits alphabetically.
1122         auto_traits.sort_by_cached_key(|did| self.tcx().def_path_str(*did));
1123
1124         for def_id in auto_traits {
1125             if !first {
1126                 p!(" + ");
1127             }
1128             first = false;
1129
1130             p!(print_def_path(def_id, &[]));
1131         }
1132
1133         Ok(self)
1134     }
1135
1136     fn pretty_fn_sig(
1137         mut self,
1138         inputs: &[Ty<'tcx>],
1139         c_variadic: bool,
1140         output: Ty<'tcx>,
1141     ) -> Result<Self, Self::Error> {
1142         define_scoped_cx!(self);
1143
1144         p!("(", comma_sep(inputs.iter().copied()));
1145         if c_variadic {
1146             if !inputs.is_empty() {
1147                 p!(", ");
1148             }
1149             p!("...");
1150         }
1151         p!(")");
1152         if !output.is_unit() {
1153             p!(" -> ", print(output));
1154         }
1155
1156         Ok(self)
1157     }
1158
1159     fn pretty_print_const(
1160         mut self,
1161         ct: ty::Const<'tcx>,
1162         print_ty: bool,
1163     ) -> Result<Self::Const, Self::Error> {
1164         define_scoped_cx!(self);
1165
1166         if self.tcx().sess.verbose() {
1167             p!(write("Const({:?}: {:?})", ct.kind(), ct.ty()));
1168             return Ok(self);
1169         }
1170
1171         macro_rules! print_underscore {
1172             () => {{
1173                 if print_ty {
1174                     self = self.typed_value(
1175                         |mut this| {
1176                             write!(this, "_")?;
1177                             Ok(this)
1178                         },
1179                         |this| this.print_type(ct.ty()),
1180                         ": ",
1181                     )?;
1182                 } else {
1183                     write!(self, "_")?;
1184                 }
1185             }};
1186         }
1187
1188         match ct.kind() {
1189             ty::ConstKind::Unevaluated(ty::Unevaluated {
1190                 def,
1191                 substs,
1192                 promoted: Some(promoted),
1193             }) => {
1194                 p!(print_value_path(def.did, substs));
1195                 p!(write("::{:?}", promoted));
1196             }
1197             ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs, promoted: None }) => {
1198                 match self.tcx().def_kind(def.did) {
1199                     DefKind::Static(..) | DefKind::Const | DefKind::AssocConst => {
1200                         p!(print_value_path(def.did, substs))
1201                     }
1202                     _ => {
1203                         if def.is_local() {
1204                             let span = self.tcx().def_span(def.did);
1205                             if let Ok(snip) = self.tcx().sess.source_map().span_to_snippet(span) {
1206                                 p!(write("{}", snip))
1207                             } else {
1208                                 print_underscore!()
1209                             }
1210                         } else {
1211                             print_underscore!()
1212                         }
1213                     }
1214                 }
1215             }
1216             ty::ConstKind::Infer(infer_ct) => {
1217                 match infer_ct {
1218                     ty::InferConst::Var(ct_vid)
1219                         if let Some(name) = self.const_infer_name(ct_vid) =>
1220                             p!(write("{}", name)),
1221                     _ => print_underscore!(),
1222                 }
1223             }
1224             ty::ConstKind::Param(ParamConst { name, .. }) => p!(write("{}", name)),
1225             ty::ConstKind::Value(value) => {
1226                 return self.pretty_print_const_valtree(value, ct.ty(), print_ty);
1227             }
1228
1229             ty::ConstKind::Bound(debruijn, bound_var) => {
1230                 self.pretty_print_bound_var(debruijn, bound_var)?
1231             }
1232             ty::ConstKind::Placeholder(placeholder) => p!(write("Placeholder({:?})", placeholder)),
1233             ty::ConstKind::Error(_) => p!("[const error]"),
1234         };
1235         Ok(self)
1236     }
1237
1238     fn pretty_print_const_scalar(
1239         self,
1240         scalar: Scalar,
1241         ty: Ty<'tcx>,
1242         print_ty: bool,
1243     ) -> Result<Self::Const, Self::Error> {
1244         match scalar {
1245             Scalar::Ptr(ptr, _size) => self.pretty_print_const_scalar_ptr(ptr, ty, print_ty),
1246             Scalar::Int(int) => self.pretty_print_const_scalar_int(int, ty, print_ty),
1247         }
1248     }
1249
1250     fn pretty_print_const_scalar_ptr(
1251         mut self,
1252         ptr: Pointer,
1253         ty: Ty<'tcx>,
1254         print_ty: bool,
1255     ) -> Result<Self::Const, Self::Error> {
1256         define_scoped_cx!(self);
1257
1258         let (alloc_id, offset) = ptr.into_parts();
1259         match ty.kind() {
1260             // Byte strings (&[u8; N])
1261             ty::Ref(_, inner, _) => {
1262                 if let ty::Array(elem, len) = inner.kind() {
1263                     if let ty::Uint(ty::UintTy::U8) = elem.kind() {
1264                         if let ty::ConstKind::Value(ty::ValTree::Leaf(int)) = len.kind() {
1265                             match self.tcx().get_global_alloc(alloc_id) {
1266                                 Some(GlobalAlloc::Memory(alloc)) => {
1267                                     let len = int.assert_bits(self.tcx().data_layout.pointer_size);
1268                                     let range =
1269                                         AllocRange { start: offset, size: Size::from_bytes(len) };
1270                                     if let Ok(byte_str) =
1271                                         alloc.inner().get_bytes(&self.tcx(), range)
1272                                     {
1273                                         p!(pretty_print_byte_str(byte_str))
1274                                     } else {
1275                                         p!("<too short allocation>")
1276                                     }
1277                                 }
1278                                 // FIXME: for statics and functions, we could in principle print more detail.
1279                                 Some(GlobalAlloc::Static(def_id)) => {
1280                                     p!(write("<static({:?})>", def_id))
1281                                 }
1282                                 Some(GlobalAlloc::Function(_)) => p!("<function>"),
1283                                 None => p!("<dangling pointer>"),
1284                             }
1285                             return Ok(self);
1286                         }
1287                     }
1288                 }
1289             }
1290             ty::FnPtr(_) => {
1291                 // FIXME: We should probably have a helper method to share code with the "Byte strings"
1292                 // printing above (which also has to handle pointers to all sorts of things).
1293                 if let Some(GlobalAlloc::Function(instance)) = self.tcx().get_global_alloc(alloc_id)
1294                 {
1295                     self = self.typed_value(
1296                         |this| this.print_value_path(instance.def_id(), instance.substs),
1297                         |this| this.print_type(ty),
1298                         " as ",
1299                     )?;
1300                     return Ok(self);
1301                 }
1302             }
1303             _ => {}
1304         }
1305         // Any pointer values not covered by a branch above
1306         self = self.pretty_print_const_pointer(ptr, ty, print_ty)?;
1307         Ok(self)
1308     }
1309
1310     fn pretty_print_const_scalar_int(
1311         mut self,
1312         int: ScalarInt,
1313         ty: Ty<'tcx>,
1314         print_ty: bool,
1315     ) -> Result<Self::Const, Self::Error> {
1316         define_scoped_cx!(self);
1317
1318         match ty.kind() {
1319             // Bool
1320             ty::Bool if int == ScalarInt::FALSE => p!("false"),
1321             ty::Bool if int == ScalarInt::TRUE => p!("true"),
1322             // Float
1323             ty::Float(ty::FloatTy::F32) => {
1324                 p!(write("{}f32", Single::try_from(int).unwrap()))
1325             }
1326             ty::Float(ty::FloatTy::F64) => {
1327                 p!(write("{}f64", Double::try_from(int).unwrap()))
1328             }
1329             // Int
1330             ty::Uint(_) | ty::Int(_) => {
1331                 let int =
1332                     ConstInt::new(int, matches!(ty.kind(), ty::Int(_)), ty.is_ptr_sized_integral());
1333                 if print_ty { p!(write("{:#?}", int)) } else { p!(write("{:?}", int)) }
1334             }
1335             // Char
1336             ty::Char if char::try_from(int).is_ok() => {
1337                 p!(write("{:?}", char::try_from(int).unwrap()))
1338             }
1339             // Pointer types
1340             ty::Ref(..) | ty::RawPtr(_) | ty::FnPtr(_) => {
1341                 let data = int.assert_bits(self.tcx().data_layout.pointer_size);
1342                 self = self.typed_value(
1343                     |mut this| {
1344                         write!(this, "0x{:x}", data)?;
1345                         Ok(this)
1346                     },
1347                     |this| this.print_type(ty),
1348                     " as ",
1349                 )?;
1350             }
1351             // For function type zsts just printing the path is enough
1352             ty::FnDef(d, s) if int == ScalarInt::ZST => {
1353                 p!(print_value_path(*d, s))
1354             }
1355             // Nontrivial types with scalar bit representation
1356             _ => {
1357                 let print = |mut this: Self| {
1358                     if int.size() == Size::ZERO {
1359                         write!(this, "transmute(())")?;
1360                     } else {
1361                         write!(this, "transmute(0x{:x})", int)?;
1362                     }
1363                     Ok(this)
1364                 };
1365                 self = if print_ty {
1366                     self.typed_value(print, |this| this.print_type(ty), ": ")?
1367                 } else {
1368                     print(self)?
1369                 };
1370             }
1371         }
1372         Ok(self)
1373     }
1374
1375     /// This is overridden for MIR printing because we only want to hide alloc ids from users, not
1376     /// from MIR where it is actually useful.
1377     fn pretty_print_const_pointer<Tag: Provenance>(
1378         mut self,
1379         _: Pointer<Tag>,
1380         ty: Ty<'tcx>,
1381         print_ty: bool,
1382     ) -> Result<Self::Const, Self::Error> {
1383         if print_ty {
1384             self.typed_value(
1385                 |mut this| {
1386                     this.write_str("&_")?;
1387                     Ok(this)
1388                 },
1389                 |this| this.print_type(ty),
1390                 ": ",
1391             )
1392         } else {
1393             self.write_str("&_")?;
1394             Ok(self)
1395         }
1396     }
1397
1398     fn pretty_print_byte_str(mut self, byte_str: &'tcx [u8]) -> Result<Self::Const, Self::Error> {
1399         define_scoped_cx!(self);
1400         p!("b\"");
1401         for &c in byte_str {
1402             for e in std::ascii::escape_default(c) {
1403                 self.write_char(e as char)?;
1404             }
1405         }
1406         p!("\"");
1407         Ok(self)
1408     }
1409
1410     fn pretty_print_const_valtree(
1411         mut self,
1412         valtree: ty::ValTree<'tcx>,
1413         ty: Ty<'tcx>,
1414         print_ty: bool,
1415     ) -> Result<Self::Const, Self::Error> {
1416         define_scoped_cx!(self);
1417
1418         if self.tcx().sess.verbose() {
1419             p!(write("ValTree({:?}: ", valtree), print(ty), ")");
1420             return Ok(self);
1421         }
1422
1423         let u8_type = self.tcx().types.u8;
1424         match (valtree, ty.kind()) {
1425             (ty::ValTree::Branch(_), ty::Ref(_, inner_ty, _)) => match inner_ty.kind() {
1426                 ty::Slice(t) if *t == u8_type => {
1427                     let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
1428                         bug!(
1429                             "expected to convert valtree {:?} to raw bytes for type {:?}",
1430                             valtree,
1431                             t
1432                         )
1433                     });
1434                     return self.pretty_print_byte_str(bytes);
1435                 }
1436                 ty::Str => {
1437                     let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
1438                         bug!("expected to convert valtree to raw bytes for type {:?}", ty)
1439                     });
1440                     p!(write("{:?}", String::from_utf8_lossy(bytes)));
1441                     return Ok(self);
1442                 }
1443                 _ => {}
1444             },
1445             (ty::ValTree::Branch(_), ty::Array(t, _)) if *t == u8_type => {
1446                 let bytes = valtree.try_to_raw_bytes(self.tcx(), *t).unwrap_or_else(|| {
1447                     bug!("expected to convert valtree to raw bytes for type {:?}", t)
1448                 });
1449                 p!("*");
1450                 p!(pretty_print_byte_str(bytes));
1451                 return Ok(self);
1452             }
1453             // Aggregates, printed as array/tuple/struct/variant construction syntax.
1454             (ty::ValTree::Branch(_), ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) => {
1455                 let Some(contents) = self.tcx().try_destructure_const(
1456                     ty::Const::from_value(self.tcx(), valtree, ty)
1457                 ) else {
1458                     // Fall back to debug pretty printing for invalid constants.
1459                     p!(write("{:?}", valtree));
1460                     if print_ty {
1461                         p!(": ", print(ty));
1462                     }
1463                     return Ok(self);
1464                 };
1465                 let fields = contents.fields.iter().copied();
1466                 match *ty.kind() {
1467                     ty::Array(..) => {
1468                         p!("[", comma_sep(fields), "]");
1469                     }
1470                     ty::Tuple(..) => {
1471                         p!("(", comma_sep(fields));
1472                         if contents.fields.len() == 1 {
1473                             p!(",");
1474                         }
1475                         p!(")");
1476                     }
1477                     ty::Adt(def, _) if def.variants().is_empty() => {
1478                         self = self.typed_value(
1479                             |mut this| {
1480                                 write!(this, "unreachable()")?;
1481                                 Ok(this)
1482                             },
1483                             |this| this.print_type(ty),
1484                             ": ",
1485                         )?;
1486                     }
1487                     ty::Adt(def, substs) => {
1488                         let variant_idx =
1489                             contents.variant.expect("destructed const of adt without variant idx");
1490                         let variant_def = &def.variant(variant_idx);
1491                         p!(print_value_path(variant_def.def_id, substs));
1492                         match variant_def.ctor_kind {
1493                             CtorKind::Const => {}
1494                             CtorKind::Fn => {
1495                                 p!("(", comma_sep(fields), ")");
1496                             }
1497                             CtorKind::Fictive => {
1498                                 p!(" {{ ");
1499                                 let mut first = true;
1500                                 for (field_def, field) in iter::zip(&variant_def.fields, fields) {
1501                                     if !first {
1502                                         p!(", ");
1503                                     }
1504                                     p!(write("{}: ", field_def.name), print(field));
1505                                     first = false;
1506                                 }
1507                                 p!(" }}");
1508                             }
1509                         }
1510                     }
1511                     _ => unreachable!(),
1512                 }
1513                 return Ok(self);
1514             }
1515             (ty::ValTree::Leaf(leaf), _) => {
1516                 return self.pretty_print_const_scalar_int(leaf, ty, print_ty);
1517             }
1518             // FIXME(oli-obk): also pretty print arrays and other aggregate constants by reading
1519             // their fields instead of just dumping the memory.
1520             _ => {}
1521         }
1522
1523         // fallback
1524         if valtree == ty::ValTree::zst() {
1525             p!(write("<ZST>"));
1526         } else {
1527             p!(write("{:?}", valtree));
1528         }
1529         if print_ty {
1530             p!(": ", print(ty));
1531         }
1532         Ok(self)
1533     }
1534 }
1535
1536 // HACK(eddyb) boxed to avoid moving around a large struct by-value.
1537 pub struct FmtPrinter<'a, 'tcx>(Box<FmtPrinterData<'a, 'tcx>>);
1538
1539 pub struct FmtPrinterData<'a, 'tcx> {
1540     tcx: TyCtxt<'tcx>,
1541     fmt: String,
1542
1543     empty_path: bool,
1544     in_value: bool,
1545     pub print_alloc_ids: bool,
1546
1547     used_region_names: FxHashSet<Symbol>,
1548     region_index: usize,
1549     binder_depth: usize,
1550     printed_type_count: usize,
1551
1552     pub region_highlight_mode: RegionHighlightMode<'tcx>,
1553
1554     pub ty_infer_name_resolver: Option<Box<dyn Fn(ty::TyVid) -> Option<String> + 'a>>,
1555     pub const_infer_name_resolver: Option<Box<dyn Fn(ty::ConstVid<'tcx>) -> Option<String> + 'a>>,
1556 }
1557
1558 impl<'a, 'tcx> Deref for FmtPrinter<'a, 'tcx> {
1559     type Target = FmtPrinterData<'a, 'tcx>;
1560     fn deref(&self) -> &Self::Target {
1561         &self.0
1562     }
1563 }
1564
1565 impl DerefMut for FmtPrinter<'_, '_> {
1566     fn deref_mut(&mut self) -> &mut Self::Target {
1567         &mut self.0
1568     }
1569 }
1570
1571 impl<'a, 'tcx> FmtPrinter<'a, 'tcx> {
1572     pub fn new(tcx: TyCtxt<'tcx>, ns: Namespace) -> Self {
1573         FmtPrinter(Box::new(FmtPrinterData {
1574             tcx,
1575             // Estimated reasonable capacity to allocate upfront based on a few
1576             // benchmarks.
1577             fmt: String::with_capacity(64),
1578             empty_path: false,
1579             in_value: ns == Namespace::ValueNS,
1580             print_alloc_ids: false,
1581             used_region_names: Default::default(),
1582             region_index: 0,
1583             binder_depth: 0,
1584             printed_type_count: 0,
1585             region_highlight_mode: RegionHighlightMode::new(tcx),
1586             ty_infer_name_resolver: None,
1587             const_infer_name_resolver: None,
1588         }))
1589     }
1590
1591     pub fn into_buffer(self) -> String {
1592         self.0.fmt
1593     }
1594 }
1595
1596 // HACK(eddyb) get rid of `def_path_str` and/or pass `Namespace` explicitly always
1597 // (but also some things just print a `DefId` generally so maybe we need this?)
1598 fn guess_def_namespace(tcx: TyCtxt<'_>, def_id: DefId) -> Namespace {
1599     match tcx.def_key(def_id).disambiguated_data.data {
1600         DefPathData::TypeNs(..) | DefPathData::CrateRoot | DefPathData::ImplTrait => {
1601             Namespace::TypeNS
1602         }
1603
1604         DefPathData::ValueNs(..)
1605         | DefPathData::AnonConst
1606         | DefPathData::ClosureExpr
1607         | DefPathData::Ctor => Namespace::ValueNS,
1608
1609         DefPathData::MacroNs(..) => Namespace::MacroNS,
1610
1611         _ => Namespace::TypeNS,
1612     }
1613 }
1614
1615 impl<'t> TyCtxt<'t> {
1616     /// Returns a string identifying this `DefId`. This string is
1617     /// suitable for user output.
1618     pub fn def_path_str(self, def_id: DefId) -> String {
1619         self.def_path_str_with_substs(def_id, &[])
1620     }
1621
1622     pub fn def_path_str_with_substs(self, def_id: DefId, substs: &'t [GenericArg<'t>]) -> String {
1623         let ns = guess_def_namespace(self, def_id);
1624         debug!("def_path_str: def_id={:?}, ns={:?}", def_id, ns);
1625         FmtPrinter::new(self, ns).print_def_path(def_id, substs).unwrap().into_buffer()
1626     }
1627 }
1628
1629 impl fmt::Write for FmtPrinter<'_, '_> {
1630     fn write_str(&mut self, s: &str) -> fmt::Result {
1631         self.fmt.push_str(s);
1632         Ok(())
1633     }
1634 }
1635
1636 impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
1637     type Error = fmt::Error;
1638
1639     type Path = Self;
1640     type Region = Self;
1641     type Type = Self;
1642     type DynExistential = Self;
1643     type Const = Self;
1644
1645     fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
1646         self.tcx
1647     }
1648
1649     fn print_def_path(
1650         mut self,
1651         def_id: DefId,
1652         substs: &'tcx [GenericArg<'tcx>],
1653     ) -> Result<Self::Path, Self::Error> {
1654         define_scoped_cx!(self);
1655
1656         if substs.is_empty() {
1657             match self.try_print_trimmed_def_path(def_id)? {
1658                 (cx, true) => return Ok(cx),
1659                 (cx, false) => self = cx,
1660             }
1661
1662             match self.try_print_visible_def_path(def_id)? {
1663                 (cx, true) => return Ok(cx),
1664                 (cx, false) => self = cx,
1665             }
1666         }
1667
1668         let key = self.tcx.def_key(def_id);
1669         if let DefPathData::Impl = key.disambiguated_data.data {
1670             // Always use types for non-local impls, where types are always
1671             // available, and filename/line-number is mostly uninteresting.
1672             let use_types = !def_id.is_local() || {
1673                 // Otherwise, use filename/line-number if forced.
1674                 let force_no_types = FORCE_IMPL_FILENAME_LINE.with(|f| f.get());
1675                 !force_no_types
1676             };
1677
1678             if !use_types {
1679                 // If no type info is available, fall back to
1680                 // pretty printing some span information. This should
1681                 // only occur very early in the compiler pipeline.
1682                 let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id };
1683                 let span = self.tcx.def_span(def_id);
1684
1685                 self = self.print_def_path(parent_def_id, &[])?;
1686
1687                 // HACK(eddyb) copy of `path_append` to avoid
1688                 // constructing a `DisambiguatedDefPathData`.
1689                 if !self.empty_path {
1690                     write!(self, "::")?;
1691                 }
1692                 write!(
1693                     self,
1694                     "<impl at {}>",
1695                     // This may end up in stderr diagnostics but it may also be emitted
1696                     // into MIR. Hence we use the remapped path if available
1697                     self.tcx.sess.source_map().span_to_embeddable_string(span)
1698                 )?;
1699                 self.empty_path = false;
1700
1701                 return Ok(self);
1702             }
1703         }
1704
1705         self.default_print_def_path(def_id, substs)
1706     }
1707
1708     fn print_region(self, region: ty::Region<'tcx>) -> Result<Self::Region, Self::Error> {
1709         self.pretty_print_region(region)
1710     }
1711
1712     fn print_type(mut self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
1713         let type_length_limit = self.tcx.type_length_limit();
1714         if type_length_limit.value_within_limit(self.printed_type_count) {
1715             self.printed_type_count += 1;
1716             self.pretty_print_type(ty)
1717         } else {
1718             write!(self, "...")?;
1719             Ok(self)
1720         }
1721     }
1722
1723     fn print_dyn_existential(
1724         self,
1725         predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
1726     ) -> Result<Self::DynExistential, Self::Error> {
1727         self.pretty_print_dyn_existential(predicates)
1728     }
1729
1730     fn print_const(self, ct: ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
1731         self.pretty_print_const(ct, true)
1732     }
1733
1734     fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
1735         self.empty_path = true;
1736         if cnum == LOCAL_CRATE {
1737             if self.tcx.sess.rust_2018() {
1738                 // We add the `crate::` keyword on Rust 2018, only when desired.
1739                 if SHOULD_PREFIX_WITH_CRATE.with(|flag| flag.get()) {
1740                     write!(self, "{}", kw::Crate)?;
1741                     self.empty_path = false;
1742                 }
1743             }
1744         } else {
1745             write!(self, "{}", self.tcx.crate_name(cnum))?;
1746             self.empty_path = false;
1747         }
1748         Ok(self)
1749     }
1750
1751     fn path_qualified(
1752         mut self,
1753         self_ty: Ty<'tcx>,
1754         trait_ref: Option<ty::TraitRef<'tcx>>,
1755     ) -> Result<Self::Path, Self::Error> {
1756         self = self.pretty_path_qualified(self_ty, trait_ref)?;
1757         self.empty_path = false;
1758         Ok(self)
1759     }
1760
1761     fn path_append_impl(
1762         mut self,
1763         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1764         _disambiguated_data: &DisambiguatedDefPathData,
1765         self_ty: Ty<'tcx>,
1766         trait_ref: Option<ty::TraitRef<'tcx>>,
1767     ) -> Result<Self::Path, Self::Error> {
1768         self = self.pretty_path_append_impl(
1769             |mut cx| {
1770                 cx = print_prefix(cx)?;
1771                 if !cx.empty_path {
1772                     write!(cx, "::")?;
1773                 }
1774
1775                 Ok(cx)
1776             },
1777             self_ty,
1778             trait_ref,
1779         )?;
1780         self.empty_path = false;
1781         Ok(self)
1782     }
1783
1784     fn path_append(
1785         mut self,
1786         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1787         disambiguated_data: &DisambiguatedDefPathData,
1788     ) -> Result<Self::Path, Self::Error> {
1789         self = print_prefix(self)?;
1790
1791         // Skip `::{{extern}}` blocks and `::{{constructor}}` on tuple/unit structs.
1792         if let DefPathData::ForeignMod | DefPathData::Ctor = disambiguated_data.data {
1793             return Ok(self);
1794         }
1795
1796         let name = disambiguated_data.data.name();
1797         if !self.empty_path {
1798             write!(self, "::")?;
1799         }
1800
1801         if let DefPathDataName::Named(name) = name {
1802             if Ident::with_dummy_span(name).is_raw_guess() {
1803                 write!(self, "r#")?;
1804             }
1805         }
1806
1807         let verbose = self.tcx.sess.verbose();
1808         disambiguated_data.fmt_maybe_verbose(&mut self, verbose)?;
1809
1810         self.empty_path = false;
1811
1812         Ok(self)
1813     }
1814
1815     fn path_generic_args(
1816         mut self,
1817         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1818         args: &[GenericArg<'tcx>],
1819     ) -> Result<Self::Path, Self::Error> {
1820         self = print_prefix(self)?;
1821
1822         // Don't print `'_` if there's no unerased regions.
1823         let print_regions = self.tcx.sess.verbose()
1824             || args.iter().any(|arg| match arg.unpack() {
1825                 GenericArgKind::Lifetime(r) => !r.is_erased(),
1826                 _ => false,
1827             });
1828         let args = args.iter().cloned().filter(|arg| match arg.unpack() {
1829             GenericArgKind::Lifetime(_) => print_regions,
1830             _ => true,
1831         });
1832
1833         if args.clone().next().is_some() {
1834             if self.in_value {
1835                 write!(self, "::")?;
1836             }
1837             self.generic_delimiters(|cx| cx.comma_sep(args))
1838         } else {
1839             Ok(self)
1840         }
1841     }
1842 }
1843
1844 impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
1845     fn ty_infer_name(&self, id: ty::TyVid) -> Option<String> {
1846         self.0.ty_infer_name_resolver.as_ref().and_then(|func| func(id))
1847     }
1848
1849     fn const_infer_name(&self, id: ty::ConstVid<'tcx>) -> Option<String> {
1850         self.0.const_infer_name_resolver.as_ref().and_then(|func| func(id))
1851     }
1852
1853     fn print_value_path(
1854         mut self,
1855         def_id: DefId,
1856         substs: &'tcx [GenericArg<'tcx>],
1857     ) -> Result<Self::Path, Self::Error> {
1858         let was_in_value = std::mem::replace(&mut self.in_value, true);
1859         self = self.print_def_path(def_id, substs)?;
1860         self.in_value = was_in_value;
1861
1862         Ok(self)
1863     }
1864
1865     fn in_binder<T>(self, value: &ty::Binder<'tcx, T>) -> Result<Self, Self::Error>
1866     where
1867         T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>,
1868     {
1869         self.pretty_in_binder(value)
1870     }
1871
1872     fn wrap_binder<T, C: Fn(&T, Self) -> Result<Self, Self::Error>>(
1873         self,
1874         value: &ty::Binder<'tcx, T>,
1875         f: C,
1876     ) -> Result<Self, Self::Error>
1877     where
1878         T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>,
1879     {
1880         self.pretty_wrap_binder(value, f)
1881     }
1882
1883     fn typed_value(
1884         mut self,
1885         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
1886         t: impl FnOnce(Self) -> Result<Self, Self::Error>,
1887         conversion: &str,
1888     ) -> Result<Self::Const, Self::Error> {
1889         self.write_str("{")?;
1890         self = f(self)?;
1891         self.write_str(conversion)?;
1892         let was_in_value = std::mem::replace(&mut self.in_value, false);
1893         self = t(self)?;
1894         self.in_value = was_in_value;
1895         self.write_str("}")?;
1896         Ok(self)
1897     }
1898
1899     fn generic_delimiters(
1900         mut self,
1901         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
1902     ) -> Result<Self, Self::Error> {
1903         write!(self, "<")?;
1904
1905         let was_in_value = std::mem::replace(&mut self.in_value, false);
1906         let mut inner = f(self)?;
1907         inner.in_value = was_in_value;
1908
1909         write!(inner, ">")?;
1910         Ok(inner)
1911     }
1912
1913     fn should_print_region(&self, region: ty::Region<'tcx>) -> bool {
1914         let highlight = self.region_highlight_mode;
1915         if highlight.region_highlighted(region).is_some() {
1916             return true;
1917         }
1918
1919         if self.tcx.sess.verbose() {
1920             return true;
1921         }
1922
1923         let identify_regions = self.tcx.sess.opts.debugging_opts.identify_regions;
1924
1925         match *region {
1926             ty::ReEarlyBound(ref data) => {
1927                 data.name != kw::Empty && data.name != kw::UnderscoreLifetime
1928             }
1929
1930             ty::ReLateBound(_, ty::BoundRegion { kind: br, .. })
1931             | ty::ReFree(ty::FreeRegion { bound_region: br, .. })
1932             | ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
1933                 if let ty::BrNamed(_, name) = br {
1934                     if name != kw::Empty && name != kw::UnderscoreLifetime {
1935                         return true;
1936                     }
1937                 }
1938
1939                 if let Some((region, _)) = highlight.highlight_bound_region {
1940                     if br == region {
1941                         return true;
1942                     }
1943                 }
1944
1945                 false
1946             }
1947
1948             ty::ReVar(_) if identify_regions => true,
1949
1950             ty::ReVar(_) | ty::ReErased => false,
1951
1952             ty::ReStatic | ty::ReEmpty(_) => true,
1953         }
1954     }
1955
1956     fn pretty_print_const_pointer<Tag: Provenance>(
1957         self,
1958         p: Pointer<Tag>,
1959         ty: Ty<'tcx>,
1960         print_ty: bool,
1961     ) -> Result<Self::Const, Self::Error> {
1962         let print = |mut this: Self| {
1963             define_scoped_cx!(this);
1964             if this.print_alloc_ids {
1965                 p!(write("{:?}", p));
1966             } else {
1967                 p!("&_");
1968             }
1969             Ok(this)
1970         };
1971         if print_ty {
1972             self.typed_value(print, |this| this.print_type(ty), ": ")
1973         } else {
1974             print(self)
1975         }
1976     }
1977 }
1978
1979 // HACK(eddyb) limited to `FmtPrinter` because of `region_highlight_mode`.
1980 impl<'tcx> FmtPrinter<'_, 'tcx> {
1981     pub fn pretty_print_region(mut self, region: ty::Region<'tcx>) -> Result<Self, fmt::Error> {
1982         define_scoped_cx!(self);
1983
1984         // Watch out for region highlights.
1985         let highlight = self.region_highlight_mode;
1986         if let Some(n) = highlight.region_highlighted(region) {
1987             p!(write("'{}", n));
1988             return Ok(self);
1989         }
1990
1991         if self.tcx.sess.verbose() {
1992             p!(write("{:?}", region));
1993             return Ok(self);
1994         }
1995
1996         let identify_regions = self.tcx.sess.opts.debugging_opts.identify_regions;
1997
1998         // These printouts are concise.  They do not contain all the information
1999         // the user might want to diagnose an error, but there is basically no way
2000         // to fit that into a short string.  Hence the recommendation to use
2001         // `explain_region()` or `note_and_explain_region()`.
2002         match *region {
2003             ty::ReEarlyBound(ref data) => {
2004                 if data.name != kw::Empty {
2005                     p!(write("{}", data.name));
2006                     return Ok(self);
2007                 }
2008             }
2009             ty::ReLateBound(_, ty::BoundRegion { kind: br, .. })
2010             | ty::ReFree(ty::FreeRegion { bound_region: br, .. })
2011             | ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
2012                 if let ty::BrNamed(_, name) = br {
2013                     if name != kw::Empty && name != kw::UnderscoreLifetime {
2014                         p!(write("{}", name));
2015                         return Ok(self);
2016                     }
2017                 }
2018
2019                 if let Some((region, counter)) = highlight.highlight_bound_region {
2020                     if br == region {
2021                         p!(write("'{}", counter));
2022                         return Ok(self);
2023                     }
2024                 }
2025             }
2026             ty::ReVar(region_vid) if identify_regions => {
2027                 p!(write("{:?}", region_vid));
2028                 return Ok(self);
2029             }
2030             ty::ReVar(_) => {}
2031             ty::ReErased => {}
2032             ty::ReStatic => {
2033                 p!("'static");
2034                 return Ok(self);
2035             }
2036             ty::ReEmpty(ty::UniverseIndex::ROOT) => {
2037                 p!("'<empty>");
2038                 return Ok(self);
2039             }
2040             ty::ReEmpty(ui) => {
2041                 p!(write("'<empty:{:?}>", ui));
2042                 return Ok(self);
2043             }
2044         }
2045
2046         p!("'_");
2047
2048         Ok(self)
2049     }
2050 }
2051
2052 /// Folds through bound vars and placeholders, naming them
2053 struct RegionFolder<'a, 'tcx> {
2054     tcx: TyCtxt<'tcx>,
2055     current_index: ty::DebruijnIndex,
2056     region_map: BTreeMap<ty::BoundRegion, ty::Region<'tcx>>,
2057     name: &'a mut (dyn FnMut(ty::BoundRegion) -> ty::Region<'tcx> + 'a),
2058 }
2059
2060 impl<'a, 'tcx> ty::TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
2061     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
2062         self.tcx
2063     }
2064
2065     fn fold_binder<T: TypeFoldable<'tcx>>(
2066         &mut self,
2067         t: ty::Binder<'tcx, T>,
2068     ) -> ty::Binder<'tcx, T> {
2069         self.current_index.shift_in(1);
2070         let t = t.super_fold_with(self);
2071         self.current_index.shift_out(1);
2072         t
2073     }
2074
2075     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
2076         match *t.kind() {
2077             _ if t.has_vars_bound_at_or_above(self.current_index) || t.has_placeholders() => {
2078                 return t.super_fold_with(self);
2079             }
2080             _ => {}
2081         }
2082         t
2083     }
2084
2085     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
2086         let name = &mut self.name;
2087         let region = match *r {
2088             ty::ReLateBound(_, br) => *self.region_map.entry(br).or_insert_with(|| name(br)),
2089             ty::RePlaceholder(ty::PlaceholderRegion { name: kind, .. }) => {
2090                 // If this is an anonymous placeholder, don't rename. Otherwise, in some
2091                 // async fns, we get a `for<'r> Send` bound
2092                 match kind {
2093                     ty::BrAnon(_) | ty::BrEnv => r,
2094                     _ => {
2095                         // Index doesn't matter, since this is just for naming and these never get bound
2096                         let br = ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind };
2097                         *self.region_map.entry(br).or_insert_with(|| name(br))
2098                     }
2099                 }
2100             }
2101             _ => return r,
2102         };
2103         if let ty::ReLateBound(debruijn1, br) = *region {
2104             assert_eq!(debruijn1, ty::INNERMOST);
2105             self.tcx.mk_region(ty::ReLateBound(self.current_index, br))
2106         } else {
2107             region
2108         }
2109     }
2110 }
2111
2112 // HACK(eddyb) limited to `FmtPrinter` because of `binder_depth`,
2113 // `region_index` and `used_region_names`.
2114 impl<'tcx> FmtPrinter<'_, 'tcx> {
2115     pub fn name_all_regions<T>(
2116         mut self,
2117         value: &ty::Binder<'tcx, T>,
2118     ) -> Result<(Self, T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>), fmt::Error>
2119     where
2120         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
2121     {
2122         fn name_by_region_index(index: usize) -> Symbol {
2123             match index {
2124                 0 => Symbol::intern("'r"),
2125                 1 => Symbol::intern("'s"),
2126                 i => Symbol::intern(&format!("'t{}", i - 2)),
2127             }
2128         }
2129
2130         // Replace any anonymous late-bound regions with named
2131         // variants, using new unique identifiers, so that we can
2132         // clearly differentiate between named and unnamed regions in
2133         // the output. We'll probably want to tweak this over time to
2134         // decide just how much information to give.
2135         if self.binder_depth == 0 {
2136             self.prepare_late_bound_region_info(value);
2137         }
2138
2139         let mut empty = true;
2140         let mut start_or_continue = |cx: &mut Self, start: &str, cont: &str| {
2141             let w = if empty {
2142                 empty = false;
2143                 start
2144             } else {
2145                 cont
2146             };
2147             let _ = write!(cx, "{}", w);
2148         };
2149         let do_continue = |cx: &mut Self, cont: Symbol| {
2150             let _ = write!(cx, "{}", cont);
2151         };
2152
2153         define_scoped_cx!(self);
2154
2155         let mut region_index = self.region_index;
2156         let mut next_name = |this: &Self| loop {
2157             let name = name_by_region_index(region_index);
2158             region_index += 1;
2159             if !this.used_region_names.contains(&name) {
2160                 break name;
2161             }
2162         };
2163
2164         // If we want to print verbosely, then print *all* binders, even if they
2165         // aren't named. Eventually, we might just want this as the default, but
2166         // this is not *quite* right and changes the ordering of some output
2167         // anyways.
2168         let (new_value, map) = if self.tcx().sess.verbose() {
2169             let regions: Vec<_> = value
2170                 .bound_vars()
2171                 .into_iter()
2172                 .map(|var| {
2173                     let ty::BoundVariableKind::Region(var) = var else {
2174                     // This doesn't really matter because it doesn't get used,
2175                     // it's just an empty value
2176                     return ty::BrAnon(0);
2177                 };
2178                     match var {
2179                         ty::BrAnon(_) | ty::BrEnv => {
2180                             start_or_continue(&mut self, "for<", ", ");
2181                             let name = next_name(&self);
2182                             do_continue(&mut self, name);
2183                             ty::BrNamed(CRATE_DEF_ID.to_def_id(), name)
2184                         }
2185                         ty::BrNamed(def_id, kw::UnderscoreLifetime) => {
2186                             start_or_continue(&mut self, "for<", ", ");
2187                             let name = next_name(&self);
2188                             do_continue(&mut self, name);
2189                             ty::BrNamed(def_id, name)
2190                         }
2191                         ty::BrNamed(def_id, name) => {
2192                             start_or_continue(&mut self, "for<", ", ");
2193                             do_continue(&mut self, name);
2194                             ty::BrNamed(def_id, name)
2195                         }
2196                     }
2197                 })
2198                 .collect();
2199             start_or_continue(&mut self, "", "> ");
2200
2201             self.tcx.replace_late_bound_regions(value.clone(), |br| {
2202                 let kind = regions[br.var.as_usize()];
2203                 self.tcx.mk_region(ty::ReLateBound(
2204                     ty::INNERMOST,
2205                     ty::BoundRegion { var: br.var, kind },
2206                 ))
2207             })
2208         } else {
2209             let tcx = self.tcx;
2210             let mut name = |br: ty::BoundRegion| {
2211                 start_or_continue(&mut self, "for<", ", ");
2212                 let kind = match br.kind {
2213                     ty::BrAnon(_) | ty::BrEnv => {
2214                         let name = next_name(&self);
2215                         do_continue(&mut self, name);
2216                         ty::BrNamed(CRATE_DEF_ID.to_def_id(), name)
2217                     }
2218                     ty::BrNamed(def_id, kw::UnderscoreLifetime) => {
2219                         let name = next_name(&self);
2220                         do_continue(&mut self, name);
2221                         ty::BrNamed(def_id, name)
2222                     }
2223                     ty::BrNamed(_, name) => {
2224                         do_continue(&mut self, name);
2225                         br.kind
2226                     }
2227                 };
2228                 tcx.mk_region(ty::ReLateBound(ty::INNERMOST, ty::BoundRegion { var: br.var, kind }))
2229             };
2230             let mut folder = RegionFolder {
2231                 tcx,
2232                 current_index: ty::INNERMOST,
2233                 name: &mut name,
2234                 region_map: BTreeMap::new(),
2235             };
2236             let new_value = value.clone().skip_binder().fold_with(&mut folder);
2237             let region_map = folder.region_map;
2238             start_or_continue(&mut self, "", "> ");
2239             (new_value, region_map)
2240         };
2241
2242         self.binder_depth += 1;
2243         self.region_index = region_index;
2244         Ok((self, new_value, map))
2245     }
2246
2247     pub fn pretty_in_binder<T>(self, value: &ty::Binder<'tcx, T>) -> Result<Self, fmt::Error>
2248     where
2249         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
2250     {
2251         let old_region_index = self.region_index;
2252         let (new, new_value, _) = self.name_all_regions(value)?;
2253         let mut inner = new_value.print(new)?;
2254         inner.region_index = old_region_index;
2255         inner.binder_depth -= 1;
2256         Ok(inner)
2257     }
2258
2259     pub fn pretty_wrap_binder<T, C: Fn(&T, Self) -> Result<Self, fmt::Error>>(
2260         self,
2261         value: &ty::Binder<'tcx, T>,
2262         f: C,
2263     ) -> Result<Self, fmt::Error>
2264     where
2265         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
2266     {
2267         let old_region_index = self.region_index;
2268         let (new, new_value, _) = self.name_all_regions(value)?;
2269         let mut inner = f(&new_value, new)?;
2270         inner.region_index = old_region_index;
2271         inner.binder_depth -= 1;
2272         Ok(inner)
2273     }
2274
2275     fn prepare_late_bound_region_info<T>(&mut self, value: &ty::Binder<'tcx, T>)
2276     where
2277         T: TypeFoldable<'tcx>,
2278     {
2279         struct LateBoundRegionNameCollector<'a, 'tcx> {
2280             used_region_names: &'a mut FxHashSet<Symbol>,
2281             type_collector: SsoHashSet<Ty<'tcx>>,
2282         }
2283
2284         impl<'tcx> ty::fold::TypeVisitor<'tcx> for LateBoundRegionNameCollector<'_, 'tcx> {
2285             type BreakTy = ();
2286
2287             fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
2288                 trace!("address: {:p}", r.0.0);
2289                 if let ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) = *r {
2290                     self.used_region_names.insert(name);
2291                 } else if let ty::RePlaceholder(ty::PlaceholderRegion {
2292                     name: ty::BrNamed(_, name),
2293                     ..
2294                 }) = *r
2295                 {
2296                     self.used_region_names.insert(name);
2297                 }
2298                 r.super_visit_with(self)
2299             }
2300
2301             // We collect types in order to prevent really large types from compiling for
2302             // a really long time. See issue #83150 for why this is necessary.
2303             fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
2304                 let not_previously_inserted = self.type_collector.insert(ty);
2305                 if not_previously_inserted {
2306                     ty.super_visit_with(self)
2307                 } else {
2308                     ControlFlow::CONTINUE
2309                 }
2310             }
2311         }
2312
2313         self.used_region_names.clear();
2314         let mut collector = LateBoundRegionNameCollector {
2315             used_region_names: &mut self.used_region_names,
2316             type_collector: SsoHashSet::new(),
2317         };
2318         value.visit_with(&mut collector);
2319         self.region_index = 0;
2320     }
2321 }
2322
2323 impl<'tcx, T, P: PrettyPrinter<'tcx>> Print<'tcx, P> for ty::Binder<'tcx, T>
2324 where
2325     T: Print<'tcx, P, Output = P, Error = P::Error> + TypeFoldable<'tcx>,
2326 {
2327     type Output = P;
2328     type Error = P::Error;
2329
2330     fn print(&self, cx: P) -> Result<Self::Output, Self::Error> {
2331         cx.in_binder(self)
2332     }
2333 }
2334
2335 impl<'tcx, T, U, P: PrettyPrinter<'tcx>> Print<'tcx, P> for ty::OutlivesPredicate<T, U>
2336 where
2337     T: Print<'tcx, P, Output = P, Error = P::Error>,
2338     U: Print<'tcx, P, Output = P, Error = P::Error>,
2339 {
2340     type Output = P;
2341     type Error = P::Error;
2342     fn print(&self, mut cx: P) -> Result<Self::Output, Self::Error> {
2343         define_scoped_cx!(cx);
2344         p!(print(self.0), ": ", print(self.1));
2345         Ok(cx)
2346     }
2347 }
2348
2349 macro_rules! forward_display_to_print {
2350     ($($ty:ty),+) => {
2351         // Some of the $ty arguments may not actually use 'tcx
2352         $(#[allow(unused_lifetimes)] impl<'tcx> fmt::Display for $ty {
2353             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2354                 ty::tls::with(|tcx| {
2355                     let cx = tcx.lift(*self)
2356                         .expect("could not lift for printing")
2357                         .print(FmtPrinter::new(tcx, Namespace::TypeNS))?;
2358                     f.write_str(&cx.into_buffer())?;
2359                     Ok(())
2360                 })
2361             }
2362         })+
2363     };
2364 }
2365
2366 macro_rules! define_print_and_forward_display {
2367     (($self:ident, $cx:ident): $($ty:ty $print:block)+) => {
2368         $(impl<'tcx, P: PrettyPrinter<'tcx>> Print<'tcx, P> for $ty {
2369             type Output = P;
2370             type Error = fmt::Error;
2371             fn print(&$self, $cx: P) -> Result<Self::Output, Self::Error> {
2372                 #[allow(unused_mut)]
2373                 let mut $cx = $cx;
2374                 define_scoped_cx!($cx);
2375                 let _: () = $print;
2376                 #[allow(unreachable_code)]
2377                 Ok($cx)
2378             }
2379         })+
2380
2381         forward_display_to_print!($($ty),+);
2382     };
2383 }
2384
2385 /// Wrapper type for `ty::TraitRef` which opts-in to pretty printing only
2386 /// the trait path. That is, it will print `Trait<U>` instead of
2387 /// `<T as Trait<U>>`.
2388 #[derive(Copy, Clone, TypeFoldable, Lift)]
2389 pub struct TraitRefPrintOnlyTraitPath<'tcx>(ty::TraitRef<'tcx>);
2390
2391 impl<'tcx> fmt::Debug for TraitRefPrintOnlyTraitPath<'tcx> {
2392     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2393         fmt::Display::fmt(self, f)
2394     }
2395 }
2396
2397 /// Wrapper type for `ty::TraitRef` which opts-in to pretty printing only
2398 /// the trait name. That is, it will print `Trait` instead of
2399 /// `<T as Trait<U>>`.
2400 #[derive(Copy, Clone, TypeFoldable, Lift)]
2401 pub struct TraitRefPrintOnlyTraitName<'tcx>(ty::TraitRef<'tcx>);
2402
2403 impl<'tcx> fmt::Debug for TraitRefPrintOnlyTraitName<'tcx> {
2404     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2405         fmt::Display::fmt(self, f)
2406     }
2407 }
2408
2409 impl<'tcx> ty::TraitRef<'tcx> {
2410     pub fn print_only_trait_path(self) -> TraitRefPrintOnlyTraitPath<'tcx> {
2411         TraitRefPrintOnlyTraitPath(self)
2412     }
2413
2414     pub fn print_only_trait_name(self) -> TraitRefPrintOnlyTraitName<'tcx> {
2415         TraitRefPrintOnlyTraitName(self)
2416     }
2417 }
2418
2419 impl<'tcx> ty::Binder<'tcx, ty::TraitRef<'tcx>> {
2420     pub fn print_only_trait_path(self) -> ty::Binder<'tcx, TraitRefPrintOnlyTraitPath<'tcx>> {
2421         self.map_bound(|tr| tr.print_only_trait_path())
2422     }
2423 }
2424
2425 #[derive(Copy, Clone, TypeFoldable, Lift)]
2426 pub struct TraitPredPrintModifiersAndPath<'tcx>(ty::TraitPredicate<'tcx>);
2427
2428 impl<'tcx> fmt::Debug for TraitPredPrintModifiersAndPath<'tcx> {
2429     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2430         fmt::Display::fmt(self, f)
2431     }
2432 }
2433
2434 impl<'tcx> ty::TraitPredicate<'tcx> {
2435     pub fn print_modifiers_and_trait_path(self) -> TraitPredPrintModifiersAndPath<'tcx> {
2436         TraitPredPrintModifiersAndPath(self)
2437     }
2438 }
2439
2440 impl<'tcx> ty::PolyTraitPredicate<'tcx> {
2441     pub fn print_modifiers_and_trait_path(
2442         self,
2443     ) -> ty::Binder<'tcx, TraitPredPrintModifiersAndPath<'tcx>> {
2444         self.map_bound(TraitPredPrintModifiersAndPath)
2445     }
2446 }
2447
2448 forward_display_to_print! {
2449     ty::Region<'tcx>,
2450     Ty<'tcx>,
2451     &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
2452     ty::Const<'tcx>,
2453
2454     // HACK(eddyb) these are exhaustive instead of generic,
2455     // because `for<'tcx>` isn't possible yet.
2456     ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>,
2457     ty::Binder<'tcx, ty::TraitRef<'tcx>>,
2458     ty::Binder<'tcx, ty::ExistentialTraitRef<'tcx>>,
2459     ty::Binder<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
2460     ty::Binder<'tcx, TraitRefPrintOnlyTraitName<'tcx>>,
2461     ty::Binder<'tcx, ty::FnSig<'tcx>>,
2462     ty::Binder<'tcx, ty::TraitPredicate<'tcx>>,
2463     ty::Binder<'tcx, TraitPredPrintModifiersAndPath<'tcx>>,
2464     ty::Binder<'tcx, ty::SubtypePredicate<'tcx>>,
2465     ty::Binder<'tcx, ty::ProjectionPredicate<'tcx>>,
2466     ty::Binder<'tcx, ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>>,
2467     ty::Binder<'tcx, ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>>,
2468
2469     ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>,
2470     ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>
2471 }
2472
2473 define_print_and_forward_display! {
2474     (self, cx):
2475
2476     &'tcx ty::List<Ty<'tcx>> {
2477         p!("{{", comma_sep(self.iter()), "}}")
2478     }
2479
2480     ty::TypeAndMut<'tcx> {
2481         p!(write("{}", self.mutbl.prefix_str()), print(self.ty))
2482     }
2483
2484     ty::ExistentialTraitRef<'tcx> {
2485         // Use a type that can't appear in defaults of type parameters.
2486         let dummy_self = cx.tcx().mk_ty_infer(ty::FreshTy(0));
2487         let trait_ref = self.with_self_ty(cx.tcx(), dummy_self);
2488         p!(print(trait_ref.print_only_trait_path()))
2489     }
2490
2491     ty::ExistentialProjection<'tcx> {
2492         let name = cx.tcx().associated_item(self.item_def_id).name;
2493         p!(write("{} = ", name), print(self.term))
2494     }
2495
2496     ty::ExistentialPredicate<'tcx> {
2497         match *self {
2498             ty::ExistentialPredicate::Trait(x) => p!(print(x)),
2499             ty::ExistentialPredicate::Projection(x) => p!(print(x)),
2500             ty::ExistentialPredicate::AutoTrait(def_id) => {
2501                 p!(print_def_path(def_id, &[]));
2502             }
2503         }
2504     }
2505
2506     ty::FnSig<'tcx> {
2507         p!(write("{}", self.unsafety.prefix_str()));
2508
2509         if self.abi != Abi::Rust {
2510             p!(write("extern {} ", self.abi));
2511         }
2512
2513         p!("fn", pretty_fn_sig(self.inputs(), self.c_variadic, self.output()));
2514     }
2515
2516     ty::TraitRef<'tcx> {
2517         p!(write("<{} as {}>", self.self_ty(), self.print_only_trait_path()))
2518     }
2519
2520     TraitRefPrintOnlyTraitPath<'tcx> {
2521         p!(print_def_path(self.0.def_id, self.0.substs));
2522     }
2523
2524     TraitRefPrintOnlyTraitName<'tcx> {
2525         p!(print_def_path(self.0.def_id, &[]));
2526     }
2527
2528     TraitPredPrintModifiersAndPath<'tcx> {
2529         if let ty::BoundConstness::ConstIfConst = self.0.constness {
2530             p!("~const ")
2531         }
2532
2533         if let ty::ImplPolarity::Negative = self.0.polarity {
2534             p!("!")
2535         }
2536
2537         p!(print(self.0.trait_ref.print_only_trait_path()));
2538     }
2539
2540     ty::ParamTy {
2541         p!(write("{}", self.name))
2542     }
2543
2544     ty::ParamConst {
2545         p!(write("{}", self.name))
2546     }
2547
2548     ty::SubtypePredicate<'tcx> {
2549         p!(print(self.a), " <: ", print(self.b))
2550     }
2551
2552     ty::CoercePredicate<'tcx> {
2553         p!(print(self.a), " -> ", print(self.b))
2554     }
2555
2556     ty::TraitPredicate<'tcx> {
2557         p!(print(self.trait_ref.self_ty()), ": ");
2558         if let ty::BoundConstness::ConstIfConst = self.constness {
2559             p!("~const ");
2560         }
2561         p!(print(self.trait_ref.print_only_trait_path()))
2562     }
2563
2564     ty::ProjectionPredicate<'tcx> {
2565         p!(print(self.projection_ty), " == ", print(self.term))
2566     }
2567
2568     ty::Term<'tcx> {
2569       match self {
2570         ty::Term::Ty(ty) => p!(print(ty)),
2571         ty::Term::Const(c) => p!(print(c)),
2572       }
2573     }
2574
2575     ty::ProjectionTy<'tcx> {
2576         p!(print_def_path(self.item_def_id, self.substs));
2577     }
2578
2579     ty::ClosureKind {
2580         match *self {
2581             ty::ClosureKind::Fn => p!("Fn"),
2582             ty::ClosureKind::FnMut => p!("FnMut"),
2583             ty::ClosureKind::FnOnce => p!("FnOnce"),
2584         }
2585     }
2586
2587     ty::Predicate<'tcx> {
2588         let binder = self.kind();
2589         p!(print(binder))
2590     }
2591
2592     ty::PredicateKind<'tcx> {
2593         match *self {
2594             ty::PredicateKind::Trait(ref data) => {
2595                 p!(print(data))
2596             }
2597             ty::PredicateKind::Subtype(predicate) => p!(print(predicate)),
2598             ty::PredicateKind::Coerce(predicate) => p!(print(predicate)),
2599             ty::PredicateKind::RegionOutlives(predicate) => p!(print(predicate)),
2600             ty::PredicateKind::TypeOutlives(predicate) => p!(print(predicate)),
2601             ty::PredicateKind::Projection(predicate) => p!(print(predicate)),
2602             ty::PredicateKind::WellFormed(arg) => p!(print(arg), " well-formed"),
2603             ty::PredicateKind::ObjectSafe(trait_def_id) => {
2604                 p!("the trait `", print_def_path(trait_def_id, &[]), "` is object-safe")
2605             }
2606             ty::PredicateKind::ClosureKind(closure_def_id, _closure_substs, kind) => {
2607                 p!("the closure `",
2608                 print_value_path(closure_def_id, &[]),
2609                 write("` implements the trait `{}`", kind))
2610             }
2611             ty::PredicateKind::ConstEvaluatable(uv) => {
2612                 p!("the constant `", print_value_path(uv.def.did, uv.substs), "` can be evaluated")
2613             }
2614             ty::PredicateKind::ConstEquate(c1, c2) => {
2615                 p!("the constant `", print(c1), "` equals `", print(c2), "`")
2616             }
2617             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
2618                 p!("the type `", print(ty), "` is found in the environment")
2619             }
2620         }
2621     }
2622
2623     GenericArg<'tcx> {
2624         match self.unpack() {
2625             GenericArgKind::Lifetime(lt) => p!(print(lt)),
2626             GenericArgKind::Type(ty) => p!(print(ty)),
2627             GenericArgKind::Const(ct) => p!(print(ct)),
2628         }
2629     }
2630 }
2631
2632 fn for_each_def(tcx: TyCtxt<'_>, mut collect_fn: impl for<'b> FnMut(&'b Ident, Namespace, DefId)) {
2633     // Iterate all local crate items no matter where they are defined.
2634     let hir = tcx.hir();
2635     for id in hir.items() {
2636         if matches!(tcx.def_kind(id.def_id), DefKind::Use) {
2637             continue;
2638         }
2639
2640         let item = hir.item(id);
2641         if item.ident.name == kw::Empty {
2642             continue;
2643         }
2644
2645         let def_id = item.def_id.to_def_id();
2646         let ns = tcx.def_kind(def_id).ns().unwrap_or(Namespace::TypeNS);
2647         collect_fn(&item.ident, ns, def_id);
2648     }
2649
2650     // Now take care of extern crate items.
2651     let queue = &mut Vec::new();
2652     let mut seen_defs: DefIdSet = Default::default();
2653
2654     for &cnum in tcx.crates(()).iter() {
2655         let def_id = cnum.as_def_id();
2656
2657         // Ignore crates that are not direct dependencies.
2658         match tcx.extern_crate(def_id) {
2659             None => continue,
2660             Some(extern_crate) => {
2661                 if !extern_crate.is_direct() {
2662                     continue;
2663                 }
2664             }
2665         }
2666
2667         queue.push(def_id);
2668     }
2669
2670     // Iterate external crate defs but be mindful about visibility
2671     while let Some(def) = queue.pop() {
2672         for child in tcx.module_children(def).iter() {
2673             if !child.vis.is_public() {
2674                 continue;
2675             }
2676
2677             match child.res {
2678                 def::Res::Def(DefKind::AssocTy, _) => {}
2679                 def::Res::Def(DefKind::TyAlias, _) => {}
2680                 def::Res::Def(defkind, def_id) => {
2681                     if let Some(ns) = defkind.ns() {
2682                         collect_fn(&child.ident, ns, def_id);
2683                     }
2684
2685                     if matches!(defkind, DefKind::Mod | DefKind::Enum | DefKind::Trait)
2686                         && seen_defs.insert(def_id)
2687                     {
2688                         queue.push(def_id);
2689                     }
2690                 }
2691                 _ => {}
2692             }
2693         }
2694     }
2695 }
2696
2697 /// The purpose of this function is to collect public symbols names that are unique across all
2698 /// crates in the build. Later, when printing about types we can use those names instead of the
2699 /// full exported path to them.
2700 ///
2701 /// So essentially, if a symbol name can only be imported from one place for a type, and as
2702 /// long as it was not glob-imported anywhere in the current crate, we can trim its printed
2703 /// path and print only the name.
2704 ///
2705 /// This has wide implications on error messages with types, for example, shortening
2706 /// `std::vec::Vec` to just `Vec`, as long as there is no other `Vec` importable anywhere.
2707 ///
2708 /// The implementation uses similar import discovery logic to that of 'use' suggestions.
2709 fn trimmed_def_paths(tcx: TyCtxt<'_>, (): ()) -> FxHashMap<DefId, Symbol> {
2710     let mut map: FxHashMap<DefId, Symbol> = FxHashMap::default();
2711
2712     if let TrimmedDefPaths::GoodPath = tcx.sess.opts.trimmed_def_paths {
2713         // For good paths causing this bug, the `rustc_middle::ty::print::with_no_trimmed_paths`
2714         // wrapper can be used to suppress this query, in exchange for full paths being formatted.
2715         tcx.sess.delay_good_path_bug("trimmed_def_paths constructed");
2716     }
2717
2718     let unique_symbols_rev: &mut FxHashMap<(Namespace, Symbol), Option<DefId>> =
2719         &mut FxHashMap::default();
2720
2721     for symbol_set in tcx.resolutions(()).glob_map.values() {
2722         for symbol in symbol_set {
2723             unique_symbols_rev.insert((Namespace::TypeNS, *symbol), None);
2724             unique_symbols_rev.insert((Namespace::ValueNS, *symbol), None);
2725             unique_symbols_rev.insert((Namespace::MacroNS, *symbol), None);
2726         }
2727     }
2728
2729     for_each_def(tcx, |ident, ns, def_id| {
2730         use std::collections::hash_map::Entry::{Occupied, Vacant};
2731
2732         match unique_symbols_rev.entry((ns, ident.name)) {
2733             Occupied(mut v) => match v.get() {
2734                 None => {}
2735                 Some(existing) => {
2736                     if *existing != def_id {
2737                         v.insert(None);
2738                     }
2739                 }
2740             },
2741             Vacant(v) => {
2742                 v.insert(Some(def_id));
2743             }
2744         }
2745     });
2746
2747     for ((_, symbol), opt_def_id) in unique_symbols_rev.drain() {
2748         use std::collections::hash_map::Entry::{Occupied, Vacant};
2749
2750         if let Some(def_id) = opt_def_id {
2751             match map.entry(def_id) {
2752                 Occupied(mut v) => {
2753                     // A single DefId can be known under multiple names (e.g.,
2754                     // with a `pub use ... as ...;`). We need to ensure that the
2755                     // name placed in this map is chosen deterministically, so
2756                     // if we find multiple names (`symbol`) resolving to the
2757                     // same `def_id`, we prefer the lexicographically smallest
2758                     // name.
2759                     //
2760                     // Any stable ordering would be fine here though.
2761                     if *v.get() != symbol {
2762                         if v.get().as_str() > symbol.as_str() {
2763                             v.insert(symbol);
2764                         }
2765                     }
2766                 }
2767                 Vacant(v) => {
2768                     v.insert(symbol);
2769                 }
2770             }
2771         }
2772     }
2773
2774     map
2775 }
2776
2777 pub fn provide(providers: &mut ty::query::Providers) {
2778     *providers = ty::query::Providers { trimmed_def_paths, ..*providers };
2779 }
2780
2781 #[derive(Default)]
2782 pub struct OpaqueFnEntry<'tcx> {
2783     // The trait ref is already stored as a key, so just track if we have it as a real predicate
2784     has_fn_once: bool,
2785     fn_mut_trait_ref: Option<ty::PolyTraitRef<'tcx>>,
2786     fn_trait_ref: Option<ty::PolyTraitRef<'tcx>>,
2787     return_ty: Option<ty::Binder<'tcx, Term<'tcx>>>,
2788 }