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

   1 use crate::mir::interpret::{AllocRange, GlobalAlloc, Pointer, Provenance, Scalar};
   2 use crate::ty::{
   3     self, ConstInt, DefIdTree, ParamConst, ScalarInt, Term, TermKind, Ty, TyCtxt, TypeFoldable,
   4     TypeSuperFoldable, TypeSuperVisitable, TypeVisitable,
   5 };
   6 use crate::ty::{GenericArg, GenericArgKind};
   7 use rustc_apfloat::ieee::{Double, Single};
   8 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
   9 use rustc_data_structures::sso::SsoHashSet;
  10 use rustc_hir as hir;
  11 use rustc_hir::def::{self, CtorKind, DefKind, Namespace};
  12 use rustc_hir::def_id::{DefId, DefIdSet, CRATE_DEF_ID, LOCAL_CRATE};
  13 use rustc_hir::definitions::{DefKey, DefPathData, DefPathDataName, DisambiguatedDefPathData};
  14 use rustc_hir::LangItem;
  15 use rustc_session::config::TrimmedDefPaths;
  16 use rustc_session::cstore::{ExternCrate, ExternCrateSource};
  17 use rustc_session::Limit;
  18 use rustc_span::symbol::{kw, Ident, Symbol};
  19 use rustc_span::FileNameDisplayPreference;
  20 use rustc_target::abi::Size;
  21 use rustc_target::spec::abi::Abi;
  22 use smallvec::SmallVec;
  23
  24 use std::cell::Cell;
  25 use std::char;
  26 use std::collections::BTreeMap;
  27 use std::fmt::{self, Write as _};
  28 use std::iter;
  29 use std::ops::{ControlFlow, Deref, DerefMut};
  30
  31 // `pretty` is a separate module only for organization.
  32 use super::*;
  33
  34 macro_rules! p {
  35     (@$lit:literal) => {
  36         write!(scoped_cx!(), $lit)?
  37     };
  38     (@write($($data:expr),+)) => {
  39         write!(scoped_cx!(), $($data),+)?
  40     };
  41     (@print($x:expr)) => {
  42         scoped_cx!() = $x.print(scoped_cx!())?
  43     };
  44     (@$method:ident($($arg:expr),*)) => {
  45         scoped_cx!() = scoped_cx!().$method($($arg),*)?
  46     };
  47     ($($elem:tt $(($($args:tt)*))?),+) => {{
  48         $(p!(@ $elem $(($($args)*))?);)+
  49     }};
  50 }
  51 macro_rules! define_scoped_cx {
  52     ($cx:ident) => {
  53         #[allow(unused_macros)]
  54         macro_rules! scoped_cx {
  55             () => {
  56                 $cx
  57             };
  58         }
  59     };
  60 }
  61
  62 thread_local! {
  63     static FORCE_IMPL_FILENAME_LINE: Cell<bool> = const { Cell::new(false) };
  64     static SHOULD_PREFIX_WITH_CRATE: Cell<bool> = const { Cell::new(false) };
  65     static NO_TRIMMED_PATH: Cell<bool> = const { Cell::new(false) };
  66     static FORCE_TRIMMED_PATH: Cell<bool> = const { Cell::new(false) };
  67     static NO_QUERIES: Cell<bool> = const { Cell::new(false) };
  68     static NO_VISIBLE_PATH: Cell<bool> = const { Cell::new(false) };
  69 }
  70
  71 macro_rules! define_helper {
  72     ($($(#[$a:meta])* fn $name:ident($helper:ident, $tl:ident);)+) => {
  73         $(
  74             #[must_use]
  75             pub struct $helper(bool);
  76
  77             impl $helper {
  78                 pub fn new() -> $helper {
  79                     $helper($tl.with(|c| c.replace(true)))
  80                 }
  81             }
  82
  83             $(#[$a])*
  84             pub macro $name($e:expr) {
  85                 {
  86                     let _guard = $helper::new();
  87                     $e
  88                 }
  89             }
  90
  91             impl Drop for $helper {
  92                 fn drop(&mut self) {
  93                     $tl.with(|c| c.set(self.0))
  94                 }
  95             }
  96         )+
  97     }
  98 }
  99
 100 define_helper!(
 101     /// Avoids running any queries during any prints that occur
 102     /// during the closure. This may alter the appearance of some
 103     /// types (e.g. forcing verbose printing for opaque types).
 104     /// This method is used during some queries (e.g. `explicit_item_bounds`
 105     /// for opaque types), to ensure that any debug printing that
 106     /// occurs during the query computation does not end up recursively
 107     /// calling the same query.
 108     fn with_no_queries(NoQueriesGuard, NO_QUERIES);
 109     /// Force us to name impls with just the filename/line number. We
 110     /// normally try to use types. But at some points, notably while printing
 111     /// cycle errors, this can result in extra or suboptimal error output,
 112     /// so this variable disables that check.
 113     fn with_forced_impl_filename_line(ForcedImplGuard, FORCE_IMPL_FILENAME_LINE);
 114     /// Adds the `crate::` prefix to paths where appropriate.
 115     fn with_crate_prefix(CratePrefixGuard, SHOULD_PREFIX_WITH_CRATE);
 116     /// Prevent path trimming if it is turned on. Path trimming affects `Display` impl
 117     /// of various rustc types, for example `std::vec::Vec` would be trimmed to `Vec`,
 118     /// if no other `Vec` is found.
 119     fn with_no_trimmed_paths(NoTrimmedGuard, NO_TRIMMED_PATH);
 120     fn with_forced_trimmed_paths(ForceTrimmedGuard, FORCE_TRIMMED_PATH);
 121     /// Prevent selection of visible paths. `Display` impl of DefId will prefer
 122     /// visible (public) reexports of types as paths.
 123     fn with_no_visible_paths(NoVisibleGuard, NO_VISIBLE_PATH);
 124 );
 125
 126 /// The "region highlights" are used to control region printing during
 127 /// specific error messages. When a "region highlight" is enabled, it
 128 /// gives an alternate way to print specific regions. For now, we
 129 /// always print those regions using a number, so something like "`'0`".
 130 ///
 131 /// Regions not selected by the region highlight mode are presently
 132 /// unaffected.
 133 #[derive(Copy, Clone)]
 134 pub struct RegionHighlightMode<'tcx> {
 135     tcx: TyCtxt<'tcx>,
 136
 137     /// If enabled, when we see the selected region, use "`'N`"
 138     /// instead of the ordinary behavior.
 139     highlight_regions: [Option<(ty::Region<'tcx>, usize)>; 3],
 140
 141     /// If enabled, when printing a "free region" that originated from
 142     /// the given `ty::BoundRegionKind`, print it as "`'1`". Free regions that would ordinarily
 143     /// have names print as normal.
 144     ///
 145     /// This is used when you have a signature like `fn foo(x: &u32,
 146     /// y: &'a u32)` and we want to give a name to the region of the
 147     /// reference `x`.
 148     highlight_bound_region: Option<(ty::BoundRegionKind, usize)>,
 149 }
 150
 151 impl<'tcx> RegionHighlightMode<'tcx> {
 152     pub fn new(tcx: TyCtxt<'tcx>) -> Self {
 153         Self {
 154             tcx,
 155             highlight_regions: Default::default(),
 156             highlight_bound_region: Default::default(),
 157         }
 158     }
 159
 160     /// If `region` and `number` are both `Some`, invokes
 161     /// `highlighting_region`.
 162     pub fn maybe_highlighting_region(
 163         &mut self,
 164         region: Option<ty::Region<'tcx>>,
 165         number: Option<usize>,
 166     ) {
 167         if let Some(k) = region {
 168             if let Some(n) = number {
 169                 self.highlighting_region(k, n);
 170             }
 171         }
 172     }
 173
 174     /// Highlights the region inference variable `vid` as `'N`.
 175     pub fn highlighting_region(&mut self, region: ty::Region<'tcx>, number: usize) {
 176         let num_slots = self.highlight_regions.len();
 177         let first_avail_slot =
 178             self.highlight_regions.iter_mut().find(|s| s.is_none()).unwrap_or_else(|| {
 179                 bug!("can only highlight {} placeholders at a time", num_slots,)
 180             });
 181         *first_avail_slot = Some((region, number));
 182     }
 183
 184     /// Convenience wrapper for `highlighting_region`.
 185     pub fn highlighting_region_vid(&mut self, vid: ty::RegionVid, number: usize) {
 186         self.highlighting_region(self.tcx.mk_region(ty::ReVar(vid)), number)
 187     }
 188
 189     /// Returns `Some(n)` with the number to use for the given region, if any.
 190     fn region_highlighted(&self, region: ty::Region<'tcx>) -> Option<usize> {
 191         self.highlight_regions.iter().find_map(|h| match h {
 192             Some((r, n)) if *r == region => Some(*n),
 193             _ => None,
 194         })
 195     }
 196
 197     /// Highlight the given bound region.
 198     /// We can only highlight one bound region at a time. See
 199     /// the field `highlight_bound_region` for more detailed notes.
 200     pub fn highlighting_bound_region(&mut self, br: ty::BoundRegionKind, number: usize) {
 201         assert!(self.highlight_bound_region.is_none());
 202         self.highlight_bound_region = Some((br, number));
 203     }
 204 }
 205
 206 /// Trait for printers that pretty-print using `fmt::Write` to the printer.
 207 pub trait PrettyPrinter<'tcx>:
 208     Printer<
 209         'tcx,
 210         Error = fmt::Error,
 211         Path = Self,
 212         Region = Self,
 213         Type = Self,
 214         DynExistential = Self,
 215         Const = Self,
 216     > + fmt::Write
 217 {
 218     /// Like `print_def_path` but for value paths.
 219     fn print_value_path(
 220         self,
 221         def_id: DefId,
 222         substs: &'tcx [GenericArg<'tcx>],
 223     ) -> Result<Self::Path, Self::Error> {
 224         self.print_def_path(def_id, substs)
 225     }
 226
 227     fn in_binder<T>(self, value: &ty::Binder<'tcx, T>) -> Result<Self, Self::Error>
 228     where
 229         T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>,
 230     {
 231         value.as_ref().skip_binder().print(self)
 232     }
 233
 234     fn wrap_binder<T, F: FnOnce(&T, Self) -> Result<Self, fmt::Error>>(
 235         self,
 236         value: &ty::Binder<'tcx, T>,
 237         f: F,
 238     ) -> Result<Self, Self::Error>
 239     where
 240         T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>,
 241     {
 242         f(value.as_ref().skip_binder(), self)
 243     }
 244
 245     /// Prints comma-separated elements.
 246     fn comma_sep<T>(mut self, mut elems: impl Iterator<Item = T>) -> Result<Self, Self::Error>
 247     where
 248         T: Print<'tcx, Self, Output = Self, Error = Self::Error>,
 249     {
 250         if let Some(first) = elems.next() {
 251             self = first.print(self)?;
 252             for elem in elems {
 253                 self.write_str(", ")?;
 254                 self = elem.print(self)?;
 255             }
 256         }
 257         Ok(self)
 258     }
 259
 260     /// Prints `{f: t}` or `{f as t}` depending on the `cast` argument
 261     fn typed_value(
 262         mut self,
 263         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
 264         t: impl FnOnce(Self) -> Result<Self, Self::Error>,
 265         conversion: &str,
 266     ) -> Result<Self::Const, Self::Error> {
 267         self.write_str("{")?;
 268         self = f(self)?;
 269         self.write_str(conversion)?;
 270         self = t(self)?;
 271         self.write_str("}")?;
 272         Ok(self)
 273     }
 274
 275     /// Prints `<...>` around what `f` prints.
 276     fn generic_delimiters(
 277         self,
 278         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
 279     ) -> Result<Self, Self::Error>;
 280
 281     /// Returns `true` if the region should be printed in
 282     /// optional positions, e.g., `&'a T` or `dyn Tr + 'b`.
 283     /// This is typically the case for all non-`'_` regions.
 284     fn should_print_region(&self, region: ty::Region<'tcx>) -> bool;
 285
 286     fn reset_type_limit(&mut self) {}
 287
 288     // Defaults (should not be overridden):
 289
 290     /// If possible, this returns a global path resolving to `def_id` that is visible
 291     /// from at least one local module, and returns `true`. If the crate defining `def_id` is
 292     /// declared with an `extern crate`, the path is guaranteed to use the `extern crate`.
 293     fn try_print_visible_def_path(self, def_id: DefId) -> Result<(Self, bool), Self::Error> {
 294         if NO_VISIBLE_PATH.with(|flag| flag.get()) {
 295             return Ok((self, false));
 296         }
 297
 298         let mut callers = Vec::new();
 299         self.try_print_visible_def_path_recur(def_id, &mut callers)
 300     }
 301
 302     // Given a `DefId`, produce a short name. For types and traits, it prints *only* its name,
 303     // For associated items on traits it prints out the trait's name and the associated item's name.
 304     // For enum variants, if they have an unique name, then we only print the name, otherwise we
 305     // print the enum name and the variant name. Otherwise, we do not print anything and let the
 306     // caller use the `print_def_path` fallback.
 307     fn force_print_trimmed_def_path(
 308         mut self,
 309         def_id: DefId,
 310     ) -> Result<(Self::Path, bool), Self::Error> {
 311         let key = self.tcx().def_key(def_id);
 312         let visible_parent_map = self.tcx().visible_parent_map(());
 313         let kind = self.tcx().def_kind(def_id);
 314
 315         let get_local_name = |this: &Self, name, def_id, key: DefKey| {
 316             if let Some(visible_parent) = visible_parent_map.get(&def_id)
 317                 && let actual_parent = this.tcx().opt_parent(def_id)
 318                 && let DefPathData::TypeNs(_) = key.disambiguated_data.data
 319                 && Some(*visible_parent) != actual_parent
 320             {
 321                 this
 322                     .tcx()
 323                     .module_children(visible_parent)
 324                     .iter()
 325                     .filter(|child| child.res.opt_def_id() == Some(def_id))
 326                     .find(|child| child.vis.is_public() && child.ident.name != kw::Underscore)
 327                     .map(|child| child.ident.name)
 328                     .unwrap_or(name)
 329             } else {
 330                 name
 331             }
 332         };
 333         if let DefKind::Variant = kind
 334             && let Some(symbol) = self.tcx().trimmed_def_paths(()).get(&def_id)
 335         {
 336             // If `Assoc` is unique, we don't want to talk about `Trait::Assoc`.
 337             self.write_str(get_local_name(&self, *symbol, def_id, key).as_str())?;
 338             return Ok((self, true));
 339         }
 340         if let Some(symbol) = key.get_opt_name() {
 341             if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = kind
 342                 && let Some(parent) = self.tcx().opt_parent(def_id)
 343                 && let parent_key = self.tcx().def_key(parent)
 344                 && let Some(symbol) = parent_key.get_opt_name()
 345             {
 346                 // Trait
 347                 self.write_str(get_local_name(&self, symbol, parent, parent_key).as_str())?;
 348                 self.write_str("::")?;
 349             } else if let DefKind::Variant = kind
 350                 && let Some(parent) = self.tcx().opt_parent(def_id)
 351                 && let parent_key = self.tcx().def_key(parent)
 352                 && let Some(symbol) = parent_key.get_opt_name()
 353             {
 354                 // Enum
 355
 356                 // For associated items and variants, we want the "full" path, namely, include
 357                 // the parent type in the path. For example, `Iterator::Item`.
 358                 self.write_str(get_local_name(&self, symbol, parent, parent_key).as_str())?;
 359                 self.write_str("::")?;
 360             } else if let DefKind::Struct | DefKind::Union | DefKind::Enum | DefKind::Trait
 361                 | DefKind::TyAlias | DefKind::Fn | DefKind::Const | DefKind::Static(_) = kind
 362             {
 363             } else {
 364                 // If not covered above, like for example items out of `impl` blocks, fallback.
 365                 return Ok((self, false));
 366             }
 367             self.write_str(get_local_name(&self, symbol, def_id, key).as_str())?;
 368             return Ok((self, true));
 369         }
 370         Ok((self, false))
 371     }
 372
 373     /// Try to see if this path can be trimmed to a unique symbol name.
 374     fn try_print_trimmed_def_path(
 375         mut self,
 376         def_id: DefId,
 377     ) -> Result<(Self::Path, bool), Self::Error> {
 378         if FORCE_TRIMMED_PATH.with(|flag| flag.get()) {
 379             let (s, trimmed) = self.force_print_trimmed_def_path(def_id)?;
 380             if trimmed {
 381                 return Ok((s, true));
 382             }
 383             self = s;
 384         }
 385         if !self.tcx().sess.opts.unstable_opts.trim_diagnostic_paths
 386             || matches!(self.tcx().sess.opts.trimmed_def_paths, TrimmedDefPaths::Never)
 387             || NO_TRIMMED_PATH.with(|flag| flag.get())
 388             || SHOULD_PREFIX_WITH_CRATE.with(|flag| flag.get())
 389         {
 390             return Ok((self, false));
 391         }
 392
 393         match self.tcx().trimmed_def_paths(()).get(&def_id) {
 394             None => Ok((self, false)),
 395             Some(symbol) => {
 396                 write!(self, "{}", Ident::with_dummy_span(*symbol))?;
 397                 Ok((self, true))
 398             }
 399         }
 400     }
 401
 402     /// Does the work of `try_print_visible_def_path`, building the
 403     /// full definition path recursively before attempting to
 404     /// post-process it into the valid and visible version that
 405     /// accounts for re-exports.
 406     ///
 407     /// This method should only be called by itself or
 408     /// `try_print_visible_def_path`.
 409     ///
 410     /// `callers` is a chain of visible_parent's leading to `def_id`,
 411     /// to support cycle detection during recursion.
 412     ///
 413     /// This method returns false if we can't print the visible path, so
 414     /// `print_def_path` can fall back on the item's real definition path.
 415     fn try_print_visible_def_path_recur(
 416         mut self,
 417         def_id: DefId,
 418         callers: &mut Vec<DefId>,
 419     ) -> Result<(Self, bool), Self::Error> {
 420         define_scoped_cx!(self);
 421
 422         debug!("try_print_visible_def_path: def_id={:?}", def_id);
 423
 424         // If `def_id` is a direct or injected extern crate, return the
 425         // path to the crate followed by the path to the item within the crate.
 426         if let Some(cnum) = def_id.as_crate_root() {
 427             if cnum == LOCAL_CRATE {
 428                 return Ok((self.path_crate(cnum)?, true));
 429             }
 430
 431             // In local mode, when we encounter a crate other than
 432             // LOCAL_CRATE, execution proceeds in one of two ways:
 433             //
 434             // 1. For a direct dependency, where user added an
 435             //    `extern crate` manually, we put the `extern
 436             //    crate` as the parent. So you wind up with
 437             //    something relative to the current crate.
 438             // 2. For an extern inferred from a path or an indirect crate,
 439             //    where there is no explicit `extern crate`, we just prepend
 440             //    the crate name.
 441             match self.tcx().extern_crate(def_id) {
 442                 Some(&ExternCrate { src, dependency_of, span, .. }) => match (src, dependency_of) {
 443                     (ExternCrateSource::Extern(def_id), LOCAL_CRATE) => {
 444                         // NOTE(eddyb) the only reason `span` might be dummy,
 445                         // that we're aware of, is that it's the `std`/`core`
 446                         // `extern crate` injected by default.
 447                         // FIXME(eddyb) find something better to key this on,
 448                         // or avoid ending up with `ExternCrateSource::Extern`,
 449                         // for the injected `std`/`core`.
 450                         if span.is_dummy() {
 451                             return Ok((self.path_crate(cnum)?, true));
 452                         }
 453
 454                         // Disable `try_print_trimmed_def_path` behavior within
 455                         // the `print_def_path` call, to avoid infinite recursion
 456                         // in cases where the `extern crate foo` has non-trivial
 457                         // parents, e.g. it's nested in `impl foo::Trait for Bar`
 458                         // (see also issues #55779 and #87932).
 459                         self = with_no_visible_paths!(self.print_def_path(def_id, &[])?);
 460
 461                         return Ok((self, true));
 462                     }
 463                     (ExternCrateSource::Path, LOCAL_CRATE) => {
 464                         return Ok((self.path_crate(cnum)?, true));
 465                     }
 466                     _ => {}
 467                 },
 468                 None => {
 469                     return Ok((self.path_crate(cnum)?, true));
 470                 }
 471             }
 472         }
 473
 474         if def_id.is_local() {
 475             return Ok((self, false));
 476         }
 477
 478         let visible_parent_map = self.tcx().visible_parent_map(());
 479
 480         let mut cur_def_key = self.tcx().def_key(def_id);
 481         debug!("try_print_visible_def_path: cur_def_key={:?}", cur_def_key);
 482
 483         // For a constructor, we want the name of its parent rather than <unnamed>.
 484         if let DefPathData::Ctor = cur_def_key.disambiguated_data.data {
 485             let parent = DefId {
 486                 krate: def_id.krate,
 487                 index: cur_def_key
 488                     .parent
 489                     .expect("`DefPathData::Ctor` / `VariantData` missing a parent"),
 490             };
 491
 492             cur_def_key = self.tcx().def_key(parent);
 493         }
 494
 495         let Some(visible_parent) = visible_parent_map.get(&def_id).cloned() else {
 496             return Ok((self, false));
 497         };
 498
 499         let actual_parent = self.tcx().opt_parent(def_id);
 500         debug!(
 501             "try_print_visible_def_path: visible_parent={:?} actual_parent={:?}",
 502             visible_parent, actual_parent,
 503         );
 504
 505         let mut data = cur_def_key.disambiguated_data.data;
 506         debug!(
 507             "try_print_visible_def_path: data={:?} visible_parent={:?} actual_parent={:?}",
 508             data, visible_parent, actual_parent,
 509         );
 510
 511         match data {
 512             // In order to output a path that could actually be imported (valid and visible),
 513             // we need to handle re-exports correctly.
 514             //
 515             // For example, take `std::os::unix::process::CommandExt`, this trait is actually
 516             // defined at `std::sys::unix::ext::process::CommandExt` (at time of writing).
 517             //
 518             // `std::os::unix` reexports the contents of `std::sys::unix::ext`. `std::sys` is
 519             // private so the "true" path to `CommandExt` isn't accessible.
 520             //
 521             // In this case, the `visible_parent_map` will look something like this:
 522             //
 523             // (child) -> (parent)
 524             // `std::sys::unix::ext::process::CommandExt` -> `std::sys::unix::ext::process`
 525             // `std::sys::unix::ext::process` -> `std::sys::unix::ext`
 526             // `std::sys::unix::ext` -> `std::os`
 527             //
 528             // This is correct, as the visible parent of `std::sys::unix::ext` is in fact
 529             // `std::os`.
 530             //
 531             // When printing the path to `CommandExt` and looking at the `cur_def_key` that
 532             // corresponds to `std::sys::unix::ext`, we would normally print `ext` and then go
 533             // to the parent - resulting in a mangled path like
 534             // `std::os::ext::process::CommandExt`.
 535             //
 536             // Instead, we must detect that there was a re-export and instead print `unix`
 537             // (which is the name `std::sys::unix::ext` was re-exported as in `std::os`). To
 538             // do this, we compare the parent of `std::sys::unix::ext` (`std::sys::unix`) with
 539             // the visible parent (`std::os`). If these do not match, then we iterate over
 540             // the children of the visible parent (as was done when computing
 541             // `visible_parent_map`), looking for the specific child we currently have and then
 542             // have access to the re-exported name.
 543             DefPathData::TypeNs(ref mut name) if Some(visible_parent) != actual_parent => {
 544                 // Item might be re-exported several times, but filter for the one
 545                 // that's public and whose identifier isn't `_`.
 546                 let reexport = self
 547                     .tcx()
 548                     .module_children(visible_parent)
 549                     .iter()
 550                     .filter(|child| child.res.opt_def_id() == Some(def_id))
 551                     .find(|child| child.vis.is_public() && child.ident.name != kw::Underscore)
 552                     .map(|child| child.ident.name);
 553
 554                 if let Some(new_name) = reexport {
 555                     *name = new_name;
 556                 } else {
 557                     // There is no name that is public and isn't `_`, so bail.
 558                     return Ok((self, false));
 559                 }
 560             }
 561             // Re-exported `extern crate` (#43189).
 562             DefPathData::CrateRoot => {
 563                 data = DefPathData::TypeNs(self.tcx().crate_name(def_id.krate));
 564             }
 565             _ => {}
 566         }
 567         debug!("try_print_visible_def_path: data={:?}", data);
 568
 569         if callers.contains(&visible_parent) {
 570             return Ok((self, false));
 571         }
 572         callers.push(visible_parent);
 573         // HACK(eddyb) this bypasses `path_append`'s prefix printing to avoid
 574         // knowing ahead of time whether the entire path will succeed or not.
 575         // To support printers that do not implement `PrettyPrinter`, a `Vec` or
 576         // linked list on the stack would need to be built, before any printing.
 577         match self.try_print_visible_def_path_recur(visible_parent, callers)? {
 578             (cx, false) => return Ok((cx, false)),
 579             (cx, true) => self = cx,
 580         }
 581         callers.pop();
 582
 583         Ok((self.path_append(Ok, &DisambiguatedDefPathData { data, disambiguator: 0 })?, true))
 584     }
 585
 586     fn pretty_path_qualified(
 587         self,
 588         self_ty: Ty<'tcx>,
 589         trait_ref: Option<ty::TraitRef<'tcx>>,
 590     ) -> Result<Self::Path, Self::Error> {
 591         if trait_ref.is_none() {
 592             // Inherent impls. Try to print `Foo::bar` for an inherent
 593             // impl on `Foo`, but fallback to `<Foo>::bar` if self-type is
 594             // anything other than a simple path.
 595             match self_ty.kind() {
 596                 ty::Adt(..)
 597                 | ty::Foreign(_)
 598                 | ty::Bool
 599                 | ty::Char
 600                 | ty::Str
 601                 | ty::Int(_)
 602                 | ty::Uint(_)
 603                 | ty::Float(_) => {
 604                     return self_ty.print(self);
 605                 }
 606
 607                 _ => {}
 608             }
 609         }
 610
 611         self.generic_delimiters(|mut cx| {
 612             define_scoped_cx!(cx);
 613
 614             p!(print(self_ty));
 615             if let Some(trait_ref) = trait_ref {
 616                 p!(" as ", print(trait_ref.print_only_trait_path()));
 617             }
 618             Ok(cx)
 619         })
 620     }
 621
 622     fn pretty_path_append_impl(
 623         mut self,
 624         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 625         self_ty: Ty<'tcx>,
 626         trait_ref: Option<ty::TraitRef<'tcx>>,
 627     ) -> Result<Self::Path, Self::Error> {
 628         self = print_prefix(self)?;
 629
 630         self.generic_delimiters(|mut cx| {
 631             define_scoped_cx!(cx);
 632
 633             p!("impl ");
 634             if let Some(trait_ref) = trait_ref {
 635                 p!(print(trait_ref.print_only_trait_path()), " for ");
 636             }
 637             p!(print(self_ty));
 638
 639             Ok(cx)
 640         })
 641     }
 642
 643     fn pretty_print_type(mut self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
 644         define_scoped_cx!(self);
 645
 646         match *ty.kind() {
 647             ty::Bool => p!("bool"),
 648             ty::Char => p!("char"),
 649             ty::Int(t) => p!(write("{}", t.name_str())),
 650             ty::Uint(t) => p!(write("{}", t.name_str())),
 651             ty::Float(t) => p!(write("{}", t.name_str())),
 652             ty::RawPtr(ref tm) => {
 653                 p!(write(
 654                     "*{} ",
 655                     match tm.mutbl {
 656                         hir::Mutability::Mut => "mut",
 657                         hir::Mutability::Not => "const",
 658                     }
 659                 ));
 660                 p!(print(tm.ty))
 661             }
 662             ty::Ref(r, ty, mutbl) => {
 663                 p!("&");
 664                 if self.should_print_region(r) {
 665                     p!(print(r), " ");
 666                 }
 667                 p!(print(ty::TypeAndMut { ty, mutbl }))
 668             }
 669             ty::Never => p!("!"),
 670             ty::Tuple(ref tys) => {
 671                 p!("(", comma_sep(tys.iter()));
 672                 if tys.len() == 1 {
 673                     p!(",");
 674                 }
 675                 p!(")")
 676             }
 677             ty::FnDef(def_id, substs) => {
 678                 let sig = self.tcx().fn_sig(def_id).subst(self.tcx(), substs);
 679                 p!(print(sig), " {{", print_value_path(def_id, substs), "}}");
 680             }
 681             ty::FnPtr(ref bare_fn) => p!(print(bare_fn)),
 682             ty::Infer(infer_ty) => {
 683                 let verbose = self.should_print_verbose();
 684                 if let ty::TyVar(ty_vid) = infer_ty {
 685                     if let Some(name) = self.ty_infer_name(ty_vid) {
 686                         p!(write("{}", name))
 687                     } else {
 688                         if verbose {
 689                             p!(write("{:?}", infer_ty))
 690                         } else {
 691                             p!(write("{}", infer_ty))
 692                         }
 693                     }
 694                 } else {
 695                     if verbose { p!(write("{:?}", infer_ty)) } else { p!(write("{}", infer_ty)) }
 696                 }
 697             }
 698             ty::Error(_) => p!("[type error]"),
 699             ty::Param(ref param_ty) => p!(print(param_ty)),
 700             ty::Bound(debruijn, bound_ty) => match bound_ty.kind {
 701                 ty::BoundTyKind::Anon => self.pretty_print_bound_var(debruijn, bound_ty.var)?,
 702                 ty::BoundTyKind::Param(p) => p!(write("{}", p)),
 703             },
 704             ty::Adt(def, substs) => {
 705                 p!(print_def_path(def.did(), substs));
 706             }
 707             ty::Dynamic(data, r, repr) => {
 708                 let print_r = self.should_print_region(r);
 709                 if print_r {
 710                     p!("(");
 711                 }
 712                 match repr {
 713                     ty::Dyn => p!("dyn "),
 714                     ty::DynStar => p!("dyn* "),
 715                 }
 716                 p!(print(data));
 717                 if print_r {
 718                     p!(" + ", print(r), ")");
 719                 }
 720             }
 721             ty::Foreign(def_id) => {
 722                 p!(print_def_path(def_id, &[]));
 723             }
 724             ty::Alias(ty::Projection, ref data) => {
 725                 if !(self.should_print_verbose() || NO_QUERIES.with(|q| q.get()))
 726                     && self.tcx().def_kind(data.def_id) == DefKind::ImplTraitPlaceholder
 727                 {
 728                     return self.pretty_print_opaque_impl_type(data.def_id, data.substs);
 729                 } else {
 730                     p!(print(data))
 731                 }
 732             }
 733             ty::Placeholder(placeholder) => p!(write("Placeholder({:?})", placeholder)),
 734             ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => {
 735                 // FIXME(eddyb) print this with `print_def_path`.
 736                 // We use verbose printing in 'NO_QUERIES' mode, to
 737                 // avoid needing to call `predicates_of`. This should
 738                 // only affect certain debug messages (e.g. messages printed
 739                 // from `rustc_middle::ty` during the computation of `tcx.predicates_of`),
 740                 // and should have no effect on any compiler output.
 741                 if self.should_print_verbose() || NO_QUERIES.with(|q| q.get()) {
 742                     p!(write("Opaque({:?}, {:?})", def_id, substs));
 743                     return Ok(self);
 744                 }
 745
 746                 let parent = self.tcx().parent(def_id);
 747                 match self.tcx().def_kind(parent) {
 748                     DefKind::TyAlias | DefKind::AssocTy => {
 749                         if let ty::Alias(ty::Opaque, ty::AliasTy { def_id: d, .. }) =
 750                             *self.tcx().type_of(parent).kind()
 751                         {
 752                             if d == def_id {
 753                                 // If the type alias directly starts with the `impl` of the
 754                                 // opaque type we're printing, then skip the `::{opaque#1}`.
 755                                 p!(print_def_path(parent, substs));
 756                                 return Ok(self);
 757                             }
 758                         }
 759                         // Complex opaque type, e.g. `type Foo = (i32, impl Debug);`
 760                         p!(print_def_path(def_id, substs));
 761                         return Ok(self);
 762                     }
 763                     _ => return self.pretty_print_opaque_impl_type(def_id, substs),
 764                 }
 765             }
 766             ty::Str => p!("str"),
 767             ty::Generator(did, substs, movability) => {
 768                 p!(write("["));
 769                 let generator_kind = self.tcx().generator_kind(did).unwrap();
 770                 let should_print_movability =
 771                     self.should_print_verbose() || generator_kind == hir::GeneratorKind::Gen;
 772
 773                 if should_print_movability {
 774                     match movability {
 775                         hir::Movability::Movable => {}
 776                         hir::Movability::Static => p!("static "),
 777                     }
 778                 }
 779
 780                 if !self.should_print_verbose() {
 781                     p!(write("{}", generator_kind));
 782                     // FIXME(eddyb) should use `def_span`.
 783                     if let Some(did) = did.as_local() {
 784                         let span = self.tcx().def_span(did);
 785                         p!(write(
 786                             "@{}",
 787                             // This may end up in stderr diagnostics but it may also be emitted
 788                             // into MIR. Hence we use the remapped path if available
 789                             self.tcx().sess.source_map().span_to_embeddable_string(span)
 790                         ));
 791                     } else {
 792                         p!(write("@"), print_def_path(did, substs));
 793                     }
 794                 } else {
 795                     p!(print_def_path(did, substs));
 796                     p!(" upvar_tys=(");
 797                     if !substs.as_generator().is_valid() {
 798                         p!("unavailable");
 799                     } else {
 800                         self = self.comma_sep(substs.as_generator().upvar_tys())?;
 801                     }
 802                     p!(")");
 803
 804                     if substs.as_generator().is_valid() {
 805                         p!(" ", print(substs.as_generator().witness()));
 806                     }
 807                 }
 808
 809                 p!("]")
 810             }
 811             ty::GeneratorWitness(types) => {
 812                 p!(in_binder(&types));
 813             }
 814             ty::GeneratorWitnessMIR(did, substs) => {
 815                 p!(write("["));
 816                 if !self.tcx().sess.verbose() {
 817                     p!("generator witness");
 818                     // FIXME(eddyb) should use `def_span`.
 819                     if let Some(did) = did.as_local() {
 820                         let span = self.tcx().def_span(did);
 821                         p!(write(
 822                             "@{}",
 823                             // This may end up in stderr diagnostics but it may also be emitted
 824                             // into MIR. Hence we use the remapped path if available
 825                             self.tcx().sess.source_map().span_to_embeddable_string(span)
 826                         ));
 827                     } else {
 828                         p!(write("@"), print_def_path(did, substs));
 829                     }
 830                 } else {
 831                     p!(print_def_path(did, substs));
 832                 }
 833
 834                 p!("]")
 835             }
 836             ty::Closure(did, substs) => {
 837                 p!(write("["));
 838                 if !self.should_print_verbose() {
 839                     p!(write("closure"));
 840                     // FIXME(eddyb) should use `def_span`.
 841                     if let Some(did) = did.as_local() {
 842                         if self.tcx().sess.opts.unstable_opts.span_free_formats {
 843                             p!("@", print_def_path(did.to_def_id(), substs));
 844                         } else {
 845                             let span = self.tcx().def_span(did);
 846                             let preference = if FORCE_TRIMMED_PATH.with(|flag| flag.get()) {
 847                                 FileNameDisplayPreference::Short
 848                             } else {
 849                                 FileNameDisplayPreference::Remapped
 850                             };
 851                             p!(write(
 852                                 "@{}",
 853                                 // This may end up in stderr diagnostics but it may also be emitted
 854                                 // into MIR. Hence we use the remapped path if available
 855                                 self.tcx().sess.source_map().span_to_string(span, preference)
 856                             ));
 857                         }
 858                     } else {
 859                         p!(write("@"), print_def_path(did, substs));
 860                     }
 861                 } else {
 862                     p!(print_def_path(did, substs));
 863                     if !substs.as_closure().is_valid() {
 864                         p!(" closure_substs=(unavailable)");
 865                         p!(write(" substs={:?}", substs));
 866                     } else {
 867                         p!(" closure_kind_ty=", print(substs.as_closure().kind_ty()));
 868                         p!(
 869                             " closure_sig_as_fn_ptr_ty=",
 870                             print(substs.as_closure().sig_as_fn_ptr_ty())
 871                         );
 872                         p!(" upvar_tys=(");
 873                         self = self.comma_sep(substs.as_closure().upvar_tys())?;
 874                         p!(")");
 875                     }
 876                 }
 877                 p!("]");
 878             }
 879             ty::Array(ty, sz) => p!("[", print(ty), "; ", print(sz), "]"),
 880             ty::Slice(ty) => p!("[", print(ty), "]"),
 881         }
 882
 883         Ok(self)
 884     }
 885
 886     fn pretty_print_opaque_impl_type(
 887         mut self,
 888         def_id: DefId,
 889         substs: &'tcx ty::List<ty::GenericArg<'tcx>>,
 890     ) -> Result<Self::Type, Self::Error> {
 891         let tcx = self.tcx();
 892
 893         // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
 894         // by looking up the projections associated with the def_id.
 895         let bounds = tcx.bound_explicit_item_bounds(def_id);
 896
 897         let mut traits = FxIndexMap::default();
 898         let mut fn_traits = FxIndexMap::default();
 899         let mut is_sized = false;
 900         let mut lifetimes = SmallVec::<[ty::Region<'tcx>; 1]>::new();
 901
 902         for (predicate, _) in bounds.subst_iter_copied(tcx, substs) {
 903             let bound_predicate = predicate.kind();
 904
 905             match bound_predicate.skip_binder() {
 906                 ty::PredicateKind::Clause(ty::Clause::Trait(pred)) => {
 907                     let trait_ref = bound_predicate.rebind(pred.trait_ref);
 908
 909                     // Don't print + Sized, but rather + ?Sized if absent.
 910                     if Some(trait_ref.def_id()) == tcx.lang_items().sized_trait() {
 911                         is_sized = true;
 912                         continue;
 913                     }
 914
 915                     self.insert_trait_and_projection(trait_ref, None, &mut traits, &mut fn_traits);
 916                 }
 917                 ty::PredicateKind::Clause(ty::Clause::Projection(pred)) => {
 918                     let proj_ref = bound_predicate.rebind(pred);
 919                     let trait_ref = proj_ref.required_poly_trait_ref(tcx);
 920
 921                     // Projection type entry -- the def-id for naming, and the ty.
 922                     let proj_ty = (proj_ref.projection_def_id(), proj_ref.term());
 923
 924                     self.insert_trait_and_projection(
 925                         trait_ref,
 926                         Some(proj_ty),
 927                         &mut traits,
 928                         &mut fn_traits,
 929                     );
 930                 }
 931                 ty::PredicateKind::Clause(ty::Clause::TypeOutlives(outlives)) => {
 932                     lifetimes.push(outlives.1);
 933                 }
 934                 _ => {}
 935             }
 936         }
 937
 938         write!(self, "impl ")?;
 939
 940         let mut first = true;
 941         // Insert parenthesis around (Fn(A, B) -> C) if the opaque ty has more than one other trait
 942         let paren_needed = fn_traits.len() > 1 || traits.len() > 0 || !is_sized;
 943
 944         for (fn_once_trait_ref, entry) in fn_traits {
 945             write!(self, "{}", if first { "" } else { " + " })?;
 946             write!(self, "{}", if paren_needed { "(" } else { "" })?;
 947
 948             self = self.wrap_binder(&fn_once_trait_ref, |trait_ref, mut cx| {
 949                 define_scoped_cx!(cx);
 950                 // Get the (single) generic ty (the args) of this FnOnce trait ref.
 951                 let generics = tcx.generics_of(trait_ref.def_id);
 952                 let args = generics.own_substs_no_defaults(tcx, trait_ref.substs);
 953
 954                 match (entry.return_ty, args[0].expect_ty()) {
 955                     // We can only print `impl Fn() -> ()` if we have a tuple of args and we recorded
 956                     // a return type.
 957                     (Some(return_ty), arg_tys) if matches!(arg_tys.kind(), ty::Tuple(_)) => {
 958                         let name = if entry.fn_trait_ref.is_some() {
 959                             "Fn"
 960                         } else if entry.fn_mut_trait_ref.is_some() {
 961                             "FnMut"
 962                         } else {
 963                             "FnOnce"
 964                         };
 965
 966                         p!(write("{}(", name));
 967
 968                         for (idx, ty) in arg_tys.tuple_fields().iter().enumerate() {
 969                             if idx > 0 {
 970                                 p!(", ");
 971                             }
 972                             p!(print(ty));
 973                         }
 974
 975                         p!(")");
 976                         if let Some(ty) = return_ty.skip_binder().ty() {
 977                             if !ty.is_unit() {
 978                                 p!(" -> ", print(return_ty));
 979                             }
 980                         }
 981                         p!(write("{}", if paren_needed { ")" } else { "" }));
 982
 983                         first = false;
 984                     }
 985                     // If we got here, we can't print as a `impl Fn(A, B) -> C`. Just record the
 986                     // trait_refs we collected in the OpaqueFnEntry as normal trait refs.
 987                     _ => {
 988                         if entry.has_fn_once {
 989                             traits.entry(fn_once_trait_ref).or_default().extend(
 990                                 // Group the return ty with its def id, if we had one.
 991                                 entry
 992                                     .return_ty
 993                                     .map(|ty| (tcx.require_lang_item(LangItem::FnOnce, None), ty)),
 994                             );
 995                         }
 996                         if let Some(trait_ref) = entry.fn_mut_trait_ref {
 997                             traits.entry(trait_ref).or_default();
 998                         }
 999                         if let Some(trait_ref) = entry.fn_trait_ref {
1000                             traits.entry(trait_ref).or_default();
1001                         }
1002                     }
1003                 }
1004
1005                 Ok(cx)
1006             })?;
1007         }
1008
1009         // Print the rest of the trait types (that aren't Fn* family of traits)
1010         for (trait_ref, assoc_items) in traits {
1011             write!(self, "{}", if first { "" } else { " + " })?;
1012
1013             self = self.wrap_binder(&trait_ref, |trait_ref, mut cx| {
1014                 define_scoped_cx!(cx);
1015                 p!(print(trait_ref.print_only_trait_name()));
1016
1017                 let generics = tcx.generics_of(trait_ref.def_id);
1018                 let args = generics.own_substs_no_defaults(tcx, trait_ref.substs);
1019
1020                 if !args.is_empty() || !assoc_items.is_empty() {
1021                     let mut first = true;
1022
1023                     for ty in args {
1024                         if first {
1025                             p!("<");
1026                             first = false;
1027                         } else {
1028                             p!(", ");
1029                         }
1030                         p!(print(ty));
1031                     }
1032
1033                     for (assoc_item_def_id, term) in assoc_items {
1034                         // Skip printing `<[generator@] as Generator<_>>::Return` from async blocks,
1035                         // unless we can find out what generator return type it comes from.
1036                         let term = if let Some(ty) = term.skip_binder().ty()
1037                             && let ty::Alias(ty::Projection, proj) = ty.kind()
1038                             && let Some(assoc) = tcx.opt_associated_item(proj.def_id)
1039                             && assoc.trait_container(tcx) == tcx.lang_items().gen_trait()
1040                             && assoc.name == rustc_span::sym::Return
1041                         {
1042                             if let ty::Generator(_, substs, _) = substs.type_at(0).kind() {
1043                                 let return_ty = substs.as_generator().return_ty();
1044                                 if !return_ty.is_ty_var() {
1045                                     return_ty.into()
1046                                 } else {
1047                                     continue;
1048                                 }
1049                             } else {
1050                                 continue;
1051                             }
1052                         } else {
1053                             term.skip_binder()
1054                         };
1055
1056                         if first {
1057                             p!("<");
1058                             first = false;
1059                         } else {
1060                             p!(", ");
1061                         }
1062
1063                         p!(write("{} = ", tcx.associated_item(assoc_item_def_id).name));
1064
1065                         match term.unpack() {
1066                             TermKind::Ty(ty) => p!(print(ty)),
1067                             TermKind::Const(c) => p!(print(c)),
1068                         };
1069                     }
1070
1071                     if !first {
1072                         p!(">");
1073                     }
1074                 }
1075
1076                 first = false;
1077                 Ok(cx)
1078             })?;
1079         }
1080
1081         if !is_sized {
1082             write!(self, "{}?Sized", if first { "" } else { " + " })?;
1083         } else if first {
1084             write!(self, "Sized")?;
1085         }
1086
1087         for re in lifetimes {
1088             write!(self, " + ")?;
1089             self = self.print_region(re)?;
1090         }
1091
1092         Ok(self)
1093     }
1094
1095     /// Insert the trait ref and optionally a projection type associated with it into either the
1096     /// traits map or fn_traits map, depending on if the trait is in the Fn* family of traits.
1097     fn insert_trait_and_projection(
1098         &mut self,
1099         trait_ref: ty::PolyTraitRef<'tcx>,
1100         proj_ty: Option<(DefId, ty::Binder<'tcx, Term<'tcx>>)>,
1101         traits: &mut FxIndexMap<
1102             ty::PolyTraitRef<'tcx>,
1103             FxIndexMap<DefId, ty::Binder<'tcx, Term<'tcx>>>,
1104         >,
1105         fn_traits: &mut FxIndexMap<ty::PolyTraitRef<'tcx>, OpaqueFnEntry<'tcx>>,
1106     ) {
1107         let trait_def_id = trait_ref.def_id();
1108
1109         // If our trait_ref is FnOnce or any of its children, project it onto the parent FnOnce
1110         // super-trait ref and record it there.
1111         if let Some(fn_once_trait) = self.tcx().lang_items().fn_once_trait() {
1112             // If we have a FnOnce, then insert it into
1113             if trait_def_id == fn_once_trait {
1114                 let entry = fn_traits.entry(trait_ref).or_default();
1115                 // Optionally insert the return_ty as well.
1116                 if let Some((_, ty)) = proj_ty {
1117                     entry.return_ty = Some(ty);
1118                 }
1119                 entry.has_fn_once = true;
1120                 return;
1121             } else if Some(trait_def_id) == self.tcx().lang_items().fn_mut_trait() {
1122                 let super_trait_ref = crate::traits::util::supertraits(self.tcx(), trait_ref)
1123                     .find(|super_trait_ref| super_trait_ref.def_id() == fn_once_trait)
1124                     .unwrap();
1125
1126                 fn_traits.entry(super_trait_ref).or_default().fn_mut_trait_ref = Some(trait_ref);
1127                 return;
1128             } else if Some(trait_def_id) == self.tcx().lang_items().fn_trait() {
1129                 let super_trait_ref = crate::traits::util::supertraits(self.tcx(), trait_ref)
1130                     .find(|super_trait_ref| super_trait_ref.def_id() == fn_once_trait)
1131                     .unwrap();
1132
1133                 fn_traits.entry(super_trait_ref).or_default().fn_trait_ref = Some(trait_ref);
1134                 return;
1135             }
1136         }
1137
1138         // Otherwise, just group our traits and projection types.
1139         traits.entry(trait_ref).or_default().extend(proj_ty);
1140     }
1141
1142     fn pretty_print_bound_var(
1143         &mut self,
1144         debruijn: ty::DebruijnIndex,
1145         var: ty::BoundVar,
1146     ) -> Result<(), Self::Error> {
1147         if debruijn == ty::INNERMOST {
1148             write!(self, "^{}", var.index())
1149         } else {
1150             write!(self, "^{}_{}", debruijn.index(), var.index())
1151         }
1152     }
1153
1154     fn ty_infer_name(&self, _: ty::TyVid) -> Option<Symbol> {
1155         None
1156     }
1157
1158     fn const_infer_name(&self, _: ty::ConstVid<'tcx>) -> Option<Symbol> {
1159         None
1160     }
1161
1162     fn pretty_print_dyn_existential(
1163         mut self,
1164         predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
1165     ) -> Result<Self::DynExistential, Self::Error> {
1166         // Generate the main trait ref, including associated types.
1167         let mut first = true;
1168
1169         if let Some(principal) = predicates.principal() {
1170             self = self.wrap_binder(&principal, |principal, mut cx| {
1171                 define_scoped_cx!(cx);
1172                 p!(print_def_path(principal.def_id, &[]));
1173
1174                 let mut resugared = false;
1175
1176                 // Special-case `Fn(...) -> ...` and re-sugar it.
1177                 let fn_trait_kind = cx.tcx().fn_trait_kind_from_def_id(principal.def_id);
1178                 if !cx.should_print_verbose() && fn_trait_kind.is_some() {
1179                     if let ty::Tuple(tys) = principal.substs.type_at(0).kind() {
1180                         let mut projections = predicates.projection_bounds();
1181                         if let (Some(proj), None) = (projections.next(), projections.next()) {
1182                             p!(pretty_fn_sig(
1183                                 tys,
1184                                 false,
1185                                 proj.skip_binder().term.ty().expect("Return type was a const")
1186                             ));
1187                             resugared = true;
1188                         }
1189                     }
1190                 }
1191
1192                 // HACK(eddyb) this duplicates `FmtPrinter`'s `path_generic_args`,
1193                 // in order to place the projections inside the `<...>`.
1194                 if !resugared {
1195                     // Use a type that can't appear in defaults of type parameters.
1196                     let dummy_cx = cx.tcx().mk_ty_infer(ty::FreshTy(0));
1197                     let principal = principal.with_self_ty(cx.tcx(), dummy_cx);
1198
1199                     let args = cx
1200                         .tcx()
1201                         .generics_of(principal.def_id)
1202                         .own_substs_no_defaults(cx.tcx(), principal.substs);
1203
1204                     let mut projections = predicates.projection_bounds();
1205
1206                     let mut args = args.iter().cloned();
1207                     let arg0 = args.next();
1208                     let projection0 = projections.next();
1209                     if arg0.is_some() || projection0.is_some() {
1210                         let args = arg0.into_iter().chain(args);
1211                         let projections = projection0.into_iter().chain(projections);
1212
1213                         p!(generic_delimiters(|mut cx| {
1214                             cx = cx.comma_sep(args)?;
1215                             if arg0.is_some() && projection0.is_some() {
1216                                 write!(cx, ", ")?;
1217                             }
1218                             cx.comma_sep(projections)
1219                         }));
1220                     }
1221                 }
1222                 Ok(cx)
1223             })?;
1224
1225             first = false;
1226         }
1227
1228         define_scoped_cx!(self);
1229
1230         // Builtin bounds.
1231         // FIXME(eddyb) avoid printing twice (needed to ensure
1232         // that the auto traits are sorted *and* printed via cx).
1233         let mut auto_traits: Vec<_> = predicates.auto_traits().collect();
1234
1235         // The auto traits come ordered by `DefPathHash`. While
1236         // `DefPathHash` is *stable* in the sense that it depends on
1237         // neither the host nor the phase of the moon, it depends
1238         // "pseudorandomly" on the compiler version and the target.
1239         //
1240         // To avoid causing instabilities in compiletest
1241         // output, sort the auto-traits alphabetically.
1242         auto_traits.sort_by_cached_key(|did| with_no_trimmed_paths!(self.tcx().def_path_str(*did)));
1243
1244         for def_id in auto_traits {
1245             if !first {
1246                 p!(" + ");
1247             }
1248             first = false;
1249
1250             p!(print_def_path(def_id, &[]));
1251         }
1252
1253         Ok(self)
1254     }
1255
1256     fn pretty_fn_sig(
1257         mut self,
1258         inputs: &[Ty<'tcx>],
1259         c_variadic: bool,
1260         output: Ty<'tcx>,
1261     ) -> Result<Self, Self::Error> {
1262         define_scoped_cx!(self);
1263
1264         p!("(", comma_sep(inputs.iter().copied()));
1265         if c_variadic {
1266             if !inputs.is_empty() {
1267                 p!(", ");
1268             }
1269             p!("...");
1270         }
1271         p!(")");
1272         if !output.is_unit() {
1273             p!(" -> ", print(output));
1274         }
1275
1276         Ok(self)
1277     }
1278
1279     fn pretty_print_const(
1280         mut self,
1281         ct: ty::Const<'tcx>,
1282         print_ty: bool,
1283     ) -> Result<Self::Const, Self::Error> {
1284         define_scoped_cx!(self);
1285
1286         if self.should_print_verbose() {
1287             p!(write("Const({:?}: {:?})", ct.kind(), ct.ty()));
1288             return Ok(self);
1289         }
1290
1291         macro_rules! print_underscore {
1292             () => {{
1293                 if print_ty {
1294                     self = self.typed_value(
1295                         |mut this| {
1296                             write!(this, "_")?;
1297                             Ok(this)
1298                         },
1299                         |this| this.print_type(ct.ty()),
1300                         ": ",
1301                     )?;
1302                 } else {
1303                     write!(self, "_")?;
1304                 }
1305             }};
1306         }
1307
1308         match ct.kind() {
1309             ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, substs }) => {
1310                 match self.tcx().def_kind(def.did) {
1311                     DefKind::Const | DefKind::AssocConst => {
1312                         p!(print_value_path(def.did, substs))
1313                     }
1314                     DefKind::AnonConst => {
1315                         if def.is_local()
1316                             && let span = self.tcx().def_span(def.did)
1317                             && let Ok(snip) = self.tcx().sess.source_map().span_to_snippet(span)
1318                         {
1319                             p!(write("{}", snip))
1320                         } else {
1321                             // Do not call `print_value_path` as if a parent of this anon const is an impl it will
1322                             // attempt to print out the impl trait ref i.e. `<T as Trait>::{constant#0}`. This would
1323                             // cause printing to enter an infinite recursion if the anon const is in the self type i.e.
1324                             // `impl<T: Default> Default for [T; 32 - 1 - 1 - 1] {`
1325                             // where we would try to print `<[T; /* print `constant#0` again */] as Default>::{constant#0}`
1326                             p!(write("{}::{}", self.tcx().crate_name(def.did.krate), self.tcx().def_path(def.did).to_string_no_crate_verbose()))
1327                         }
1328                     }
1329                     defkind => bug!("`{:?}` has unexpcted defkind {:?}", ct, defkind),
1330                 }
1331             }
1332             ty::ConstKind::Infer(infer_ct) => {
1333                 match infer_ct {
1334                     ty::InferConst::Var(ct_vid)
1335                         if let Some(name) = self.const_infer_name(ct_vid) =>
1336                             p!(write("{}", name)),
1337                     _ => print_underscore!(),
1338                 }
1339             }
1340             ty::ConstKind::Param(ParamConst { name, .. }) => p!(write("{}", name)),
1341             ty::ConstKind::Value(value) => {
1342                 return self.pretty_print_const_valtree(value, ct.ty(), print_ty);
1343             }
1344
1345             ty::ConstKind::Bound(debruijn, bound_var) => {
1346                 self.pretty_print_bound_var(debruijn, bound_var)?
1347             }
1348             ty::ConstKind::Placeholder(placeholder) => p!(write("Placeholder({:?})", placeholder)),
1349             // FIXME(generic_const_exprs):
1350             // write out some legible representation of an abstract const?
1351             ty::ConstKind::Expr(_) => p!("[const expr]"),
1352             ty::ConstKind::Error(_) => p!("[const error]"),
1353         };
1354         Ok(self)
1355     }
1356
1357     fn pretty_print_const_scalar(
1358         self,
1359         scalar: Scalar,
1360         ty: Ty<'tcx>,
1361         print_ty: bool,
1362     ) -> Result<Self::Const, Self::Error> {
1363         match scalar {
1364             Scalar::Ptr(ptr, _size) => self.pretty_print_const_scalar_ptr(ptr, ty, print_ty),
1365             Scalar::Int(int) => self.pretty_print_const_scalar_int(int, ty, print_ty),
1366         }
1367     }
1368
1369     fn pretty_print_const_scalar_ptr(
1370         mut self,
1371         ptr: Pointer,
1372         ty: Ty<'tcx>,
1373         print_ty: bool,
1374     ) -> Result<Self::Const, Self::Error> {
1375         define_scoped_cx!(self);
1376
1377         let (alloc_id, offset) = ptr.into_parts();
1378         match ty.kind() {
1379             // Byte strings (&[u8; N])
1380             ty::Ref(_, inner, _) => {
1381                 if let ty::Array(elem, len) = inner.kind() {
1382                     if let ty::Uint(ty::UintTy::U8) = elem.kind() {
1383                         if let ty::ConstKind::Value(ty::ValTree::Leaf(int)) = len.kind() {
1384                             match self.tcx().try_get_global_alloc(alloc_id) {
1385                                 Some(GlobalAlloc::Memory(alloc)) => {
1386                                     let len = int.assert_bits(self.tcx().data_layout.pointer_size);
1387                                     let range =
1388                                         AllocRange { start: offset, size: Size::from_bytes(len) };
1389                                     if let Ok(byte_str) =
1390                                         alloc.inner().get_bytes_strip_provenance(&self.tcx(), range)
1391                                     {
1392                                         p!(pretty_print_byte_str(byte_str))
1393                                     } else {
1394                                         p!("<too short allocation>")
1395                                     }
1396                                 }
1397                                 // FIXME: for statics, vtables, and functions, we could in principle print more detail.
1398                                 Some(GlobalAlloc::Static(def_id)) => {
1399                                     p!(write("<static({:?})>", def_id))
1400                                 }
1401                                 Some(GlobalAlloc::Function(_)) => p!("<function>"),
1402                                 Some(GlobalAlloc::VTable(..)) => p!("<vtable>"),
1403                                 None => p!("<dangling pointer>"),
1404                             }
1405                             return Ok(self);
1406                         }
1407                     }
1408                 }
1409             }
1410             ty::FnPtr(_) => {
1411                 // FIXME: We should probably have a helper method to share code with the "Byte strings"
1412                 // printing above (which also has to handle pointers to all sorts of things).
1413                 if let Some(GlobalAlloc::Function(instance)) =
1414                     self.tcx().try_get_global_alloc(alloc_id)
1415                 {
1416                     self = self.typed_value(
1417                         |this| this.print_value_path(instance.def_id(), instance.substs),
1418                         |this| this.print_type(ty),
1419                         " as ",
1420                     )?;
1421                     return Ok(self);
1422                 }
1423             }
1424             _ => {}
1425         }
1426         // Any pointer values not covered by a branch above
1427         self = self.pretty_print_const_pointer(ptr, ty, print_ty)?;
1428         Ok(self)
1429     }
1430
1431     fn pretty_print_const_scalar_int(
1432         mut self,
1433         int: ScalarInt,
1434         ty: Ty<'tcx>,
1435         print_ty: bool,
1436     ) -> Result<Self::Const, Self::Error> {
1437         define_scoped_cx!(self);
1438
1439         match ty.kind() {
1440             // Bool
1441             ty::Bool if int == ScalarInt::FALSE => p!("false"),
1442             ty::Bool if int == ScalarInt::TRUE => p!("true"),
1443             // Float
1444             ty::Float(ty::FloatTy::F32) => {
1445                 p!(write("{}f32", Single::try_from(int).unwrap()))
1446             }
1447             ty::Float(ty::FloatTy::F64) => {
1448                 p!(write("{}f64", Double::try_from(int).unwrap()))
1449             }
1450             // Int
1451             ty::Uint(_) | ty::Int(_) => {
1452                 let int =
1453                     ConstInt::new(int, matches!(ty.kind(), ty::Int(_)), ty.is_ptr_sized_integral());
1454                 if print_ty { p!(write("{:#?}", int)) } else { p!(write("{:?}", int)) }
1455             }
1456             // Char
1457             ty::Char if char::try_from(int).is_ok() => {
1458                 p!(write("{:?}", char::try_from(int).unwrap()))
1459             }
1460             // Pointer types
1461             ty::Ref(..) | ty::RawPtr(_) | ty::FnPtr(_) => {
1462                 let data = int.assert_bits(self.tcx().data_layout.pointer_size);
1463                 self = self.typed_value(
1464                     |mut this| {
1465                         write!(this, "0x{:x}", data)?;
1466                         Ok(this)
1467                     },
1468                     |this| this.print_type(ty),
1469                     " as ",
1470                 )?;
1471             }
1472             // Nontrivial types with scalar bit representation
1473             _ => {
1474                 let print = |mut this: Self| {
1475                     if int.size() == Size::ZERO {
1476                         write!(this, "transmute(())")?;
1477                     } else {
1478                         write!(this, "transmute(0x{:x})", int)?;
1479                     }
1480                     Ok(this)
1481                 };
1482                 self = if print_ty {
1483                     self.typed_value(print, |this| this.print_type(ty), ": ")?
1484                 } else {
1485                     print(self)?
1486                 };
1487             }
1488         }
1489         Ok(self)
1490     }
1491
1492     /// This is overridden for MIR printing because we only want to hide alloc ids from users, not
1493     /// from MIR where it is actually useful.
1494     fn pretty_print_const_pointer<Prov: Provenance>(
1495         mut self,
1496         _: Pointer<Prov>,
1497         ty: Ty<'tcx>,
1498         print_ty: bool,
1499     ) -> Result<Self::Const, Self::Error> {
1500         if print_ty {
1501             self.typed_value(
1502                 |mut this| {
1503                     this.write_str("&_")?;
1504                     Ok(this)
1505                 },
1506                 |this| this.print_type(ty),
1507                 ": ",
1508             )
1509         } else {
1510             self.write_str("&_")?;
1511             Ok(self)
1512         }
1513     }
1514
1515     fn pretty_print_byte_str(mut self, byte_str: &'tcx [u8]) -> Result<Self::Const, Self::Error> {
1516         write!(self, "b\"{}\"", byte_str.escape_ascii())?;
1517         Ok(self)
1518     }
1519
1520     fn pretty_print_const_valtree(
1521         mut self,
1522         valtree: ty::ValTree<'tcx>,
1523         ty: Ty<'tcx>,
1524         print_ty: bool,
1525     ) -> Result<Self::Const, Self::Error> {
1526         define_scoped_cx!(self);
1527
1528         if self.should_print_verbose() {
1529             p!(write("ValTree({:?}: ", valtree), print(ty), ")");
1530             return Ok(self);
1531         }
1532
1533         let u8_type = self.tcx().types.u8;
1534         match (valtree, ty.kind()) {
1535             (ty::ValTree::Branch(_), ty::Ref(_, inner_ty, _)) => match inner_ty.kind() {
1536                 ty::Slice(t) if *t == u8_type => {
1537                     let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
1538                         bug!(
1539                             "expected to convert valtree {:?} to raw bytes for type {:?}",
1540                             valtree,
1541                             t
1542                         )
1543                     });
1544                     return self.pretty_print_byte_str(bytes);
1545                 }
1546                 ty::Str => {
1547                     let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
1548                         bug!("expected to convert valtree to raw bytes for type {:?}", ty)
1549                     });
1550                     p!(write("{:?}", String::from_utf8_lossy(bytes)));
1551                     return Ok(self);
1552                 }
1553                 _ => {
1554                     p!("&");
1555                     p!(pretty_print_const_valtree(valtree, *inner_ty, print_ty));
1556                     return Ok(self);
1557                 }
1558             },
1559             (ty::ValTree::Branch(_), ty::Array(t, _)) if *t == u8_type => {
1560                 let bytes = valtree.try_to_raw_bytes(self.tcx(), ty).unwrap_or_else(|| {
1561                     bug!("expected to convert valtree to raw bytes for type {:?}", t)
1562                 });
1563                 p!("*");
1564                 p!(pretty_print_byte_str(bytes));
1565                 return Ok(self);
1566             }
1567             // Aggregates, printed as array/tuple/struct/variant construction syntax.
1568             (ty::ValTree::Branch(_), ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) => {
1569                 let contents = self.tcx().destructure_const(self.tcx().mk_const(valtree, ty));
1570                 let fields = contents.fields.iter().copied();
1571                 match *ty.kind() {
1572                     ty::Array(..) => {
1573                         p!("[", comma_sep(fields), "]");
1574                     }
1575                     ty::Tuple(..) => {
1576                         p!("(", comma_sep(fields));
1577                         if contents.fields.len() == 1 {
1578                             p!(",");
1579                         }
1580                         p!(")");
1581                     }
1582                     ty::Adt(def, _) if def.variants().is_empty() => {
1583                         self = self.typed_value(
1584                             |mut this| {
1585                                 write!(this, "unreachable()")?;
1586                                 Ok(this)
1587                             },
1588                             |this| this.print_type(ty),
1589                             ": ",
1590                         )?;
1591                     }
1592                     ty::Adt(def, substs) => {
1593                         let variant_idx =
1594                             contents.variant.expect("destructed const of adt without variant idx");
1595                         let variant_def = &def.variant(variant_idx);
1596                         p!(print_value_path(variant_def.def_id, substs));
1597                         match variant_def.ctor_kind() {
1598                             Some(CtorKind::Const) => {}
1599                             Some(CtorKind::Fn) => {
1600                                 p!("(", comma_sep(fields), ")");
1601                             }
1602                             None => {
1603                                 p!(" {{ ");
1604                                 let mut first = true;
1605                                 for (field_def, field) in iter::zip(&variant_def.fields, fields) {
1606                                     if !first {
1607                                         p!(", ");
1608                                     }
1609                                     p!(write("{}: ", field_def.name), print(field));
1610                                     first = false;
1611                                 }
1612                                 p!(" }}");
1613                             }
1614                         }
1615                     }
1616                     _ => unreachable!(),
1617                 }
1618                 return Ok(self);
1619             }
1620             (ty::ValTree::Leaf(leaf), ty::Ref(_, inner_ty, _)) => {
1621                 p!(write("&"));
1622                 return self.pretty_print_const_scalar_int(leaf, *inner_ty, print_ty);
1623             }
1624             (ty::ValTree::Leaf(leaf), _) => {
1625                 return self.pretty_print_const_scalar_int(leaf, ty, print_ty);
1626             }
1627             // FIXME(oli-obk): also pretty print arrays and other aggregate constants by reading
1628             // their fields instead of just dumping the memory.
1629             _ => {}
1630         }
1631
1632         // fallback
1633         if valtree == ty::ValTree::zst() {
1634             p!(write("<ZST>"));
1635         } else {
1636             p!(write("{:?}", valtree));
1637         }
1638         if print_ty {
1639             p!(": ", print(ty));
1640         }
1641         Ok(self)
1642     }
1643
1644     fn pretty_closure_as_impl(
1645         mut self,
1646         closure: ty::ClosureSubsts<'tcx>,
1647     ) -> Result<Self::Const, Self::Error> {
1648         let sig = closure.sig();
1649         let kind = closure.kind_ty().to_opt_closure_kind().unwrap_or(ty::ClosureKind::Fn);
1650
1651         write!(self, "impl ")?;
1652         self.wrap_binder(&sig, |sig, mut cx| {
1653             define_scoped_cx!(cx);
1654
1655             p!(print(kind), "(");
1656             for (i, arg) in sig.inputs()[0].tuple_fields().iter().enumerate() {
1657                 if i > 0 {
1658                     p!(", ");
1659                 }
1660                 p!(print(arg));
1661             }
1662             p!(")");
1663
1664             if !sig.output().is_unit() {
1665                 p!(" -> ", print(sig.output()));
1666             }
1667
1668             Ok(cx)
1669         })
1670     }
1671
1672     fn should_print_verbose(&self) -> bool {
1673         self.tcx().sess.verbose()
1674     }
1675 }
1676
1677 // HACK(eddyb) boxed to avoid moving around a large struct by-value.
1678 pub struct FmtPrinter<'a, 'tcx>(Box<FmtPrinterData<'a, 'tcx>>);
1679
1680 pub struct FmtPrinterData<'a, 'tcx> {
1681     tcx: TyCtxt<'tcx>,
1682     fmt: String,
1683
1684     empty_path: bool,
1685     in_value: bool,
1686     pub print_alloc_ids: bool,
1687
1688     // set of all named (non-anonymous) region names
1689     used_region_names: FxHashSet<Symbol>,
1690
1691     region_index: usize,
1692     binder_depth: usize,
1693     printed_type_count: usize,
1694     type_length_limit: Limit,
1695     truncated: bool,
1696
1697     pub region_highlight_mode: RegionHighlightMode<'tcx>,
1698
1699     pub ty_infer_name_resolver: Option<Box<dyn Fn(ty::TyVid) -> Option<Symbol> + 'a>>,
1700     pub const_infer_name_resolver: Option<Box<dyn Fn(ty::ConstVid<'tcx>) -> Option<Symbol> + 'a>>,
1701 }
1702
1703 impl<'a, 'tcx> Deref for FmtPrinter<'a, 'tcx> {
1704     type Target = FmtPrinterData<'a, 'tcx>;
1705     fn deref(&self) -> &Self::Target {
1706         &self.0
1707     }
1708 }
1709
1710 impl DerefMut for FmtPrinter<'_, '_> {
1711     fn deref_mut(&mut self) -> &mut Self::Target {
1712         &mut self.0
1713     }
1714 }
1715
1716 impl<'a, 'tcx> FmtPrinter<'a, 'tcx> {
1717     pub fn new(tcx: TyCtxt<'tcx>, ns: Namespace) -> Self {
1718         Self::new_with_limit(tcx, ns, tcx.type_length_limit())
1719     }
1720
1721     pub fn new_with_limit(tcx: TyCtxt<'tcx>, ns: Namespace, type_length_limit: Limit) -> Self {
1722         FmtPrinter(Box::new(FmtPrinterData {
1723             tcx,
1724             // Estimated reasonable capacity to allocate upfront based on a few
1725             // benchmarks.
1726             fmt: String::with_capacity(64),
1727             empty_path: false,
1728             in_value: ns == Namespace::ValueNS,
1729             print_alloc_ids: false,
1730             used_region_names: Default::default(),
1731             region_index: 0,
1732             binder_depth: 0,
1733             printed_type_count: 0,
1734             type_length_limit,
1735             truncated: false,
1736             region_highlight_mode: RegionHighlightMode::new(tcx),
1737             ty_infer_name_resolver: None,
1738             const_infer_name_resolver: None,
1739         }))
1740     }
1741
1742     pub fn into_buffer(self) -> String {
1743         self.0.fmt
1744     }
1745 }
1746
1747 // HACK(eddyb) get rid of `def_path_str` and/or pass `Namespace` explicitly always
1748 // (but also some things just print a `DefId` generally so maybe we need this?)
1749 fn guess_def_namespace(tcx: TyCtxt<'_>, def_id: DefId) -> Namespace {
1750     match tcx.def_key(def_id).disambiguated_data.data {
1751         DefPathData::TypeNs(..) | DefPathData::CrateRoot | DefPathData::ImplTrait => {
1752             Namespace::TypeNS
1753         }
1754
1755         DefPathData::ValueNs(..)
1756         | DefPathData::AnonConst
1757         | DefPathData::ClosureExpr
1758         | DefPathData::Ctor => Namespace::ValueNS,
1759
1760         DefPathData::MacroNs(..) => Namespace::MacroNS,
1761
1762         _ => Namespace::TypeNS,
1763     }
1764 }
1765
1766 impl<'t> TyCtxt<'t> {
1767     /// Returns a string identifying this `DefId`. This string is
1768     /// suitable for user output.
1769     pub fn def_path_str(self, def_id: DefId) -> String {
1770         self.def_path_str_with_substs(def_id, &[])
1771     }
1772
1773     pub fn def_path_str_with_substs(self, def_id: DefId, substs: &'t [GenericArg<'t>]) -> String {
1774         let ns = guess_def_namespace(self, def_id);
1775         debug!("def_path_str: def_id={:?}, ns={:?}", def_id, ns);
1776         FmtPrinter::new(self, ns).print_def_path(def_id, substs).unwrap().into_buffer()
1777     }
1778
1779     pub fn value_path_str_with_substs(self, def_id: DefId, substs: &'t [GenericArg<'t>]) -> String {
1780         let ns = guess_def_namespace(self, def_id);
1781         debug!("value_path_str: def_id={:?}, ns={:?}", def_id, ns);
1782         FmtPrinter::new(self, ns).print_value_path(def_id, substs).unwrap().into_buffer()
1783     }
1784 }
1785
1786 impl fmt::Write for FmtPrinter<'_, '_> {
1787     fn write_str(&mut self, s: &str) -> fmt::Result {
1788         self.fmt.push_str(s);
1789         Ok(())
1790     }
1791 }
1792
1793 impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
1794     type Error = fmt::Error;
1795
1796     type Path = Self;
1797     type Region = Self;
1798     type Type = Self;
1799     type DynExistential = Self;
1800     type Const = Self;
1801
1802     fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
1803         self.tcx
1804     }
1805
1806     fn print_def_path(
1807         mut self,
1808         def_id: DefId,
1809         substs: &'tcx [GenericArg<'tcx>],
1810     ) -> Result<Self::Path, Self::Error> {
1811         define_scoped_cx!(self);
1812
1813         if substs.is_empty() {
1814             match self.try_print_trimmed_def_path(def_id)? {
1815                 (cx, true) => return Ok(cx),
1816                 (cx, false) => self = cx,
1817             }
1818
1819             match self.try_print_visible_def_path(def_id)? {
1820                 (cx, true) => return Ok(cx),
1821                 (cx, false) => self = cx,
1822             }
1823         }
1824
1825         let key = self.tcx.def_key(def_id);
1826         if let DefPathData::Impl = key.disambiguated_data.data {
1827             // Always use types for non-local impls, where types are always
1828             // available, and filename/line-number is mostly uninteresting.
1829             let use_types = !def_id.is_local() || {
1830                 // Otherwise, use filename/line-number if forced.
1831                 let force_no_types = FORCE_IMPL_FILENAME_LINE.with(|f| f.get());
1832                 !force_no_types
1833             };
1834
1835             if !use_types {
1836                 // If no type info is available, fall back to
1837                 // pretty printing some span information. This should
1838                 // only occur very early in the compiler pipeline.
1839                 let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id };
1840                 let span = self.tcx.def_span(def_id);
1841
1842                 self = self.print_def_path(parent_def_id, &[])?;
1843
1844                 // HACK(eddyb) copy of `path_append` to avoid
1845                 // constructing a `DisambiguatedDefPathData`.
1846                 if !self.empty_path {
1847                     write!(self, "::")?;
1848                 }
1849                 write!(
1850                     self,
1851                     "<impl at {}>",
1852                     // This may end up in stderr diagnostics but it may also be emitted
1853                     // into MIR. Hence we use the remapped path if available
1854                     self.tcx.sess.source_map().span_to_embeddable_string(span)
1855                 )?;
1856                 self.empty_path = false;
1857
1858                 return Ok(self);
1859             }
1860         }
1861
1862         self.default_print_def_path(def_id, substs)
1863     }
1864
1865     fn print_region(self, region: ty::Region<'tcx>) -> Result<Self::Region, Self::Error> {
1866         self.pretty_print_region(region)
1867     }
1868
1869     fn print_type(mut self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
1870         if self.type_length_limit.value_within_limit(self.printed_type_count) {
1871             self.printed_type_count += 1;
1872             self.pretty_print_type(ty)
1873         } else {
1874             self.truncated = true;
1875             write!(self, "...")?;
1876             Ok(self)
1877         }
1878     }
1879
1880     fn print_dyn_existential(
1881         self,
1882         predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
1883     ) -> Result<Self::DynExistential, Self::Error> {
1884         self.pretty_print_dyn_existential(predicates)
1885     }
1886
1887     fn print_const(self, ct: ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
1888         self.pretty_print_const(ct, false)
1889     }
1890
1891     fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
1892         self.empty_path = true;
1893         if cnum == LOCAL_CRATE {
1894             if self.tcx.sess.rust_2018() {
1895                 // We add the `crate::` keyword on Rust 2018, only when desired.
1896                 if SHOULD_PREFIX_WITH_CRATE.with(|flag| flag.get()) {
1897                     write!(self, "{}", kw::Crate)?;
1898                     self.empty_path = false;
1899                 }
1900             }
1901         } else {
1902             write!(self, "{}", self.tcx.crate_name(cnum))?;
1903             self.empty_path = false;
1904         }
1905         Ok(self)
1906     }
1907
1908     fn path_qualified(
1909         mut self,
1910         self_ty: Ty<'tcx>,
1911         trait_ref: Option<ty::TraitRef<'tcx>>,
1912     ) -> Result<Self::Path, Self::Error> {
1913         self = self.pretty_path_qualified(self_ty, trait_ref)?;
1914         self.empty_path = false;
1915         Ok(self)
1916     }
1917
1918     fn path_append_impl(
1919         mut self,
1920         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1921         _disambiguated_data: &DisambiguatedDefPathData,
1922         self_ty: Ty<'tcx>,
1923         trait_ref: Option<ty::TraitRef<'tcx>>,
1924     ) -> Result<Self::Path, Self::Error> {
1925         self = self.pretty_path_append_impl(
1926             |mut cx| {
1927                 cx = print_prefix(cx)?;
1928                 if !cx.empty_path {
1929                     write!(cx, "::")?;
1930                 }
1931
1932                 Ok(cx)
1933             },
1934             self_ty,
1935             trait_ref,
1936         )?;
1937         self.empty_path = false;
1938         Ok(self)
1939     }
1940
1941     fn path_append(
1942         mut self,
1943         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1944         disambiguated_data: &DisambiguatedDefPathData,
1945     ) -> Result<Self::Path, Self::Error> {
1946         self = print_prefix(self)?;
1947
1948         // Skip `::{{extern}}` blocks and `::{{constructor}}` on tuple/unit structs.
1949         if let DefPathData::ForeignMod | DefPathData::Ctor = disambiguated_data.data {
1950             return Ok(self);
1951         }
1952
1953         let name = disambiguated_data.data.name();
1954         if !self.empty_path {
1955             write!(self, "::")?;
1956         }
1957
1958         if let DefPathDataName::Named(name) = name {
1959             if Ident::with_dummy_span(name).is_raw_guess() {
1960                 write!(self, "r#")?;
1961             }
1962         }
1963
1964         let verbose = self.should_print_verbose();
1965         disambiguated_data.fmt_maybe_verbose(&mut self, verbose)?;
1966
1967         self.empty_path = false;
1968
1969         Ok(self)
1970     }
1971
1972     fn path_generic_args(
1973         mut self,
1974         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1975         args: &[GenericArg<'tcx>],
1976     ) -> Result<Self::Path, Self::Error> {
1977         self = print_prefix(self)?;
1978
1979         if args.first().is_some() {
1980             if self.in_value {
1981                 write!(self, "::")?;
1982             }
1983             self.generic_delimiters(|cx| cx.comma_sep(args.iter().cloned()))
1984         } else {
1985             Ok(self)
1986         }
1987     }
1988 }
1989
1990 impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
1991     fn ty_infer_name(&self, id: ty::TyVid) -> Option<Symbol> {
1992         self.0.ty_infer_name_resolver.as_ref().and_then(|func| func(id))
1993     }
1994
1995     fn reset_type_limit(&mut self) {
1996         self.printed_type_count = 0;
1997     }
1998
1999     fn const_infer_name(&self, id: ty::ConstVid<'tcx>) -> Option<Symbol> {
2000         self.0.const_infer_name_resolver.as_ref().and_then(|func| func(id))
2001     }
2002
2003     fn print_value_path(
2004         mut self,
2005         def_id: DefId,
2006         substs: &'tcx [GenericArg<'tcx>],
2007     ) -> Result<Self::Path, Self::Error> {
2008         let was_in_value = std::mem::replace(&mut self.in_value, true);
2009         self = self.print_def_path(def_id, substs)?;
2010         self.in_value = was_in_value;
2011
2012         Ok(self)
2013     }
2014
2015     fn in_binder<T>(self, value: &ty::Binder<'tcx, T>) -> Result<Self, Self::Error>
2016     where
2017         T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>,
2018     {
2019         self.pretty_in_binder(value)
2020     }
2021
2022     fn wrap_binder<T, C: FnOnce(&T, Self) -> Result<Self, Self::Error>>(
2023         self,
2024         value: &ty::Binder<'tcx, T>,
2025         f: C,
2026     ) -> Result<Self, Self::Error>
2027     where
2028         T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>,
2029     {
2030         self.pretty_wrap_binder(value, f)
2031     }
2032
2033     fn typed_value(
2034         mut self,
2035         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
2036         t: impl FnOnce(Self) -> Result<Self, Self::Error>,
2037         conversion: &str,
2038     ) -> Result<Self::Const, Self::Error> {
2039         self.write_str("{")?;
2040         self = f(self)?;
2041         self.write_str(conversion)?;
2042         let was_in_value = std::mem::replace(&mut self.in_value, false);
2043         self = t(self)?;
2044         self.in_value = was_in_value;
2045         self.write_str("}")?;
2046         Ok(self)
2047     }
2048
2049     fn generic_delimiters(
2050         mut self,
2051         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
2052     ) -> Result<Self, Self::Error> {
2053         write!(self, "<")?;
2054
2055         let was_in_value = std::mem::replace(&mut self.in_value, false);
2056         let mut inner = f(self)?;
2057         inner.in_value = was_in_value;
2058
2059         write!(inner, ">")?;
2060         Ok(inner)
2061     }
2062
2063     fn should_print_region(&self, region: ty::Region<'tcx>) -> bool {
2064         let highlight = self.region_highlight_mode;
2065         if highlight.region_highlighted(region).is_some() {
2066             return true;
2067         }
2068
2069         if self.should_print_verbose() {
2070             return true;
2071         }
2072
2073         let identify_regions = self.tcx.sess.opts.unstable_opts.identify_regions;
2074
2075         match *region {
2076             ty::ReEarlyBound(ref data) => data.has_name(),
2077
2078             ty::ReLateBound(_, ty::BoundRegion { kind: br, .. })
2079             | ty::ReFree(ty::FreeRegion { bound_region: br, .. })
2080             | ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
2081                 if br.is_named() {
2082                     return true;
2083                 }
2084
2085                 if let Some((region, _)) = highlight.highlight_bound_region {
2086                     if br == region {
2087                         return true;
2088                     }
2089                 }
2090
2091                 false
2092             }
2093
2094             ty::ReVar(_) if identify_regions => true,
2095
2096             ty::ReVar(_) | ty::ReErased => false,
2097
2098             ty::ReStatic => true,
2099         }
2100     }
2101
2102     fn pretty_print_const_pointer<Prov: Provenance>(
2103         self,
2104         p: Pointer<Prov>,
2105         ty: Ty<'tcx>,
2106         print_ty: bool,
2107     ) -> Result<Self::Const, Self::Error> {
2108         let print = |mut this: Self| {
2109             define_scoped_cx!(this);
2110             if this.print_alloc_ids {
2111                 p!(write("{:?}", p));
2112             } else {
2113                 p!("&_");
2114             }
2115             Ok(this)
2116         };
2117         if print_ty {
2118             self.typed_value(print, |this| this.print_type(ty), ": ")
2119         } else {
2120             print(self)
2121         }
2122     }
2123 }
2124
2125 // HACK(eddyb) limited to `FmtPrinter` because of `region_highlight_mode`.
2126 impl<'tcx> FmtPrinter<'_, 'tcx> {
2127     pub fn pretty_print_region(mut self, region: ty::Region<'tcx>) -> Result<Self, fmt::Error> {
2128         define_scoped_cx!(self);
2129
2130         // Watch out for region highlights.
2131         let highlight = self.region_highlight_mode;
2132         if let Some(n) = highlight.region_highlighted(region) {
2133             p!(write("'{}", n));
2134             return Ok(self);
2135         }
2136
2137         if self.should_print_verbose() {
2138             p!(write("{:?}", region));
2139             return Ok(self);
2140         }
2141
2142         let identify_regions = self.tcx.sess.opts.unstable_opts.identify_regions;
2143
2144         // These printouts are concise. They do not contain all the information
2145         // the user might want to diagnose an error, but there is basically no way
2146         // to fit that into a short string. Hence the recommendation to use
2147         // `explain_region()` or `note_and_explain_region()`.
2148         match *region {
2149             ty::ReEarlyBound(ref data) => {
2150                 if data.name != kw::Empty {
2151                     p!(write("{}", data.name));
2152                     return Ok(self);
2153                 }
2154             }
2155             ty::ReLateBound(_, ty::BoundRegion { kind: br, .. })
2156             | ty::ReFree(ty::FreeRegion { bound_region: br, .. })
2157             | ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
2158                 if let ty::BrNamed(_, name) = br && br.is_named() {
2159                     p!(write("{}", name));
2160                     return Ok(self);
2161                 }
2162
2163                 if let Some((region, counter)) = highlight.highlight_bound_region {
2164                     if br == region {
2165                         p!(write("'{}", counter));
2166                         return Ok(self);
2167                     }
2168                 }
2169             }
2170             ty::ReVar(region_vid) if identify_regions => {
2171                 p!(write("{:?}", region_vid));
2172                 return Ok(self);
2173             }
2174             ty::ReVar(_) => {}
2175             ty::ReErased => {}
2176             ty::ReStatic => {
2177                 p!("'static");
2178                 return Ok(self);
2179             }
2180         }
2181
2182         p!("'_");
2183
2184         Ok(self)
2185     }
2186 }
2187
2188 /// Folds through bound vars and placeholders, naming them
2189 struct RegionFolder<'a, 'tcx> {
2190     tcx: TyCtxt<'tcx>,
2191     current_index: ty::DebruijnIndex,
2192     region_map: BTreeMap<ty::BoundRegion, ty::Region<'tcx>>,
2193     name: &'a mut (
2194                 dyn FnMut(
2195         Option<ty::DebruijnIndex>, // Debruijn index of the folded late-bound region
2196         ty::DebruijnIndex,         // Index corresponding to binder level
2197         ty::BoundRegion,
2198     ) -> ty::Region<'tcx>
2199                     + 'a
2200             ),
2201 }
2202
2203 impl<'a, 'tcx> ty::TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
2204     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
2205         self.tcx
2206     }
2207
2208     fn fold_binder<T: TypeFoldable<'tcx>>(
2209         &mut self,
2210         t: ty::Binder<'tcx, T>,
2211     ) -> ty::Binder<'tcx, T> {
2212         self.current_index.shift_in(1);
2213         let t = t.super_fold_with(self);
2214         self.current_index.shift_out(1);
2215         t
2216     }
2217
2218     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
2219         match *t.kind() {
2220             _ if t.has_vars_bound_at_or_above(self.current_index) || t.has_placeholders() => {
2221                 return t.super_fold_with(self);
2222             }
2223             _ => {}
2224         }
2225         t
2226     }
2227
2228     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
2229         let name = &mut self.name;
2230         let region = match *r {
2231             ty::ReLateBound(db, br) if db >= self.current_index => {
2232                 *self.region_map.entry(br).or_insert_with(|| name(Some(db), self.current_index, br))
2233             }
2234             ty::RePlaceholder(ty::PlaceholderRegion { name: kind, .. }) => {
2235                 // If this is an anonymous placeholder, don't rename. Otherwise, in some
2236                 // async fns, we get a `for<'r> Send` bound
2237                 match kind {
2238                     ty::BrAnon(..) | ty::BrEnv => r,
2239                     _ => {
2240                         // Index doesn't matter, since this is just for naming and these never get bound
2241                         let br = ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind };
2242                         *self
2243                             .region_map
2244                             .entry(br)
2245                             .or_insert_with(|| name(None, self.current_index, br))
2246                     }
2247                 }
2248             }
2249             _ => return r,
2250         };
2251         if let ty::ReLateBound(debruijn1, br) = *region {
2252             assert_eq!(debruijn1, ty::INNERMOST);
2253             self.tcx.mk_region(ty::ReLateBound(self.current_index, br))
2254         } else {
2255             region
2256         }
2257     }
2258 }
2259
2260 // HACK(eddyb) limited to `FmtPrinter` because of `binder_depth`,
2261 // `region_index` and `used_region_names`.
2262 impl<'tcx> FmtPrinter<'_, 'tcx> {
2263     pub fn name_all_regions<T>(
2264         mut self,
2265         value: &ty::Binder<'tcx, T>,
2266     ) -> Result<(Self, T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>), fmt::Error>
2267     where
2268         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
2269     {
2270         fn name_by_region_index(
2271             index: usize,
2272             available_names: &mut Vec<Symbol>,
2273             num_available: usize,
2274         ) -> Symbol {
2275             if let Some(name) = available_names.pop() {
2276                 name
2277             } else {
2278                 Symbol::intern(&format!("'z{}", index - num_available))
2279             }
2280         }
2281
2282         debug!("name_all_regions");
2283
2284         // Replace any anonymous late-bound regions with named
2285         // variants, using new unique identifiers, so that we can
2286         // clearly differentiate between named and unnamed regions in
2287         // the output. We'll probably want to tweak this over time to
2288         // decide just how much information to give.
2289         if self.binder_depth == 0 {
2290             self.prepare_region_info(value);
2291         }
2292
2293         debug!("self.used_region_names: {:?}", &self.used_region_names);
2294
2295         let mut empty = true;
2296         let mut start_or_continue = |cx: &mut Self, start: &str, cont: &str| {
2297             let w = if empty {
2298                 empty = false;
2299                 start
2300             } else {
2301                 cont
2302             };
2303             let _ = write!(cx, "{}", w);
2304         };
2305         let do_continue = |cx: &mut Self, cont: Symbol| {
2306             let _ = write!(cx, "{}", cont);
2307         };
2308
2309         define_scoped_cx!(self);
2310
2311         let possible_names = ('a'..='z').rev().map(|s| Symbol::intern(&format!("'{s}")));
2312
2313         let mut available_names = possible_names
2314             .filter(|name| !self.used_region_names.contains(&name))
2315             .collect::<Vec<_>>();
2316         debug!(?available_names);
2317         let num_available = available_names.len();
2318
2319         let mut region_index = self.region_index;
2320         let mut next_name = |this: &Self| {
2321             let mut name;
2322
2323             loop {
2324                 name = name_by_region_index(region_index, &mut available_names, num_available);
2325                 region_index += 1;
2326
2327                 if !this.used_region_names.contains(&name) {
2328                     break;
2329                 }
2330             }
2331
2332             name
2333         };
2334
2335         // If we want to print verbosely, then print *all* binders, even if they
2336         // aren't named. Eventually, we might just want this as the default, but
2337         // this is not *quite* right and changes the ordering of some output
2338         // anyways.
2339         let (new_value, map) = if self.should_print_verbose() {
2340             for var in value.bound_vars().iter() {
2341                 start_or_continue(&mut self, "for<", ", ");
2342                 write!(self, "{:?}", var)?;
2343             }
2344             start_or_continue(&mut self, "", "> ");
2345             (value.clone().skip_binder(), BTreeMap::default())
2346         } else {
2347             let tcx = self.tcx;
2348
2349             // Closure used in `RegionFolder` to create names for anonymous late-bound
2350             // regions. We use two `DebruijnIndex`es (one for the currently folded
2351             // late-bound region and the other for the binder level) to determine
2352             // whether a name has already been created for the currently folded region,
2353             // see issue #102392.
2354             let mut name = |lifetime_idx: Option<ty::DebruijnIndex>,
2355                             binder_level_idx: ty::DebruijnIndex,
2356                             br: ty::BoundRegion| {
2357                 let (name, kind) = match br.kind {
2358                     ty::BrAnon(..) | ty::BrEnv => {
2359                         let name = next_name(&self);
2360
2361                         if let Some(lt_idx) = lifetime_idx {
2362                             if lt_idx > binder_level_idx {
2363                                 let kind = ty::BrNamed(CRATE_DEF_ID.to_def_id(), name);
2364                                 return tcx.mk_region(ty::ReLateBound(
2365                                     ty::INNERMOST,
2366                                     ty::BoundRegion { var: br.var, kind },
2367                                 ));
2368                             }
2369                         }
2370
2371                         (name, ty::BrNamed(CRATE_DEF_ID.to_def_id(), name))
2372                     }
2373                     ty::BrNamed(def_id, kw::UnderscoreLifetime | kw::Empty) => {
2374                         let name = next_name(&self);
2375
2376                         if let Some(lt_idx) = lifetime_idx {
2377                             if lt_idx > binder_level_idx {
2378                                 let kind = ty::BrNamed(def_id, name);
2379                                 return tcx.mk_region(ty::ReLateBound(
2380                                     ty::INNERMOST,
2381                                     ty::BoundRegion { var: br.var, kind },
2382                                 ));
2383                             }
2384                         }
2385
2386                         (name, ty::BrNamed(def_id, name))
2387                     }
2388                     ty::BrNamed(_, name) => {
2389                         if let Some(lt_idx) = lifetime_idx {
2390                             if lt_idx > binder_level_idx {
2391                                 let kind = br.kind;
2392                                 return tcx.mk_region(ty::ReLateBound(
2393                                     ty::INNERMOST,
2394                                     ty::BoundRegion { var: br.var, kind },
2395                                 ));
2396                             }
2397                         }
2398
2399                         (name, br.kind)
2400                     }
2401                 };
2402
2403                 start_or_continue(&mut self, "for<", ", ");
2404                 do_continue(&mut self, name);
2405                 tcx.mk_region(ty::ReLateBound(ty::INNERMOST, ty::BoundRegion { var: br.var, kind }))
2406             };
2407             let mut folder = RegionFolder {
2408                 tcx,
2409                 current_index: ty::INNERMOST,
2410                 name: &mut name,
2411                 region_map: BTreeMap::new(),
2412             };
2413             let new_value = value.clone().skip_binder().fold_with(&mut folder);
2414             let region_map = folder.region_map;
2415             start_or_continue(&mut self, "", "> ");
2416             (new_value, region_map)
2417         };
2418
2419         self.binder_depth += 1;
2420         self.region_index = region_index;
2421         Ok((self, new_value, map))
2422     }
2423
2424     pub fn pretty_in_binder<T>(self, value: &ty::Binder<'tcx, T>) -> Result<Self, fmt::Error>
2425     where
2426         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
2427     {
2428         let old_region_index = self.region_index;
2429         let (new, new_value, _) = self.name_all_regions(value)?;
2430         let mut inner = new_value.print(new)?;
2431         inner.region_index = old_region_index;
2432         inner.binder_depth -= 1;
2433         Ok(inner)
2434     }
2435
2436     pub fn pretty_wrap_binder<T, C: FnOnce(&T, Self) -> Result<Self, fmt::Error>>(
2437         self,
2438         value: &ty::Binder<'tcx, T>,
2439         f: C,
2440     ) -> Result<Self, fmt::Error>
2441     where
2442         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
2443     {
2444         let old_region_index = self.region_index;
2445         let (new, new_value, _) = self.name_all_regions(value)?;
2446         let mut inner = f(&new_value, new)?;
2447         inner.region_index = old_region_index;
2448         inner.binder_depth -= 1;
2449         Ok(inner)
2450     }
2451
2452     fn prepare_region_info<T>(&mut self, value: &ty::Binder<'tcx, T>)
2453     where
2454         T: TypeVisitable<'tcx>,
2455     {
2456         struct RegionNameCollector<'tcx> {
2457             used_region_names: FxHashSet<Symbol>,
2458             type_collector: SsoHashSet<Ty<'tcx>>,
2459         }
2460
2461         impl<'tcx> RegionNameCollector<'tcx> {
2462             fn new() -> Self {
2463                 RegionNameCollector {
2464                     used_region_names: Default::default(),
2465                     type_collector: SsoHashSet::new(),
2466                 }
2467             }
2468         }
2469
2470         impl<'tcx> ty::visit::TypeVisitor<'tcx> for RegionNameCollector<'tcx> {
2471             type BreakTy = ();
2472
2473             fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
2474                 trace!("address: {:p}", r.0.0);
2475
2476                 // Collect all named lifetimes. These allow us to prevent duplication
2477                 // of already existing lifetime names when introducing names for
2478                 // anonymous late-bound regions.
2479                 if let Some(name) = r.get_name() {
2480                     self.used_region_names.insert(name);
2481                 }
2482
2483                 r.super_visit_with(self)
2484             }
2485
2486             // We collect types in order to prevent really large types from compiling for
2487             // a really long time. See issue #83150 for why this is necessary.
2488             fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
2489                 let not_previously_inserted = self.type_collector.insert(ty);
2490                 if not_previously_inserted {
2491                     ty.super_visit_with(self)
2492                 } else {
2493                     ControlFlow::Continue(())
2494                 }
2495             }
2496         }
2497
2498         let mut collector = RegionNameCollector::new();
2499         value.visit_with(&mut collector);
2500         self.used_region_names = collector.used_region_names;
2501         self.region_index = 0;
2502     }
2503 }
2504
2505 impl<'tcx, T, P: PrettyPrinter<'tcx>> Print<'tcx, P> for ty::Binder<'tcx, T>
2506 where
2507     T: Print<'tcx, P, Output = P, Error = P::Error> + TypeFoldable<'tcx>,
2508 {
2509     type Output = P;
2510     type Error = P::Error;
2511
2512     fn print(&self, cx: P) -> Result<Self::Output, Self::Error> {
2513         cx.in_binder(self)
2514     }
2515 }
2516
2517 impl<'tcx, T, U, P: PrettyPrinter<'tcx>> Print<'tcx, P> for ty::OutlivesPredicate<T, U>
2518 where
2519     T: Print<'tcx, P, Output = P, Error = P::Error>,
2520     U: Print<'tcx, P, Output = P, Error = P::Error>,
2521 {
2522     type Output = P;
2523     type Error = P::Error;
2524     fn print(&self, mut cx: P) -> Result<Self::Output, Self::Error> {
2525         define_scoped_cx!(cx);
2526         p!(print(self.0), ": ", print(self.1));
2527         Ok(cx)
2528     }
2529 }
2530
2531 macro_rules! forward_display_to_print {
2532     ($($ty:ty),+) => {
2533         // Some of the $ty arguments may not actually use 'tcx
2534         $(#[allow(unused_lifetimes)] impl<'tcx> fmt::Display for $ty {
2535             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2536                 ty::tls::with(|tcx| {
2537                     let cx = tcx.lift(*self)
2538                         .expect("could not lift for printing")
2539                         .print(FmtPrinter::new(tcx, Namespace::TypeNS))?;
2540                     f.write_str(&cx.into_buffer())?;
2541                     Ok(())
2542                 })
2543             }
2544         })+
2545     };
2546 }
2547
2548 macro_rules! define_print_and_forward_display {
2549     (($self:ident, $cx:ident): $($ty:ty $print:block)+) => {
2550         $(impl<'tcx, P: PrettyPrinter<'tcx>> Print<'tcx, P> for $ty {
2551             type Output = P;
2552             type Error = fmt::Error;
2553             fn print(&$self, $cx: P) -> Result<Self::Output, Self::Error> {
2554                 #[allow(unused_mut)]
2555                 let mut $cx = $cx;
2556                 define_scoped_cx!($cx);
2557                 let _: () = $print;
2558                 #[allow(unreachable_code)]
2559                 Ok($cx)
2560             }
2561         })+
2562
2563         forward_display_to_print!($($ty),+);
2564     };
2565 }
2566
2567 /// Wrapper type for `ty::TraitRef` which opts-in to pretty printing only
2568 /// the trait path. That is, it will print `Trait<U>` instead of
2569 /// `<T as Trait<U>>`.
2570 #[derive(Copy, Clone, TypeFoldable, TypeVisitable, Lift)]
2571 pub struct TraitRefPrintOnlyTraitPath<'tcx>(ty::TraitRef<'tcx>);
2572
2573 impl<'tcx> fmt::Debug for TraitRefPrintOnlyTraitPath<'tcx> {
2574     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2575         fmt::Display::fmt(self, f)
2576     }
2577 }
2578
2579 /// Wrapper type for `ty::TraitRef` which opts-in to pretty printing only
2580 /// the trait name. That is, it will print `Trait` instead of
2581 /// `<T as Trait<U>>`.
2582 #[derive(Copy, Clone, TypeFoldable, TypeVisitable, Lift)]
2583 pub struct TraitRefPrintOnlyTraitName<'tcx>(ty::TraitRef<'tcx>);
2584
2585 impl<'tcx> fmt::Debug for TraitRefPrintOnlyTraitName<'tcx> {
2586     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2587         fmt::Display::fmt(self, f)
2588     }
2589 }
2590
2591 impl<'tcx> ty::TraitRef<'tcx> {
2592     pub fn print_only_trait_path(self) -> TraitRefPrintOnlyTraitPath<'tcx> {
2593         TraitRefPrintOnlyTraitPath(self)
2594     }
2595
2596     pub fn print_only_trait_name(self) -> TraitRefPrintOnlyTraitName<'tcx> {
2597         TraitRefPrintOnlyTraitName(self)
2598     }
2599 }
2600
2601 impl<'tcx> ty::Binder<'tcx, ty::TraitRef<'tcx>> {
2602     pub fn print_only_trait_path(self) -> ty::Binder<'tcx, TraitRefPrintOnlyTraitPath<'tcx>> {
2603         self.map_bound(|tr| tr.print_only_trait_path())
2604     }
2605 }
2606
2607 #[derive(Copy, Clone, TypeFoldable, TypeVisitable, Lift)]
2608 pub struct TraitPredPrintModifiersAndPath<'tcx>(ty::TraitPredicate<'tcx>);
2609
2610 impl<'tcx> fmt::Debug for TraitPredPrintModifiersAndPath<'tcx> {
2611     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2612         fmt::Display::fmt(self, f)
2613     }
2614 }
2615
2616 impl<'tcx> ty::TraitPredicate<'tcx> {
2617     pub fn print_modifiers_and_trait_path(self) -> TraitPredPrintModifiersAndPath<'tcx> {
2618         TraitPredPrintModifiersAndPath(self)
2619     }
2620 }
2621
2622 impl<'tcx> ty::PolyTraitPredicate<'tcx> {
2623     pub fn print_modifiers_and_trait_path(
2624         self,
2625     ) -> ty::Binder<'tcx, TraitPredPrintModifiersAndPath<'tcx>> {
2626         self.map_bound(TraitPredPrintModifiersAndPath)
2627     }
2628 }
2629
2630 #[derive(Debug, Copy, Clone, TypeFoldable, TypeVisitable, Lift)]
2631 pub struct PrintClosureAsImpl<'tcx> {
2632     pub closure: ty::ClosureSubsts<'tcx>,
2633 }
2634
2635 forward_display_to_print! {
2636     ty::Region<'tcx>,
2637     Ty<'tcx>,
2638     &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
2639     ty::Const<'tcx>,
2640
2641     // HACK(eddyb) these are exhaustive instead of generic,
2642     // because `for<'tcx>` isn't possible yet.
2643     ty::PolyExistentialPredicate<'tcx>,
2644     ty::Binder<'tcx, ty::TraitRef<'tcx>>,
2645     ty::Binder<'tcx, ty::ExistentialTraitRef<'tcx>>,
2646     ty::Binder<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
2647     ty::Binder<'tcx, TraitRefPrintOnlyTraitName<'tcx>>,
2648     ty::Binder<'tcx, ty::FnSig<'tcx>>,
2649     ty::Binder<'tcx, ty::TraitPredicate<'tcx>>,
2650     ty::Binder<'tcx, TraitPredPrintModifiersAndPath<'tcx>>,
2651     ty::Binder<'tcx, ty::SubtypePredicate<'tcx>>,
2652     ty::Binder<'tcx, ty::ProjectionPredicate<'tcx>>,
2653     ty::Binder<'tcx, ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>>,
2654     ty::Binder<'tcx, ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>>,
2655
2656     ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>,
2657     ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>
2658 }
2659
2660 define_print_and_forward_display! {
2661     (self, cx):
2662
2663     &'tcx ty::List<Ty<'tcx>> {
2664         p!("{{", comma_sep(self.iter()), "}}")
2665     }
2666
2667     ty::TypeAndMut<'tcx> {
2668         p!(write("{}", self.mutbl.prefix_str()), print(self.ty))
2669     }
2670
2671     ty::ExistentialTraitRef<'tcx> {
2672         // Use a type that can't appear in defaults of type parameters.
2673         let dummy_self = cx.tcx().mk_ty_infer(ty::FreshTy(0));
2674         let trait_ref = self.with_self_ty(cx.tcx(), dummy_self);
2675         p!(print(trait_ref.print_only_trait_path()))
2676     }
2677
2678     ty::ExistentialProjection<'tcx> {
2679         let name = cx.tcx().associated_item(self.def_id).name;
2680         p!(write("{} = ", name), print(self.term))
2681     }
2682
2683     ty::ExistentialPredicate<'tcx> {
2684         match *self {
2685             ty::ExistentialPredicate::Trait(x) => p!(print(x)),
2686             ty::ExistentialPredicate::Projection(x) => p!(print(x)),
2687             ty::ExistentialPredicate::AutoTrait(def_id) => {
2688                 p!(print_def_path(def_id, &[]));
2689             }
2690         }
2691     }
2692
2693     ty::FnSig<'tcx> {
2694         p!(write("{}", self.unsafety.prefix_str()));
2695
2696         if self.abi != Abi::Rust {
2697             p!(write("extern {} ", self.abi));
2698         }
2699
2700         p!("fn", pretty_fn_sig(self.inputs(), self.c_variadic, self.output()));
2701     }
2702
2703     ty::TraitRef<'tcx> {
2704         p!(write("<{} as {}>", self.self_ty(), self.print_only_trait_path()))
2705     }
2706
2707     TraitRefPrintOnlyTraitPath<'tcx> {
2708         p!(print_def_path(self.0.def_id, self.0.substs));
2709     }
2710
2711     TraitRefPrintOnlyTraitName<'tcx> {
2712         p!(print_def_path(self.0.def_id, &[]));
2713     }
2714
2715     TraitPredPrintModifiersAndPath<'tcx> {
2716         if let ty::BoundConstness::ConstIfConst = self.0.constness {
2717             p!("~const ")
2718         }
2719
2720         if let ty::ImplPolarity::Negative = self.0.polarity {
2721             p!("!")
2722         }
2723
2724         p!(print(self.0.trait_ref.print_only_trait_path()));
2725     }
2726
2727     PrintClosureAsImpl<'tcx> {
2728         p!(pretty_closure_as_impl(self.closure))
2729     }
2730
2731     ty::ParamTy {
2732         p!(write("{}", self.name))
2733     }
2734
2735     ty::ParamConst {
2736         p!(write("{}", self.name))
2737     }
2738
2739     ty::SubtypePredicate<'tcx> {
2740         p!(print(self.a), " <: ");
2741         cx.reset_type_limit();
2742         p!(print(self.b))
2743     }
2744
2745     ty::CoercePredicate<'tcx> {
2746         p!(print(self.a), " -> ");
2747         cx.reset_type_limit();
2748         p!(print(self.b))
2749     }
2750
2751     ty::TraitPredicate<'tcx> {
2752         p!(print(self.trait_ref.self_ty()), ": ");
2753         if let ty::BoundConstness::ConstIfConst = self.constness && cx.tcx().features().const_trait_impl {
2754             p!("~const ");
2755         }
2756         p!(print(self.trait_ref.print_only_trait_path()))
2757     }
2758
2759     ty::ProjectionPredicate<'tcx> {
2760         p!(print(self.projection_ty), " == ");
2761         cx.reset_type_limit();
2762         p!(print(self.term))
2763     }
2764
2765     ty::Term<'tcx> {
2766       match self.unpack() {
2767         ty::TermKind::Ty(ty) => p!(print(ty)),
2768         ty::TermKind::Const(c) => p!(print(c)),
2769       }
2770     }
2771
2772     ty::AliasTy<'tcx> {
2773         p!(print_def_path(self.def_id, self.substs));
2774     }
2775
2776     ty::ClosureKind {
2777         match *self {
2778             ty::ClosureKind::Fn => p!("Fn"),
2779             ty::ClosureKind::FnMut => p!("FnMut"),
2780             ty::ClosureKind::FnOnce => p!("FnOnce"),
2781         }
2782     }
2783
2784     ty::Predicate<'tcx> {
2785         let binder = self.kind();
2786         p!(print(binder))
2787     }
2788
2789     ty::PredicateKind<'tcx> {
2790         match *self {
2791             ty::PredicateKind::Clause(ty::Clause::Trait(ref data)) => {
2792                 p!(print(data))
2793             }
2794             ty::PredicateKind::Subtype(predicate) => p!(print(predicate)),
2795             ty::PredicateKind::Coerce(predicate) => p!(print(predicate)),
2796             ty::PredicateKind::Clause(ty::Clause::RegionOutlives(predicate)) => p!(print(predicate)),
2797             ty::PredicateKind::Clause(ty::Clause::TypeOutlives(predicate)) => p!(print(predicate)),
2798             ty::PredicateKind::Clause(ty::Clause::Projection(predicate)) => p!(print(predicate)),
2799             ty::PredicateKind::WellFormed(arg) => p!(print(arg), " well-formed"),
2800             ty::PredicateKind::ObjectSafe(trait_def_id) => {
2801                 p!("the trait `", print_def_path(trait_def_id, &[]), "` is object-safe")
2802             }
2803             ty::PredicateKind::ClosureKind(closure_def_id, _closure_substs, kind) => {
2804                 p!("the closure `",
2805                 print_value_path(closure_def_id, &[]),
2806                 write("` implements the trait `{}`", kind))
2807             }
2808             ty::PredicateKind::ConstEvaluatable(ct) => {
2809                 p!("the constant `", print(ct), "` can be evaluated")
2810             }
2811             ty::PredicateKind::ConstEquate(c1, c2) => {
2812                 p!("the constant `", print(c1), "` equals `", print(c2), "`")
2813             }
2814             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
2815                 p!("the type `", print(ty), "` is found in the environment")
2816             }
2817             ty::PredicateKind::Ambiguous => p!("ambiguous"),
2818         }
2819     }
2820
2821     GenericArg<'tcx> {
2822         match self.unpack() {
2823             GenericArgKind::Lifetime(lt) => p!(print(lt)),
2824             GenericArgKind::Type(ty) => p!(print(ty)),
2825             GenericArgKind::Const(ct) => p!(print(ct)),
2826         }
2827     }
2828 }
2829
2830 fn for_each_def(tcx: TyCtxt<'_>, mut collect_fn: impl for<'b> FnMut(&'b Ident, Namespace, DefId)) {
2831     // Iterate all local crate items no matter where they are defined.
2832     let hir = tcx.hir();
2833     for id in hir.items() {
2834         if matches!(tcx.def_kind(id.owner_id), DefKind::Use) {
2835             continue;
2836         }
2837
2838         let item = hir.item(id);
2839         if item.ident.name == kw::Empty {
2840             continue;
2841         }
2842
2843         let def_id = item.owner_id.to_def_id();
2844         let ns = tcx.def_kind(def_id).ns().unwrap_or(Namespace::TypeNS);
2845         collect_fn(&item.ident, ns, def_id);
2846     }
2847
2848     // Now take care of extern crate items.
2849     let queue = &mut Vec::new();
2850     let mut seen_defs: DefIdSet = Default::default();
2851
2852     for &cnum in tcx.crates(()).iter() {
2853         let def_id = cnum.as_def_id();
2854
2855         // Ignore crates that are not direct dependencies.
2856         match tcx.extern_crate(def_id) {
2857             None => continue,
2858             Some(extern_crate) => {
2859                 if !extern_crate.is_direct() {
2860                     continue;
2861                 }
2862             }
2863         }
2864
2865         queue.push(def_id);
2866     }
2867
2868     // Iterate external crate defs but be mindful about visibility
2869     while let Some(def) = queue.pop() {
2870         for child in tcx.module_children(def).iter() {
2871             if !child.vis.is_public() {
2872                 continue;
2873             }
2874
2875             match child.res {
2876                 def::Res::Def(DefKind::AssocTy, _) => {}
2877                 def::Res::Def(DefKind::TyAlias, _) => {}
2878                 def::Res::Def(defkind, def_id) => {
2879                     if let Some(ns) = defkind.ns() {
2880                         collect_fn(&child.ident, ns, def_id);
2881                     }
2882
2883                     if matches!(defkind, DefKind::Mod | DefKind::Enum | DefKind::Trait)
2884                         && seen_defs.insert(def_id)
2885                     {
2886                         queue.push(def_id);
2887                     }
2888                 }
2889                 _ => {}
2890             }
2891         }
2892     }
2893 }
2894
2895 /// The purpose of this function is to collect public symbols names that are unique across all
2896 /// crates in the build. Later, when printing about types we can use those names instead of the
2897 /// full exported path to them.
2898 ///
2899 /// So essentially, if a symbol name can only be imported from one place for a type, and as
2900 /// long as it was not glob-imported anywhere in the current crate, we can trim its printed
2901 /// path and print only the name.
2902 ///
2903 /// This has wide implications on error messages with types, for example, shortening
2904 /// `std::vec::Vec` to just `Vec`, as long as there is no other `Vec` importable anywhere.
2905 ///
2906 /// The implementation uses similar import discovery logic to that of 'use' suggestions.
2907 ///
2908 /// See also [`DelayDm`](rustc_error_messages::DelayDm) and [`with_no_trimmed_paths`].
2909 fn trimmed_def_paths(tcx: TyCtxt<'_>, (): ()) -> FxHashMap<DefId, Symbol> {
2910     let mut map: FxHashMap<DefId, Symbol> = FxHashMap::default();
2911
2912     if let TrimmedDefPaths::GoodPath = tcx.sess.opts.trimmed_def_paths {
2913         // Trimming paths is expensive and not optimized, since we expect it to only be used for error reporting.
2914         //
2915         // For good paths causing this bug, the `rustc_middle::ty::print::with_no_trimmed_paths`
2916         // wrapper can be used to suppress this query, in exchange for full paths being formatted.
2917         tcx.sess.delay_good_path_bug(
2918             "trimmed_def_paths constructed but no error emitted; use `DelayDm` for lints or `with_no_trimmed_paths` for debugging",
2919         );
2920     }
2921
2922     let unique_symbols_rev: &mut FxHashMap<(Namespace, Symbol), Option<DefId>> =
2923         &mut FxHashMap::default();
2924
2925     for symbol_set in tcx.resolutions(()).glob_map.values() {
2926         for symbol in symbol_set {
2927             unique_symbols_rev.insert((Namespace::TypeNS, *symbol), None);
2928             unique_symbols_rev.insert((Namespace::ValueNS, *symbol), None);
2929             unique_symbols_rev.insert((Namespace::MacroNS, *symbol), None);
2930         }
2931     }
2932
2933     for_each_def(tcx, |ident, ns, def_id| {
2934         use std::collections::hash_map::Entry::{Occupied, Vacant};
2935
2936         match unique_symbols_rev.entry((ns, ident.name)) {
2937             Occupied(mut v) => match v.get() {
2938                 None => {}
2939                 Some(existing) => {
2940                     if *existing != def_id {
2941                         v.insert(None);
2942                     }
2943                 }
2944             },
2945             Vacant(v) => {
2946                 v.insert(Some(def_id));
2947             }
2948         }
2949     });
2950
2951     for ((_, symbol), opt_def_id) in unique_symbols_rev.drain() {
2952         use std::collections::hash_map::Entry::{Occupied, Vacant};
2953
2954         if let Some(def_id) = opt_def_id {
2955             match map.entry(def_id) {
2956                 Occupied(mut v) => {
2957                     // A single DefId can be known under multiple names (e.g.,
2958                     // with a `pub use ... as ...;`). We need to ensure that the
2959                     // name placed in this map is chosen deterministically, so
2960                     // if we find multiple names (`symbol`) resolving to the
2961                     // same `def_id`, we prefer the lexicographically smallest
2962                     // name.
2963                     //
2964                     // Any stable ordering would be fine here though.
2965                     if *v.get() != symbol {
2966                         if v.get().as_str() > symbol.as_str() {
2967                             v.insert(symbol);
2968                         }
2969                     }
2970                 }
2971                 Vacant(v) => {
2972                     v.insert(symbol);
2973                 }
2974             }
2975         }
2976     }
2977
2978     map
2979 }
2980
2981 pub fn provide(providers: &mut ty::query::Providers) {
2982     *providers = ty::query::Providers { trimmed_def_paths, ..*providers };
2983 }
2984
2985 #[derive(Default)]
2986 pub struct OpaqueFnEntry<'tcx> {
2987     // The trait ref is already stored as a key, so just track if we have it as a real predicate
2988     has_fn_once: bool,
2989     fn_mut_trait_ref: Option<ty::PolyTraitRef<'tcx>>,
2990     fn_trait_ref: Option<ty::PolyTraitRef<'tcx>>,
2991     return_ty: Option<ty::Binder<'tcx, Term<'tcx>>>,
2992 }