1 use crate::hir::def::Namespace;
2 use crate::hir::map::DefPathData;
3 use crate::hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
4 use crate::middle::region;
5 use crate::ty::{self, DefIdTree, Ty, TyCtxt, TypeFoldable};
6 use crate::ty::subst::{Kind, Subst, SubstsRef, UnpackedKind};
7 use crate::middle::cstore::{ExternCrate, ExternCrateSource};
8 use syntax::symbol::{keywords, Symbol};
10 use rustc_data_structures::fx::FxHashSet;
11 use syntax::symbol::InternedString;
14 use std::fmt::{self, Write as _};
19 static FORCE_IMPL_FILENAME_LINE: Cell<bool> = Cell::new(false);
20 static SHOULD_PREFIX_WITH_CRATE: Cell<bool> = Cell::new(false);
23 /// Force us to name impls with just the filename/line number. We
24 /// normally try to use types. But at some points, notably while printing
25 /// cycle errors, this can result in extra or suboptimal error output,
26 /// so this variable disables that check.
27 pub fn with_forced_impl_filename_line<F: FnOnce() -> R, R>(f: F) -> R {
28 FORCE_IMPL_FILENAME_LINE.with(|force| {
29 let old = force.get();
37 /// Adds the `crate::` prefix to paths where appropriate.
38 pub fn with_crate_prefix<F: FnOnce() -> R, R>(f: F) -> R {
39 SHOULD_PREFIX_WITH_CRATE.with(|flag| {
48 // FIXME(eddyb) this module uses `pub(crate)` for things used only
49 // from `ppaux` - when that is removed, they can be re-privatized.
51 /// The "region highlights" are used to control region printing during
52 /// specific error messages. When a "region highlight" is enabled, it
53 /// gives an alternate way to print specific regions. For now, we
54 /// always print those regions using a number, so something like "`'0`".
56 /// Regions not selected by the region highlight mode are presently
58 #[derive(Copy, Clone, Default)]
59 pub struct RegionHighlightMode {
60 /// If enabled, when we see the selected region, use "`'N`"
61 /// instead of the ordinary behavior.
62 highlight_regions: [Option<(ty::RegionKind, usize)>; 3],
64 /// If enabled, when printing a "free region" that originated from
65 /// the given `ty::BoundRegion`, print it as "`'1`". Free regions that would ordinarily
66 /// have names print as normal.
68 /// This is used when you have a signature like `fn foo(x: &u32,
69 /// y: &'a u32)` and we want to give a name to the region of the
71 highlight_bound_region: Option<(ty::BoundRegion, usize)>,
74 impl RegionHighlightMode {
75 /// If `region` and `number` are both `Some`, invokes
76 /// `highlighting_region`.
77 pub fn maybe_highlighting_region(
79 region: Option<ty::Region<'_>>,
80 number: Option<usize>,
82 if let Some(k) = region {
83 if let Some(n) = number {
84 self.highlighting_region(k, n);
89 /// Highlights the region inference variable `vid` as `'N`.
90 pub fn highlighting_region(
92 region: ty::Region<'_>,
95 let num_slots = self.highlight_regions.len();
96 let first_avail_slot = self.highlight_regions.iter_mut()
97 .filter(|s| s.is_none())
101 "can only highlight {} placeholders at a time",
105 *first_avail_slot = Some((*region, number));
108 /// Convenience wrapper for `highlighting_region`.
109 pub fn highlighting_region_vid(
114 self.highlighting_region(&ty::ReVar(vid), number)
117 /// Returns `Some(n)` with the number to use for the given region, if any.
118 fn region_highlighted(&self, region: ty::Region<'_>) -> Option<usize> {
122 .filter_map(|h| match h {
123 Some((r, n)) if r == region => Some(*n),
129 /// Highlight the given bound region.
130 /// We can only highlight one bound region at a time. See
131 /// the field `highlight_bound_region` for more detailed notes.
132 pub fn highlighting_bound_region(
137 assert!(self.highlight_bound_region.is_none());
138 self.highlight_bound_region = Some((br, number));
142 struct LateBoundRegionNameCollector(FxHashSet<InternedString>);
143 impl<'tcx> ty::fold::TypeVisitor<'tcx> for LateBoundRegionNameCollector {
144 fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
146 ty::ReLateBound(_, ty::BrNamed(_, name)) => {
151 r.super_visit_with(self)
155 pub(crate) struct PrintConfig {
156 pub(crate) is_debug: bool,
157 pub(crate) is_verbose: bool,
158 pub(crate) identify_regions: bool,
159 pub(crate) used_region_names: Option<FxHashSet<InternedString>>,
160 pub(crate) region_index: usize,
161 pub(crate) binder_depth: usize,
165 pub(crate) fn new(tcx: TyCtxt<'_, '_, '_>) -> Self {
168 is_verbose: tcx.sess.verbose(),
169 identify_regions: tcx.sess.opts.debugging_opts.identify_regions,
170 used_region_names: None,
177 pub struct PrintCx<'a, 'gcx, 'tcx, P> {
178 pub tcx: TyCtxt<'a, 'gcx, 'tcx>,
180 pub(crate) config: &'a mut PrintConfig,
183 // HACK(eddyb) this is solely for `self: PrintCx<Self>`, e.g. to
184 // implement traits on the printer and call the methods on the context.
185 impl<P> Deref for PrintCx<'_, '_, '_, P> {
187 fn deref(&self) -> &P {
192 impl<'a, 'gcx, 'tcx, P> PrintCx<'a, 'gcx, 'tcx, P> {
194 tcx: TyCtxt<'a, 'gcx, 'tcx>,
196 f: impl FnOnce(PrintCx<'_, 'gcx, 'tcx, P>) -> R,
201 config: &mut PrintConfig::new(tcx),
205 pub(crate) fn with_tls_tcx<R>(printer: P, f: impl FnOnce(PrintCx<'_, '_, '_, P>) -> R) -> R {
206 ty::tls::with(|tcx| PrintCx::with(tcx, printer, f))
208 pub(crate) fn prepare_late_bound_region_info<T>(&mut self, value: &ty::Binder<T>)
209 where T: TypeFoldable<'tcx>
211 let mut collector = LateBoundRegionNameCollector(Default::default());
212 value.visit_with(&mut collector);
213 self.config.used_region_names = Some(collector.0);
214 self.config.region_index = 0;
218 pub trait Print<'tcx, P> {
222 fn print(&self, cx: PrintCx<'_, '_, 'tcx, P>) -> Result<Self::Output, Self::Error>;
225 cx: PrintCx<'_, '_, 'tcx, P>,
226 ) -> Result<Self::Output, Self::Error> {
227 let old_debug = cx.config.is_debug;
228 cx.config.is_debug = false;
229 let result = self.print(PrintCx {
234 cx.config.is_debug = old_debug;
237 fn print_debug(&self, cx: PrintCx<'_, '_, 'tcx, P>) -> Result<Self::Output, Self::Error> {
238 let old_debug = cx.config.is_debug;
239 cx.config.is_debug = true;
240 let result = self.print(PrintCx {
245 cx.config.is_debug = old_debug;
250 pub trait Printer: Sized {
258 self: PrintCx<'_, '_, 'tcx, Self>,
260 substs: Option<SubstsRef<'tcx>>,
262 projections: impl Iterator<Item = ty::ExistentialProjection<'tcx>>,
263 ) -> Result<Self::Path, Self::Error> {
264 self.default_print_def_path(def_id, substs, ns, projections)
267 self: PrintCx<'_, '_, 'tcx, Self>,
269 substs: Option<SubstsRef<'tcx>>,
272 trait_ref: Option<ty::TraitRef<'tcx>>,
273 ) -> Result<Self::Path, Self::Error> {
274 self.default_print_impl_path(impl_def_id, substs, ns, self_ty, trait_ref)
278 self: PrintCx<'_, '_, '_, Self>,
279 region: ty::Region<'_>,
280 ) -> Result<Self::Region, Self::Error>;
283 self: PrintCx<'_, '_, 'tcx, Self>,
285 ) -> Result<Self::Type, Self::Error>;
288 self: PrintCx<'_, '_, '_, Self>,
290 ) -> Result<Self::Path, Self::Error>;
292 self: PrintCx<'_, '_, 'tcx, Self>,
294 trait_ref: Option<ty::TraitRef<'tcx>>,
296 ) -> Result<Self::Path, Self::Error>;
298 fn path_append_impl<'gcx, 'tcx>(
299 self: PrintCx<'_, 'gcx, 'tcx, Self>,
300 print_prefix: impl FnOnce(
301 PrintCx<'_, 'gcx, 'tcx, Self>,
302 ) -> Result<Self::Path, Self::Error>,
304 trait_ref: Option<ty::TraitRef<'tcx>>,
305 ) -> Result<Self::Path, Self::Error>;
306 fn path_append<'gcx, 'tcx>(
307 self: PrintCx<'_, 'gcx, 'tcx, Self>,
308 print_prefix: impl FnOnce(
309 PrintCx<'_, 'gcx, 'tcx, Self>,
310 ) -> Result<Self::Path, Self::Error>,
312 ) -> Result<Self::Path, Self::Error>;
313 fn path_generic_args<'gcx, 'tcx>(
314 self: PrintCx<'_, 'gcx, 'tcx, Self>,
315 print_prefix: impl FnOnce(
316 PrintCx<'_, 'gcx, 'tcx, Self>,
317 ) -> Result<Self::Path, Self::Error>,
318 params: &[ty::GenericParamDef],
319 substs: SubstsRef<'tcx>,
321 projections: impl Iterator<Item = ty::ExistentialProjection<'tcx>>,
322 ) -> Result<Self::Path, Self::Error>;
325 /// Trait for printers that pretty-print using `fmt::Write` to the printer.
326 pub trait PrettyPrinter:
335 /// Enter a nested print context, for pretty-printing
336 /// nested components in some larger context.
337 fn nest<'a, 'gcx, 'tcx, E>(
338 self: PrintCx<'a, 'gcx, 'tcx, Self>,
339 f: impl for<'b> FnOnce(PrintCx<'b, 'gcx, 'tcx, Self>) -> Result<Self, E>,
340 ) -> Result<PrintCx<'a, 'gcx, 'tcx, Self>, E> {
341 let printer = f(PrintCx {
343 printer: self.printer,
353 /// Return `true` if the region should be printed in path generic args
354 /// even when it's `'_`, such as in e.g. `Foo<'_, '_, '_>`.
355 fn always_print_region_in_paths(
356 self: &PrintCx<'_, '_, '_, Self>,
357 _region: ty::Region<'_>,
362 // HACK(eddyb) Trying to print a lifetime might not print anything, which
363 // may need special handling in the caller (of `ty::RegionKind::print`).
364 // To avoid printing to a temporary string (which isn't even supported),
365 // the `print_region_outputs_anything` method can instead be used to
366 // determine this, ahead of time.
368 // NB: this must be kept in sync with the implementation of `print_region`.
369 fn print_region_outputs_anything(
370 self: &PrintCx<'_, '_, '_, Self>,
371 region: ty::Region<'_>,
376 ($cx:ident, $closure:expr) => {
377 $cx = $cx.nest($closure)?
381 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
382 // HACK(eddyb) get rid of `def_path_str` and/or pass `Namespace` explicitly always
383 // (but also some things just print a `DefId` generally so maybe we need this?)
384 fn guess_def_namespace(self, def_id: DefId) -> Namespace {
385 match self.def_key(def_id).disambiguated_data.data {
386 DefPathData::ValueNs(..) |
387 DefPathData::EnumVariant(..) |
388 DefPathData::Field(..) |
389 DefPathData::AnonConst |
390 DefPathData::ConstParam(..) |
391 DefPathData::ClosureExpr |
392 DefPathData::StructCtor => Namespace::ValueNS,
394 DefPathData::MacroDef(..) => Namespace::MacroNS,
396 _ => Namespace::TypeNS,
400 /// Returns a string identifying this `DefId`. This string is
401 /// suitable for user output.
402 pub fn def_path_str(self, def_id: DefId) -> String {
403 let ns = self.guess_def_namespace(def_id);
404 debug!("def_path_str: def_id={:?}, ns={:?}", def_id, ns);
405 let mut s = String::new();
406 let _ = PrintCx::with(self, FmtPrinter::new(&mut s), |cx| {
407 cx.print_def_path(def_id, None, ns, iter::empty())
413 impl<P: Printer> PrintCx<'a, 'gcx, 'tcx, P> {
414 pub fn default_print_def_path(
417 substs: Option<SubstsRef<'tcx>>,
419 projections: impl Iterator<Item = ty::ExistentialProjection<'tcx>>,
420 ) -> Result<P::Path, P::Error> {
421 debug!("default_print_def_path: def_id={:?}, substs={:?}, ns={:?}", def_id, substs, ns);
422 let key = self.tcx.def_key(def_id);
423 debug!("default_print_def_path: key={:?}", key);
425 match key.disambiguated_data.data {
426 DefPathData::CrateRoot => {
427 assert!(key.parent.is_none());
428 self.path_crate(def_id.krate)
431 DefPathData::Impl => {
432 let mut self_ty = self.tcx.type_of(def_id);
433 if let Some(substs) = substs {
434 self_ty = self_ty.subst(self.tcx, substs);
437 let mut impl_trait_ref = self.tcx.impl_trait_ref(def_id);
438 if let Some(substs) = substs {
439 impl_trait_ref = impl_trait_ref.subst(self.tcx, substs);
441 self.print_impl_path(def_id, substs, ns, self_ty, impl_trait_ref)
445 let generics = substs.map(|_| self.tcx.generics_of(def_id));
446 let generics_parent = generics.as_ref().and_then(|g| g.parent);
447 let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id };
448 let print_parent_path = |cx: PrintCx<'_, 'gcx, 'tcx, P>| {
449 if let Some(generics_parent_def_id) = generics_parent {
450 assert_eq!(parent_def_id, generics_parent_def_id);
452 // FIXME(eddyb) try to move this into the parent's printing
453 // logic, instead of doing it when printing the child.
454 let parent_generics = cx.tcx.generics_of(parent_def_id);
455 let parent_has_own_self =
456 parent_generics.has_self && parent_generics.parent_count == 0;
457 if let (Some(substs), true) = (substs, parent_has_own_self) {
458 let trait_ref = ty::TraitRef::new(parent_def_id, substs);
459 cx.path_qualified(trait_ref.self_ty(), Some(trait_ref), ns)
461 cx.print_def_path(parent_def_id, substs, ns, iter::empty())
464 cx.print_def_path(parent_def_id, None, ns, iter::empty())
467 let print_path = |cx: PrintCx<'_, 'gcx, 'tcx, P>| {
468 match key.disambiguated_data.data {
469 // Skip `::{{constructor}}` on tuple/unit structs.
470 DefPathData::StructCtor => print_parent_path(cx),
475 &key.disambiguated_data.data.as_interned_str().as_str(),
481 if let (Some(generics), Some(substs)) = (generics, substs) {
482 let has_own_self = generics.has_self && generics.parent_count == 0;
483 let params = &generics.params[has_own_self as usize..];
484 self.path_generic_args(print_path, params, substs, ns, projections)
492 fn default_print_impl_path(
495 _substs: Option<SubstsRef<'tcx>>,
498 impl_trait_ref: Option<ty::TraitRef<'tcx>>,
499 ) -> Result<P::Path, P::Error> {
500 debug!("default_print_impl_path: impl_def_id={:?}, self_ty={}, impl_trait_ref={:?}",
501 impl_def_id, self_ty, impl_trait_ref);
503 // Decide whether to print the parent path for the impl.
504 // Logically, since impls are global, it's never needed, but
505 // users may find it useful. Currently, we omit the parent if
506 // the impl is either in the same module as the self-type or
508 let parent_def_id = self.tcx.parent(impl_def_id).unwrap();
509 let in_self_mod = match characteristic_def_id_of_type(self_ty) {
511 Some(ty_def_id) => self.tcx.parent(ty_def_id) == Some(parent_def_id),
513 let in_trait_mod = match impl_trait_ref {
515 Some(trait_ref) => self.tcx.parent(trait_ref.def_id) == Some(parent_def_id),
518 if !in_self_mod && !in_trait_mod {
519 // If the impl is not co-located with either self-type or
520 // trait-type, then fallback to a format that identifies
521 // the module more clearly.
522 self.path_append_impl(
523 |cx| cx.print_def_path(parent_def_id, None, ns, iter::empty()),
528 // Otherwise, try to give a good form that would be valid language
529 // syntax. Preferably using associated item notation.
530 self.path_qualified(self_ty, impl_trait_ref, ns)
535 /// As a heuristic, when we see an impl, if we see that the
536 /// 'self type' is a type defined in the same module as the impl,
537 /// we can omit including the path to the impl itself. This
538 /// function tries to find a "characteristic `DefId`" for a
539 /// type. It's just a heuristic so it makes some questionable
540 /// decisions and we may want to adjust it later.
541 pub fn characteristic_def_id_of_type(ty: Ty<'_>) -> Option<DefId> {
543 ty::Adt(adt_def, _) => Some(adt_def.did),
545 ty::Dynamic(data, ..) => data.principal_def_id(),
547 ty::Array(subty, _) |
548 ty::Slice(subty) => characteristic_def_id_of_type(subty),
550 ty::RawPtr(mt) => characteristic_def_id_of_type(mt.ty),
552 ty::Ref(_, ty, _) => characteristic_def_id_of_type(ty),
554 ty::Tuple(ref tys) => tys.iter()
555 .filter_map(|ty| characteristic_def_id_of_type(ty))
558 ty::FnDef(def_id, _) |
559 ty::Closure(def_id, _) |
560 ty::Generator(def_id, _, _) |
561 ty::Foreign(def_id) => Some(def_id),
570 ty::Placeholder(..) |
571 ty::UnnormalizedProjection(..) |
577 ty::GeneratorWitness(..) |
579 ty::Float(_) => None,
583 pub struct FmtPrinter<F: fmt::Write> {
586 pub region_highlight_mode: RegionHighlightMode,
589 impl<F: fmt::Write> FmtPrinter<F> {
590 pub fn new(fmt: F) -> Self {
594 region_highlight_mode: RegionHighlightMode::default(),
599 impl<'gcx, 'tcx, P: PrettyPrinter> PrintCx<'_, 'gcx, 'tcx, P> {
600 /// If possible, this returns a global path resolving to `def_id` that is visible
601 /// from at least one local module and returns true. If the crate defining `def_id` is
602 /// declared with an `extern crate`, the path is guaranteed to use the `extern crate`.
603 fn try_print_visible_def_path(
606 ) -> Result<(P, bool), P::Error> {
607 debug!("try_print_visible_def_path: def_id={:?}", def_id);
609 // If `def_id` is a direct or injected extern crate, return the
610 // path to the crate followed by the path to the item within the crate.
611 if def_id.index == CRATE_DEF_INDEX {
612 let cnum = def_id.krate;
614 if cnum == LOCAL_CRATE {
615 return Ok((self.path_crate(cnum)?, true));
618 // In local mode, when we encounter a crate other than
619 // LOCAL_CRATE, execution proceeds in one of two ways:
621 // 1. for a direct dependency, where user added an
622 // `extern crate` manually, we put the `extern
623 // crate` as the parent. So you wind up with
624 // something relative to the current crate.
625 // 2. for an extern inferred from a path or an indirect crate,
626 // where there is no explicit `extern crate`, we just prepend
628 match *self.tcx.extern_crate(def_id) {
630 src: ExternCrateSource::Extern(def_id),
635 debug!("try_print_visible_def_path: def_id={:?}", def_id);
636 return Ok((if !span.is_dummy() {
637 self.print_def_path(def_id, None, Namespace::TypeNS, iter::empty())?
639 self.path_crate(cnum)?
643 return Ok((self.path_crate(cnum)?, true));
649 if def_id.is_local() {
650 return Ok((self.printer, false));
653 let visible_parent_map = self.tcx.visible_parent_map(LOCAL_CRATE);
655 let mut cur_def_key = self.tcx.def_key(def_id);
656 debug!("try_print_visible_def_path: cur_def_key={:?}", cur_def_key);
658 // For a UnitStruct or TupleStruct we want the name of its parent rather than <unnamed>.
659 if let DefPathData::StructCtor = cur_def_key.disambiguated_data.data {
662 index: cur_def_key.parent.expect("DefPathData::StructCtor missing a parent"),
665 cur_def_key = self.tcx.def_key(parent);
668 let visible_parent = match visible_parent_map.get(&def_id).cloned() {
669 Some(parent) => parent,
670 None => return Ok((self.printer, false)),
672 // HACK(eddyb) this uses `nest` to avoid knowing ahead of time whether
673 // the entire path will succeed or not. To support printers that do not
674 // implement `PrettyPrinter`, a `Vec` or linked list on the stack would
675 // need to be built, before starting to print anything.
676 let mut prefix_success = false;
678 let (printer, success) = cx.try_print_visible_def_path(visible_parent)?;
679 prefix_success = success;
683 return Ok((self.printer, false));
685 let actual_parent = self.tcx.parent(def_id);
687 let data = cur_def_key.disambiguated_data.data;
689 "try_print_visible_def_path: data={:?} visible_parent={:?} actual_parent={:?}",
690 data, visible_parent, actual_parent,
693 let symbol = match data {
694 // In order to output a path that could actually be imported (valid and visible),
695 // we need to handle re-exports correctly.
697 // For example, take `std::os::unix::process::CommandExt`, this trait is actually
698 // defined at `std::sys::unix::ext::process::CommandExt` (at time of writing).
700 // `std::os::unix` rexports the contents of `std::sys::unix::ext`. `std::sys` is
701 // private so the "true" path to `CommandExt` isn't accessible.
703 // In this case, the `visible_parent_map` will look something like this:
705 // (child) -> (parent)
706 // `std::sys::unix::ext::process::CommandExt` -> `std::sys::unix::ext::process`
707 // `std::sys::unix::ext::process` -> `std::sys::unix::ext`
708 // `std::sys::unix::ext` -> `std::os`
710 // This is correct, as the visible parent of `std::sys::unix::ext` is in fact
713 // When printing the path to `CommandExt` and looking at the `cur_def_key` that
714 // corresponds to `std::sys::unix::ext`, we would normally print `ext` and then go
715 // to the parent - resulting in a mangled path like
716 // `std::os::ext::process::CommandExt`.
718 // Instead, we must detect that there was a re-export and instead print `unix`
719 // (which is the name `std::sys::unix::ext` was re-exported as in `std::os`). To
720 // do this, we compare the parent of `std::sys::unix::ext` (`std::sys::unix`) with
721 // the visible parent (`std::os`). If these do not match, then we iterate over
722 // the children of the visible parent (as was done when computing
723 // `visible_parent_map`), looking for the specific child we currently have and then
724 // have access to the re-exported name.
725 DefPathData::Module(actual_name) |
726 DefPathData::TypeNs(actual_name) if Some(visible_parent) != actual_parent => {
727 self.tcx.item_children(visible_parent)
729 .find(|child| child.def.def_id() == def_id)
730 .map(|child| child.ident.as_str())
731 .unwrap_or_else(|| actual_name.as_str())
734 data.get_opt_name().map(|n| n.as_str()).unwrap_or_else(|| {
735 // Re-exported `extern crate` (#43189).
736 if let DefPathData::CrateRoot = data {
737 self.tcx.original_crate_name(def_id.krate).as_str()
739 Symbol::intern("<unnamed>").as_str()
744 debug!("try_print_visible_def_path: symbol={:?}", symbol);
745 Ok((self.path_append(|cx| Ok(cx.printer), &symbol)?, true))
748 pub fn pretty_path_qualified(
751 trait_ref: Option<ty::TraitRef<'tcx>>,
753 ) -> Result<P::Path, P::Error> {
754 if trait_ref.is_none() {
755 // Inherent impls. Try to print `Foo::bar` for an inherent
756 // impl on `Foo`, but fallback to `<Foo>::bar` if self-type is
757 // anything other than a simple path.
759 ty::Adt(adt_def, substs) => {
760 return self.print_def_path(adt_def.did, Some(substs), ns, iter::empty());
762 ty::Foreign(did) => {
763 return self.print_def_path(did, None, ns, iter::empty());
766 ty::Bool | ty::Char | ty::Str |
767 ty::Int(_) | ty::Uint(_) | ty::Float(_) => {
768 return self_ty.print_display(self);
775 write!(self.printer, "<")?;
776 nest!(self, |cx| self_ty.print_display(cx));
777 if let Some(trait_ref) = trait_ref {
778 write!(self.printer, " as ")?;
779 nest!(self, |cx| cx.print_def_path(
781 Some(trait_ref.substs),
786 write!(self.printer, ">")?;
791 pub fn pretty_path_append_impl(
793 print_prefix: impl FnOnce(
794 PrintCx<'_, 'gcx, 'tcx, P>,
795 ) -> Result<P::Path, P::Error>,
797 trait_ref: Option<ty::TraitRef<'tcx>>,
798 ) -> Result<P::Path, P::Error> {
799 // HACK(eddyb) going through `path_append` means symbol name
800 // computation gets to handle its equivalent of `::` correctly.
801 nest!(self, |cx| cx.path_append(print_prefix, "<impl "));
802 if let Some(trait_ref) = trait_ref {
803 nest!(self, |cx| trait_ref.print_display(cx));
804 write!(self.printer, " for ")?;
806 nest!(self, |cx| self_ty.print_display(cx));
807 write!(self.printer, ">")?;
812 pub fn pretty_path_generic_args(
814 print_prefix: impl FnOnce(
815 PrintCx<'_, 'gcx, 'tcx, P>,
816 ) -> Result<P::Path, P::Error>,
817 params: &[ty::GenericParamDef],
818 substs: SubstsRef<'tcx>,
820 projections: impl Iterator<Item = ty::ExistentialProjection<'tcx>>,
821 ) -> Result<P::Path, P::Error> {
822 nest!(self, |cx| print_prefix(cx));
824 let mut empty = true;
825 let mut start_or_continue = |cx: &mut Self, start: &str, cont: &str| {
826 write!(cx.printer, "{}", if empty {
834 let start = if ns == Namespace::ValueNS { "::<" } else { "<" };
836 // Don't print `'_` if there's no printed region.
837 let print_regions = params.iter().any(|param| {
838 match substs[param.index as usize].unpack() {
839 UnpackedKind::Lifetime(r) => {
840 self.always_print_region_in_paths(r) ||
841 self.print_region_outputs_anything(r)
847 // Don't print args that are the defaults of their respective parameters.
848 let num_supplied_defaults = if self.config.is_verbose {
851 params.iter().rev().take_while(|param| {
853 ty::GenericParamDefKind::Lifetime => false,
854 ty::GenericParamDefKind::Type { has_default, .. } => {
855 has_default && substs[param.index as usize] == Kind::from(
856 self.tcx.type_of(param.def_id).subst(self.tcx, substs)
859 ty::GenericParamDefKind::Const => false, // FIXME(const_generics:defaults)
864 for param in ¶ms[..params.len() - num_supplied_defaults] {
865 match substs[param.index as usize].unpack() {
866 UnpackedKind::Lifetime(region) => {
870 start_or_continue(&mut self, start, ", ")?;
871 if !self.print_region_outputs_anything(region) {
872 // This happens when the value of the region
873 // parameter is not easily serialized. This may be
874 // because the user omitted it in the first place,
875 // or because it refers to some block in the code,
876 // etc. I'm not sure how best to serialize this.
877 write!(self.printer, "'_")?;
879 nest!(self, |cx| region.print_display(cx));
882 UnpackedKind::Type(ty) => {
883 start_or_continue(&mut self, start, ", ")?;
884 nest!(self, |cx| ty.print_display(cx));
886 UnpackedKind::Const(ct) => {
887 start_or_continue(&mut self, start, ", ")?;
888 nest!(self, |cx| ct.print_display(cx));
893 for projection in projections {
894 start_or_continue(&mut self, start, ", ")?;
895 write!(self.printer, "{}=",
896 self.tcx.associated_item(projection.item_def_id).ident)?;
897 nest!(self, |cx| projection.ty.print_display(cx));
900 start_or_continue(&mut self, "", ">")?;
906 impl<F: fmt::Write> fmt::Write for FmtPrinter<F> {
907 fn write_str(&mut self, s: &str) -> fmt::Result {
908 self.empty &= s.is_empty();
909 self.fmt.write_str(s)
913 impl<F: fmt::Write> Printer for FmtPrinter<F> {
914 type Error = fmt::Error;
921 mut self: PrintCx<'_, '_, 'tcx, Self>,
923 substs: Option<SubstsRef<'tcx>>,
925 projections: impl Iterator<Item = ty::ExistentialProjection<'tcx>>,
926 ) -> Result<Self::Path, Self::Error> {
927 // FIXME(eddyb) avoid querying `tcx.generics_of` and `tcx.def_key`
928 // both here and in `default_print_def_path`.
929 let generics = substs.map(|_| self.tcx.generics_of(def_id));
930 if generics.as_ref().and_then(|g| g.parent).is_none() {
931 let mut visible_path_success = false;
933 let (printer, success) = cx.try_print_visible_def_path(def_id)?;
934 visible_path_success = success;
937 if visible_path_success {
938 return if let (Some(generics), Some(substs)) = (generics, substs) {
939 let has_own_self = generics.has_self && generics.parent_count == 0;
940 let params = &generics.params[has_own_self as usize..];
941 self.path_generic_args(|cx| Ok(cx.printer), params, substs, ns, projections)
948 let key = self.tcx.def_key(def_id);
949 if let DefPathData::Impl = key.disambiguated_data.data {
950 // Always use types for non-local impls, where types are always
951 // available, and filename/line-number is mostly uninteresting.
953 !def_id.is_local() || {
954 // Otherwise, use filename/line-number if forced.
955 let force_no_types = FORCE_IMPL_FILENAME_LINE.with(|f| f.get());
960 // If no type info is available, fall back to
961 // pretty printing some span information. This should
962 // only occur very early in the compiler pipeline.
963 let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id };
964 let span = self.tcx.def_span(def_id);
965 return self.path_append(
966 |cx| cx.print_def_path(parent_def_id, None, ns, iter::empty()),
967 &format!("<impl at {:?}>", span),
972 self.default_print_def_path(def_id, substs, ns, projections)
976 mut self: PrintCx<'_, '_, '_, Self>,
977 region: ty::Region<'_>,
978 ) -> Result<Self::Region, Self::Error> {
979 // Watch out for region highlights.
980 let highlight = self.printer.region_highlight_mode;
981 if let Some(n) = highlight.region_highlighted(region) {
982 write!(self.printer, "'{}", n)?;
983 return Ok(self.printer);
986 if self.config.is_verbose {
987 return region.print_debug(self);
990 // These printouts are concise. They do not contain all the information
991 // the user might want to diagnose an error, but there is basically no way
992 // to fit that into a short string. Hence the recommendation to use
993 // `explain_region()` or `note_and_explain_region()`.
995 ty::ReEarlyBound(ref data) => {
996 if data.name != "'_" {
997 write!(self.printer, "{}", data.name)?;
1000 ty::ReLateBound(_, br) |
1001 ty::ReFree(ty::FreeRegion { bound_region: br, .. }) |
1002 ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
1003 if let ty::BrNamed(_, name) = br {
1004 if name != "" && name != "'_" {
1005 write!(self.printer, "{}", name)?;
1006 return Ok(self.printer);
1010 if let Some((region, counter)) = highlight.highlight_bound_region {
1012 write!(self.printer, "'{}", counter)?;
1016 ty::ReScope(scope) if self.config.identify_regions => {
1018 region::ScopeData::Node =>
1019 write!(self.printer, "'{}s", scope.item_local_id().as_usize())?,
1020 region::ScopeData::CallSite =>
1021 write!(self.printer, "'{}cs", scope.item_local_id().as_usize())?,
1022 region::ScopeData::Arguments =>
1023 write!(self.printer, "'{}as", scope.item_local_id().as_usize())?,
1024 region::ScopeData::Destruction =>
1025 write!(self.printer, "'{}ds", scope.item_local_id().as_usize())?,
1026 region::ScopeData::Remainder(first_statement_index) => write!(self.printer,
1028 scope.item_local_id().as_usize(),
1029 first_statement_index.index()
1033 ty::ReVar(region_vid) if self.config.identify_regions => {
1034 write!(self.printer, "{:?}", region_vid)?;
1039 ty::ReStatic => write!(self.printer, "'static")?,
1040 ty::ReEmpty => write!(self.printer, "'<empty>")?,
1042 // The user should never encounter these in unsubstituted form.
1043 ty::ReClosureBound(vid) => write!(self.printer, "{:?}", vid)?,
1050 self: PrintCx<'_, '_, 'tcx, Self>,
1052 ) -> Result<Self::Type, Self::Error> {
1053 self.pretty_print_type(ty)
1057 mut self: PrintCx<'_, '_, '_, Self>,
1059 ) -> Result<Self::Path, Self::Error> {
1060 if cnum == LOCAL_CRATE {
1061 if self.tcx.sess.rust_2018() {
1062 // We add the `crate::` keyword on Rust 2018, only when desired.
1063 if SHOULD_PREFIX_WITH_CRATE.with(|flag| flag.get()) {
1064 write!(self.printer, "{}", keywords::Crate.name())?;
1069 write!(self.printer, "{}", self.tcx.crate_name(cnum))?;
1074 self: PrintCx<'_, '_, 'tcx, Self>,
1076 trait_ref: Option<ty::TraitRef<'tcx>>,
1078 ) -> Result<Self::Path, Self::Error> {
1079 self.pretty_path_qualified(self_ty, trait_ref, ns)
1082 fn path_append_impl<'gcx, 'tcx>(
1083 self: PrintCx<'_, 'gcx, 'tcx, Self>,
1084 print_prefix: impl FnOnce(
1085 PrintCx<'_, 'gcx, 'tcx, Self>,
1086 ) -> Result<Self::Path, Self::Error>,
1088 trait_ref: Option<ty::TraitRef<'tcx>>,
1089 ) -> Result<Self::Path, Self::Error> {
1090 self.pretty_path_append_impl(print_prefix, self_ty, trait_ref)
1092 fn path_append<'gcx, 'tcx>(
1093 self: PrintCx<'_, 'gcx, 'tcx, Self>,
1094 print_prefix: impl FnOnce(
1095 PrintCx<'_, 'gcx, 'tcx, Self>,
1096 ) -> Result<Self::Path, Self::Error>,
1098 ) -> Result<Self::Path, Self::Error> {
1099 let mut printer = print_prefix(self)?;
1101 // FIXME(eddyb) `text` should never be empty, but it
1102 // currently is for `extern { ... }` "foreign modules".
1103 if !text.is_empty() {
1105 write!(printer, "::")?;
1107 write!(printer, "{}", text)?;
1112 fn path_generic_args<'gcx, 'tcx>(
1113 self: PrintCx<'_, 'gcx, 'tcx, Self>,
1114 print_prefix: impl FnOnce(
1115 PrintCx<'_, 'gcx, 'tcx, Self>,
1116 ) -> Result<Self::Path, Self::Error>,
1117 params: &[ty::GenericParamDef],
1118 substs: SubstsRef<'tcx>,
1120 projections: impl Iterator<Item = ty::ExistentialProjection<'tcx>>,
1121 ) -> Result<Self::Path, Self::Error> {
1122 self.pretty_path_generic_args(print_prefix, params, substs, ns, projections)
1126 impl<F: fmt::Write> PrettyPrinter for FmtPrinter<F> {
1127 fn nest<'a, 'gcx, 'tcx, E>(
1128 mut self: PrintCx<'a, 'gcx, 'tcx, Self>,
1129 f: impl for<'b> FnOnce(PrintCx<'b, 'gcx, 'tcx, Self>) -> Result<Self, E>,
1130 ) -> Result<PrintCx<'a, 'gcx, 'tcx, Self>, E> {
1131 let was_empty = std::mem::replace(&mut self.printer.empty, true);
1132 let mut printer = f(PrintCx {
1134 printer: self.printer,
1135 config: self.config,
1137 printer.empty &= was_empty;
1141 config: self.config,
1145 fn always_print_region_in_paths(
1146 self: &PrintCx<'_, '_, '_, Self>,
1147 region: ty::Region<'_>,
1149 *region != ty::ReErased
1152 fn print_region_outputs_anything(
1153 self: &PrintCx<'_, '_, '_, Self>,
1154 region: ty::Region<'_>,
1156 let highlight = self.printer.region_highlight_mode;
1157 if highlight.region_highlighted(region).is_some() {
1161 if self.config.is_verbose {
1166 ty::ReEarlyBound(ref data) => {
1167 data.name != "" && data.name != "'_"
1170 ty::ReLateBound(_, br) |
1171 ty::ReFree(ty::FreeRegion { bound_region: br, .. }) |
1172 ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
1173 if let ty::BrNamed(_, name) = br {
1174 if name != "" && name != "'_" {
1179 if let Some((region, _)) = highlight.highlight_bound_region {
1189 ty::ReVar(_) if self.config.identify_regions => true,
1193 ty::ReErased => false,
1197 ty::ReClosureBound(_) => true,