1 //! The `HirDisplay` trait, which serves two purposes: Turning various bits from
2 //! HIR back into source code, and just displaying them for debugging/testing
5 use std::fmt::{self, Debug};
8 use chalk_ir::BoundVar;
13 generics::{TypeOrConstParamData, TypeParamProvenance},
14 intern::{Internable, Interned},
16 path::{Path, PathKind},
17 type_ref::{ConstScalar, TraitBoundModifier, TypeBound, TypeRef},
18 visibility::Visibility,
19 HasModule, ItemContainerId, Lookup, ModuleDefId, ModuleId, TraitId,
21 use hir_expand::{hygiene::Hygiene, name::Name};
22 use itertools::Itertools;
23 use smallvec::SmallVec;
28 from_assoc_type_id, from_foreign_def_id, from_placeholder_idx, lt_from_placeholder_idx,
30 primitive, to_assoc_type_id,
31 utils::{self, generics},
32 AdtId, AliasEq, AliasTy, Binders, CallableDefId, CallableSig, Const, ConstValue, DomainGoal,
33 GenericArg, ImplTraitId, Interner, Lifetime, LifetimeData, LifetimeOutlives, Mutability,
34 OpaqueTy, ProjectionTy, ProjectionTyExt, QuantifiedWhereClause, Scalar, Substitution, TraitRef,
35 TraitRefExt, Ty, TyExt, TyKind, WhereClause,
38 pub trait HirWrite: fmt::Write {
39 fn start_location_link(&mut self, location: ModuleDefId);
40 fn end_location_link(&mut self);
43 // String will ignore link metadata
44 impl HirWrite for String {
45 fn start_location_link(&mut self, _: ModuleDefId) {}
47 fn end_location_link(&mut self) {}
50 // `core::Formatter` will ignore metadata
51 impl HirWrite for fmt::Formatter<'_> {
52 fn start_location_link(&mut self, _: ModuleDefId) {}
53 fn end_location_link(&mut self) {}
56 pub struct HirFormatter<'a> {
57 pub db: &'a dyn HirDatabase,
58 fmt: &'a mut dyn HirWrite,
61 pub(crate) max_size: Option<usize>,
62 omit_verbose_types: bool,
63 display_target: DisplayTarget,
66 impl HirFormatter<'_> {
67 fn start_location_link(&mut self, location: ModuleDefId) {
68 self.fmt.start_location_link(location);
71 fn end_location_link(&mut self) {
72 self.fmt.end_location_link();
76 pub trait HirDisplay {
77 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError>;
79 /// Returns a `Display`able type that is human-readable.
80 fn into_displayable<'a>(
82 db: &'a dyn HirDatabase,
83 max_size: Option<usize>,
84 omit_verbose_types: bool,
85 display_target: DisplayTarget,
86 ) -> HirDisplayWrapper<'a, Self>
91 !matches!(display_target, DisplayTarget::SourceCode { .. }),
92 "HirDisplayWrapper cannot fail with DisplaySourceCodeError, use HirDisplay::hir_fmt directly instead"
94 HirDisplayWrapper { db, t: self, max_size, omit_verbose_types, display_target }
97 /// Returns a `Display`able type that is human-readable.
98 /// Use this for showing types to the user (e.g. diagnostics)
99 fn display<'a>(&'a self, db: &'a dyn HirDatabase) -> HirDisplayWrapper<'a, Self>
107 omit_verbose_types: false,
108 display_target: DisplayTarget::Diagnostics,
112 /// Returns a `Display`able type that is human-readable and tries to be succinct.
113 /// Use this for showing types to the user where space is constrained (e.g. doc popups)
114 fn display_truncated<'a>(
116 db: &'a dyn HirDatabase,
117 max_size: Option<usize>,
118 ) -> HirDisplayWrapper<'a, Self>
126 omit_verbose_types: true,
127 display_target: DisplayTarget::Diagnostics,
131 /// Returns a String representation of `self` that can be inserted into the given module.
132 /// Use this when generating code (e.g. assists)
133 fn display_source_code<'a>(
135 db: &'a dyn HirDatabase,
137 ) -> Result<String, DisplaySourceCodeError> {
138 let mut result = String::new();
139 match self.hir_fmt(&mut HirFormatter {
142 buf: String::with_capacity(20),
145 omit_verbose_types: false,
146 display_target: DisplayTarget::SourceCode { module_id },
149 Err(HirDisplayError::FmtError) => panic!("Writing to String can't fail!"),
150 Err(HirDisplayError::DisplaySourceCodeError(e)) => return Err(e),
155 /// Returns a String representation of `self` for test purposes
156 fn display_test<'a>(&'a self, db: &'a dyn HirDatabase) -> HirDisplayWrapper<'a, Self>
164 omit_verbose_types: false,
165 display_target: DisplayTarget::Test,
170 impl<'a> HirFormatter<'a> {
171 pub fn write_joined<T: HirDisplay>(
173 iter: impl IntoIterator<Item = T>,
175 ) -> Result<(), HirDisplayError> {
176 let mut first = true;
179 write!(self, "{sep}")?;
183 // Abbreviate multiple omitted types with a single ellipsis.
184 if self.should_truncate() {
185 return write!(self, "{TYPE_HINT_TRUNCATION}");
193 /// This allows using the `write!` macro directly with a `HirFormatter`.
194 pub fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> Result<(), HirDisplayError> {
195 // We write to a buffer first to track output size
197 fmt::write(&mut self.buf, args)?;
198 self.curr_size += self.buf.len();
200 // Then we write to the internal formatter from the buffer
201 self.fmt.write_str(&self.buf).map_err(HirDisplayError::from)
204 pub fn write_str(&mut self, s: &str) -> Result<(), HirDisplayError> {
205 self.fmt.write_str(s)?;
209 pub fn write_char(&mut self, c: char) -> Result<(), HirDisplayError> {
210 self.fmt.write_char(c)?;
214 pub fn should_truncate(&self) -> bool {
215 match self.max_size {
216 Some(max_size) => self.curr_size >= max_size,
221 pub fn omit_verbose_types(&self) -> bool {
222 self.omit_verbose_types
226 #[derive(Clone, Copy)]
227 pub enum DisplayTarget {
228 /// Display types for inlays, doc popups, autocompletion, etc...
229 /// Showing `{unknown}` or not qualifying paths is fine here.
230 /// There's no reason for this to fail.
232 /// Display types for inserting them in source files.
233 /// The generated code should compile, so paths need to be qualified.
234 SourceCode { module_id: ModuleId },
235 /// Only for test purpose to keep real types
240 fn is_source_code(&self) -> bool {
241 matches!(self, Self::SourceCode { .. })
243 fn is_test(&self) -> bool {
244 matches!(self, Self::Test)
249 pub enum DisplaySourceCodeError {
256 pub enum HirDisplayError {
257 /// Errors that can occur when generating source code
258 DisplaySourceCodeError(DisplaySourceCodeError),
259 /// `FmtError` is required to be compatible with std::fmt::Display
262 impl From<fmt::Error> for HirDisplayError {
263 fn from(_: fmt::Error) -> Self {
268 pub struct HirDisplayWrapper<'a, T> {
269 db: &'a dyn HirDatabase,
271 max_size: Option<usize>,
272 omit_verbose_types: bool,
273 display_target: DisplayTarget,
276 impl<T: HirDisplay> HirDisplayWrapper<'_, T> {
277 pub fn write_to<F: HirWrite>(&self, f: &mut F) -> Result<(), HirDisplayError> {
278 self.t.hir_fmt(&mut HirFormatter {
281 buf: String::with_capacity(20),
283 max_size: self.max_size,
284 omit_verbose_types: self.omit_verbose_types,
285 display_target: self.display_target,
290 impl<'a, T> fmt::Display for HirDisplayWrapper<'a, T>
294 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
295 match self.write_to(f) {
297 Err(HirDisplayError::FmtError) => Err(fmt::Error),
298 Err(HirDisplayError::DisplaySourceCodeError(_)) => {
299 // This should never happen
300 panic!("HirDisplay::hir_fmt failed with DisplaySourceCodeError when calling Display::fmt!")
306 const TYPE_HINT_TRUNCATION: &str = "…";
308 impl<T: HirDisplay> HirDisplay for &'_ T {
309 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
310 HirDisplay::hir_fmt(*self, f)
314 impl<T: HirDisplay + Internable> HirDisplay for Interned<T> {
315 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
316 HirDisplay::hir_fmt(self.as_ref(), f)
320 impl HirDisplay for ProjectionTy {
321 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
322 if f.should_truncate() {
323 return write!(f, "{TYPE_HINT_TRUNCATION}");
326 let trait_ref = self.trait_ref(f.db);
328 fmt_trait_ref(&trait_ref, f, true)?;
329 write!(f, ">::{}", f.db.type_alias_data(from_assoc_type_id(self.associated_ty_id)).name)?;
330 let proj_params_count =
331 self.substitution.len(Interner) - trait_ref.substitution.len(Interner);
332 let proj_params = &self.substitution.as_slice(Interner)[..proj_params_count];
333 if !proj_params.is_empty() {
335 f.write_joined(proj_params, ", ")?;
342 impl HirDisplay for OpaqueTy {
343 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
344 if f.should_truncate() {
345 return write!(f, "{TYPE_HINT_TRUNCATION}");
348 self.substitution.at(Interner, 0).hir_fmt(f)
352 impl HirDisplay for GenericArg {
353 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
354 match self.interned() {
355 crate::GenericArgData::Ty(ty) => ty.hir_fmt(f),
356 crate::GenericArgData::Lifetime(lt) => lt.hir_fmt(f),
357 crate::GenericArgData::Const(c) => c.hir_fmt(f),
362 impl HirDisplay for Const {
363 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
364 let data = self.interned();
366 ConstValue::BoundVar(idx) => idx.hir_fmt(f),
367 ConstValue::InferenceVar(..) => write!(f, "#c#"),
368 ConstValue::Placeholder(idx) => {
369 let id = from_placeholder_idx(f.db, idx);
370 let generics = generics(f.db.upcast(), id.parent);
371 let param_data = &generics.params.type_or_consts[id.local_id];
372 write!(f, "{}", param_data.name().unwrap())
374 ConstValue::Concrete(c) => write!(f, "{}", c.interned),
379 impl HirDisplay for BoundVar {
380 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
381 write!(f, "?{}.{}", self.debruijn.depth(), self.index)
385 impl HirDisplay for Ty {
386 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
387 if f.should_truncate() {
388 return write!(f, "{TYPE_HINT_TRUNCATION}");
391 match self.kind(Interner) {
392 TyKind::Never => write!(f, "!")?,
393 TyKind::Str => write!(f, "str")?,
394 TyKind::Scalar(Scalar::Bool) => write!(f, "bool")?,
395 TyKind::Scalar(Scalar::Char) => write!(f, "char")?,
396 &TyKind::Scalar(Scalar::Float(t)) => write!(f, "{}", primitive::float_ty_to_string(t))?,
397 &TyKind::Scalar(Scalar::Int(t)) => write!(f, "{}", primitive::int_ty_to_string(t))?,
398 &TyKind::Scalar(Scalar::Uint(t)) => write!(f, "{}", primitive::uint_ty_to_string(t))?,
399 TyKind::Slice(t) => {
404 TyKind::Array(t, c) => {
411 TyKind::Raw(m, t) | TyKind::Ref(m, _, t) => {
412 if matches!(self.kind(Interner), TyKind::Raw(..)) {
417 Mutability::Not => "const ",
418 Mutability::Mut => "mut ",
426 Mutability::Not => "",
427 Mutability::Mut => "mut ",
432 // FIXME: all this just to decide whether to use parentheses...
433 let contains_impl_fn = |bounds: &[QuantifiedWhereClause]| {
434 bounds.iter().any(|bound| {
435 if let WhereClause::Implemented(trait_ref) = bound.skip_binders() {
436 let trait_ = trait_ref.hir_trait_id();
437 fn_traits(f.db.upcast(), trait_).any(|it| it == trait_)
443 let (preds_to_print, has_impl_fn_pred) = match t.kind(Interner) {
444 TyKind::Dyn(dyn_ty) if dyn_ty.bounds.skip_binders().interned().len() > 1 => {
445 let bounds = dyn_ty.bounds.skip_binders().interned();
446 (bounds.len(), contains_impl_fn(bounds))
448 TyKind::Alias(AliasTy::Opaque(OpaqueTy {
450 substitution: parameters,
452 | TyKind::OpaqueType(opaque_ty_id, parameters) => {
454 f.db.lookup_intern_impl_trait_id((*opaque_ty_id).into());
455 if let ImplTraitId::ReturnTypeImplTrait(func, idx) = impl_trait_id {
457 f.db.return_type_impl_traits(func)
458 .expect("impl trait id without data");
461 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
462 let bounds = data.substitute(Interner, parameters);
463 let mut len = bounds.skip_binders().len();
465 // Don't count Sized but count when it absent
466 // (i.e. when explicit ?Sized bound is set).
467 let default_sized = SizedByDefault::Sized {
468 anchor: func.lookup(f.db.upcast()).module(f.db.upcast()).krate(),
470 let sized_bounds = bounds
476 WhereClause::Implemented(trait_ref)
477 if default_sized.is_sized_trait(
478 trait_ref.hir_trait_id(),
487 len = len.saturating_sub(sized_bounds);
491 (len, contains_impl_fn(bounds.skip_binders()))
499 if has_impl_fn_pred && preds_to_print <= 2 {
503 if preds_to_print > 1 {
511 TyKind::Tuple(_, substs) => {
512 if substs.len(Interner) == 1 {
514 substs.at(Interner, 0).hir_fmt(f)?;
518 f.write_joined(&*substs.as_slice(Interner), ", ")?;
522 TyKind::Function(fn_ptr) => {
523 let sig = CallableSig::from_fn_ptr(fn_ptr);
526 TyKind::FnDef(def, parameters) => {
527 let def = from_chalk(f.db, *def);
528 let sig = f.db.callable_item_signature(def).substitute(Interner, parameters);
530 CallableDefId::FunctionId(ff) => {
531 write!(f, "fn {}", f.db.function_data(ff).name)?
533 CallableDefId::StructId(s) => write!(f, "{}", f.db.struct_data(s).name)?,
534 CallableDefId::EnumVariantId(e) => {
535 write!(f, "{}", f.db.enum_data(e.parent).variants[e.local_id].name)?
538 if parameters.len(Interner) > 0 {
539 let generics = generics(f.db.upcast(), def.into());
540 let (parent_params, self_param, type_params, const_params, _impl_trait_params) =
541 generics.provenance_split();
542 let total_len = parent_params + self_param + type_params + const_params;
543 // We print all params except implicit impl Trait params. Still a bit weird; should we leave out parent and self?
545 // `parameters` are in the order of fn's params (including impl traits),
546 // parent's params (those from enclosing impl or trait, if any).
547 let parameters = parameters.as_slice(Interner);
548 let fn_params_len = self_param + type_params + const_params;
549 let fn_params = parameters.get(..fn_params_len);
550 let parent_params = parameters.get(parameters.len() - parent_params..);
551 let params = parent_params.into_iter().chain(fn_params).flatten();
553 f.write_joined(params, ", ")?;
558 f.write_joined(sig.params(), ", ")?;
566 TyKind::Adt(AdtId(def_id), parameters) => {
567 f.start_location_link((*def_id).into());
568 match f.display_target {
569 DisplayTarget::Diagnostics | DisplayTarget::Test => {
570 let name = match *def_id {
571 hir_def::AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
572 hir_def::AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
573 hir_def::AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
575 write!(f, "{name}")?;
577 DisplayTarget::SourceCode { module_id } => {
578 if let Some(path) = find_path::find_path(
580 ItemInNs::Types((*def_id).into()),
584 write!(f, "{path}")?;
586 return Err(HirDisplayError::DisplaySourceCodeError(
587 DisplaySourceCodeError::PathNotFound,
592 f.end_location_link();
594 if parameters.len(Interner) > 0 {
595 let parameters_to_write = if f.display_target.is_source_code()
596 || f.omit_verbose_types()
599 .as_generic_def(f.db)
600 .map(|generic_def_id| f.db.generic_defaults(generic_def_id))
601 .filter(|defaults| !defaults.is_empty())
603 None => parameters.as_slice(Interner),
604 Some(default_parameters) => {
606 parameter: &GenericArg,
607 default_parameters: &[Binders<GenericArg>],
609 parameters: &Substitution,
611 if parameter.ty(Interner).map(|x| x.kind(Interner))
612 == Some(&TyKind::Error)
616 if let Some(ConstValue::Concrete(c)) =
617 parameter.constant(Interner).map(|x| x.data(Interner).value)
619 if c.interned == ConstScalar::Unknown {
623 let default_parameter = match default_parameters.get(i) {
628 default_parameter.clone().substitute(Interner, ¶meters);
629 parameter != &actual_default
631 let mut default_from = 0;
632 for (i, parameter) in parameters.iter(Interner).enumerate() {
633 if should_show(parameter, &default_parameters, i, parameters) {
634 default_from = i + 1;
637 ¶meters.as_slice(Interner)[0..default_from]
641 parameters.as_slice(Interner)
643 if !parameters_to_write.is_empty() {
646 if f.display_target.is_source_code() {
647 let mut first = true;
648 for generic_arg in parameters_to_write {
654 if generic_arg.ty(Interner).map(|ty| ty.kind(Interner))
655 == Some(&TyKind::Error)
659 generic_arg.hir_fmt(f)?;
663 f.write_joined(parameters_to_write, ", ")?;
670 TyKind::AssociatedType(assoc_type_id, parameters) => {
671 let type_alias = from_assoc_type_id(*assoc_type_id);
672 let trait_ = match type_alias.lookup(f.db.upcast()).container {
673 ItemContainerId::TraitId(it) => it,
674 _ => panic!("not an associated type"),
676 let trait_ = f.db.trait_data(trait_);
677 let type_alias_data = f.db.type_alias_data(type_alias);
679 // Use placeholder associated types when the target is test (https://rust-lang.github.io/chalk/book/clauses/type_equality.html#placeholder-associated-types)
680 if f.display_target.is_test() {
681 write!(f, "{}::{}", trait_.name, type_alias_data.name)?;
682 // Note that the generic args for the associated type come before those for the
683 // trait (including the self type).
684 // FIXME: reconsider the generic args order upon formatting?
685 if parameters.len(Interner) > 0 {
687 f.write_joined(parameters.as_slice(Interner), ", ")?;
691 let projection_ty = ProjectionTy {
692 associated_ty_id: to_assoc_type_id(type_alias),
693 substitution: parameters.clone(),
696 projection_ty.hir_fmt(f)?;
699 TyKind::Foreign(type_alias) => {
700 let type_alias = f.db.type_alias_data(from_foreign_def_id(*type_alias));
701 write!(f, "{}", type_alias.name)?;
703 TyKind::OpaqueType(opaque_ty_id, parameters) => {
704 let impl_trait_id = f.db.lookup_intern_impl_trait_id((*opaque_ty_id).into());
705 match impl_trait_id {
706 ImplTraitId::ReturnTypeImplTrait(func, idx) => {
708 f.db.return_type_impl_traits(func).expect("impl trait id without data");
711 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
712 let bounds = data.substitute(Interner, ¶meters);
713 let krate = func.lookup(f.db.upcast()).module(f.db.upcast()).krate();
714 write_bounds_like_dyn_trait_with_prefix(
716 bounds.skip_binders(),
717 SizedByDefault::Sized { anchor: krate },
720 // FIXME: it would maybe be good to distinguish this from the alias type (when debug printing), and to show the substitution
722 ImplTraitId::AsyncBlockTypeImplTrait(..) => {
723 write!(f, "impl Future<Output = ")?;
724 parameters.at(Interner, 0).hir_fmt(f)?;
729 TyKind::Closure(.., substs) => {
730 if f.display_target.is_source_code() {
731 return Err(HirDisplayError::DisplaySourceCodeError(
732 DisplaySourceCodeError::Closure,
735 let sig = substs.at(Interner, 0).assert_ty_ref(Interner).callable_sig(f.db);
736 if let Some(sig) = sig {
737 if sig.params().is_empty() {
739 } else if f.should_truncate() {
740 write!(f, "|{TYPE_HINT_TRUNCATION}|")?;
743 f.write_joined(sig.params(), ", ")?;
748 sig.ret().hir_fmt(f)?;
750 write!(f, "{{closure}}")?;
753 TyKind::Placeholder(idx) => {
754 let id = from_placeholder_idx(f.db, *idx);
755 let generics = generics(f.db.upcast(), id.parent);
756 let param_data = &generics.params.type_or_consts[id.local_id];
758 TypeOrConstParamData::TypeParamData(p) => match p.provenance {
759 TypeParamProvenance::TypeParamList | TypeParamProvenance::TraitSelf => {
760 write!(f, "{}", p.name.clone().unwrap_or_else(Name::missing))?
762 TypeParamProvenance::ArgumentImplTrait => {
763 let substs = generics.placeholder_subst(f.db);
765 f.db.generic_predicates(id.parent)
767 .map(|pred| pred.clone().substitute(Interner, &substs))
768 .filter(|wc| match &wc.skip_binders() {
769 WhereClause::Implemented(tr) => {
770 &tr.self_type_parameter(Interner) == self
772 WhereClause::AliasEq(AliasEq {
773 alias: AliasTy::Projection(proj),
775 }) => &proj.self_type_parameter(f.db) == self,
778 .collect::<Vec<_>>();
779 let krate = id.parent.module(f.db.upcast()).krate();
780 write_bounds_like_dyn_trait_with_prefix(
783 SizedByDefault::Sized { anchor: krate },
788 TypeOrConstParamData::ConstParamData(p) => {
789 write!(f, "{}", p.name)?;
793 TyKind::BoundVar(idx) => idx.hir_fmt(f)?,
794 TyKind::Dyn(dyn_ty) => {
795 // Reorder bounds to satisfy `write_bounds_like_dyn_trait()`'s expectation.
796 // FIXME: `Iterator::partition_in_place()` or `Vec::drain_filter()` may make it
797 // more efficient when either of them hits stable.
798 let mut bounds: SmallVec<[_; 4]> =
799 dyn_ty.bounds.skip_binders().iter(Interner).cloned().collect();
800 let (auto_traits, others): (SmallVec<[_; 4]>, _) =
801 bounds.drain(1..).partition(|b| b.skip_binders().trait_id().is_some());
802 bounds.extend(others);
803 bounds.extend(auto_traits);
805 write_bounds_like_dyn_trait_with_prefix(
808 SizedByDefault::NotSized,
812 TyKind::Alias(AliasTy::Projection(p_ty)) => p_ty.hir_fmt(f)?,
813 TyKind::Alias(AliasTy::Opaque(opaque_ty)) => {
814 let impl_trait_id = f.db.lookup_intern_impl_trait_id(opaque_ty.opaque_ty_id.into());
815 match impl_trait_id {
816 ImplTraitId::ReturnTypeImplTrait(func, idx) => {
818 f.db.return_type_impl_traits(func).expect("impl trait id without data");
821 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
822 let bounds = data.substitute(Interner, &opaque_ty.substitution);
823 let krate = func.lookup(f.db.upcast()).module(f.db.upcast()).krate();
824 write_bounds_like_dyn_trait_with_prefix(
826 bounds.skip_binders(),
827 SizedByDefault::Sized { anchor: krate },
831 ImplTraitId::AsyncBlockTypeImplTrait(..) => {
832 write!(f, "{{async block}}")?;
837 if f.display_target.is_source_code() {
838 return Err(HirDisplayError::DisplaySourceCodeError(
839 DisplaySourceCodeError::UnknownType,
842 write!(f, "{{unknown}}")?;
844 TyKind::InferenceVar(..) => write!(f, "_")?,
845 TyKind::Generator(_, subst) => {
846 if f.display_target.is_source_code() {
847 return Err(HirDisplayError::DisplaySourceCodeError(
848 DisplaySourceCodeError::Generator,
852 let subst = subst.as_slice(Interner);
853 let a: Option<SmallVec<[&Ty; 3]>> = subst
854 .get(subst.len() - 3..)
855 .map(|args| args.iter().map(|arg| arg.ty(Interner)).collect())
858 if let Some([resume_ty, yield_ty, ret_ty]) = a.as_deref() {
860 resume_ty.hir_fmt(f)?;
863 write!(f, " yields ")?;
864 yield_ty.hir_fmt(f)?;
869 // This *should* be unreachable, but fallback just in case.
870 write!(f, "{{generator}}")?;
873 TyKind::GeneratorWitness(..) => write!(f, "{{generator witness}}")?,
879 impl HirDisplay for CallableSig {
880 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
882 f.write_joined(self.params(), ", ")?;
884 if self.params().is_empty() {
891 let ret = self.ret();
900 fn fn_traits(db: &dyn DefDatabase, trait_: TraitId) -> impl Iterator<Item = TraitId> {
901 let krate = trait_.lookup(db).container.krate();
902 utils::fn_traits(db, krate)
905 #[derive(Clone, Copy, PartialEq, Eq)]
906 pub enum SizedByDefault {
908 Sized { anchor: CrateId },
911 impl SizedByDefault {
912 fn is_sized_trait(self, trait_: TraitId, db: &dyn DefDatabase) -> bool {
914 Self::NotSized => false,
915 Self::Sized { anchor } => {
917 .lang_item(anchor, SmolStr::new_inline("sized"))
918 .and_then(|lang_item| lang_item.as_trait());
919 Some(trait_) == sized_trait
925 pub fn write_bounds_like_dyn_trait_with_prefix(
927 predicates: &[QuantifiedWhereClause],
928 default_sized: SizedByDefault,
929 f: &mut HirFormatter<'_>,
930 ) -> Result<(), HirDisplayError> {
931 write!(f, "{prefix}")?;
932 if !predicates.is_empty()
933 || predicates.is_empty() && matches!(default_sized, SizedByDefault::Sized { .. })
936 write_bounds_like_dyn_trait(predicates, default_sized, f)
942 fn write_bounds_like_dyn_trait(
943 predicates: &[QuantifiedWhereClause],
944 default_sized: SizedByDefault,
945 f: &mut HirFormatter<'_>,
946 ) -> Result<(), HirDisplayError> {
947 // Note: This code is written to produce nice results (i.e.
948 // corresponding to surface Rust) for types that can occur in
949 // actual Rust. It will have weird results if the predicates
950 // aren't as expected (i.e. self types = $0, projection
951 // predicates for a certain trait come after the Implemented
952 // predicate for that trait).
953 let mut first = true;
954 let mut angle_open = false;
955 let mut is_fn_trait = false;
956 let mut is_sized = false;
957 for p in predicates.iter() {
958 match p.skip_binders() {
959 WhereClause::Implemented(trait_ref) => {
960 let trait_ = trait_ref.hir_trait_id();
961 if default_sized.is_sized_trait(trait_, f.db.upcast()) {
963 if matches!(default_sized, SizedByDefault::Sized { .. }) {
964 // Don't print +Sized, but rather +?Sized if absent.
969 is_fn_trait = fn_traits(f.db.upcast(), trait_).any(|it| it == trait_);
971 if !is_fn_trait && angle_open {
978 // We assume that the self type is ^0.0 (i.e. the
979 // existential) here, which is the only thing that's
980 // possible in actual Rust, and hence don't print it
981 write!(f, "{}", f.db.trait_data(trait_).name)?;
982 if let [_, params @ ..] = &*trait_ref.substitution.as_slice(Interner) {
985 params.first().and_then(|it| it.assert_ty_ref(Interner).as_tuple())
988 f.write_joined(args.as_slice(Interner), ", ")?;
991 } else if !params.is_empty() {
993 f.write_joined(params, ", ")?;
994 // there might be assoc type bindings, so we leave the angle brackets open
999 WhereClause::AliasEq(alias_eq) if is_fn_trait => {
1000 is_fn_trait = false;
1001 if !alias_eq.ty.is_unit() {
1003 alias_eq.ty.hir_fmt(f)?;
1006 WhereClause::AliasEq(AliasEq { ty, alias }) => {
1007 // in types in actual Rust, these will always come
1008 // after the corresponding Implemented predicate
1015 if let AliasTy::Projection(proj) = alias {
1016 let assoc_ty_id = from_assoc_type_id(proj.associated_ty_id);
1017 let type_alias = f.db.type_alias_data(assoc_ty_id);
1018 write!(f, "{}", type_alias.name)?;
1020 let proj_arg_count = generics(f.db.upcast(), assoc_ty_id.into()).len_self();
1021 if proj_arg_count > 0 {
1024 &proj.substitution.as_slice(Interner)[..proj_arg_count],
1034 // FIXME implement these
1035 WhereClause::LifetimeOutlives(_) => {}
1036 WhereClause::TypeOutlives(_) => {}
1043 if matches!(default_sized, SizedByDefault::Sized { .. }) {
1045 write!(f, "{}?Sized", if first { "" } else { " + " })?;
1047 write!(f, "Sized")?;
1055 f: &mut HirFormatter<'_>,
1057 ) -> Result<(), HirDisplayError> {
1058 if f.should_truncate() {
1059 return write!(f, "{TYPE_HINT_TRUNCATION}");
1062 tr.self_type_parameter(Interner).hir_fmt(f)?;
1068 write!(f, "{}", f.db.trait_data(tr.hir_trait_id()).name)?;
1069 if tr.substitution.len(Interner) > 1 {
1071 f.write_joined(&tr.substitution.as_slice(Interner)[1..], ", ")?;
1077 impl HirDisplay for TraitRef {
1078 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
1079 fmt_trait_ref(self, f, false)
1083 impl HirDisplay for WhereClause {
1084 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
1085 if f.should_truncate() {
1086 return write!(f, "{TYPE_HINT_TRUNCATION}");
1090 WhereClause::Implemented(trait_ref) => trait_ref.hir_fmt(f)?,
1091 WhereClause::AliasEq(AliasEq { alias: AliasTy::Projection(projection_ty), ty }) => {
1093 fmt_trait_ref(&projection_ty.trait_ref(f.db), f, true)?;
1097 f.db.type_alias_data(from_assoc_type_id(projection_ty.associated_ty_id)).name,
1101 WhereClause::AliasEq(_) => write!(f, "{{error}}")?,
1103 // FIXME implement these
1104 WhereClause::TypeOutlives(..) => {}
1105 WhereClause::LifetimeOutlives(..) => {}
1111 impl HirDisplay for LifetimeOutlives {
1112 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
1119 impl HirDisplay for Lifetime {
1120 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
1121 self.interned().hir_fmt(f)
1125 impl HirDisplay for LifetimeData {
1126 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
1128 LifetimeData::BoundVar(idx) => idx.hir_fmt(f),
1129 LifetimeData::InferenceVar(_) => write!(f, "_"),
1130 LifetimeData::Placeholder(idx) => {
1131 let id = lt_from_placeholder_idx(f.db, *idx);
1132 let generics = generics(f.db.upcast(), id.parent);
1133 let param_data = &generics.params.lifetimes[id.local_id];
1134 write!(f, "{}", param_data.name)
1136 LifetimeData::Static => write!(f, "'static"),
1137 LifetimeData::Erased => Ok(()),
1138 LifetimeData::Phantom(_, _) => Ok(()),
1143 impl HirDisplay for DomainGoal {
1144 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
1146 DomainGoal::Holds(wc) => {
1147 write!(f, "Holds(")?;
1151 _ => write!(f, "?")?,
1157 pub fn write_visibility(
1158 module_id: ModuleId,
1160 f: &mut HirFormatter<'_>,
1161 ) -> Result<(), HirDisplayError> {
1163 Visibility::Public => write!(f, "pub "),
1164 Visibility::Module(vis_id) => {
1165 let def_map = module_id.def_map(f.db.upcast());
1166 let root_module_id = def_map.module_id(def_map.root());
1167 if vis_id == module_id {
1168 // pub(self) or omitted
1170 } else if root_module_id == vis_id {
1171 write!(f, "pub(crate) ")
1172 } else if module_id.containing_module(f.db.upcast()) == Some(vis_id) {
1173 write!(f, "pub(super) ")
1175 write!(f, "pub(in ...) ")
1181 impl HirDisplay for TypeRef {
1182 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
1184 TypeRef::Never => write!(f, "!")?,
1185 TypeRef::Placeholder => write!(f, "_")?,
1186 TypeRef::Tuple(elems) => {
1188 f.write_joined(elems, ", ")?;
1189 if elems.len() == 1 {
1194 TypeRef::Path(path) => path.hir_fmt(f)?,
1195 TypeRef::RawPtr(inner, mutability) => {
1196 let mutability = match mutability {
1197 hir_def::type_ref::Mutability::Shared => "*const ",
1198 hir_def::type_ref::Mutability::Mut => "*mut ",
1200 write!(f, "{mutability}")?;
1203 TypeRef::Reference(inner, lifetime, mutability) => {
1204 let mutability = match mutability {
1205 hir_def::type_ref::Mutability::Shared => "",
1206 hir_def::type_ref::Mutability::Mut => "mut ",
1209 if let Some(lifetime) = lifetime {
1210 write!(f, "{} ", lifetime.name)?;
1212 write!(f, "{mutability}")?;
1215 TypeRef::Array(inner, len) => {
1218 write!(f, "; {len}]")?;
1220 TypeRef::Slice(inner) => {
1225 &TypeRef::Fn(ref parameters, is_varargs, is_unsafe) => {
1226 // FIXME: Function pointer qualifiers.
1228 write!(f, "unsafe ")?;
1231 if let Some(((_, return_type), function_parameters)) = parameters.split_last() {
1232 for index in 0..function_parameters.len() {
1233 let (param_name, param_type) = &function_parameters[index];
1234 if let Some(name) = param_name {
1235 write!(f, "{name}: ")?;
1238 param_type.hir_fmt(f)?;
1240 if index != function_parameters.len() - 1 {
1245 write!(f, "{}...", if parameters.len() == 1 { "" } else { ", " })?;
1248 match &return_type {
1249 TypeRef::Tuple(tup) if tup.is_empty() => {}
1252 return_type.hir_fmt(f)?;
1257 TypeRef::ImplTrait(bounds) => {
1258 write!(f, "impl ")?;
1259 f.write_joined(bounds, " + ")?;
1261 TypeRef::DynTrait(bounds) => {
1263 f.write_joined(bounds, " + ")?;
1265 TypeRef::Macro(macro_call) => {
1266 let macro_call = macro_call.to_node(f.db.upcast());
1267 let ctx = body::LowerCtx::with_hygiene(f.db.upcast(), &Hygiene::new_unhygienic());
1268 match macro_call.path() {
1269 Some(path) => match Path::from_src(path, &ctx) {
1270 Some(path) => path.hir_fmt(f)?,
1271 None => write!(f, "{{macro}}")?,
1273 None => write!(f, "{{macro}}")?,
1275 write!(f, "!(..)")?;
1277 TypeRef::Error => write!(f, "{{error}}")?,
1283 impl HirDisplay for TypeBound {
1284 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
1286 TypeBound::Path(path, modifier) => {
1288 TraitBoundModifier::None => (),
1289 TraitBoundModifier::Maybe => write!(f, "?")?,
1293 TypeBound::Lifetime(lifetime) => write!(f, "{}", lifetime.name),
1294 TypeBound::ForLifetime(lifetimes, path) => {
1295 write!(f, "for<{}> ", lifetimes.iter().format(", "))?;
1298 TypeBound::Error => write!(f, "{{error}}"),
1303 impl HirDisplay for Path {
1304 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
1305 match (self.type_anchor(), self.kind()) {
1306 (Some(anchor), _) => {
1311 (_, PathKind::Plain) => {}
1312 (_, PathKind::Abs) => {}
1313 (_, PathKind::Crate) => write!(f, "crate")?,
1314 (_, PathKind::Super(0)) => write!(f, "self")?,
1315 (_, PathKind::Super(n)) => {
1320 write!(f, "super")?;
1323 (_, PathKind::DollarCrate(id)) => {
1324 // Resolve `$crate` to the crate's display name.
1325 // FIXME: should use the dependency name instead if available, but that depends on
1326 // the crate invoking `HirDisplay`
1327 let crate_graph = f.db.crate_graph();
1328 let name = crate_graph[*id]
1331 .map(|name| name.canonical_name())
1332 .unwrap_or("$crate");
1333 write!(f, "{name}")?
1337 for (seg_idx, segment) in self.segments().iter().enumerate() {
1338 if !matches!(self.kind(), PathKind::Plain) || seg_idx > 0 {
1341 write!(f, "{}", segment.name)?;
1342 if let Some(generic_args) = segment.args_and_bindings {
1343 // We should be in type context, so format as `Foo<Bar>` instead of `Foo::<Bar>`.
1344 // Do we actually format expressions?
1345 if generic_args.desugared_from_fn {
1346 // First argument will be a tuple, which already includes the parentheses.
1347 // If the tuple only contains 1 item, write it manually to avoid the trailing `,`.
1348 if let hir_def::path::GenericArg::Type(TypeRef::Tuple(v)) =
1349 &generic_args.args[0]
1356 generic_args.args[0].hir_fmt(f)?;
1359 if let Some(ret) = &generic_args.bindings[0].type_ref {
1360 if !matches!(ret, TypeRef::Tuple(v) if v.is_empty()) {
1369 let mut first = true;
1370 for arg in &generic_args.args {
1373 if generic_args.has_self_type {
1374 // FIXME: Convert to `<Ty as Trait>` form.
1375 write!(f, "Self = ")?;
1382 for binding in &generic_args.bindings {
1388 write!(f, "{}", binding.name)?;
1389 match &binding.type_ref {
1396 f.write_joined(&binding.bounds, " + ")?;
1407 impl HirDisplay for hir_def::path::GenericArg {
1408 fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
1410 hir_def::path::GenericArg::Type(ty) => ty.hir_fmt(f),
1411 hir_def::path::GenericArg::Const(c) => write!(f, "{c}"),
1412 hir_def::path::GenericArg::Lifetime(lifetime) => write!(f, "{}", lifetime.name),