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::TypeParamProvenance,
14 intern::{Internable, Interned},
16 path::{Path, PathKind},
17 type_ref::{TraitBoundModifier, TypeBound, TypeRef},
18 visibility::Visibility,
19 HasModule, ItemContainerId, Lookup, ModuleId, TraitId,
21 use hir_expand::{hygiene::Hygiene, name::Name};
22 use itertools::Itertools;
26 const_from_placeholder_idx,
28 from_assoc_type_id, from_foreign_def_id, from_placeholder_idx, lt_from_placeholder_idx,
30 primitive, subst_prefix, to_assoc_type_id,
31 utils::{self, generics},
32 AdtId, AliasEq, AliasTy, CallableDefId, CallableSig, Const, ConstValue, DomainGoal, GenericArg,
33 ImplTraitId, Interner, Lifetime, LifetimeData, LifetimeOutlives, Mutability, OpaqueTy,
34 ProjectionTy, ProjectionTyExt, QuantifiedWhereClause, Scalar, TraitRef, TraitRefExt, Ty, TyExt,
38 pub struct HirFormatter<'a> {
39 pub db: &'a dyn HirDatabase,
40 fmt: &'a mut dyn fmt::Write,
43 pub(crate) max_size: Option<usize>,
44 omit_verbose_types: bool,
45 display_target: DisplayTarget,
48 pub trait HirDisplay {
49 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError>;
51 /// Returns a `Display`able type that is human-readable.
52 fn into_displayable<'a>(
54 db: &'a dyn HirDatabase,
55 max_size: Option<usize>,
56 omit_verbose_types: bool,
57 display_target: DisplayTarget,
58 ) -> HirDisplayWrapper<'a, Self>
63 !matches!(display_target, DisplayTarget::SourceCode { .. }),
64 "HirDisplayWrapper cannot fail with DisplaySourceCodeError, use HirDisplay::hir_fmt directly instead"
66 HirDisplayWrapper { db, t: self, max_size, omit_verbose_types, display_target }
69 /// Returns a `Display`able type that is human-readable.
70 /// Use this for showing types to the user (e.g. diagnostics)
71 fn display<'a>(&'a self, db: &'a dyn HirDatabase) -> HirDisplayWrapper<'a, Self>
79 omit_verbose_types: false,
80 display_target: DisplayTarget::Diagnostics,
84 /// Returns a `Display`able type that is human-readable and tries to be succinct.
85 /// Use this for showing types to the user where space is constrained (e.g. doc popups)
86 fn display_truncated<'a>(
88 db: &'a dyn HirDatabase,
89 max_size: Option<usize>,
90 ) -> HirDisplayWrapper<'a, Self>
98 omit_verbose_types: true,
99 display_target: DisplayTarget::Diagnostics,
103 /// Returns a String representation of `self` that can be inserted into the given module.
104 /// Use this when generating code (e.g. assists)
105 fn display_source_code<'a>(
107 db: &'a dyn HirDatabase,
109 ) -> Result<String, DisplaySourceCodeError> {
110 let mut result = String::new();
111 match self.hir_fmt(&mut HirFormatter {
114 buf: String::with_capacity(20),
117 omit_verbose_types: false,
118 display_target: DisplayTarget::SourceCode { module_id },
121 Err(HirDisplayError::FmtError) => panic!("Writing to String can't fail!"),
122 Err(HirDisplayError::DisplaySourceCodeError(e)) => return Err(e),
127 /// Returns a String representation of `self` for test purposes
128 fn display_test<'a>(&'a self, db: &'a dyn HirDatabase) -> HirDisplayWrapper<'a, Self>
136 omit_verbose_types: false,
137 display_target: DisplayTarget::Test,
142 impl<'a> HirFormatter<'a> {
143 pub fn write_joined<T: HirDisplay>(
145 iter: impl IntoIterator<Item = T>,
147 ) -> Result<(), HirDisplayError> {
148 let mut first = true;
151 write!(self, "{}", sep)?;
155 // Abbreviate multiple omitted types with a single ellipsis.
156 if self.should_truncate() {
157 return write!(self, "{}", TYPE_HINT_TRUNCATION);
165 /// This allows using the `write!` macro directly with a `HirFormatter`.
166 pub fn write_fmt(&mut self, args: fmt::Arguments) -> Result<(), HirDisplayError> {
167 // We write to a buffer first to track output size
169 fmt::write(&mut self.buf, args)?;
170 self.curr_size += self.buf.len();
172 // Then we write to the internal formatter from the buffer
173 self.fmt.write_str(&self.buf).map_err(HirDisplayError::from)
176 pub fn should_truncate(&self) -> bool {
177 match self.max_size {
178 Some(max_size) => self.curr_size >= max_size,
183 pub fn omit_verbose_types(&self) -> bool {
184 self.omit_verbose_types
188 #[derive(Clone, Copy)]
189 pub enum DisplayTarget {
190 /// Display types for inlays, doc popups, autocompletion, etc...
191 /// Showing `{unknown}` or not qualifying paths is fine here.
192 /// There's no reason for this to fail.
194 /// Display types for inserting them in source files.
195 /// The generated code should compile, so paths need to be qualified.
196 SourceCode { module_id: ModuleId },
197 /// Only for test purpose to keep real types
202 fn is_source_code(&self) -> bool {
203 matches!(self, Self::SourceCode { .. })
205 fn is_test(&self) -> bool {
206 matches!(self, Self::Test)
211 pub enum DisplaySourceCodeError {
217 pub enum HirDisplayError {
218 /// Errors that can occur when generating source code
219 DisplaySourceCodeError(DisplaySourceCodeError),
220 /// `FmtError` is required to be compatible with std::fmt::Display
223 impl From<fmt::Error> for HirDisplayError {
224 fn from(_: fmt::Error) -> Self {
229 pub struct HirDisplayWrapper<'a, T> {
230 db: &'a dyn HirDatabase,
232 max_size: Option<usize>,
233 omit_verbose_types: bool,
234 display_target: DisplayTarget,
237 impl<'a, T> fmt::Display for HirDisplayWrapper<'a, T>
241 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
242 match self.t.hir_fmt(&mut HirFormatter {
245 buf: String::with_capacity(20),
247 max_size: self.max_size,
248 omit_verbose_types: self.omit_verbose_types,
249 display_target: self.display_target,
252 Err(HirDisplayError::FmtError) => Err(fmt::Error),
253 Err(HirDisplayError::DisplaySourceCodeError(_)) => {
254 // This should never happen
255 panic!("HirDisplay::hir_fmt failed with DisplaySourceCodeError when calling Display::fmt!")
261 const TYPE_HINT_TRUNCATION: &str = "…";
263 impl<T: HirDisplay> HirDisplay for &'_ T {
264 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
265 HirDisplay::hir_fmt(*self, f)
269 impl<T: HirDisplay + Internable> HirDisplay for Interned<T> {
270 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
271 HirDisplay::hir_fmt(self.as_ref(), f)
275 impl HirDisplay for ProjectionTy {
276 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
277 if f.should_truncate() {
278 return write!(f, "{}", TYPE_HINT_TRUNCATION);
281 let trait_ = f.db.trait_data(self.trait_(f.db));
283 self.self_type_parameter(Interner).hir_fmt(f)?;
284 write!(f, " as {}", trait_.name)?;
285 if self.substitution.len(Interner) > 1 {
287 f.write_joined(&self.substitution.as_slice(Interner)[1..], ", ")?;
290 write!(f, ">::{}", f.db.type_alias_data(from_assoc_type_id(self.associated_ty_id)).name)?;
295 impl HirDisplay for OpaqueTy {
296 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
297 if f.should_truncate() {
298 return write!(f, "{}", TYPE_HINT_TRUNCATION);
301 self.substitution.at(Interner, 0).hir_fmt(f)
305 impl HirDisplay for GenericArg {
306 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
307 match self.interned() {
308 crate::GenericArgData::Ty(ty) => ty.hir_fmt(f),
309 crate::GenericArgData::Lifetime(lt) => lt.hir_fmt(f),
310 crate::GenericArgData::Const(c) => c.hir_fmt(f),
315 impl HirDisplay for Const {
316 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
317 let data = self.interned();
319 ConstValue::BoundVar(idx) => idx.hir_fmt(f),
320 ConstValue::InferenceVar(..) => write!(f, "_"),
321 ConstValue::Placeholder(idx) => {
322 let id = const_from_placeholder_idx(f.db, idx);
323 let generics = generics(f.db.upcast(), id.parent);
324 let param_data = &generics.params.consts[id.local_id];
325 write!(f, "{}", param_data.name)
327 ConstValue::Concrete(c) => write!(f, "{}", c.interned),
332 impl HirDisplay for BoundVar {
333 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
334 write!(f, "?{}.{}", self.debruijn.depth(), self.index)
338 impl HirDisplay for Ty {
339 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
340 if f.should_truncate() {
341 return write!(f, "{}", TYPE_HINT_TRUNCATION);
344 match self.kind(Interner) {
345 TyKind::Never => write!(f, "!")?,
346 TyKind::Str => write!(f, "str")?,
347 TyKind::Scalar(Scalar::Bool) => write!(f, "bool")?,
348 TyKind::Scalar(Scalar::Char) => write!(f, "char")?,
349 &TyKind::Scalar(Scalar::Float(t)) => write!(f, "{}", primitive::float_ty_to_string(t))?,
350 &TyKind::Scalar(Scalar::Int(t)) => write!(f, "{}", primitive::int_ty_to_string(t))?,
351 &TyKind::Scalar(Scalar::Uint(t)) => write!(f, "{}", primitive::uint_ty_to_string(t))?,
352 TyKind::Slice(t) => {
357 TyKind::Array(t, c) => {
364 TyKind::Raw(m, t) | TyKind::Ref(m, _, t) => {
365 if matches!(self.kind(Interner), TyKind::Raw(..)) {
370 Mutability::Not => "const ",
371 Mutability::Mut => "mut ",
379 Mutability::Not => "",
380 Mutability::Mut => "mut ",
385 // FIXME: all this just to decide whether to use parentheses...
386 let contains_impl_fn = |bounds: &[QuantifiedWhereClause]| {
387 bounds.iter().any(|bound| {
388 if let WhereClause::Implemented(trait_ref) = bound.skip_binders() {
389 let trait_ = trait_ref.hir_trait_id();
390 fn_traits(f.db.upcast(), trait_).any(|it| it == trait_)
396 let (preds_to_print, has_impl_fn_pred) = match t.kind(Interner) {
397 TyKind::Dyn(dyn_ty) if dyn_ty.bounds.skip_binders().interned().len() > 1 => {
398 let bounds = dyn_ty.bounds.skip_binders().interned();
399 (bounds.len(), contains_impl_fn(bounds))
401 TyKind::Alias(AliasTy::Opaque(OpaqueTy {
403 substitution: parameters,
405 | TyKind::OpaqueType(opaque_ty_id, parameters) => {
407 f.db.lookup_intern_impl_trait_id((*opaque_ty_id).into());
408 if let ImplTraitId::ReturnTypeImplTrait(func, idx) = impl_trait_id {
410 f.db.return_type_impl_traits(func)
411 .expect("impl trait id without data");
414 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
415 let bounds = data.substitute(Interner, parameters);
416 let mut len = bounds.skip_binders().len();
418 // Don't count Sized but count when it absent
419 // (i.e. when explicit ?Sized bound is set).
420 let default_sized = SizedByDefault::Sized {
421 anchor: func.lookup(f.db.upcast()).module(f.db.upcast()).krate(),
423 let sized_bounds = bounds
429 WhereClause::Implemented(trait_ref)
430 if default_sized.is_sized_trait(
431 trait_ref.hir_trait_id(),
440 len = len.saturating_sub(sized_bounds);
444 (len, contains_impl_fn(bounds.skip_binders()))
452 if has_impl_fn_pred && preds_to_print <= 2 {
456 if preds_to_print > 1 {
464 TyKind::Tuple(_, substs) => {
465 if substs.len(Interner) == 1 {
467 substs.at(Interner, 0).hir_fmt(f)?;
471 f.write_joined(&*substs.as_slice(Interner), ", ")?;
475 TyKind::Function(fn_ptr) => {
476 let sig = CallableSig::from_fn_ptr(fn_ptr);
479 TyKind::FnDef(def, parameters) => {
480 let def = from_chalk(f.db, *def);
481 let sig = f.db.callable_item_signature(def).substitute(Interner, parameters);
483 CallableDefId::FunctionId(ff) => {
484 write!(f, "fn {}", f.db.function_data(ff).name)?
486 CallableDefId::StructId(s) => write!(f, "{}", f.db.struct_data(s).name)?,
487 CallableDefId::EnumVariantId(e) => {
488 write!(f, "{}", f.db.enum_data(e.parent).variants[e.local_id].name)?
491 if parameters.len(Interner) > 0 {
492 let generics = generics(f.db.upcast(), def.into());
493 let (parent_params, self_param, type_params, _impl_trait_params) =
494 generics.provenance_split();
495 let total_len = parent_params + self_param + type_params;
496 // We print all params except implicit impl Trait params. Still a bit weird; should we leave out parent and self?
499 f.write_joined(¶meters.as_slice(Interner)[..total_len], ", ")?;
504 f.write_joined(sig.params(), ", ")?;
512 TyKind::Adt(AdtId(def_id), parameters) => {
513 match f.display_target {
514 DisplayTarget::Diagnostics | DisplayTarget::Test => {
515 let name = match *def_id {
516 hir_def::AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
517 hir_def::AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
518 hir_def::AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
520 write!(f, "{}", name)?;
522 DisplayTarget::SourceCode { module_id } => {
523 if let Some(path) = find_path::find_path(
525 ItemInNs::Types((*def_id).into()),
528 write!(f, "{}", path)?;
530 return Err(HirDisplayError::DisplaySourceCodeError(
531 DisplaySourceCodeError::PathNotFound,
537 if parameters.len(Interner) > 0 {
538 let parameters_to_write = if f.display_target.is_source_code()
539 || f.omit_verbose_types()
542 .as_generic_def(f.db)
543 .map(|generic_def_id| f.db.generic_defaults(generic_def_id))
544 .filter(|defaults| !defaults.is_empty())
546 None => parameters.as_slice(Interner),
547 Some(default_parameters) => {
548 let mut default_from = 0;
549 for (i, parameter) in parameters.iter(Interner).enumerate() {
551 parameter.assert_ty_ref(Interner).kind(Interner),
552 default_parameters.get(i),
554 (&TyKind::Error, _) | (_, None) => {
555 default_from = i + 1;
557 (_, Some(default_parameter)) => {
558 let actual_default = default_parameter
560 .substitute(Interner, &subst_prefix(parameters, i));
561 if parameter.assert_ty_ref(Interner) != &actual_default
563 default_from = i + 1;
568 ¶meters.as_slice(Interner)[0..default_from]
572 parameters.as_slice(Interner)
574 if !parameters_to_write.is_empty() {
577 if f.display_target.is_source_code() {
578 let mut first = true;
579 for generic_arg in parameters_to_write {
585 if generic_arg.ty(Interner).map(|ty| ty.kind(Interner))
586 == Some(&TyKind::Error)
590 generic_arg.hir_fmt(f)?;
594 f.write_joined(parameters_to_write, ", ")?;
601 TyKind::AssociatedType(assoc_type_id, parameters) => {
602 let type_alias = from_assoc_type_id(*assoc_type_id);
603 let trait_ = match type_alias.lookup(f.db.upcast()).container {
604 ItemContainerId::TraitId(it) => it,
605 _ => panic!("not an associated type"),
607 let trait_ = f.db.trait_data(trait_);
608 let type_alias_data = f.db.type_alias_data(type_alias);
610 // Use placeholder associated types when the target is test (https://rust-lang.github.io/chalk/book/clauses/type_equality.html#placeholder-associated-types)
611 if f.display_target.is_test() {
612 write!(f, "{}::{}", trait_.name, type_alias_data.name)?;
613 if parameters.len(Interner) > 0 {
615 f.write_joined(&*parameters.as_slice(Interner), ", ")?;
619 let projection_ty = ProjectionTy {
620 associated_ty_id: to_assoc_type_id(type_alias),
621 substitution: parameters.clone(),
624 projection_ty.hir_fmt(f)?;
627 TyKind::Foreign(type_alias) => {
628 let type_alias = f.db.type_alias_data(from_foreign_def_id(*type_alias));
629 write!(f, "{}", type_alias.name)?;
631 TyKind::OpaqueType(opaque_ty_id, parameters) => {
632 let impl_trait_id = f.db.lookup_intern_impl_trait_id((*opaque_ty_id).into());
633 match impl_trait_id {
634 ImplTraitId::ReturnTypeImplTrait(func, idx) => {
636 f.db.return_type_impl_traits(func).expect("impl trait id without data");
639 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
640 let bounds = data.substitute(Interner, ¶meters);
641 let krate = func.lookup(f.db.upcast()).module(f.db.upcast()).krate();
642 write_bounds_like_dyn_trait_with_prefix(
644 bounds.skip_binders(),
645 SizedByDefault::Sized { anchor: krate },
648 // FIXME: it would maybe be good to distinguish this from the alias type (when debug printing), and to show the substitution
650 ImplTraitId::AsyncBlockTypeImplTrait(..) => {
651 write!(f, "impl Future<Output = ")?;
652 parameters.at(Interner, 0).hir_fmt(f)?;
657 TyKind::Closure(.., substs) => {
658 if f.display_target.is_source_code() {
659 return Err(HirDisplayError::DisplaySourceCodeError(
660 DisplaySourceCodeError::Closure,
663 let sig = substs.at(Interner, 0).assert_ty_ref(Interner).callable_sig(f.db);
664 if let Some(sig) = sig {
665 if sig.params().is_empty() {
667 } else if f.should_truncate() {
668 write!(f, "|{}|", TYPE_HINT_TRUNCATION)?;
671 f.write_joined(sig.params(), ", ")?;
676 sig.ret().hir_fmt(f)?;
678 write!(f, "{{closure}}")?;
681 TyKind::Placeholder(idx) => {
682 let id = from_placeholder_idx(f.db, *idx);
683 let generics = generics(f.db.upcast(), id.parent);
684 let param_data = &generics.params.types[id.local_id];
685 match param_data.provenance {
686 TypeParamProvenance::TypeParamList | TypeParamProvenance::TraitSelf => {
687 write!(f, "{}", param_data.name.clone().unwrap_or_else(Name::missing))?
689 TypeParamProvenance::ArgumentImplTrait => {
690 let substs = generics.type_params_subst(f.db);
692 f.db.generic_predicates(id.parent)
694 .map(|pred| pred.clone().substitute(Interner, &substs))
695 .filter(|wc| match &wc.skip_binders() {
696 WhereClause::Implemented(tr) => {
697 &tr.self_type_parameter(Interner) == self
699 WhereClause::AliasEq(AliasEq {
700 alias: AliasTy::Projection(proj),
702 }) => &proj.self_type_parameter(Interner) == self,
705 .collect::<Vec<_>>();
706 let krate = id.parent.module(f.db.upcast()).krate();
707 write_bounds_like_dyn_trait_with_prefix(
710 SizedByDefault::Sized { anchor: krate },
716 TyKind::BoundVar(idx) => idx.hir_fmt(f)?,
717 TyKind::Dyn(dyn_ty) => {
718 write_bounds_like_dyn_trait_with_prefix(
720 dyn_ty.bounds.skip_binders().interned(),
721 SizedByDefault::NotSized,
725 TyKind::Alias(AliasTy::Projection(p_ty)) => p_ty.hir_fmt(f)?,
726 TyKind::Alias(AliasTy::Opaque(opaque_ty)) => {
727 let impl_trait_id = f.db.lookup_intern_impl_trait_id(opaque_ty.opaque_ty_id.into());
728 match impl_trait_id {
729 ImplTraitId::ReturnTypeImplTrait(func, idx) => {
731 f.db.return_type_impl_traits(func).expect("impl trait id without data");
734 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
735 let bounds = data.substitute(Interner, &opaque_ty.substitution);
736 let krate = func.lookup(f.db.upcast()).module(f.db.upcast()).krate();
737 write_bounds_like_dyn_trait_with_prefix(
739 bounds.skip_binders(),
740 SizedByDefault::Sized { anchor: krate },
744 ImplTraitId::AsyncBlockTypeImplTrait(..) => {
745 write!(f, "{{async block}}")?;
750 if f.display_target.is_source_code() {
751 return Err(HirDisplayError::DisplaySourceCodeError(
752 DisplaySourceCodeError::UnknownType,
755 write!(f, "{{unknown}}")?;
757 TyKind::InferenceVar(..) => write!(f, "_")?,
758 TyKind::Generator(..) => write!(f, "{{generator}}")?,
759 TyKind::GeneratorWitness(..) => write!(f, "{{generator witness}}")?,
765 impl HirDisplay for CallableSig {
766 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
768 f.write_joined(self.params(), ", ")?;
770 if self.params().is_empty() {
777 let ret = self.ret();
786 fn fn_traits(db: &dyn DefDatabase, trait_: TraitId) -> impl Iterator<Item = TraitId> {
787 let krate = trait_.lookup(db).container.krate();
788 utils::fn_traits(db, krate)
791 #[derive(Clone, Copy, PartialEq, Eq)]
792 pub enum SizedByDefault {
794 Sized { anchor: CrateId },
797 impl SizedByDefault {
798 fn is_sized_trait(self, trait_: TraitId, db: &dyn DefDatabase) -> bool {
800 Self::NotSized => false,
801 Self::Sized { anchor } => {
803 .lang_item(anchor, SmolStr::new_inline("sized"))
804 .and_then(|lang_item| lang_item.as_trait());
805 Some(trait_) == sized_trait
811 pub fn write_bounds_like_dyn_trait_with_prefix(
813 predicates: &[QuantifiedWhereClause],
814 default_sized: SizedByDefault,
815 f: &mut HirFormatter,
816 ) -> Result<(), HirDisplayError> {
817 write!(f, "{}", prefix)?;
818 if !predicates.is_empty()
819 || predicates.is_empty() && matches!(default_sized, SizedByDefault::Sized { .. })
822 write_bounds_like_dyn_trait(predicates, default_sized, f)
828 fn write_bounds_like_dyn_trait(
829 predicates: &[QuantifiedWhereClause],
830 default_sized: SizedByDefault,
831 f: &mut HirFormatter,
832 ) -> Result<(), HirDisplayError> {
833 // Note: This code is written to produce nice results (i.e.
834 // corresponding to surface Rust) for types that can occur in
835 // actual Rust. It will have weird results if the predicates
836 // aren't as expected (i.e. self types = $0, projection
837 // predicates for a certain trait come after the Implemented
838 // predicate for that trait).
839 let mut first = true;
840 let mut angle_open = false;
841 let mut is_fn_trait = false;
842 let mut is_sized = false;
843 for p in predicates.iter() {
844 match p.skip_binders() {
845 WhereClause::Implemented(trait_ref) => {
846 let trait_ = trait_ref.hir_trait_id();
847 if default_sized.is_sized_trait(trait_, f.db.upcast()) {
849 if matches!(default_sized, SizedByDefault::Sized { .. }) {
850 // Don't print +Sized, but rather +?Sized if absent.
855 is_fn_trait = fn_traits(f.db.upcast(), trait_).any(|it| it == trait_);
857 if !is_fn_trait && angle_open {
864 // We assume that the self type is ^0.0 (i.e. the
865 // existential) here, which is the only thing that's
866 // possible in actual Rust, and hence don't print it
867 write!(f, "{}", f.db.trait_data(trait_).name)?;
868 if let [_, params @ ..] = &*trait_ref.substitution.as_slice(Interner) {
871 params.first().and_then(|it| it.assert_ty_ref(Interner).as_tuple())
874 f.write_joined(args.as_slice(Interner), ", ")?;
877 } else if !params.is_empty() {
879 f.write_joined(params, ", ")?;
880 // there might be assoc type bindings, so we leave the angle brackets open
885 WhereClause::AliasEq(alias_eq) if is_fn_trait => {
887 if !alias_eq.ty.is_unit() {
889 alias_eq.ty.hir_fmt(f)?;
892 WhereClause::AliasEq(AliasEq { ty, alias }) => {
893 // in types in actual Rust, these will always come
894 // after the corresponding Implemented predicate
901 if let AliasTy::Projection(proj) = alias {
903 f.db.type_alias_data(from_assoc_type_id(proj.associated_ty_id));
904 write!(f, "{} = ", type_alias.name)?;
909 // FIXME implement these
910 WhereClause::LifetimeOutlives(_) => {}
911 WhereClause::TypeOutlives(_) => {}
918 if matches!(default_sized, SizedByDefault::Sized { .. }) {
920 write!(f, "{}?Sized", if first { "" } else { " + " })?;
928 fn fmt_trait_ref(tr: &TraitRef, f: &mut HirFormatter, use_as: bool) -> Result<(), HirDisplayError> {
929 if f.should_truncate() {
930 return write!(f, "{}", TYPE_HINT_TRUNCATION);
933 tr.self_type_parameter(Interner).hir_fmt(f)?;
939 write!(f, "{}", f.db.trait_data(tr.hir_trait_id()).name)?;
940 if tr.substitution.len(Interner) > 1 {
942 f.write_joined(&tr.substitution.as_slice(Interner)[1..], ", ")?;
948 impl HirDisplay for TraitRef {
949 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
950 fmt_trait_ref(self, f, false)
954 impl HirDisplay for WhereClause {
955 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
956 if f.should_truncate() {
957 return write!(f, "{}", TYPE_HINT_TRUNCATION);
961 WhereClause::Implemented(trait_ref) => trait_ref.hir_fmt(f)?,
962 WhereClause::AliasEq(AliasEq { alias: AliasTy::Projection(projection_ty), ty }) => {
964 fmt_trait_ref(&projection_ty.trait_ref(f.db), f, true)?;
968 f.db.type_alias_data(from_assoc_type_id(projection_ty.associated_ty_id)).name,
972 WhereClause::AliasEq(_) => write!(f, "{{error}}")?,
974 // FIXME implement these
975 WhereClause::TypeOutlives(..) => {}
976 WhereClause::LifetimeOutlives(..) => {}
982 impl HirDisplay for LifetimeOutlives {
983 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
990 impl HirDisplay for Lifetime {
991 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
992 self.interned().hir_fmt(f)
996 impl HirDisplay for LifetimeData {
997 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
999 LifetimeData::BoundVar(idx) => idx.hir_fmt(f),
1000 LifetimeData::InferenceVar(_) => write!(f, "_"),
1001 LifetimeData::Placeholder(idx) => {
1002 let id = lt_from_placeholder_idx(f.db, *idx);
1003 let generics = generics(f.db.upcast(), id.parent);
1004 let param_data = &generics.params.lifetimes[id.local_id];
1005 write!(f, "{}", param_data.name)
1007 LifetimeData::Static => write!(f, "'static"),
1008 LifetimeData::Empty(_) => Ok(()),
1009 LifetimeData::Erased => Ok(()),
1010 LifetimeData::Phantom(_, _) => Ok(()),
1015 impl HirDisplay for DomainGoal {
1016 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
1018 DomainGoal::Holds(wc) => {
1019 write!(f, "Holds(")?;
1023 _ => write!(f, "?")?,
1029 pub fn write_visibility(
1030 module_id: ModuleId,
1032 f: &mut HirFormatter,
1033 ) -> Result<(), HirDisplayError> {
1035 Visibility::Public => write!(f, "pub "),
1036 Visibility::Module(vis_id) => {
1037 let def_map = module_id.def_map(f.db.upcast());
1038 let root_module_id = def_map.module_id(def_map.root());
1039 if vis_id == module_id {
1040 // pub(self) or omitted
1042 } else if root_module_id == vis_id {
1043 write!(f, "pub(crate) ")
1044 } else if module_id.containing_module(f.db.upcast()) == Some(vis_id) {
1045 write!(f, "pub(super) ")
1047 write!(f, "pub(in ...) ")
1053 impl HirDisplay for TypeRef {
1054 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
1056 TypeRef::Never => write!(f, "!")?,
1057 TypeRef::Placeholder => write!(f, "_")?,
1058 TypeRef::Tuple(elems) => {
1060 f.write_joined(elems, ", ")?;
1061 if elems.len() == 1 {
1066 TypeRef::Path(path) => path.hir_fmt(f)?,
1067 TypeRef::RawPtr(inner, mutability) => {
1068 let mutability = match mutability {
1069 hir_def::type_ref::Mutability::Shared => "*const ",
1070 hir_def::type_ref::Mutability::Mut => "*mut ",
1072 write!(f, "{}", mutability)?;
1075 TypeRef::Reference(inner, lifetime, mutability) => {
1076 let mutability = match mutability {
1077 hir_def::type_ref::Mutability::Shared => "",
1078 hir_def::type_ref::Mutability::Mut => "mut ",
1081 if let Some(lifetime) = lifetime {
1082 write!(f, "{} ", lifetime.name)?;
1084 write!(f, "{}", mutability)?;
1087 TypeRef::Array(inner, len) => {
1090 write!(f, "; {}]", len)?;
1092 TypeRef::Slice(inner) => {
1097 TypeRef::Fn(parameters, is_varargs) => {
1099 for index in 0..parameters.len() - 1 {
1100 let (param_name,param_type) = ¶meters[index];
1103 write!(f, "{}: ", name)?;
1104 param_type.hir_fmt(f)?;
1106 None => write!(f, " : {:?}", param_type)?,
1109 if index != parameters.len() - 2 {
1114 write!(f, "{}...", if parameters.len() == 1 { "" } else { ", " })?;
1117 let ret_ty = ¶meters.last().unwrap().1;
1119 TypeRef::Tuple(tup) if tup.is_empty() => {}
1126 TypeRef::ImplTrait(bounds) => {
1127 write!(f, "impl ")?;
1128 f.write_joined(bounds, " + ")?;
1130 TypeRef::DynTrait(bounds) => {
1132 f.write_joined(bounds, " + ")?;
1134 TypeRef::Macro(macro_call) => {
1135 let macro_call = macro_call.to_node(f.db.upcast());
1136 let ctx = body::LowerCtx::with_hygiene(f.db.upcast(), &Hygiene::new_unhygienic());
1137 match macro_call.path() {
1138 Some(path) => match Path::from_src(path, &ctx) {
1139 Some(path) => path.hir_fmt(f)?,
1140 None => write!(f, "{{macro}}")?,
1142 None => write!(f, "{{macro}}")?,
1144 write!(f, "!(..)")?;
1146 TypeRef::Error => write!(f, "{{error}}")?,
1152 impl HirDisplay for TypeBound {
1153 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
1155 TypeBound::Path(path, modifier) => {
1157 TraitBoundModifier::None => (),
1158 TraitBoundModifier::Maybe => write!(f, "?")?,
1162 TypeBound::Lifetime(lifetime) => write!(f, "{}", lifetime.name),
1163 TypeBound::ForLifetime(lifetimes, path) => {
1164 write!(f, "for<{}> ", lifetimes.iter().format(", "))?;
1167 TypeBound::Error => write!(f, "{{error}}"),
1172 impl HirDisplay for Path {
1173 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
1174 match (self.type_anchor(), self.kind()) {
1175 (Some(anchor), _) => {
1180 (_, PathKind::Plain) => {}
1181 (_, PathKind::Abs) => {}
1182 (_, PathKind::Crate) => write!(f, "crate")?,
1183 (_, PathKind::Super(0)) => write!(f, "self")?,
1184 (_, PathKind::Super(n)) => {
1189 write!(f, "super")?;
1192 (_, PathKind::DollarCrate(_)) => write!(f, "{{extern_crate}}")?,
1195 for (seg_idx, segment) in self.segments().iter().enumerate() {
1196 if !matches!(self.kind(), PathKind::Plain) || seg_idx > 0 {
1199 write!(f, "{}", segment.name)?;
1200 if let Some(generic_args) = segment.args_and_bindings {
1201 // We should be in type context, so format as `Foo<Bar>` instead of `Foo::<Bar>`.
1202 // Do we actually format expressions?
1203 if generic_args.desugared_from_fn {
1204 // First argument will be a tuple, which already includes the parentheses.
1205 // If the tuple only contains 1 item, write it manually to avoid the trailing `,`.
1206 if let hir_def::path::GenericArg::Type(TypeRef::Tuple(v)) =
1207 &generic_args.args[0]
1214 generic_args.args[0].hir_fmt(f)?;
1217 if let Some(ret) = &generic_args.bindings[0].type_ref {
1218 if !matches!(ret, TypeRef::Tuple(v) if v.is_empty()) {
1227 let mut first = true;
1228 for arg in &generic_args.args {
1231 if generic_args.has_self_type {
1232 // FIXME: Convert to `<Ty as Trait>` form.
1233 write!(f, "Self = ")?;
1240 for binding in &generic_args.bindings {
1246 write!(f, "{}", binding.name)?;
1247 match &binding.type_ref {
1254 f.write_joined(&binding.bounds, " + ")?;
1265 impl HirDisplay for hir_def::path::GenericArg {
1266 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
1268 hir_def::path::GenericArg::Type(ty) => ty.hir_fmt(f),
1269 hir_def::path::GenericArg::Lifetime(lifetime) => write!(f, "{}", lifetime.name),