1 //! FIXME: write short doc here
3 use std::{borrow::Cow, fmt};
5 use arrayvec::ArrayVec;
6 use chalk_ir::Mutability;
8 db::DefDatabase, find_path, generics::TypeParamProvenance, item_scope::ItemInNs,
9 AssocContainerId, Lookup, ModuleId, TraitId,
11 use hir_expand::name::Name;
14 db::HirDatabase, from_assoc_type_id, from_foreign_def_id, primitive, to_assoc_type_id,
15 utils::generics, AdtId, AliasTy, CallableDefId, CallableSig, GenericPredicate, Interner,
16 Lifetime, Obligation, OpaqueTy, OpaqueTyId, ProjectionTy, Scalar, Substs, TraitRef, Ty, TyKind,
19 pub struct HirFormatter<'a> {
20 pub db: &'a dyn HirDatabase,
21 fmt: &'a mut dyn fmt::Write,
24 pub(crate) max_size: Option<usize>,
25 omit_verbose_types: bool,
26 display_target: DisplayTarget,
29 pub trait HirDisplay {
30 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError>;
32 /// Returns a `Display`able type that is human-readable.
33 fn into_displayable<'a>(
35 db: &'a dyn HirDatabase,
36 max_size: Option<usize>,
37 omit_verbose_types: bool,
38 display_target: DisplayTarget,
39 ) -> HirDisplayWrapper<'a, Self>
43 HirDisplayWrapper { db, t: self, max_size, omit_verbose_types, display_target }
46 /// Returns a `Display`able type that is human-readable.
47 /// Use this for showing types to the user (e.g. diagnostics)
48 fn display<'a>(&'a self, db: &'a dyn HirDatabase) -> HirDisplayWrapper<'a, Self>
56 omit_verbose_types: false,
57 display_target: DisplayTarget::Diagnostics,
61 /// Returns a `Display`able type that is human-readable and tries to be succinct.
62 /// Use this for showing types to the user where space is constrained (e.g. doc popups)
63 fn display_truncated<'a>(
65 db: &'a dyn HirDatabase,
66 max_size: Option<usize>,
67 ) -> HirDisplayWrapper<'a, Self>
75 omit_verbose_types: true,
76 display_target: DisplayTarget::Diagnostics,
80 /// Returns a String representation of `self` that can be inserted into the given module.
81 /// Use this when generating code (e.g. assists)
82 fn display_source_code<'a>(
84 db: &'a dyn HirDatabase,
86 ) -> Result<String, DisplaySourceCodeError> {
87 let mut result = String::new();
88 match self.hir_fmt(&mut HirFormatter {
91 buf: String::with_capacity(20),
94 omit_verbose_types: false,
95 display_target: DisplayTarget::SourceCode { module_id },
98 Err(HirDisplayError::FmtError) => panic!("Writing to String can't fail!"),
99 Err(HirDisplayError::DisplaySourceCodeError(e)) => return Err(e),
104 /// Returns a String representation of `self` for test purposes
105 fn display_test<'a>(&'a self, db: &'a dyn HirDatabase) -> HirDisplayWrapper<'a, Self>
113 omit_verbose_types: false,
114 display_target: DisplayTarget::Test,
119 impl<'a> HirFormatter<'a> {
120 pub fn write_joined<T: HirDisplay>(
122 iter: impl IntoIterator<Item = T>,
124 ) -> Result<(), HirDisplayError> {
125 let mut first = true;
128 write!(self, "{}", sep)?;
136 /// This allows using the `write!` macro directly with a `HirFormatter`.
137 pub fn write_fmt(&mut self, args: fmt::Arguments) -> Result<(), HirDisplayError> {
138 // We write to a buffer first to track output size
140 fmt::write(&mut self.buf, args)?;
141 self.curr_size += self.buf.len();
143 // Then we write to the internal formatter from the buffer
144 self.fmt.write_str(&self.buf).map_err(HirDisplayError::from)
147 pub fn should_truncate(&self) -> bool {
148 if let Some(max_size) = self.max_size {
149 self.curr_size >= max_size
155 pub fn omit_verbose_types(&self) -> bool {
156 self.omit_verbose_types
160 #[derive(Clone, Copy)]
161 pub enum DisplayTarget {
162 /// Display types for inlays, doc popups, autocompletion, etc...
163 /// Showing `{unknown}` or not qualifying paths is fine here.
164 /// There's no reason for this to fail.
166 /// Display types for inserting them in source files.
167 /// The generated code should compile, so paths need to be qualified.
168 SourceCode { module_id: ModuleId },
169 /// Only for test purpose to keep real types
174 fn is_source_code(&self) -> bool {
175 matches!(self, Self::SourceCode { .. })
177 fn is_test(&self) -> bool {
178 matches!(self, Self::Test)
183 pub enum DisplaySourceCodeError {
188 pub enum HirDisplayError {
189 /// Errors that can occur when generating source code
190 DisplaySourceCodeError(DisplaySourceCodeError),
191 /// `FmtError` is required to be compatible with std::fmt::Display
194 impl From<fmt::Error> for HirDisplayError {
195 fn from(_: fmt::Error) -> Self {
200 pub struct HirDisplayWrapper<'a, T> {
201 db: &'a dyn HirDatabase,
203 max_size: Option<usize>,
204 omit_verbose_types: bool,
205 display_target: DisplayTarget,
208 impl<'a, T> fmt::Display for HirDisplayWrapper<'a, T>
212 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
213 match self.t.hir_fmt(&mut HirFormatter {
216 buf: String::with_capacity(20),
218 max_size: self.max_size,
219 omit_verbose_types: self.omit_verbose_types,
220 display_target: self.display_target,
223 Err(HirDisplayError::FmtError) => Err(fmt::Error),
224 Err(HirDisplayError::DisplaySourceCodeError(_)) => {
225 // This should never happen
226 panic!("HirDisplay failed when calling Display::fmt!")
232 const TYPE_HINT_TRUNCATION: &str = "…";
234 impl HirDisplay for &Ty {
235 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
236 HirDisplay::hir_fmt(*self, f)
240 impl HirDisplay for ProjectionTy {
241 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
242 if f.should_truncate() {
243 return write!(f, "{}", TYPE_HINT_TRUNCATION);
246 let trait_ = f.db.trait_data(self.trait_(f.db));
247 let first_parameter = self.parameters[0].into_displayable(
250 f.omit_verbose_types,
253 write!(f, "<{} as {}", first_parameter, trait_.name)?;
254 if self.parameters.len() > 1 {
256 f.write_joined(&self.parameters[1..], ", ")?;
259 write!(f, ">::{}", f.db.type_alias_data(from_assoc_type_id(self.associated_ty)).name)?;
264 impl HirDisplay for Ty {
265 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
266 if f.should_truncate() {
267 return write!(f, "{}", TYPE_HINT_TRUNCATION);
270 match self.interned(&Interner) {
271 TyKind::Never => write!(f, "!")?,
272 TyKind::Str => write!(f, "str")?,
273 TyKind::Scalar(Scalar::Bool) => write!(f, "bool")?,
274 TyKind::Scalar(Scalar::Char) => write!(f, "char")?,
275 &TyKind::Scalar(Scalar::Float(t)) => write!(f, "{}", primitive::float_ty_to_string(t))?,
276 &TyKind::Scalar(Scalar::Int(t)) => write!(f, "{}", primitive::int_ty_to_string(t))?,
277 &TyKind::Scalar(Scalar::Uint(t)) => write!(f, "{}", primitive::uint_ty_to_string(t))?,
278 TyKind::Slice(parameters) => {
279 let t = parameters.as_single();
284 TyKind::Array(parameters) => {
285 let t = parameters.as_single();
290 TyKind::Raw(m, parameters) | TyKind::Ref(m, parameters) => {
291 let t = parameters.as_single();
293 t.into_displayable(f.db, f.max_size, f.omit_verbose_types, f.display_target);
295 if matches!(self.interned(&Interner), TyKind::Raw(..)) {
300 Mutability::Not => "const ",
301 Mutability::Mut => "mut ",
309 Mutability::Not => "",
310 Mutability::Mut => "mut ",
316 let predicates = match t.interned(&Interner) {
317 TyKind::Dyn(predicates) if predicates.len() > 1 => {
318 Cow::Borrowed(predicates.as_ref())
320 &TyKind::Alias(AliasTy::Opaque(OpaqueTy {
321 opaque_ty_id: OpaqueTyId::ReturnTypeImplTrait(func, idx),
325 f.db.return_type_impl_traits(func).expect("impl trait id without data");
328 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
329 let bounds = data.subst(parameters);
330 Cow::Owned(bounds.value)
332 _ => Cow::Borrowed(&[][..]),
335 if let [GenericPredicate::Implemented(trait_ref), _] = predicates.as_ref() {
336 let trait_ = trait_ref.trait_;
337 if fn_traits(f.db.upcast(), trait_).any(|it| it == trait_) {
338 return write!(f, "{}", ty_display);
342 if predicates.len() > 1 {
344 write!(f, "{}", ty_display)?;
347 write!(f, "{}", ty_display)?;
350 TyKind::Tuple(_, substs) => {
351 if substs.len() == 1 {
353 substs[0].hir_fmt(f)?;
357 f.write_joined(&*substs.0, ", ")?;
361 TyKind::Function(fn_ptr) => {
362 let sig = CallableSig::from_fn_ptr(fn_ptr);
365 TyKind::FnDef(def, parameters) => {
367 let sig = f.db.callable_item_signature(def).subst(parameters);
369 CallableDefId::FunctionId(ff) => {
370 write!(f, "fn {}", f.db.function_data(ff).name)?
372 CallableDefId::StructId(s) => write!(f, "{}", f.db.struct_data(s).name)?,
373 CallableDefId::EnumVariantId(e) => {
374 write!(f, "{}", f.db.enum_data(e.parent).variants[e.local_id].name)?
377 if parameters.len() > 0 {
378 let generics = generics(f.db.upcast(), def.into());
379 let (parent_params, self_param, type_params, _impl_trait_params) =
380 generics.provenance_split();
381 let total_len = parent_params + self_param + type_params;
382 // We print all params except implicit impl Trait params. Still a bit weird; should we leave out parent and self?
385 f.write_joined(¶meters.0[..total_len], ", ")?;
390 f.write_joined(sig.params(), ", ")?;
393 if *ret != Ty::unit() {
394 let ret_display = ret.into_displayable(
397 f.omit_verbose_types,
401 write!(f, " -> {}", ret_display)?;
404 TyKind::Adt(AdtId(def_id), parameters) => {
405 match f.display_target {
406 DisplayTarget::Diagnostics | DisplayTarget::Test => {
407 let name = match *def_id {
408 hir_def::AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
409 hir_def::AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
410 hir_def::AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
412 write!(f, "{}", name)?;
414 DisplayTarget::SourceCode { module_id } => {
415 if let Some(path) = find_path::find_path(
417 ItemInNs::Types((*def_id).into()),
420 write!(f, "{}", path)?;
422 return Err(HirDisplayError::DisplaySourceCodeError(
423 DisplaySourceCodeError::PathNotFound,
429 if parameters.len() > 0 {
430 let parameters_to_write = if f.display_target.is_source_code()
431 || f.omit_verbose_types()
435 .map(|generic_def_id| f.db.generic_defaults(generic_def_id))
436 .filter(|defaults| !defaults.is_empty())
438 None => parameters.0.as_ref(),
439 Some(default_parameters) => {
440 let mut default_from = 0;
441 for (i, parameter) in parameters.iter().enumerate() {
442 match (parameter.interned(&Interner), default_parameters.get(i))
444 (&TyKind::Unknown, _) | (_, None) => {
445 default_from = i + 1;
447 (_, Some(default_parameter)) => {
448 let actual_default = default_parameter
450 .subst(¶meters.prefix(i));
451 if parameter != &actual_default {
452 default_from = i + 1;
457 ¶meters.0[0..default_from]
461 parameters.0.as_ref()
463 if !parameters_to_write.is_empty() {
465 f.write_joined(parameters_to_write, ", ")?;
470 TyKind::AssociatedType(assoc_type_id, parameters) => {
471 let type_alias = from_assoc_type_id(*assoc_type_id);
472 let trait_ = match type_alias.lookup(f.db.upcast()).container {
473 AssocContainerId::TraitId(it) => it,
474 _ => panic!("not an associated type"),
476 let trait_ = f.db.trait_data(trait_);
477 let type_alias_data = f.db.type_alias_data(type_alias);
479 // Use placeholder associated types when the target is test (https://rust-lang.github.io/chalk/book/clauses/type_equality.html#placeholder-associated-types)
480 if f.display_target.is_test() {
481 write!(f, "{}::{}", trait_.name, type_alias_data.name)?;
482 if parameters.len() > 0 {
484 f.write_joined(&*parameters.0, ", ")?;
488 let projection_ty = ProjectionTy {
489 associated_ty: to_assoc_type_id(type_alias),
490 parameters: parameters.clone(),
493 projection_ty.hir_fmt(f)?;
496 TyKind::ForeignType(type_alias) => {
497 let type_alias = f.db.type_alias_data(from_foreign_def_id(*type_alias));
498 write!(f, "{}", type_alias.name)?;
500 TyKind::OpaqueType(opaque_ty_id, parameters) => {
502 &OpaqueTyId::ReturnTypeImplTrait(func, idx) => {
504 f.db.return_type_impl_traits(func).expect("impl trait id without data");
507 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
508 let bounds = data.subst(¶meters);
509 write_bounds_like_dyn_trait_with_prefix("impl", &bounds.value, f)?;
510 // FIXME: it would maybe be good to distinguish this from the alias type (when debug printing), and to show the substitution
512 OpaqueTyId::AsyncBlockTypeImplTrait(..) => {
513 write!(f, "impl Future<Output = ")?;
514 parameters[0].hir_fmt(f)?;
519 TyKind::Closure(.., substs) => {
520 let sig = substs[0].callable_sig(f.db);
521 if let Some(sig) = sig {
522 if sig.params().is_empty() {
524 } else if f.omit_verbose_types() {
525 write!(f, "|{}|", TYPE_HINT_TRUNCATION)?;
528 f.write_joined(sig.params(), ", ")?;
532 let ret_display = sig.ret().into_displayable(
535 f.omit_verbose_types,
538 write!(f, " -> {}", ret_display)?;
540 write!(f, "{{closure}}")?;
543 TyKind::Placeholder(id) => {
544 let generics = generics(f.db.upcast(), id.parent);
545 let param_data = &generics.params.types[id.local_id];
546 match param_data.provenance {
547 TypeParamProvenance::TypeParamList | TypeParamProvenance::TraitSelf => {
548 write!(f, "{}", param_data.name.clone().unwrap_or_else(Name::missing))?
550 TypeParamProvenance::ArgumentImplTrait => {
551 let bounds = f.db.generic_predicates_for_param(*id);
552 let substs = Substs::type_params_for_generics(&generics);
553 write_bounds_like_dyn_trait_with_prefix(
555 &bounds.iter().map(|b| b.clone().subst(&substs)).collect::<Vec<_>>(),
561 TyKind::BoundVar(idx) => write!(f, "?{}.{}", idx.debruijn.depth(), idx.index)?,
562 TyKind::Dyn(predicates) => {
563 write_bounds_like_dyn_trait_with_prefix("dyn", predicates, f)?;
565 TyKind::Alias(AliasTy::Projection(p_ty)) => p_ty.hir_fmt(f)?,
566 TyKind::Alias(AliasTy::Opaque(opaque_ty)) => {
567 match opaque_ty.opaque_ty_id {
568 OpaqueTyId::ReturnTypeImplTrait(func, idx) => {
570 f.db.return_type_impl_traits(func).expect("impl trait id without data");
573 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
574 let bounds = data.subst(&opaque_ty.parameters);
575 write_bounds_like_dyn_trait_with_prefix("impl", &bounds.value, f)?;
577 OpaqueTyId::AsyncBlockTypeImplTrait(..) => {
578 write!(f, "{{async block}}")?;
583 if f.display_target.is_source_code() {
584 return Err(HirDisplayError::DisplaySourceCodeError(
585 DisplaySourceCodeError::UnknownType,
588 write!(f, "{{unknown}}")?;
590 TyKind::InferenceVar(..) => write!(f, "_")?,
596 impl HirDisplay for CallableSig {
597 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
599 f.write_joined(self.params(), ", ")?;
601 if self.params().is_empty() {
608 let ret = self.ret();
609 if *ret != Ty::unit() {
611 ret.into_displayable(f.db, f.max_size, f.omit_verbose_types, f.display_target);
612 write!(f, " -> {}", ret_display)?;
618 fn fn_traits(db: &dyn DefDatabase, trait_: TraitId) -> impl Iterator<Item = TraitId> {
619 let krate = trait_.lookup(db).container.krate();
621 db.lang_item(krate, "fn".into()),
622 db.lang_item(krate, "fn_mut".into()),
623 db.lang_item(krate, "fn_once".into()),
625 // FIXME: Replace ArrayVec when into_iter is a thing on arrays
626 ArrayVec::from(fn_traits).into_iter().flatten().flat_map(|it| it.as_trait())
629 pub fn write_bounds_like_dyn_trait_with_prefix(
631 predicates: &[GenericPredicate],
632 f: &mut HirFormatter,
633 ) -> Result<(), HirDisplayError> {
634 write!(f, "{}", prefix)?;
635 if !predicates.is_empty() {
637 write_bounds_like_dyn_trait(predicates, f)
643 fn write_bounds_like_dyn_trait(
644 predicates: &[GenericPredicate],
645 f: &mut HirFormatter,
646 ) -> Result<(), HirDisplayError> {
647 // Note: This code is written to produce nice results (i.e.
648 // corresponding to surface Rust) for types that can occur in
649 // actual Rust. It will have weird results if the predicates
650 // aren't as expected (i.e. self types = $0, projection
651 // predicates for a certain trait come after the Implemented
652 // predicate for that trait).
653 let mut first = true;
654 let mut angle_open = false;
655 let mut is_fn_trait = false;
656 for p in predicates.iter() {
658 GenericPredicate::Implemented(trait_ref) => {
659 let trait_ = trait_ref.trait_;
661 is_fn_trait = fn_traits(f.db.upcast(), trait_).any(|it| it == trait_);
663 if !is_fn_trait && angle_open {
670 // We assume that the self type is $0 (i.e. the
671 // existential) here, which is the only thing that's
672 // possible in actual Rust, and hence don't print it
673 write!(f, "{}", f.db.trait_data(trait_).name)?;
674 if let [_, params @ ..] = &*trait_ref.substs.0 {
676 if let Some(args) = params.first().and_then(|it| it.as_tuple()) {
678 f.write_joined(&*args.0, ", ")?;
681 } else if !params.is_empty() {
683 f.write_joined(params, ", ")?;
684 // there might be assoc type bindings, so we leave the angle brackets open
689 GenericPredicate::Projection(projection_pred) if is_fn_trait => {
692 projection_pred.ty.hir_fmt(f)?;
694 GenericPredicate::Projection(projection_pred) => {
695 // in types in actual Rust, these will always come
696 // after the corresponding Implemented predicate
703 let type_alias = f.db.type_alias_data(from_assoc_type_id(
704 projection_pred.projection_ty.associated_ty,
706 write!(f, "{} = ", type_alias.name)?;
707 projection_pred.ty.hir_fmt(f)?;
709 GenericPredicate::Error => {
711 // impl Trait<X, {error}>
714 // impl Trait + {error}
729 fn hir_fmt_ext(&self, f: &mut HirFormatter, use_as: bool) -> Result<(), HirDisplayError> {
730 if f.should_truncate() {
731 return write!(f, "{}", TYPE_HINT_TRUNCATION);
734 self.substs[0].hir_fmt(f)?;
740 write!(f, "{}", f.db.trait_data(self.trait_).name)?;
741 if self.substs.len() > 1 {
743 f.write_joined(&self.substs[1..], ", ")?;
750 impl HirDisplay for TraitRef {
751 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
752 self.hir_fmt_ext(f, false)
756 impl HirDisplay for &GenericPredicate {
757 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
758 HirDisplay::hir_fmt(*self, f)
762 impl HirDisplay for GenericPredicate {
763 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
764 if f.should_truncate() {
765 return write!(f, "{}", TYPE_HINT_TRUNCATION);
769 GenericPredicate::Implemented(trait_ref) => trait_ref.hir_fmt(f)?,
770 GenericPredicate::Projection(projection_pred) => {
772 projection_pred.projection_ty.trait_ref(f.db).hir_fmt_ext(f, true)?;
776 f.db.type_alias_data(from_assoc_type_id(
777 projection_pred.projection_ty.associated_ty
781 projection_pred.ty.hir_fmt(f)?;
783 GenericPredicate::Error => write!(f, "{{error}}")?,
789 impl HirDisplay for Lifetime {
790 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
792 Lifetime::Parameter(id) => {
793 let generics = generics(f.db.upcast(), id.parent);
794 let param_data = &generics.params.lifetimes[id.local_id];
795 write!(f, "{}", ¶m_data.name)
797 Lifetime::Static => write!(f, "'static"),
802 impl HirDisplay for Obligation {
803 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
805 Obligation::Trait(tr) => {
806 write!(f, "Implements(")?;
810 Obligation::Projection(proj) => {
811 write!(f, "Normalize(")?;
812 proj.projection_ty.hir_fmt(f)?;