1 //! FIXME: write short doc here
3 use std::{borrow::Cow, fmt};
6 db::HirDatabase, primitive, utils::generics, AliasTy, CallableDefId, CallableSig,
7 GenericPredicate, Lifetime, Obligation, OpaqueTy, OpaqueTyId, ProjectionTy, Scalar, Substs,
10 use arrayvec::ArrayVec;
11 use chalk_ir::Mutability;
13 db::DefDatabase, find_path, generics::TypeParamProvenance, item_scope::ItemInNs, AdtId,
14 AssocContainerId, HasModule, Lookup, ModuleId, TraitId,
16 use hir_expand::name::Name;
18 pub struct HirFormatter<'a> {
19 pub db: &'a dyn HirDatabase,
20 fmt: &'a mut dyn fmt::Write,
23 pub(crate) max_size: Option<usize>,
24 omit_verbose_types: bool,
25 display_target: DisplayTarget,
28 pub trait HirDisplay {
29 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError>;
31 /// Returns a `Display`able type that is human-readable.
32 fn into_displayable<'a>(
34 db: &'a dyn HirDatabase,
35 max_size: Option<usize>,
36 omit_verbose_types: bool,
37 display_target: DisplayTarget,
38 ) -> HirDisplayWrapper<'a, Self>
42 HirDisplayWrapper { db, t: self, max_size, omit_verbose_types, display_target }
45 /// Returns a `Display`able type that is human-readable.
46 /// Use this for showing types to the user (e.g. diagnostics)
47 fn display<'a>(&'a self, db: &'a dyn HirDatabase) -> HirDisplayWrapper<'a, Self>
55 omit_verbose_types: false,
56 display_target: DisplayTarget::Diagnostics,
60 /// Returns a `Display`able type that is human-readable and tries to be succinct.
61 /// Use this for showing types to the user where space is constrained (e.g. doc popups)
62 fn display_truncated<'a>(
64 db: &'a dyn HirDatabase,
65 max_size: Option<usize>,
66 ) -> HirDisplayWrapper<'a, Self>
74 omit_verbose_types: true,
75 display_target: DisplayTarget::Diagnostics,
79 /// Returns a String representation of `self` that can be inserted into the given module.
80 /// Use this when generating code (e.g. assists)
81 fn display_source_code<'a>(
83 db: &'a dyn HirDatabase,
85 ) -> Result<String, DisplaySourceCodeError> {
86 let mut result = String::new();
87 match self.hir_fmt(&mut HirFormatter {
90 buf: String::with_capacity(20),
93 omit_verbose_types: false,
94 display_target: DisplayTarget::SourceCode { module_id },
97 Err(HirDisplayError::FmtError) => panic!("Writing to String can't fail!"),
98 Err(HirDisplayError::DisplaySourceCodeError(e)) => return Err(e),
103 /// Returns a String representation of `self` for test purposes
104 fn display_test<'a>(&'a self, db: &'a dyn HirDatabase) -> HirDisplayWrapper<'a, Self>
112 omit_verbose_types: false,
113 display_target: DisplayTarget::Test,
118 impl<'a> HirFormatter<'a> {
119 pub fn write_joined<T: HirDisplay>(
121 iter: impl IntoIterator<Item = T>,
123 ) -> Result<(), HirDisplayError> {
124 let mut first = true;
127 write!(self, "{}", sep)?;
135 /// This allows using the `write!` macro directly with a `HirFormatter`.
136 pub fn write_fmt(&mut self, args: fmt::Arguments) -> Result<(), HirDisplayError> {
137 // We write to a buffer first to track output size
139 fmt::write(&mut self.buf, args)?;
140 self.curr_size += self.buf.len();
142 // Then we write to the internal formatter from the buffer
143 self.fmt.write_str(&self.buf).map_err(HirDisplayError::from)
146 pub fn should_truncate(&self) -> bool {
147 if let Some(max_size) = self.max_size {
148 self.curr_size >= max_size
154 pub fn omit_verbose_types(&self) -> bool {
155 self.omit_verbose_types
159 #[derive(Clone, Copy)]
160 pub enum DisplayTarget {
161 /// Display types for inlays, doc popups, autocompletion, etc...
162 /// Showing `{unknown}` or not qualifying paths is fine here.
163 /// There's no reason for this to fail.
165 /// Display types for inserting them in source files.
166 /// The generated code should compile, so paths need to be qualified.
167 SourceCode { module_id: ModuleId },
168 /// Only for test purpose to keep real types
173 fn is_source_code(&self) -> bool {
174 matches!(self, Self::SourceCode { .. })
176 fn is_test(&self) -> bool {
177 matches!(self, Self::Test)
182 pub enum DisplaySourceCodeError {
187 pub enum HirDisplayError {
188 /// Errors that can occur when generating source code
189 DisplaySourceCodeError(DisplaySourceCodeError),
190 /// `FmtError` is required to be compatible with std::fmt::Display
193 impl From<fmt::Error> for HirDisplayError {
194 fn from(_: fmt::Error) -> Self {
199 pub struct HirDisplayWrapper<'a, T> {
200 db: &'a dyn HirDatabase,
202 max_size: Option<usize>,
203 omit_verbose_types: bool,
204 display_target: DisplayTarget,
207 impl<'a, T> fmt::Display for HirDisplayWrapper<'a, T>
211 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
212 match self.t.hir_fmt(&mut HirFormatter {
215 buf: String::with_capacity(20),
217 max_size: self.max_size,
218 omit_verbose_types: self.omit_verbose_types,
219 display_target: self.display_target,
222 Err(HirDisplayError::FmtError) => Err(fmt::Error),
223 Err(HirDisplayError::DisplaySourceCodeError(_)) => {
224 // This should never happen
225 panic!("HirDisplay failed when calling Display::fmt!")
231 const TYPE_HINT_TRUNCATION: &str = "…";
233 impl HirDisplay for &Ty {
234 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
235 HirDisplay::hir_fmt(*self, f)
239 impl HirDisplay for ProjectionTy {
240 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
241 if f.should_truncate() {
242 return write!(f, "{}", TYPE_HINT_TRUNCATION);
245 let trait_ = f.db.trait_data(self.trait_(f.db));
246 let first_parameter = self.parameters[0].into_displayable(
249 f.omit_verbose_types,
252 write!(f, "<{} as {}", first_parameter, trait_.name)?;
253 if self.parameters.len() > 1 {
255 f.write_joined(&self.parameters[1..], ", ")?;
258 write!(f, ">::{}", f.db.type_alias_data(self.associated_ty).name)?;
263 impl HirDisplay for Ty {
264 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
265 if f.should_truncate() {
266 return write!(f, "{}", TYPE_HINT_TRUNCATION);
270 Ty::Never => write!(f, "!")?,
271 Ty::Str => write!(f, "str")?,
272 Ty::Scalar(Scalar::Bool) => write!(f, "bool")?,
273 Ty::Scalar(Scalar::Char) => write!(f, "char")?,
274 &Ty::Scalar(Scalar::Float(t)) => write!(f, "{}", primitive::float_ty_to_string(t))?,
275 &Ty::Scalar(Scalar::Int(t)) => write!(f, "{}", primitive::int_ty_to_string(t))?,
276 &Ty::Scalar(Scalar::Uint(t)) => write!(f, "{}", primitive::uint_ty_to_string(t))?,
277 Ty::Slice(parameters) => {
278 let t = parameters.as_single();
283 Ty::Array(parameters) => {
284 let t = parameters.as_single();
289 Ty::Raw(m, parameters) | Ty::Ref(m, parameters) => {
290 let t = parameters.as_single();
292 t.into_displayable(f.db, f.max_size, f.omit_verbose_types, f.display_target);
294 if matches!(self, Ty::Raw(..)) {
299 Mutability::Not => "const ",
300 Mutability::Mut => "mut ",
308 Mutability::Not => "",
309 Mutability::Mut => "mut ",
315 let predicates = match t {
316 Ty::Dyn(predicates) if predicates.len() > 1 => {
317 Cow::Borrowed(predicates.as_ref())
319 &Ty::Alias(AliasTy::Opaque(OpaqueTy {
320 opaque_ty_id: OpaqueTyId::ReturnTypeImplTrait(func, idx),
324 f.db.return_type_impl_traits(func).expect("impl trait id without data");
327 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
328 let bounds = data.subst(parameters);
329 Cow::Owned(bounds.value)
331 _ => Cow::Borrowed(&[][..]),
334 if let [GenericPredicate::Implemented(trait_ref), _] = predicates.as_ref() {
335 let trait_ = trait_ref.trait_;
336 if fn_traits(f.db.upcast(), trait_).any(|it| it == trait_) {
337 return write!(f, "{}", ty_display);
341 if predicates.len() > 1 {
343 write!(f, "{}", ty_display)?;
346 write!(f, "{}", ty_display)?;
349 Ty::Tuple(_, substs) => {
350 if substs.len() == 1 {
352 substs[0].hir_fmt(f)?;
356 f.write_joined(&*substs.0, ", ")?;
360 Ty::Function(fn_ptr) => {
361 let sig = CallableSig::from_fn_ptr(fn_ptr);
364 Ty::FnDef(def, parameters) => {
366 let sig = f.db.callable_item_signature(def).subst(parameters);
368 CallableDefId::FunctionId(ff) => {
369 write!(f, "fn {}", f.db.function_data(ff).name)?
371 CallableDefId::StructId(s) => write!(f, "{}", f.db.struct_data(s).name)?,
372 CallableDefId::EnumVariantId(e) => {
373 write!(f, "{}", f.db.enum_data(e.parent).variants[e.local_id].name)?
376 if parameters.len() > 0 {
377 let generics = generics(f.db.upcast(), def.into());
378 let (parent_params, self_param, type_params, _impl_trait_params) =
379 generics.provenance_split();
380 let total_len = parent_params + self_param + type_params;
381 // We print all params except implicit impl Trait params. Still a bit weird; should we leave out parent and self?
384 f.write_joined(¶meters.0[..total_len], ", ")?;
389 f.write_joined(sig.params(), ", ")?;
392 if *ret != Ty::unit() {
393 let ret_display = ret.into_displayable(
396 f.omit_verbose_types,
400 write!(f, " -> {}", ret_display)?;
403 Ty::Adt(def_id, parameters) => {
404 match f.display_target {
405 DisplayTarget::Diagnostics | DisplayTarget::Test => {
406 let name = match *def_id {
407 AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
408 AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
409 AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
411 write!(f, "{}", name)?;
413 DisplayTarget::SourceCode { module_id } => {
414 if let Some(path) = find_path::find_path(
416 ItemInNs::Types((*def_id).into()),
419 write!(f, "{}", path)?;
421 return Err(HirDisplayError::DisplaySourceCodeError(
422 DisplaySourceCodeError::PathNotFound,
428 if parameters.len() > 0 {
429 let parameters_to_write =
430 if f.display_target.is_source_code() || f.omit_verbose_types() {
433 .map(|generic_def_id| f.db.generic_defaults(generic_def_id))
434 .filter(|defaults| !defaults.is_empty())
436 None => parameters.0.as_ref(),
437 Some(default_parameters) => {
438 let mut default_from = 0;
439 for (i, parameter) in parameters.iter().enumerate() {
440 match (parameter, default_parameters.get(i)) {
441 (&Ty::Unknown, _) | (_, None) => {
442 default_from = i + 1;
444 (_, Some(default_parameter)) => {
445 let actual_default = default_parameter
447 .subst(¶meters.prefix(i));
448 if parameter != &actual_default {
449 default_from = i + 1;
454 ¶meters.0[0..default_from]
458 parameters.0.as_ref()
460 if !parameters_to_write.is_empty() {
462 f.write_joined(parameters_to_write, ", ")?;
467 Ty::AssociatedType(type_alias, parameters) => {
468 let trait_ = match type_alias.lookup(f.db.upcast()).container {
469 AssocContainerId::TraitId(it) => it,
470 _ => panic!("not an associated type"),
472 let trait_ = f.db.trait_data(trait_);
473 let type_alias_data = f.db.type_alias_data(*type_alias);
475 // Use placeholder associated types when the target is test (https://rust-lang.github.io/chalk/book/clauses/type_equality.html#placeholder-associated-types)
476 if f.display_target.is_test() {
477 write!(f, "{}::{}", trait_.name, type_alias_data.name)?;
478 if parameters.len() > 0 {
480 f.write_joined(&*parameters.0, ", ")?;
485 ProjectionTy { associated_ty: *type_alias, parameters: parameters.clone() };
487 projection_ty.hir_fmt(f)?;
490 Ty::ForeignType(type_alias) => {
491 let type_alias = f.db.type_alias_data(*type_alias);
492 write!(f, "{}", type_alias.name)?;
494 Ty::OpaqueType(opaque_ty_id, parameters) => {
496 &OpaqueTyId::ReturnTypeImplTrait(func, idx) => {
498 f.db.return_type_impl_traits(func).expect("impl trait id without data");
501 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
502 let bounds = data.subst(¶meters);
503 write_bounds_like_dyn_trait_with_prefix("impl", &bounds.value, f)?;
504 // FIXME: it would maybe be good to distinguish this from the alias type (when debug printing), and to show the substitution
506 OpaqueTyId::AsyncBlockTypeImplTrait(..) => {
507 write!(f, "impl Future<Output = ")?;
508 parameters[0].hir_fmt(f)?;
513 Ty::Closure(.., substs) => {
514 let sig = substs[0].callable_sig(f.db);
515 if let Some(sig) = sig {
516 if sig.params().is_empty() {
518 } else if f.omit_verbose_types() {
519 write!(f, "|{}|", TYPE_HINT_TRUNCATION)?;
522 f.write_joined(sig.params(), ", ")?;
526 let ret_display = sig.ret().into_displayable(
529 f.omit_verbose_types,
532 write!(f, " -> {}", ret_display)?;
534 write!(f, "{{closure}}")?;
537 Ty::Placeholder(id) => {
538 let generics = generics(f.db.upcast(), id.parent);
539 let param_data = &generics.params.types[id.local_id];
540 match param_data.provenance {
541 TypeParamProvenance::TypeParamList | TypeParamProvenance::TraitSelf => {
542 write!(f, "{}", param_data.name.clone().unwrap_or_else(Name::missing))?
544 TypeParamProvenance::ArgumentImplTrait => {
545 let bounds = f.db.generic_predicates_for_param(*id);
546 let substs = Substs::type_params_for_generics(&generics);
547 write_bounds_like_dyn_trait_with_prefix(
549 &bounds.iter().map(|b| b.clone().subst(&substs)).collect::<Vec<_>>(),
555 Ty::BoundVar(idx) => write!(f, "?{}.{}", idx.debruijn.depth(), idx.index)?,
556 Ty::Dyn(predicates) => {
557 write_bounds_like_dyn_trait_with_prefix("dyn", predicates, f)?;
559 Ty::Alias(AliasTy::Projection(p_ty)) => p_ty.hir_fmt(f)?,
560 Ty::Alias(AliasTy::Opaque(opaque_ty)) => {
561 match opaque_ty.opaque_ty_id {
562 OpaqueTyId::ReturnTypeImplTrait(func, idx) => {
564 f.db.return_type_impl_traits(func).expect("impl trait id without data");
567 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
568 let bounds = data.subst(&opaque_ty.parameters);
569 write_bounds_like_dyn_trait_with_prefix("impl", &bounds.value, f)?;
571 OpaqueTyId::AsyncBlockTypeImplTrait(..) => {
572 write!(f, "{{async block}}")?;
577 if f.display_target.is_source_code() {
578 return Err(HirDisplayError::DisplaySourceCodeError(
579 DisplaySourceCodeError::UnknownType,
582 write!(f, "{{unknown}}")?;
584 Ty::InferenceVar(..) => write!(f, "_")?,
590 impl HirDisplay for CallableSig {
591 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
593 f.write_joined(self.params(), ", ")?;
595 if self.params().is_empty() {
602 let ret = self.ret();
603 if *ret != Ty::unit() {
605 ret.into_displayable(f.db, f.max_size, f.omit_verbose_types, f.display_target);
606 write!(f, " -> {}", ret_display)?;
612 fn fn_traits(db: &dyn DefDatabase, trait_: TraitId) -> impl Iterator<Item = TraitId> {
613 let krate = trait_.lookup(db).container.module(db).krate();
615 db.lang_item(krate, "fn".into()),
616 db.lang_item(krate, "fn_mut".into()),
617 db.lang_item(krate, "fn_once".into()),
619 // FIXME: Replace ArrayVec when into_iter is a thing on arrays
620 ArrayVec::from(fn_traits).into_iter().flatten().flat_map(|it| it.as_trait())
623 pub fn write_bounds_like_dyn_trait_with_prefix(
625 predicates: &[GenericPredicate],
626 f: &mut HirFormatter,
627 ) -> Result<(), HirDisplayError> {
628 write!(f, "{}", prefix)?;
629 if !predicates.is_empty() {
631 write_bounds_like_dyn_trait(predicates, f)
637 fn write_bounds_like_dyn_trait(
638 predicates: &[GenericPredicate],
639 f: &mut HirFormatter,
640 ) -> Result<(), HirDisplayError> {
641 // Note: This code is written to produce nice results (i.e.
642 // corresponding to surface Rust) for types that can occur in
643 // actual Rust. It will have weird results if the predicates
644 // aren't as expected (i.e. self types = $0, projection
645 // predicates for a certain trait come after the Implemented
646 // predicate for that trait).
647 let mut first = true;
648 let mut angle_open = false;
649 let mut is_fn_trait = false;
650 for p in predicates.iter() {
652 GenericPredicate::Implemented(trait_ref) => {
653 let trait_ = trait_ref.trait_;
655 is_fn_trait = fn_traits(f.db.upcast(), trait_).any(|it| it == trait_);
657 if !is_fn_trait && angle_open {
664 // We assume that the self type is $0 (i.e. the
665 // existential) here, which is the only thing that's
666 // possible in actual Rust, and hence don't print it
667 write!(f, "{}", f.db.trait_data(trait_).name)?;
668 if let [_, params @ ..] = &*trait_ref.substs.0 {
670 if let Some(args) = params.first().and_then(|it| it.as_tuple()) {
672 f.write_joined(&*args.0, ", ")?;
675 } else if !params.is_empty() {
677 f.write_joined(params, ", ")?;
678 // there might be assoc type bindings, so we leave the angle brackets open
683 GenericPredicate::Projection(projection_pred) if is_fn_trait => {
686 projection_pred.ty.hir_fmt(f)?;
688 GenericPredicate::Projection(projection_pred) => {
689 // in types in actual Rust, these will always come
690 // after the corresponding Implemented predicate
697 let type_alias = f.db.type_alias_data(projection_pred.projection_ty.associated_ty);
698 write!(f, "{} = ", type_alias.name)?;
699 projection_pred.ty.hir_fmt(f)?;
701 GenericPredicate::Error => {
703 // impl Trait<X, {error}>
706 // impl Trait + {error}
721 fn hir_fmt_ext(&self, f: &mut HirFormatter, use_as: bool) -> Result<(), HirDisplayError> {
722 if f.should_truncate() {
723 return write!(f, "{}", TYPE_HINT_TRUNCATION);
726 self.substs[0].hir_fmt(f)?;
732 write!(f, "{}", f.db.trait_data(self.trait_).name)?;
733 if self.substs.len() > 1 {
735 f.write_joined(&self.substs[1..], ", ")?;
742 impl HirDisplay for TraitRef {
743 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
744 self.hir_fmt_ext(f, false)
748 impl HirDisplay for &GenericPredicate {
749 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
750 HirDisplay::hir_fmt(*self, f)
754 impl HirDisplay for GenericPredicate {
755 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
756 if f.should_truncate() {
757 return write!(f, "{}", TYPE_HINT_TRUNCATION);
761 GenericPredicate::Implemented(trait_ref) => trait_ref.hir_fmt(f)?,
762 GenericPredicate::Projection(projection_pred) => {
764 projection_pred.projection_ty.trait_ref(f.db).hir_fmt_ext(f, true)?;
768 f.db.type_alias_data(projection_pred.projection_ty.associated_ty).name,
770 projection_pred.ty.hir_fmt(f)?;
772 GenericPredicate::Error => write!(f, "{{error}}")?,
778 impl HirDisplay for Lifetime {
779 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
781 Lifetime::Parameter(id) => {
782 let generics = generics(f.db.upcast(), id.parent);
783 let param_data = &generics.params.lifetimes[id.local_id];
784 write!(f, "{}", ¶m_data.name)
786 Lifetime::Static => write!(f, "'static"),
791 impl HirDisplay for Obligation {
792 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
794 Obligation::Trait(tr) => {
795 write!(f, "Implements(")?;
799 Obligation::Projection(proj) => {
800 write!(f, "Normalize(")?;
801 proj.projection_ty.hir_fmt(f)?;