1 use crate::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
6 use rustc_macros::HashStable_Generic;
7 use rustc_span::hygiene::MacroKind;
8 use rustc_span::Symbol;
10 use std::array::IntoIter;
13 /// Encodes if a `DefKind::Ctor` is the constructor of an enum variant or a struct.
14 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
15 #[derive(HashStable_Generic)]
17 /// This `DefKind::Ctor` is a synthesized constructor of a tuple or unit struct.
19 /// This `DefKind::Ctor` is a synthesized constructor of a tuple or unit variant.
23 /// What kind of constructor something is.
24 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
25 #[derive(HashStable_Generic)]
27 /// Constructor function automatically created by a tuple struct/variant.
29 /// Constructor constant automatically created by a unit struct/variant.
31 /// Unusable name in value namespace created by a struct variant.
35 /// An attribute that is not a macro; e.g., `#[inline]` or `#[rustfmt::skip]`.
36 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
37 #[derive(HashStable_Generic)]
38 pub enum NonMacroAttrKind {
39 /// Single-segment attribute defined by the language (`#[inline]`)
41 /// Multi-segment custom attribute living in a "tool module" (`#[rustfmt::skip]`).
43 /// Single-segment custom attribute registered by a derive macro (`#[serde(default)]`).
45 /// Single-segment custom attribute registered by a derive macro
46 /// but used before that derive macro was expanded (deprecated).
48 /// Single-segment custom attribute registered with `#[register_attr]`.
52 /// What kind of definition something is; e.g., `mod` vs `struct`.
53 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
54 #[derive(HashStable_Generic)]
58 /// Refers to the struct itself, [`DefKind::Ctor`] refers to its constructor if it exists.
62 /// Refers to the variant itself, [`DefKind::Ctor`] refers to its constructor if it exists.
65 /// Type alias: `type Foo = Bar;`
67 /// Type from an `extern` block.
69 /// Trait alias: `trait IntIterator = Iterator<Item = i32>;`
71 /// Associated type: `trait MyTrait { type Assoc; }`
73 /// Type parameter: the `T` in `struct Vec<T> { ... }`
79 /// Constant generic parameter: `struct Foo<const N: usize> { ... }`
82 /// Refers to the struct or enum variant's constructor.
84 /// The reason `Ctor` exists in addition to [`DefKind::Struct`] and
85 /// [`DefKind::Variant`] is because structs and enum variants exist
86 /// in the *type* namespace, whereas struct and enum variant *constructors*
87 /// exist in the *value* namespace.
89 /// You may wonder why enum variants exist in the type namespace as opposed
90 /// to the value namespace. Check out [RFC 2593] for intuition on why that is.
92 /// [RFC 2593]: https://github.com/rust-lang/rfcs/pull/2593
93 Ctor(CtorOf, CtorKind),
94 /// Associated function: `impl MyStruct { fn associated() {} }`
96 /// Associated constant: `trait MyTrait { const ASSOC: usize; }`
102 // Not namespaced (or they are, but we don't treat them so)
105 /// An `extern` block.
107 /// Anonymous constant, e.g. the `1 + 2` in `[u8; 1 + 2]`, or `const { 1 + 2}`
109 /// Opaque type, aka `impl Trait`.
112 /// Lifetime parameter: the `'a` in `struct Foo<'a> { ... }`
114 /// A use of [`global_asm!`].
122 pub fn descr(self, def_id: DefId) -> &'static str {
124 DefKind::Fn => "function",
125 DefKind::Mod if def_id.index == CRATE_DEF_INDEX && def_id.krate != LOCAL_CRATE => {
128 DefKind::Mod => "module",
129 DefKind::Static => "static",
130 DefKind::Enum => "enum",
131 DefKind::Variant => "variant",
132 DefKind::Ctor(CtorOf::Variant, CtorKind::Fn) => "tuple variant",
133 DefKind::Ctor(CtorOf::Variant, CtorKind::Const) => "unit variant",
134 DefKind::Ctor(CtorOf::Variant, CtorKind::Fictive) => "struct variant",
135 DefKind::Struct => "struct",
136 DefKind::Ctor(CtorOf::Struct, CtorKind::Fn) => "tuple struct",
137 DefKind::Ctor(CtorOf::Struct, CtorKind::Const) => "unit struct",
138 DefKind::Ctor(CtorOf::Struct, CtorKind::Fictive) => {
139 panic!("impossible struct constructor")
141 DefKind::OpaqueTy => "opaque type",
142 DefKind::TyAlias => "type alias",
143 DefKind::TraitAlias => "trait alias",
144 DefKind::AssocTy => "associated type",
145 DefKind::Union => "union",
146 DefKind::Trait => "trait",
147 DefKind::ForeignTy => "foreign type",
148 DefKind::AssocFn => "associated function",
149 DefKind::Const => "constant",
150 DefKind::AssocConst => "associated constant",
151 DefKind::TyParam => "type parameter",
152 DefKind::ConstParam => "const parameter",
153 DefKind::Macro(macro_kind) => macro_kind.descr(),
154 DefKind::LifetimeParam => "lifetime parameter",
155 DefKind::Use => "import",
156 DefKind::ForeignMod => "foreign module",
157 DefKind::AnonConst => "constant expression",
158 DefKind::Field => "field",
159 DefKind::Impl => "implementation",
160 DefKind::Closure => "closure",
161 DefKind::Generator => "generator",
162 DefKind::ExternCrate => "extern crate",
163 DefKind::GlobalAsm => "global assembly block",
167 /// Gets an English article for the definition.
168 pub fn article(&self) -> &'static str {
171 | DefKind::AssocConst
177 | DefKind::ExternCrate => "an",
178 DefKind::Macro(macro_kind) => macro_kind.article(),
183 pub fn ns(&self) -> Option<Namespace> {
194 | DefKind::TraitAlias
196 | DefKind::TyParam => Some(Namespace::TypeNS),
200 | DefKind::ConstParam
204 | DefKind::AssocConst => Some(Namespace::ValueNS),
206 DefKind::Macro(..) => Some(Namespace::MacroNS),
211 | DefKind::LifetimeParam
212 | DefKind::ExternCrate
216 | DefKind::ForeignMod
218 | DefKind::Impl => None,
223 /// The resolution of a path or export.
225 /// For every path or identifier in Rust, the compiler must determine
226 /// what the path refers to. This process is called name resolution,
227 /// and `Res` is the primary result of name resolution.
229 /// For example, everything prefixed with `/* Res */` in this example has
230 /// an associated `Res`:
233 /// fn str_to_string(s: & /* Res */ str) -> /* Res */ String {
234 /// /* Res */ String::from(/* Res */ s)
237 /// /* Res */ str_to_string("hello");
240 /// The associated `Res`s will be:
242 /// - `str` will resolve to [`Res::PrimTy`];
243 /// - `String` will resolve to [`Res::Def`], and the `Res` will include the [`DefId`]
244 /// for `String` as defined in the standard library;
245 /// - `String::from` will also resolve to [`Res::Def`], with the [`DefId`]
246 /// pointing to `String::from`;
247 /// - `s` will resolve to [`Res::Local`];
248 /// - the call to `str_to_string` will resolve to [`Res::Def`], with the [`DefId`]
249 /// pointing to the definition of `str_to_string` in the current crate.
251 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
252 #[derive(HashStable_Generic)]
253 pub enum Res<Id = hir::HirId> {
254 /// Definition having a unique ID (`DefId`), corresponds to something defined in user code.
256 /// **Not bound to a specific namespace.**
260 /// A primitive type such as `i32` or `str`.
262 /// **Belongs to the type namespace.**
264 /// The `Self` type, optionally with the trait it is associated with
265 /// and optionally with the [`DefId`] of the impl it is associated with.
267 /// **Belongs to the type namespace.**
269 /// For example, the `Self` in
273 /// fn foo() -> Box<Self>;
277 /// would have the [`DefId`] of `Foo` associated with it. The `Self` in
283 /// fn new() -> Self { Bar }
287 /// would have the [`DefId`] of the impl associated with it. Finally, the `Self` in
290 /// impl Foo for Bar {
291 /// fn foo() -> Box<Self> { Box::new(Bar) }
295 /// would have both the [`DefId`] of `Foo` and the [`DefId`] of the impl
296 /// associated with it.
298 /// *See also [`Res::SelfCtor`].*
302 /// HACK(min_const_generics): impl self types also have an optional requirement to **not** mention
303 /// any generic parameters to allow the following with `min_const_generics`:
305 /// impl Foo { fn test() -> [u8; std::mem::size_of::<Self>()] { todo!() } }
307 /// We do however allow `Self` in repeat expression even if it is generic to not break code
308 /// which already works on stable while causing the `const_evaluatable_unchecked` future compat lint.
310 /// FIXME(lazy_normalization_consts): Remove this bodge once that feature is stable.
312 /// Optionally, the trait associated with this `Self` type.
314 /// Optionally, the impl associated with this `Self` type.
315 Option<(DefId, bool)>,
317 /// A tool attribute module; e.g., the `rustfmt` in `#[rustfmt::skip]`.
319 /// **Belongs to the type namespace.**
323 /// The `Self` constructor, along with the [`DefId`]
324 /// of the impl it is associated with.
326 /// **Belongs to the value namespace.**
328 /// *See also [`Res::SelfTy`].*
330 /// A local variable or function parameter.
332 /// **Belongs to the value namespace.**
336 /// An attribute that is *not* implemented via macro.
337 /// E.g., `#[inline]` and `#[rustfmt::skip]`, which are essentially directives,
338 /// as opposed to `#[test]`, which is a builtin macro.
340 /// **Belongs to the macro namespace.**
341 NonMacroAttr(NonMacroAttrKind), // e.g., `#[inline]` or `#[rustfmt::skip]`
344 /// Name resolution failed. We use a dummy `Res` variant so later phases
345 /// of the compiler won't crash and can instead report more errors.
347 /// **Not bound to a specific namespace.**
351 /// The result of resolving a path before lowering to HIR,
352 /// with "module" segments resolved and associated item
353 /// segments deferred to type checking.
354 /// `base_res` is the resolution of the resolved part of the
355 /// path, `unresolved_segments` is the number of unresolved
359 /// module::Type::AssocX::AssocY::MethodOrAssocType
360 /// ^~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
361 /// base_res unresolved_segments = 3
363 /// <T as Trait>::AssocX::AssocY::MethodOrAssocType
364 /// ^~~~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~
365 /// base_res unresolved_segments = 2
367 #[derive(Copy, Clone, Debug)]
368 pub struct PartialRes {
369 base_res: Res<NodeId>,
370 unresolved_segments: usize,
375 pub fn new(base_res: Res<NodeId>) -> Self {
376 PartialRes { base_res, unresolved_segments: 0 }
380 pub fn with_unresolved_segments(base_res: Res<NodeId>, mut unresolved_segments: usize) -> Self {
381 if base_res == Res::Err {
382 unresolved_segments = 0
384 PartialRes { base_res, unresolved_segments }
388 pub fn base_res(&self) -> Res<NodeId> {
393 pub fn unresolved_segments(&self) -> usize {
394 self.unresolved_segments
398 /// Different kinds of symbols can coexist even if they share the same textual name.
399 /// Therefore, they each have a separate universe (known as a "namespace").
400 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
402 /// The type namespace includes `struct`s, `enum`s, `union`s, `trait`s, and `mod`s
403 /// (and, by extension, crates).
405 /// Note that the type namespace includes other items; this is not an
408 /// The value namespace includes `fn`s, `const`s, `static`s, and local variables (including function arguments).
410 /// The macro namespace includes `macro_rules!` macros, declarative `macro`s,
411 /// procedural macros, attribute macros, `derive` macros, and non-macro attributes
412 /// like `#[inline]` and `#[rustfmt::skip]`.
417 /// The English description of the namespace.
418 pub fn descr(self) -> &'static str {
420 Self::TypeNS => "type",
421 Self::ValueNS => "value",
422 Self::MacroNS => "macro",
427 /// Just a helper ‒ separate structure for each namespace.
428 #[derive(Copy, Clone, Default, Debug)]
429 pub struct PerNS<T> {
436 pub fn map<U, F: FnMut(T) -> U>(self, mut f: F) -> PerNS<U> {
437 PerNS { value_ns: f(self.value_ns), type_ns: f(self.type_ns), macro_ns: f(self.macro_ns) }
440 pub fn into_iter(self) -> IntoIter<T, 3> {
441 IntoIter::new([self.value_ns, self.type_ns, self.macro_ns])
444 pub fn iter(&self) -> IntoIter<&T, 3> {
445 IntoIter::new([&self.value_ns, &self.type_ns, &self.macro_ns])
449 impl<T> ::std::ops::Index<Namespace> for PerNS<T> {
452 fn index(&self, ns: Namespace) -> &T {
454 Namespace::ValueNS => &self.value_ns,
455 Namespace::TypeNS => &self.type_ns,
456 Namespace::MacroNS => &self.macro_ns,
461 impl<T> ::std::ops::IndexMut<Namespace> for PerNS<T> {
462 fn index_mut(&mut self, ns: Namespace) -> &mut T {
464 Namespace::ValueNS => &mut self.value_ns,
465 Namespace::TypeNS => &mut self.type_ns,
466 Namespace::MacroNS => &mut self.macro_ns,
471 impl<T> PerNS<Option<T>> {
472 /// Returns `true` if all the items in this collection are `None`.
473 pub fn is_empty(&self) -> bool {
474 self.type_ns.is_none() && self.value_ns.is_none() && self.macro_ns.is_none()
477 /// Returns an iterator over the items which are `Some`.
478 pub fn present_items(self) -> impl Iterator<Item = T> {
479 IntoIter::new([self.type_ns, self.value_ns, self.macro_ns]).filter_map(|it| it)
484 pub fn from_ast(vdata: &ast::VariantData) -> CtorKind {
486 ast::VariantData::Tuple(..) => CtorKind::Fn,
487 ast::VariantData::Unit(..) => CtorKind::Const,
488 ast::VariantData::Struct(..) => CtorKind::Fictive,
492 pub fn from_hir(vdata: &hir::VariantData<'_>) -> CtorKind {
494 hir::VariantData::Tuple(..) => CtorKind::Fn,
495 hir::VariantData::Unit(..) => CtorKind::Const,
496 hir::VariantData::Struct(..) => CtorKind::Fictive,
501 impl NonMacroAttrKind {
502 pub fn descr(self) -> &'static str {
504 NonMacroAttrKind::Builtin(..) => "built-in attribute",
505 NonMacroAttrKind::Tool => "tool attribute",
506 NonMacroAttrKind::DeriveHelper | NonMacroAttrKind::DeriveHelperCompat => {
507 "derive helper attribute"
509 NonMacroAttrKind::Registered => "explicitly registered attribute",
513 pub fn article(self) -> &'static str {
515 NonMacroAttrKind::Registered => "an",
520 /// Users of some attributes cannot mark them as used, so they are considered always used.
521 pub fn is_used(self) -> bool {
523 NonMacroAttrKind::Tool
524 | NonMacroAttrKind::DeriveHelper
525 | NonMacroAttrKind::DeriveHelperCompat => true,
526 NonMacroAttrKind::Builtin(..) | NonMacroAttrKind::Registered => false,
532 /// Return the `DefId` of this `Def` if it has an ID, else panic.
533 pub fn def_id(&self) -> DefId
538 .unwrap_or_else(|| panic!("attempted .def_id() on invalid res: {:?}", self))
541 /// Return `Some(..)` with the `DefId` of this `Res` if it has a ID, else `None`.
542 pub fn opt_def_id(&self) -> Option<DefId> {
544 Res::Def(_, id) => Some(id),
551 | Res::NonMacroAttr(..)
556 /// Return the `DefId` of this `Res` if it represents a module.
557 pub fn mod_def_id(&self) -> Option<DefId> {
559 Res::Def(DefKind::Mod, id) => Some(id),
564 /// A human readable name for the res kind ("function", "module", etc.).
565 pub fn descr(&self) -> &'static str {
567 Res::Def(kind, def_id) => kind.descr(def_id),
568 Res::SelfCtor(..) => "self constructor",
569 Res::PrimTy(..) => "builtin type",
570 Res::Local(..) => "local variable",
571 Res::SelfTy(..) => "self type",
572 Res::ToolMod => "tool module",
573 Res::NonMacroAttr(attr_kind) => attr_kind.descr(),
574 Res::Err => "unresolved item",
578 /// Gets an English article for the `Res`.
579 pub fn article(&self) -> &'static str {
581 Res::Def(kind, _) => kind.article(),
582 Res::NonMacroAttr(kind) => kind.article(),
588 pub fn map_id<R>(self, mut map: impl FnMut(Id) -> R) -> Res<R> {
590 Res::Def(kind, id) => Res::Def(kind, id),
591 Res::SelfCtor(id) => Res::SelfCtor(id),
592 Res::PrimTy(id) => Res::PrimTy(id),
593 Res::Local(id) => Res::Local(map(id)),
594 Res::SelfTy(a, b) => Res::SelfTy(a, b),
595 Res::ToolMod => Res::ToolMod,
596 Res::NonMacroAttr(attr_kind) => Res::NonMacroAttr(attr_kind),
597 Res::Err => Res::Err,
601 pub fn macro_kind(self) -> Option<MacroKind> {
603 Res::Def(DefKind::Macro(kind), _) => Some(kind),
604 Res::NonMacroAttr(..) => Some(MacroKind::Attr),
609 /// Returns `None` if this is `Res::Err`
610 pub fn ns(&self) -> Option<Namespace> {
612 Res::Def(kind, ..) => kind.ns(),
613 Res::PrimTy(..) | Res::SelfTy(..) | Res::ToolMod => Some(Namespace::TypeNS),
614 Res::SelfCtor(..) | Res::Local(..) => Some(Namespace::ValueNS),
615 Res::NonMacroAttr(..) => Some(Namespace::MacroNS),
620 /// Always returns `true` if `self` is `Res::Err`
621 pub fn matches_ns(&self, ns: Namespace) -> bool {
622 self.ns().map_or(true, |actual_ns| actual_ns == ns)
625 /// Returns whether such a resolved path can occur in a tuple struct/variant pattern
626 pub fn expected_in_tuple_struct_pat(&self) -> bool {
627 matches!(self, Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..))