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> { ... }`
81 Static(ast::Mutability),
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]`
109 /// An inline constant, e.g. `const { 1 + 2 }`
111 /// Opaque type, aka `impl Trait`.
114 /// Lifetime parameter: the `'a` in `struct Foo<'a> { ... }`
116 /// A use of `global_asm!`.
124 pub fn descr(self, def_id: DefId) -> &'static str {
126 DefKind::Fn => "function",
127 DefKind::Mod if def_id.index == CRATE_DEF_INDEX && def_id.krate != LOCAL_CRATE => {
130 DefKind::Mod => "module",
131 DefKind::Static(..) => "static",
132 DefKind::Enum => "enum",
133 DefKind::Variant => "variant",
134 DefKind::Ctor(CtorOf::Variant, CtorKind::Fn) => "tuple variant",
135 DefKind::Ctor(CtorOf::Variant, CtorKind::Const) => "unit variant",
136 DefKind::Ctor(CtorOf::Variant, CtorKind::Fictive) => "struct variant",
137 DefKind::Struct => "struct",
138 DefKind::Ctor(CtorOf::Struct, CtorKind::Fn) => "tuple struct",
139 DefKind::Ctor(CtorOf::Struct, CtorKind::Const) => "unit struct",
140 DefKind::Ctor(CtorOf::Struct, CtorKind::Fictive) => {
141 panic!("impossible struct constructor")
143 DefKind::OpaqueTy => "opaque type",
144 DefKind::TyAlias => "type alias",
145 DefKind::TraitAlias => "trait alias",
146 DefKind::AssocTy => "associated type",
147 DefKind::Union => "union",
148 DefKind::Trait => "trait",
149 DefKind::ForeignTy => "foreign type",
150 DefKind::AssocFn => "associated function",
151 DefKind::Const => "constant",
152 DefKind::AssocConst => "associated constant",
153 DefKind::TyParam => "type parameter",
154 DefKind::ConstParam => "const parameter",
155 DefKind::Macro(macro_kind) => macro_kind.descr(),
156 DefKind::LifetimeParam => "lifetime parameter",
157 DefKind::Use => "import",
158 DefKind::ForeignMod => "foreign module",
159 DefKind::AnonConst => "constant expression",
160 DefKind::InlineConst => "inline constant",
161 DefKind::Field => "field",
162 DefKind::Impl => "implementation",
163 DefKind::Closure => "closure",
164 DefKind::Generator => "generator",
165 DefKind::ExternCrate => "extern crate",
166 DefKind::GlobalAsm => "global assembly block",
170 /// Gets an English article for the definition.
171 pub fn article(&self) -> &'static str {
174 | DefKind::AssocConst
180 | DefKind::InlineConst
181 | DefKind::ExternCrate => "an",
182 DefKind::Macro(macro_kind) => macro_kind.article(),
187 pub fn ns(&self) -> Option<Namespace> {
198 | DefKind::TraitAlias
200 | DefKind::TyParam => Some(Namespace::TypeNS),
204 | DefKind::ConstParam
205 | DefKind::Static(..)
208 | DefKind::AssocConst => Some(Namespace::ValueNS),
210 DefKind::Macro(..) => Some(Namespace::MacroNS),
214 | DefKind::InlineConst
216 | DefKind::LifetimeParam
217 | DefKind::ExternCrate
221 | DefKind::ForeignMod
223 | DefKind::Impl => None,
228 /// The resolution of a path or export.
230 /// For every path or identifier in Rust, the compiler must determine
231 /// what the path refers to. This process is called name resolution,
232 /// and `Res` is the primary result of name resolution.
234 /// For example, everything prefixed with `/* Res */` in this example has
235 /// an associated `Res`:
238 /// fn str_to_string(s: & /* Res */ str) -> /* Res */ String {
239 /// /* Res */ String::from(/* Res */ s)
242 /// /* Res */ str_to_string("hello");
245 /// The associated `Res`s will be:
247 /// - `str` will resolve to [`Res::PrimTy`];
248 /// - `String` will resolve to [`Res::Def`], and the `Res` will include the [`DefId`]
249 /// for `String` as defined in the standard library;
250 /// - `String::from` will also resolve to [`Res::Def`], with the [`DefId`]
251 /// pointing to `String::from`;
252 /// - `s` will resolve to [`Res::Local`];
253 /// - the call to `str_to_string` will resolve to [`Res::Def`], with the [`DefId`]
254 /// pointing to the definition of `str_to_string` in the current crate.
256 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
257 #[derive(HashStable_Generic)]
258 pub enum Res<Id = hir::HirId> {
259 /// Definition having a unique ID (`DefId`), corresponds to something defined in user code.
261 /// **Not bound to a specific namespace.**
265 /// A primitive type such as `i32` or `str`.
267 /// **Belongs to the type namespace.**
269 /// The `Self` type, optionally with the [`DefId`] of the trait it belongs to and
270 /// optionally with the [`DefId`] of the item introducing the `Self` type alias.
272 /// **Belongs to the type namespace.**
276 /// struct Bar(Box<Self>);
277 /// // `Res::SelfTy { trait_: None, alias_of: Some(Bar) }`
280 /// fn foo() -> Box<Self>;
281 /// // `Res::SelfTy { trait_: Some(Foo), alias_of: None }`
287 /// // `Res::SelfTy { trait_: None, alias_of: Some(::{impl#0}) }`
291 /// impl Foo for Bar {
292 /// fn foo() -> Box<Self> {
293 /// // `Res::SelfTy { trait_: Some(Foo), alias_of: Some(::{impl#1}) }`
295 /// // `Res::SelfTy { trait_: Some(Foo), alias_of: Some(::{impl#1}) }`
302 /// *See also [`Res::SelfCtor`].*
306 /// HACK(min_const_generics): self types also have an optional requirement to **not** mention
307 /// any generic parameters to allow the following with `min_const_generics`:
309 /// impl Foo { fn test() -> [u8; std::mem::size_of::<Self>()] { todo!() } }
311 /// struct Bar([u8; baz::<Self>()]);
312 /// const fn baz<T>() -> usize { 10 }
314 /// We do however allow `Self` in repeat expression even if it is generic to not break code
315 /// which already works on stable while causing the `const_evaluatable_unchecked` future compat lint:
318 /// let _bar = [1_u8; std::mem::size_of::<*mut T>()];
321 // FIXME(generic_const_exprs): Remove this bodge once that feature is stable.
323 /// The trait this `Self` is a generic arg for.
324 trait_: Option<DefId>,
325 /// The item introducing the `Self` type alias. Can be used in the `type_of` query
326 /// to get the underlying type. Additionally whether the `Self` type is disallowed
327 /// from mentioning generics (i.e. when used in an anonymous constant).
328 alias_to: Option<(DefId, bool)>,
330 /// A tool attribute module; e.g., the `rustfmt` in `#[rustfmt::skip]`.
332 /// **Belongs to the type namespace.**
336 /// The `Self` constructor, along with the [`DefId`]
337 /// of the impl it is associated with.
339 /// **Belongs to the value namespace.**
341 /// *See also [`Res::SelfTy`].*
343 /// A local variable or function parameter.
345 /// **Belongs to the value namespace.**
349 /// An attribute that is *not* implemented via macro.
350 /// E.g., `#[inline]` and `#[rustfmt::skip]`, which are essentially directives,
351 /// as opposed to `#[test]`, which is a builtin macro.
353 /// **Belongs to the macro namespace.**
354 NonMacroAttr(NonMacroAttrKind), // e.g., `#[inline]` or `#[rustfmt::skip]`
357 /// Name resolution failed. We use a dummy `Res` variant so later phases
358 /// of the compiler won't crash and can instead report more errors.
360 /// **Not bound to a specific namespace.**
364 /// The result of resolving a path before lowering to HIR,
365 /// with "module" segments resolved and associated item
366 /// segments deferred to type checking.
367 /// `base_res` is the resolution of the resolved part of the
368 /// path, `unresolved_segments` is the number of unresolved
372 /// module::Type::AssocX::AssocY::MethodOrAssocType
373 /// ^~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
374 /// base_res unresolved_segments = 3
376 /// <T as Trait>::AssocX::AssocY::MethodOrAssocType
377 /// ^~~~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~
378 /// base_res unresolved_segments = 2
380 #[derive(Copy, Clone, Debug)]
381 pub struct PartialRes {
382 base_res: Res<NodeId>,
383 unresolved_segments: usize,
388 pub fn new(base_res: Res<NodeId>) -> Self {
389 PartialRes { base_res, unresolved_segments: 0 }
393 pub fn with_unresolved_segments(base_res: Res<NodeId>, mut unresolved_segments: usize) -> Self {
394 if base_res == Res::Err {
395 unresolved_segments = 0
397 PartialRes { base_res, unresolved_segments }
401 pub fn base_res(&self) -> Res<NodeId> {
406 pub fn unresolved_segments(&self) -> usize {
407 self.unresolved_segments
411 /// Different kinds of symbols can coexist even if they share the same textual name.
412 /// Therefore, they each have a separate universe (known as a "namespace").
413 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
415 /// The type namespace includes `struct`s, `enum`s, `union`s, `trait`s, and `mod`s
416 /// (and, by extension, crates).
418 /// Note that the type namespace includes other items; this is not an
421 /// The value namespace includes `fn`s, `const`s, `static`s, and local variables (including function arguments).
423 /// The macro namespace includes `macro_rules!` macros, declarative `macro`s,
424 /// procedural macros, attribute macros, `derive` macros, and non-macro attributes
425 /// like `#[inline]` and `#[rustfmt::skip]`.
430 /// The English description of the namespace.
431 pub fn descr(self) -> &'static str {
433 Self::TypeNS => "type",
434 Self::ValueNS => "value",
435 Self::MacroNS => "macro",
440 /// Just a helper ‒ separate structure for each namespace.
441 #[derive(Copy, Clone, Default, Debug)]
442 pub struct PerNS<T> {
449 pub fn map<U, F: FnMut(T) -> U>(self, mut f: F) -> PerNS<U> {
450 PerNS { value_ns: f(self.value_ns), type_ns: f(self.type_ns), macro_ns: f(self.macro_ns) }
453 pub fn into_iter(self) -> IntoIter<T, 3> {
454 [self.value_ns, self.type_ns, self.macro_ns].into_iter()
457 pub fn iter(&self) -> IntoIter<&T, 3> {
458 [&self.value_ns, &self.type_ns, &self.macro_ns].into_iter()
462 impl<T> ::std::ops::Index<Namespace> for PerNS<T> {
465 fn index(&self, ns: Namespace) -> &T {
467 Namespace::ValueNS => &self.value_ns,
468 Namespace::TypeNS => &self.type_ns,
469 Namespace::MacroNS => &self.macro_ns,
474 impl<T> ::std::ops::IndexMut<Namespace> for PerNS<T> {
475 fn index_mut(&mut self, ns: Namespace) -> &mut T {
477 Namespace::ValueNS => &mut self.value_ns,
478 Namespace::TypeNS => &mut self.type_ns,
479 Namespace::MacroNS => &mut self.macro_ns,
484 impl<T> PerNS<Option<T>> {
485 /// Returns `true` if all the items in this collection are `None`.
486 pub fn is_empty(&self) -> bool {
487 self.type_ns.is_none() && self.value_ns.is_none() && self.macro_ns.is_none()
490 /// Returns an iterator over the items which are `Some`.
491 pub fn present_items(self) -> impl Iterator<Item = T> {
492 [self.type_ns, self.value_ns, self.macro_ns].into_iter().flatten()
497 pub fn from_ast(vdata: &ast::VariantData) -> CtorKind {
499 ast::VariantData::Tuple(..) => CtorKind::Fn,
500 ast::VariantData::Unit(..) => CtorKind::Const,
501 ast::VariantData::Struct(..) => CtorKind::Fictive,
505 pub fn from_hir(vdata: &hir::VariantData<'_>) -> CtorKind {
507 hir::VariantData::Tuple(..) => CtorKind::Fn,
508 hir::VariantData::Unit(..) => CtorKind::Const,
509 hir::VariantData::Struct(..) => CtorKind::Fictive,
514 impl NonMacroAttrKind {
515 pub fn descr(self) -> &'static str {
517 NonMacroAttrKind::Builtin(..) => "built-in attribute",
518 NonMacroAttrKind::Tool => "tool attribute",
519 NonMacroAttrKind::DeriveHelper | NonMacroAttrKind::DeriveHelperCompat => {
520 "derive helper attribute"
522 NonMacroAttrKind::Registered => "explicitly registered attribute",
526 pub fn article(self) -> &'static str {
528 NonMacroAttrKind::Registered => "an",
533 /// Users of some attributes cannot mark them as used, so they are considered always used.
534 pub fn is_used(self) -> bool {
536 NonMacroAttrKind::Tool
537 | NonMacroAttrKind::DeriveHelper
538 | NonMacroAttrKind::DeriveHelperCompat => true,
539 NonMacroAttrKind::Builtin(..) | NonMacroAttrKind::Registered => false,
545 /// Return the `DefId` of this `Def` if it has an ID, else panic.
546 pub fn def_id(&self) -> DefId
551 .unwrap_or_else(|| panic!("attempted .def_id() on invalid res: {:?}", self))
554 /// Return `Some(..)` with the `DefId` of this `Res` if it has a ID, else `None`.
555 pub fn opt_def_id(&self) -> Option<DefId> {
557 Res::Def(_, id) => Some(id),
564 | Res::NonMacroAttr(..)
569 /// Return the `DefId` of this `Res` if it represents a module.
570 pub fn mod_def_id(&self) -> Option<DefId> {
572 Res::Def(DefKind::Mod, id) => Some(id),
577 /// A human readable name for the res kind ("function", "module", etc.).
578 pub fn descr(&self) -> &'static str {
580 Res::Def(kind, def_id) => kind.descr(def_id),
581 Res::SelfCtor(..) => "self constructor",
582 Res::PrimTy(..) => "builtin type",
583 Res::Local(..) => "local variable",
584 Res::SelfTy { .. } => "self type",
585 Res::ToolMod => "tool module",
586 Res::NonMacroAttr(attr_kind) => attr_kind.descr(),
587 Res::Err => "unresolved item",
591 /// Gets an English article for the `Res`.
592 pub fn article(&self) -> &'static str {
594 Res::Def(kind, _) => kind.article(),
595 Res::NonMacroAttr(kind) => kind.article(),
601 pub fn map_id<R>(self, mut map: impl FnMut(Id) -> R) -> Res<R> {
603 Res::Def(kind, id) => Res::Def(kind, id),
604 Res::SelfCtor(id) => Res::SelfCtor(id),
605 Res::PrimTy(id) => Res::PrimTy(id),
606 Res::Local(id) => Res::Local(map(id)),
607 Res::SelfTy { trait_, alias_to } => Res::SelfTy { trait_, alias_to },
608 Res::ToolMod => Res::ToolMod,
609 Res::NonMacroAttr(attr_kind) => Res::NonMacroAttr(attr_kind),
610 Res::Err => Res::Err,
614 pub fn apply_id<R, E>(self, mut map: impl FnMut(Id) -> Result<R, E>) -> Result<Res<R>, E> {
616 Res::Def(kind, id) => Res::Def(kind, id),
617 Res::SelfCtor(id) => Res::SelfCtor(id),
618 Res::PrimTy(id) => Res::PrimTy(id),
619 Res::Local(id) => Res::Local(map(id)?),
620 Res::SelfTy { trait_, alias_to } => Res::SelfTy { trait_, alias_to },
621 Res::ToolMod => Res::ToolMod,
622 Res::NonMacroAttr(attr_kind) => Res::NonMacroAttr(attr_kind),
623 Res::Err => Res::Err,
628 pub fn expect_non_local<OtherId>(self) -> Res<OtherId> {
629 self.map_id(|_| panic!("unexpected `Res::Local`"))
632 pub fn macro_kind(self) -> Option<MacroKind> {
634 Res::Def(DefKind::Macro(kind), _) => Some(kind),
635 Res::NonMacroAttr(..) => Some(MacroKind::Attr),
640 /// Returns `None` if this is `Res::Err`
641 pub fn ns(&self) -> Option<Namespace> {
643 Res::Def(kind, ..) => kind.ns(),
644 Res::PrimTy(..) | Res::SelfTy { .. } | Res::ToolMod => Some(Namespace::TypeNS),
645 Res::SelfCtor(..) | Res::Local(..) => Some(Namespace::ValueNS),
646 Res::NonMacroAttr(..) => Some(Namespace::MacroNS),
651 /// Always returns `true` if `self` is `Res::Err`
652 pub fn matches_ns(&self, ns: Namespace) -> bool {
653 self.ns().map_or(true, |actual_ns| actual_ns == ns)
656 /// Returns whether such a resolved path can occur in a tuple struct/variant pattern
657 pub fn expected_in_tuple_struct_pat(&self) -> bool {
658 matches!(self, Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..))