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]`
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
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 trait it is associated with
270 /// and optionally with the [`DefId`] of the impl it is associated with.
272 /// **Belongs to the type namespace.**
274 /// For example, the `Self` in
278 /// fn foo() -> Box<Self>;
282 /// would have the [`DefId`] of `Foo` associated with it. The `Self` in
288 /// fn new() -> Self { Bar }
292 /// would have the [`DefId`] of the impl associated with it. Finally, the `Self` in
295 /// impl Foo for Bar {
296 /// fn foo() -> Box<Self> { Box::new(Bar) }
300 /// would have both the [`DefId`] of `Foo` and the [`DefId`] of the impl
301 /// associated with it.
303 /// *See also [`Res::SelfCtor`].*
307 /// HACK(min_const_generics): impl self types also have an optional requirement to **not** mention
308 /// any generic parameters to allow the following with `min_const_generics`:
310 /// impl Foo { fn test() -> [u8; std::mem::size_of::<Self>()] { todo!() } }
312 /// We do however allow `Self` in repeat expression even if it is generic to not break code
313 /// which already works on stable while causing the `const_evaluatable_unchecked` future compat lint.
315 /// FIXME(generic_const_exprs): Remove this bodge once that feature is stable.
317 /// Optionally, the trait associated with this `Self` type.
319 /// Optionally, the impl associated with this `Self` type.
320 Option<(DefId, bool)>,
322 /// A tool attribute module; e.g., the `rustfmt` in `#[rustfmt::skip]`.
324 /// **Belongs to the type namespace.**
328 /// The `Self` constructor, along with the [`DefId`]
329 /// of the impl it is associated with.
331 /// **Belongs to the value namespace.**
333 /// *See also [`Res::SelfTy`].*
335 /// A local variable or function parameter.
337 /// **Belongs to the value namespace.**
341 /// An attribute that is *not* implemented via macro.
342 /// E.g., `#[inline]` and `#[rustfmt::skip]`, which are essentially directives,
343 /// as opposed to `#[test]`, which is a builtin macro.
345 /// **Belongs to the macro namespace.**
346 NonMacroAttr(NonMacroAttrKind), // e.g., `#[inline]` or `#[rustfmt::skip]`
349 /// Name resolution failed. We use a dummy `Res` variant so later phases
350 /// of the compiler won't crash and can instead report more errors.
352 /// **Not bound to a specific namespace.**
356 /// The result of resolving a path before lowering to HIR,
357 /// with "module" segments resolved and associated item
358 /// segments deferred to type checking.
359 /// `base_res` is the resolution of the resolved part of the
360 /// path, `unresolved_segments` is the number of unresolved
364 /// module::Type::AssocX::AssocY::MethodOrAssocType
365 /// ^~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
366 /// base_res unresolved_segments = 3
368 /// <T as Trait>::AssocX::AssocY::MethodOrAssocType
369 /// ^~~~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~
370 /// base_res unresolved_segments = 2
372 #[derive(Copy, Clone, Debug)]
373 pub struct PartialRes {
374 base_res: Res<NodeId>,
375 unresolved_segments: usize,
380 pub fn new(base_res: Res<NodeId>) -> Self {
381 PartialRes { base_res, unresolved_segments: 0 }
385 pub fn with_unresolved_segments(base_res: Res<NodeId>, mut unresolved_segments: usize) -> Self {
386 if base_res == Res::Err {
387 unresolved_segments = 0
389 PartialRes { base_res, unresolved_segments }
393 pub fn base_res(&self) -> Res<NodeId> {
398 pub fn unresolved_segments(&self) -> usize {
399 self.unresolved_segments
403 /// Different kinds of symbols can coexist even if they share the same textual name.
404 /// Therefore, they each have a separate universe (known as a "namespace").
405 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
407 /// The type namespace includes `struct`s, `enum`s, `union`s, `trait`s, and `mod`s
408 /// (and, by extension, crates).
410 /// Note that the type namespace includes other items; this is not an
413 /// The value namespace includes `fn`s, `const`s, `static`s, and local variables (including function arguments).
415 /// The macro namespace includes `macro_rules!` macros, declarative `macro`s,
416 /// procedural macros, attribute macros, `derive` macros, and non-macro attributes
417 /// like `#[inline]` and `#[rustfmt::skip]`.
422 /// The English description of the namespace.
423 pub fn descr(self) -> &'static str {
425 Self::TypeNS => "type",
426 Self::ValueNS => "value",
427 Self::MacroNS => "macro",
432 /// Just a helper ‒ separate structure for each namespace.
433 #[derive(Copy, Clone, Default, Debug)]
434 pub struct PerNS<T> {
441 pub fn map<U, F: FnMut(T) -> U>(self, mut f: F) -> PerNS<U> {
442 PerNS { value_ns: f(self.value_ns), type_ns: f(self.type_ns), macro_ns: f(self.macro_ns) }
445 pub fn into_iter(self) -> IntoIter<T, 3> {
446 [self.value_ns, self.type_ns, self.macro_ns].into_iter()
449 pub fn iter(&self) -> IntoIter<&T, 3> {
450 [&self.value_ns, &self.type_ns, &self.macro_ns].into_iter()
454 impl<T> ::std::ops::Index<Namespace> for PerNS<T> {
457 fn index(&self, ns: Namespace) -> &T {
459 Namespace::ValueNS => &self.value_ns,
460 Namespace::TypeNS => &self.type_ns,
461 Namespace::MacroNS => &self.macro_ns,
466 impl<T> ::std::ops::IndexMut<Namespace> for PerNS<T> {
467 fn index_mut(&mut self, ns: Namespace) -> &mut T {
469 Namespace::ValueNS => &mut self.value_ns,
470 Namespace::TypeNS => &mut self.type_ns,
471 Namespace::MacroNS => &mut self.macro_ns,
476 impl<T> PerNS<Option<T>> {
477 /// Returns `true` if all the items in this collection are `None`.
478 pub fn is_empty(&self) -> bool {
479 self.type_ns.is_none() && self.value_ns.is_none() && self.macro_ns.is_none()
482 /// Returns an iterator over the items which are `Some`.
483 pub fn present_items(self) -> impl Iterator<Item = T> {
484 [self.type_ns, self.value_ns, self.macro_ns].into_iter().flatten()
489 pub fn from_ast(vdata: &ast::VariantData) -> CtorKind {
491 ast::VariantData::Tuple(..) => CtorKind::Fn,
492 ast::VariantData::Unit(..) => CtorKind::Const,
493 ast::VariantData::Struct(..) => CtorKind::Fictive,
497 pub fn from_hir(vdata: &hir::VariantData<'_>) -> CtorKind {
499 hir::VariantData::Tuple(..) => CtorKind::Fn,
500 hir::VariantData::Unit(..) => CtorKind::Const,
501 hir::VariantData::Struct(..) => CtorKind::Fictive,
506 impl NonMacroAttrKind {
507 pub fn descr(self) -> &'static str {
509 NonMacroAttrKind::Builtin(..) => "built-in attribute",
510 NonMacroAttrKind::Tool => "tool attribute",
511 NonMacroAttrKind::DeriveHelper | NonMacroAttrKind::DeriveHelperCompat => {
512 "derive helper attribute"
514 NonMacroAttrKind::Registered => "explicitly registered attribute",
518 pub fn article(self) -> &'static str {
520 NonMacroAttrKind::Registered => "an",
525 /// Users of some attributes cannot mark them as used, so they are considered always used.
526 pub fn is_used(self) -> bool {
528 NonMacroAttrKind::Tool
529 | NonMacroAttrKind::DeriveHelper
530 | NonMacroAttrKind::DeriveHelperCompat => true,
531 NonMacroAttrKind::Builtin(..) | NonMacroAttrKind::Registered => false,
537 /// Return the `DefId` of this `Def` if it has an ID, else panic.
538 pub fn def_id(&self) -> DefId
543 .unwrap_or_else(|| panic!("attempted .def_id() on invalid res: {:?}", self))
546 /// Return `Some(..)` with the `DefId` of this `Res` if it has a ID, else `None`.
547 pub fn opt_def_id(&self) -> Option<DefId> {
549 Res::Def(_, id) => Some(id),
556 | Res::NonMacroAttr(..)
561 /// Return the `DefId` of this `Res` if it represents a module.
562 pub fn mod_def_id(&self) -> Option<DefId> {
564 Res::Def(DefKind::Mod, id) => Some(id),
569 /// A human readable name for the res kind ("function", "module", etc.).
570 pub fn descr(&self) -> &'static str {
572 Res::Def(kind, def_id) => kind.descr(def_id),
573 Res::SelfCtor(..) => "self constructor",
574 Res::PrimTy(..) => "builtin type",
575 Res::Local(..) => "local variable",
576 Res::SelfTy(..) => "self type",
577 Res::ToolMod => "tool module",
578 Res::NonMacroAttr(attr_kind) => attr_kind.descr(),
579 Res::Err => "unresolved item",
583 /// Gets an English article for the `Res`.
584 pub fn article(&self) -> &'static str {
586 Res::Def(kind, _) => kind.article(),
587 Res::NonMacroAttr(kind) => kind.article(),
593 pub fn map_id<R>(self, mut map: impl FnMut(Id) -> R) -> Res<R> {
595 Res::Def(kind, id) => Res::Def(kind, id),
596 Res::SelfCtor(id) => Res::SelfCtor(id),
597 Res::PrimTy(id) => Res::PrimTy(id),
598 Res::Local(id) => Res::Local(map(id)),
599 Res::SelfTy(a, b) => Res::SelfTy(a, b),
600 Res::ToolMod => Res::ToolMod,
601 Res::NonMacroAttr(attr_kind) => Res::NonMacroAttr(attr_kind),
602 Res::Err => Res::Err,
607 pub fn expect_non_local<OtherId>(self) -> Res<OtherId> {
608 self.map_id(|_| panic!("unexpected `Res::Local`"))
611 pub fn macro_kind(self) -> Option<MacroKind> {
613 Res::Def(DefKind::Macro(kind), _) => Some(kind),
614 Res::NonMacroAttr(..) => Some(MacroKind::Attr),
619 /// Returns `None` if this is `Res::Err`
620 pub fn ns(&self) -> Option<Namespace> {
622 Res::Def(kind, ..) => kind.ns(),
623 Res::PrimTy(..) | Res::SelfTy(..) | Res::ToolMod => Some(Namespace::TypeNS),
624 Res::SelfCtor(..) | Res::Local(..) => Some(Namespace::ValueNS),
625 Res::NonMacroAttr(..) => Some(Namespace::MacroNS),
630 /// Always returns `true` if `self` is `Res::Err`
631 pub fn matches_ns(&self, ns: Namespace) -> bool {
632 self.ns().map_or(true, |actual_ns| actual_ns == ns)
635 /// Returns whether such a resolved path can occur in a tuple struct/variant pattern
636 pub fn expected_in_tuple_struct_pat(&self) -> bool {
637 matches!(self, Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..))