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fuchsia / third_party / rust / 14070659fd9b53959f7a6df5c9d00799439fb721 / . / compiler / rustc_resolve / src / late.rs
blob: 98db36b12be67f1d7f601be97340b48b6bf07b47 [file] [log] [blame]
// ignore-tidy-filelength
//! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
//! It runs when the crate is fully expanded and its module structure is fully built.
//! So it just walks through the crate and resolves all the expressions, types, etc.
//!
//! If you wonder why there's no `early.rs`, that's because it's split into three files -
//! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
use std::assert_matches::debug_assert_matches;
use std::borrow::Cow;
use std::collections::BTreeSet;
use std::collections::hash_map::Entry;
use std::mem::{replace, swap, take};
use rustc_ast::ptr::P;
use rustc_ast::visit::{AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor, visit_opt, walk_list};
use rustc_ast::*;
use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
use rustc_errors::codes::*;
use rustc_errors::{Applicability, DiagArgValue, IntoDiagArg, StashKey, Suggestions};
use rustc_hir::def::Namespace::{self, *};
use rustc_hir::def::{self, CtorKind, DefKind, LifetimeRes, NonMacroAttrKind, PartialRes, PerNS};
use rustc_hir::def_id::{CRATE_DEF_ID, DefId, LOCAL_CRATE, LocalDefId};
use rustc_hir::{MissingLifetimeKind, PrimTy, TraitCandidate};
use rustc_middle::middle::resolve_bound_vars::Set1;
use rustc_middle::ty::DelegationFnSig;
use rustc_middle::{bug, span_bug};
use rustc_session::config::{CrateType, ResolveDocLinks};
use rustc_session::lint::{self, BuiltinLintDiag};
use rustc_session::parse::feature_err;
use rustc_span::source_map::{Spanned, respan};
use rustc_span::symbol::{Ident, Symbol, kw, sym};
use rustc_span::{BytePos, Span, SyntaxContext};
use smallvec::{SmallVec, smallvec};
use tracing::{debug, instrument, trace};
use crate::{
BindingError, BindingKey, Finalize, LexicalScopeBinding, Module, ModuleOrUniformRoot,
NameBinding, ParentScope, PathResult, ResolutionError, Resolver, Segment, TyCtxt, UseError,
Used, errors, path_names_to_string, rustdoc,
};
mod diagnostics;
type Res = def::Res<NodeId>;
type IdentMap<T> = FxHashMap<Ident, T>;
use diagnostics::{ElisionFnParameter, LifetimeElisionCandidate, MissingLifetime};
#[derive(Copy, Clone, Debug)]
struct BindingInfo {
span: Span,
annotation: BindingMode,
}
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub(crate) enum PatternSource {
Match,
Let,
For,
FnParam,
}
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
enum IsRepeatExpr {
No,
Yes,
}
struct IsNeverPattern;
/// Describes whether an `AnonConst` is a type level const arg or
/// some other form of anon const (i.e. inline consts or enum discriminants)
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
enum AnonConstKind {
EnumDiscriminant,
InlineConst,
ConstArg(IsRepeatExpr),
}
impl PatternSource {
fn descr(self) -> &'static str {
match self {
PatternSource::Match => "match binding",
PatternSource::Let => "let binding",
PatternSource::For => "for binding",
PatternSource::FnParam => "function parameter",
}
}
}
impl IntoDiagArg for PatternSource {
fn into_diag_arg(self) -> DiagArgValue {
DiagArgValue::Str(Cow::Borrowed(self.descr()))
}
}
/// Denotes whether the context for the set of already bound bindings is a `Product`
/// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
/// See those functions for more information.
#[derive(PartialEq)]
enum PatBoundCtx {
/// A product pattern context, e.g., `Variant(a, b)`.
Product,
/// An or-pattern context, e.g., `p_0 | ... | p_n`.
Or,
}
/// Does this the item (from the item rib scope) allow generic parameters?
#[derive(Copy, Clone, Debug)]
pub(crate) enum HasGenericParams {
Yes(Span),
No,
}
/// May this constant have generics?
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub(crate) enum ConstantHasGenerics {
Yes,
No(NoConstantGenericsReason),
}
impl ConstantHasGenerics {
fn force_yes_if(self, b: bool) -> Self {
if b { Self::Yes } else { self }
}
}
/// Reason for why an anon const is not allowed to reference generic parameters
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub(crate) enum NoConstantGenericsReason {
/// Const arguments are only allowed to use generic parameters when:
/// - `feature(generic_const_exprs)` is enabled
/// or
/// - the const argument is a sole const generic parameter, i.e. `foo::<{ N }>()`
///
/// If neither of the above are true then this is used as the cause.
NonTrivialConstArg,
/// Enum discriminants are not allowed to reference generic parameters ever, this
/// is used when an anon const is in the following position:
///
/// ```rust,compile_fail
/// enum Foo<const N: isize> {
/// Variant = { N }, // this anon const is not allowed to use generics
/// }
/// ```
IsEnumDiscriminant,
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub(crate) enum ConstantItemKind {
Const,
Static,
}
impl ConstantItemKind {
pub(crate) fn as_str(&self) -> &'static str {
match self {
Self::Const => "const",
Self::Static => "static",
}
}
}
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
enum RecordPartialRes {
Yes,
No,
}
/// The rib kind restricts certain accesses,
/// e.g. to a `Res::Local` of an outer item.
#[derive(Copy, Clone, Debug)]
pub(crate) enum RibKind<'ra> {
/// No restriction needs to be applied.
Normal,
/// We passed through an impl or trait and are now in one of its
/// methods or associated types. Allow references to ty params that impl or trait
/// binds. Disallow any other upvars (including other ty params that are
/// upvars).
AssocItem,
/// We passed through a function, closure or coroutine signature. Disallow labels.
FnOrCoroutine,
/// We passed through an item scope. Disallow upvars.
Item(HasGenericParams, DefKind),
/// We're in a constant item. Can't refer to dynamic stuff.
///
/// The item may reference generic parameters in trivial constant expressions.
/// All other constants aren't allowed to use generic params at all.
ConstantItem(ConstantHasGenerics, Option<(Ident, ConstantItemKind)>),
/// We passed through a module.
Module(Module<'ra>),
/// We passed through a `macro_rules!` statement
MacroDefinition(DefId),
/// All bindings in this rib are generic parameters that can't be used
/// from the default of a generic parameter because they're not declared
/// before said generic parameter. Also see the `visit_generics` override.
ForwardGenericParamBan,
/// We are inside of the type of a const parameter. Can't refer to any
/// parameters.
ConstParamTy,
/// We are inside a `sym` inline assembly operand. Can only refer to
/// globals.
InlineAsmSym,
}
impl RibKind<'_> {
/// Whether this rib kind contains generic parameters, as opposed to local
/// variables.
pub(crate) fn contains_params(&self) -> bool {
match self {
RibKind::Normal
| RibKind::FnOrCoroutine
| RibKind::ConstantItem(..)
| RibKind::Module(_)
| RibKind::MacroDefinition(_)
| RibKind::ConstParamTy
| RibKind::InlineAsmSym => false,
RibKind::AssocItem | RibKind::Item(..) | RibKind::ForwardGenericParamBan => true,
}
}
/// This rib forbids referring to labels defined in upwards ribs.
fn is_label_barrier(self) -> bool {
match self {
RibKind::Normal | RibKind::MacroDefinition(..) => false,
RibKind::AssocItem
| RibKind::FnOrCoroutine
| RibKind::Item(..)
| RibKind::ConstantItem(..)
| RibKind::Module(..)
| RibKind::ForwardGenericParamBan
| RibKind::ConstParamTy
| RibKind::InlineAsmSym => true,
}
}
}
/// A single local scope.
///
/// A rib represents a scope names can live in. Note that these appear in many places, not just
/// around braces. At any place where the list of accessible names (of the given namespace)
/// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
/// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
/// etc.
///
/// Different [rib kinds](enum@RibKind) are transparent for different names.
///
/// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
/// resolving, the name is looked up from inside out.
#[derive(Debug)]
pub(crate) struct Rib<'ra, R = Res> {
pub bindings: IdentMap<R>,
pub kind: RibKind<'ra>,
}
impl<'ra, R> Rib<'ra, R> {
fn new(kind: RibKind<'ra>) -> Rib<'ra, R> {
Rib { bindings: Default::default(), kind }
}
}
#[derive(Clone, Copy, Debug)]
enum LifetimeUseSet {
One { use_span: Span, use_ctxt: visit::LifetimeCtxt },
Many,
}
#[derive(Copy, Clone, Debug)]
enum LifetimeRibKind {
// -- Ribs introducing named lifetimes
//
/// This rib declares generic parameters.
/// Only for this kind the `LifetimeRib::bindings` field can be non-empty.
Generics { binder: NodeId, span: Span, kind: LifetimeBinderKind },
// -- Ribs introducing unnamed lifetimes
//
/// Create a new anonymous lifetime parameter and reference it.
///
/// If `report_in_path`, report an error when encountering lifetime elision in a path:
/// ```compile_fail
/// struct Foo<'a> { x: &'a () }
/// async fn foo(x: Foo) {}
/// ```
///
/// Note: the error should not trigger when the elided lifetime is in a pattern or
/// expression-position path:
/// ```
/// struct Foo<'a> { x: &'a () }
/// async fn foo(Foo { x: _ }: Foo<'_>) {}
/// ```
AnonymousCreateParameter { binder: NodeId, report_in_path: bool },
/// Replace all anonymous lifetimes by provided lifetime.
Elided(LifetimeRes),
// -- Barrier ribs that stop lifetime lookup, or continue it but produce an error later.
//
/// Give a hard error when either `&` or `'_` is written. Used to
/// rule out things like `where T: Foo<'_>`. Does not imply an
/// error on default object bounds (e.g., `Box<dyn Foo>`).
AnonymousReportError,
/// Resolves elided lifetimes to `'static` if there are no other lifetimes in scope,
/// otherwise give a warning that the previous behavior of introducing a new early-bound
/// lifetime is a bug and will be removed (if `emit_lint` is enabled).
StaticIfNoLifetimeInScope { lint_id: NodeId, emit_lint: bool },
/// Signal we cannot find which should be the anonymous lifetime.
ElisionFailure,
/// This rib forbids usage of generic parameters inside of const parameter types.
///
/// While this is desirable to support eventually, it is difficult to do and so is
/// currently forbidden. See rust-lang/project-const-generics#28 for more info.
ConstParamTy,
/// Usage of generic parameters is forbidden in various positions for anon consts:
/// - const arguments when `generic_const_exprs` is not enabled
/// - enum discriminant values
///
/// This rib emits an error when a lifetime would resolve to a lifetime parameter.
ConcreteAnonConst(NoConstantGenericsReason),
/// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
Item,
}
#[derive(Copy, Clone, Debug)]
enum LifetimeBinderKind {
BareFnType,
PolyTrait,
WhereBound,
Item,
ConstItem,
Function,
Closure,
ImplBlock,
}
impl LifetimeBinderKind {
fn descr(self) -> &'static str {
use LifetimeBinderKind::*;
match self {
BareFnType => "type",
PolyTrait => "bound",
WhereBound => "bound",
Item | ConstItem => "item",
ImplBlock => "impl block",
Function => "function",
Closure => "closure",
}
}
}
#[derive(Debug)]
struct LifetimeRib {
kind: LifetimeRibKind,
// We need to preserve insertion order for async fns.
bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>,
}
impl LifetimeRib {
fn new(kind: LifetimeRibKind) -> LifetimeRib {
LifetimeRib { bindings: Default::default(), kind }
}
}
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub(crate) enum AliasPossibility {
No,
Maybe,
}
#[derive(Copy, Clone, Debug)]
pub(crate) enum PathSource<'a> {
// Type paths `Path`.
Type,
// Trait paths in bounds or impls.
Trait(AliasPossibility),
// Expression paths `path`, with optional parent context.
Expr(Option<&'a Expr>),
// Paths in path patterns `Path`.
Pat,
// Paths in struct expressions and patterns `Path { .. }`.
Struct,
// Paths in tuple struct patterns `Path(..)`.
TupleStruct(Span, &'a [Span]),
// `m::A::B` in `<T as m::A>::B::C`.
TraitItem(Namespace),
// Paths in delegation item
Delegation,
/// An arg in a `use<'a, N>` precise-capturing bound.
PreciseCapturingArg(Namespace),
// Paths that end with `(..)`, for return type notation.
ReturnTypeNotation,
}
impl<'a> PathSource<'a> {
fn namespace(self) -> Namespace {
match self {
PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
PathSource::Expr(..)
| PathSource::Pat
| PathSource::TupleStruct(..)
| PathSource::Delegation
| PathSource::ReturnTypeNotation => ValueNS,
PathSource::TraitItem(ns) => ns,
PathSource::PreciseCapturingArg(ns) => ns,
}
}
fn defer_to_typeck(self) -> bool {
match self {
PathSource::Type
| PathSource::Expr(..)
| PathSource::Pat
| PathSource::Struct
| PathSource::TupleStruct(..)
| PathSource::ReturnTypeNotation => true,
PathSource::Trait(_)
| PathSource::TraitItem(..)
| PathSource::Delegation
| PathSource::PreciseCapturingArg(..) => false,
}
}
fn descr_expected(self) -> &'static str {
match &self {
PathSource::Type => "type",
PathSource::Trait(_) => "trait",
PathSource::Pat => "unit struct, unit variant or constant",
PathSource::Struct => "struct, variant or union type",
PathSource::TupleStruct(..) => "tuple struct or tuple variant",
PathSource::TraitItem(ns) => match ns {
TypeNS => "associated type",
ValueNS => "method or associated constant",
MacroNS => bug!("associated macro"),
},
PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
// "function" here means "anything callable" rather than `DefKind::Fn`,
// this is not precise but usually more helpful than just "value".
Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
// the case of `::some_crate()`
ExprKind::Path(_, path)
if let [segment, _] = path.segments.as_slice()
&& segment.ident.name == kw::PathRoot =>
{
"external crate"
}
ExprKind::Path(_, path) => {
let mut msg = "function";
if let Some(segment) = path.segments.iter().last() {
if let Some(c) = segment.ident.to_string().chars().next() {
if c.is_uppercase() {
msg = "function, tuple struct or tuple variant";
}
}
}
msg
}
_ => "function",
},
_ => "value",
},
PathSource::ReturnTypeNotation | PathSource::Delegation => "function",
PathSource::PreciseCapturingArg(..) => "type or const parameter",
}
}
fn is_call(self) -> bool {
matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
}
pub(crate) fn is_expected(self, res: Res) -> bool {
match self {
PathSource::Type => matches!(
res,
Res::Def(
DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Trait
| DefKind::TraitAlias
| DefKind::TyAlias
| DefKind::AssocTy
| DefKind::TyParam
| DefKind::OpaqueTy
| DefKind::ForeignTy,
_,
) | Res::PrimTy(..)
| Res::SelfTyParam { .. }
| Res::SelfTyAlias { .. }
),
PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
PathSource::Trait(AliasPossibility::Maybe) => {
matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
}
PathSource::Expr(..) => matches!(
res,
Res::Def(
DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
| DefKind::Const
| DefKind::Static { .. }
| DefKind::Fn
| DefKind::AssocFn
| DefKind::AssocConst
| DefKind::ConstParam,
_,
) | Res::Local(..)
| Res::SelfCtor(..)
),
PathSource::Pat => {
res.expected_in_unit_struct_pat()
|| matches!(res, Res::Def(DefKind::Const | DefKind::AssocConst, _))
}
PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
PathSource::Struct => matches!(
res,
Res::Def(
DefKind::Struct
| DefKind::Union
| DefKind::Variant
| DefKind::TyAlias
| DefKind::AssocTy,
_,
) | Res::SelfTyParam { .. }
| Res::SelfTyAlias { .. }
),
PathSource::TraitItem(ns) => match res {
Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
_ => false,
},
PathSource::ReturnTypeNotation => match res {
Res::Def(DefKind::AssocFn, _) => true,
_ => false,
},
PathSource::Delegation => matches!(res, Res::Def(DefKind::Fn | DefKind::AssocFn, _)),
PathSource::PreciseCapturingArg(ValueNS) => {
matches!(res, Res::Def(DefKind::ConstParam, _))
}
// We allow `SelfTyAlias` here so we can give a more descriptive error later.
PathSource::PreciseCapturingArg(TypeNS) => matches!(
res,
Res::Def(DefKind::TyParam, _) | Res::SelfTyParam { .. } | Res::SelfTyAlias { .. }
),
PathSource::PreciseCapturingArg(MacroNS) => false,
}
}
fn error_code(self, has_unexpected_resolution: bool) -> ErrCode {
match (self, has_unexpected_resolution) {
(PathSource::Trait(_), true) => E0404,
(PathSource::Trait(_), false) => E0405,
(PathSource::Type, true) => E0573,
(PathSource::Type, false) => E0412,
(PathSource::Struct, true) => E0574,
(PathSource::Struct, false) => E0422,
(PathSource::Expr(..), true) | (PathSource::Delegation, true) => E0423,
(PathSource::Expr(..), false) | (PathSource::Delegation, false) => E0425,
(PathSource::Pat | PathSource::TupleStruct(..), true) => E0532,
(PathSource::Pat | PathSource::TupleStruct(..), false) => E0531,
(PathSource::TraitItem(..), true) | (PathSource::ReturnTypeNotation, true) => E0575,
(PathSource::TraitItem(..), false) | (PathSource::ReturnTypeNotation, false) => E0576,
(PathSource::PreciseCapturingArg(..), true) => E0799,
(PathSource::PreciseCapturingArg(..), false) => E0800,
}
}
}
/// At this point for most items we can answer whether that item is exported or not,
/// but some items like impls require type information to determine exported-ness, so we make a
/// conservative estimate for them (e.g. based on nominal visibility).
#[derive(Clone, Copy)]
enum MaybeExported<'a> {
Ok(NodeId),
Impl(Option<DefId>),
ImplItem(Result<DefId, &'a Visibility>),
NestedUse(&'a Visibility),
}
impl MaybeExported<'_> {
fn eval(self, r: &Resolver<'_, '_>) -> bool {
let def_id = match self {
MaybeExported::Ok(node_id) => Some(r.local_def_id(node_id)),
MaybeExported::Impl(Some(trait_def_id)) | MaybeExported::ImplItem(Ok(trait_def_id)) => {
trait_def_id.as_local()
}
MaybeExported::Impl(None) => return true,
MaybeExported::ImplItem(Err(vis)) | MaybeExported::NestedUse(vis) => {
return vis.kind.is_pub();
}
};
def_id.map_or(true, |def_id| r.effective_visibilities.is_exported(def_id))
}
}
/// Used for recording UnnecessaryQualification.
#[derive(Debug)]
pub(crate) struct UnnecessaryQualification<'ra> {
pub binding: LexicalScopeBinding<'ra>,
pub node_id: NodeId,
pub path_span: Span,
pub removal_span: Span,
}
#[derive(Default)]
struct DiagMetadata<'ast> {
/// The current trait's associated items' ident, used for diagnostic suggestions.
current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
/// The current self type if inside an impl (used for better errors).
current_self_type: Option<Ty>,
/// The current self item if inside an ADT (used for better errors).
current_self_item: Option<NodeId>,
/// The current trait (used to suggest).
current_item: Option<&'ast Item>,
/// When processing generic arguments and encountering an unresolved ident not found,
/// suggest introducing a type or const param depending on the context.
currently_processing_generic_args: bool,
/// The current enclosing (non-closure) function (used for better errors).
current_function: Option<(FnKind<'ast>, Span)>,
/// A list of labels as of yet unused. Labels will be removed from this map when
/// they are used (in a `break` or `continue` statement)
unused_labels: FxHashMap<NodeId, Span>,
/// Only used for better errors on `let x = { foo: bar };`.
/// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
/// needed for cases where this parses as a correct type ascription.
current_block_could_be_bare_struct_literal: Option<Span>,
/// Only used for better errors on `let <pat>: <expr, not type>;`.
current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
current_pat: Option<&'ast Pat>,
/// Used to detect possible `if let` written without `let` and to provide structured suggestion.
in_if_condition: Option<&'ast Expr>,
/// Used to detect possible new binding written without `let` and to provide structured suggestion.
in_assignment: Option<&'ast Expr>,
is_assign_rhs: bool,
/// If we are setting an associated type in trait impl, is it a non-GAT type?
in_non_gat_assoc_type: Option<bool>,
/// Used to detect possible `.` -> `..` typo when calling methods.
in_range: Option<(&'ast Expr, &'ast Expr)>,
/// If we are currently in a trait object definition. Used to point at the bounds when
/// encountering a struct or enum.
current_trait_object: Option<&'ast [ast::GenericBound]>,
/// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
current_where_predicate: Option<&'ast WherePredicate>,
current_type_path: Option<&'ast Ty>,
/// The current impl items (used to suggest).
current_impl_items: Option<&'ast [P<AssocItem>]>,
/// When processing impl trait
currently_processing_impl_trait: Option<(TraitRef, Ty)>,
/// Accumulate the errors due to missed lifetime elision,
/// and report them all at once for each function.
current_elision_failures: Vec<MissingLifetime>,
}
struct LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
r: &'a mut Resolver<'ra, 'tcx>,
/// The module that represents the current item scope.
parent_scope: ParentScope<'ra>,
/// The current set of local scopes for types and values.
ribs: PerNS<Vec<Rib<'ra>>>,
/// Previous popped `rib`, only used for diagnostic.
last_block_rib: Option<Rib<'ra>>,
/// The current set of local scopes, for labels.
label_ribs: Vec<Rib<'ra, NodeId>>,
/// The current set of local scopes for lifetimes.
lifetime_ribs: Vec<LifetimeRib>,
/// We are looking for lifetimes in an elision context.
/// The set contains all the resolutions that we encountered so far.
/// They will be used to determine the correct lifetime for the fn return type.
/// The `LifetimeElisionCandidate` is used for diagnostics, to suggest introducing named
/// lifetimes.
lifetime_elision_candidates: Option<Vec<(LifetimeRes, LifetimeElisionCandidate)>>,
/// The trait that the current context can refer to.
current_trait_ref: Option<(Module<'ra>, TraitRef)>,
/// Fields used to add information to diagnostic errors.
diag_metadata: Box<DiagMetadata<'ast>>,
/// State used to know whether to ignore resolution errors for function bodies.
///
/// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
/// In most cases this will be `None`, in which case errors will always be reported.
/// If it is `true`, then it will be updated when entering a nested function or trait body.
in_func_body: bool,
/// Count the number of places a lifetime is used.
lifetime_uses: FxHashMap<LocalDefId, LifetimeUseSet>,
}
/// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
impl<'ra: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
fn visit_attribute(&mut self, _: &'ast Attribute) {
// We do not want to resolve expressions that appear in attributes,
// as they do not correspond to actual code.
}
fn visit_item(&mut self, item: &'ast Item) {
let prev = replace(&mut self.diag_metadata.current_item, Some(item));
// Always report errors in items we just entered.
let old_ignore = replace(&mut self.in_func_body, false);
self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
self.in_func_body = old_ignore;
self.diag_metadata.current_item = prev;
}
fn visit_arm(&mut self, arm: &'ast Arm) {
self.resolve_arm(arm);
}
fn visit_block(&mut self, block: &'ast Block) {
let old_macro_rules = self.parent_scope.macro_rules;
self.resolve_block(block);
self.parent_scope.macro_rules = old_macro_rules;
}
fn visit_anon_const(&mut self, _constant: &'ast AnonConst) {
bug!("encountered anon const without a manual call to `resolve_anon_const`");
}
fn visit_expr(&mut self, expr: &'ast Expr) {
self.resolve_expr(expr, None);
}
fn visit_pat(&mut self, p: &'ast Pat) {
let prev = self.diag_metadata.current_pat;
self.diag_metadata.current_pat = Some(p);
visit::walk_pat(self, p);
self.diag_metadata.current_pat = prev;
}
fn visit_local(&mut self, local: &'ast Local) {
let local_spans = match local.pat.kind {
// We check for this to avoid tuple struct fields.
PatKind::Wild => None,
_ => Some((
local.pat.span,
local.ty.as_ref().map(|ty| ty.span),
local.kind.init().map(|init| init.span),
)),
};
let original = replace(&mut self.diag_metadata.current_let_binding, local_spans);
self.resolve_local(local);
self.diag_metadata.current_let_binding = original;
}
fn visit_ty(&mut self, ty: &'ast Ty) {
let prev = self.diag_metadata.current_trait_object;
let prev_ty = self.diag_metadata.current_type_path;
match &ty.kind {
TyKind::Ref(None, _) | TyKind::PinnedRef(None, _) => {
// Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
// NodeId `ty.id`.
// This span will be used in case of elision failure.
let span = self.r.tcx.sess.source_map().start_point(ty.span);
self.resolve_elided_lifetime(ty.id, span);
visit::walk_ty(self, ty);
}
TyKind::Path(qself, path) => {
self.diag_metadata.current_type_path = Some(ty);
// If we have a path that ends with `(..)`, then it must be
// return type notation. Resolve that path in the *value*
// namespace.
let source = if let Some(seg) = path.segments.last()
&& let Some(args) = &seg.args
&& matches!(**args, GenericArgs::ParenthesizedElided(..))
{
PathSource::ReturnTypeNotation
} else {
PathSource::Type
};
self.smart_resolve_path(ty.id, qself, path, source);
// Check whether we should interpret this as a bare trait object.
if qself.is_none()
&& let Some(partial_res) = self.r.partial_res_map.get(&ty.id)
&& let Some(Res::Def(DefKind::Trait | DefKind::TraitAlias, _)) =
partial_res.full_res()
{
// This path is actually a bare trait object. In case of a bare `Fn`-trait
// object with anonymous lifetimes, we need this rib to correctly place the
// synthetic lifetimes.
let span = ty.span.shrink_to_lo().to(path.span.shrink_to_lo());
self.with_generic_param_rib(
&[],
RibKind::Normal,
LifetimeRibKind::Generics {
binder: ty.id,
kind: LifetimeBinderKind::PolyTrait,
span,
},
|this| this.visit_path(path, ty.id),
);
} else {
visit::walk_ty(self, ty)
}
}
TyKind::ImplicitSelf => {
let self_ty = Ident::with_dummy_span(kw::SelfUpper);
let res = self
.resolve_ident_in_lexical_scope(
self_ty,
TypeNS,
Some(Finalize::new(ty.id, ty.span)),
None,
)
.map_or(Res::Err, |d| d.res());
self.r.record_partial_res(ty.id, PartialRes::new(res));
visit::walk_ty(self, ty)
}
TyKind::ImplTrait(node_id, _) => {
let candidates = self.lifetime_elision_candidates.take();
visit::walk_ty(self, ty);
self.record_lifetime_params_for_impl_trait(*node_id);
self.lifetime_elision_candidates = candidates;
}
TyKind::TraitObject(bounds, ..) => {
self.diag_metadata.current_trait_object = Some(&bounds[..]);
visit::walk_ty(self, ty)
}
TyKind::BareFn(bare_fn) => {
let span = ty.span.shrink_to_lo().to(bare_fn.decl_span.shrink_to_lo());
self.with_generic_param_rib(
&bare_fn.generic_params,
RibKind::Normal,
LifetimeRibKind::Generics {
binder: ty.id,
kind: LifetimeBinderKind::BareFnType,
span,
},
|this| {
this.visit_generic_params(&bare_fn.generic_params, false);
this.with_lifetime_rib(
LifetimeRibKind::AnonymousCreateParameter {
binder: ty.id,
report_in_path: false,
},
|this| {
this.resolve_fn_signature(
ty.id,
false,
// We don't need to deal with patterns in parameters, because
// they are not possible for foreign or bodiless functions.
bare_fn
.decl
.inputs
.iter()
.map(|Param { ty, .. }| (None, &**ty)),
&bare_fn.decl.output,
)
},
);
},
)
}
TyKind::Array(element_ty, length) => {
self.visit_ty(element_ty);
self.resolve_anon_const(length, AnonConstKind::ConstArg(IsRepeatExpr::No));
}
TyKind::Typeof(ct) => {
self.resolve_anon_const(ct, AnonConstKind::ConstArg(IsRepeatExpr::No))
}
_ => visit::walk_ty(self, ty),
}
self.diag_metadata.current_trait_object = prev;
self.diag_metadata.current_type_path = prev_ty;
}
fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef) {
let span = tref.span.shrink_to_lo().to(tref.trait_ref.path.span.shrink_to_lo());
self.with_generic_param_rib(
&tref.bound_generic_params,
RibKind::Normal,
LifetimeRibKind::Generics {
binder: tref.trait_ref.ref_id,
kind: LifetimeBinderKind::PolyTrait,
span,
},
|this| {
this.visit_generic_params(&tref.bound_generic_params, false);
this.smart_resolve_path(
tref.trait_ref.ref_id,
&None,
&tref.trait_ref.path,
PathSource::Trait(AliasPossibility::Maybe),
);
this.visit_trait_ref(&tref.trait_ref);
},
);
}
fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
self.resolve_doc_links(&foreign_item.attrs, MaybeExported::Ok(foreign_item.id));
let def_kind = self.r.local_def_kind(foreign_item.id);
match foreign_item.kind {
ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
self.with_generic_param_rib(
&generics.params,
RibKind::Item(HasGenericParams::Yes(generics.span), def_kind),
LifetimeRibKind::Generics {
binder: foreign_item.id,
kind: LifetimeBinderKind::Item,
span: generics.span,
},
|this| visit::walk_item(this, foreign_item),
);
}
ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
self.with_generic_param_rib(
&generics.params,
RibKind::Item(HasGenericParams::Yes(generics.span), def_kind),
LifetimeRibKind::Generics {
binder: foreign_item.id,
kind: LifetimeBinderKind::Function,
span: generics.span,
},
|this| visit::walk_item(this, foreign_item),
);
}
ForeignItemKind::Static(..) => {
self.with_static_rib(def_kind, |this| visit::walk_item(this, foreign_item))
}
ForeignItemKind::MacCall(..) => {
panic!("unexpanded macro in resolve!")
}
}
}
fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
let previous_value = self.diag_metadata.current_function;
match fn_kind {
// Bail if the function is foreign, and thus cannot validly have
// a body, or if there's no body for some other reason.
FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
| FnKind::Fn(_, _, sig, _, generics, None) => {
self.visit_fn_header(&sig.header);
self.visit_generics(generics);
self.with_lifetime_rib(
LifetimeRibKind::AnonymousCreateParameter {
binder: fn_id,
report_in_path: false,
},
|this| {
this.resolve_fn_signature(
fn_id,
sig.decl.has_self(),
sig.decl.inputs.iter().map(|Param { ty, .. }| (None, &**ty)),
&sig.decl.output,
);
if let Some((coro_node_id, _)) = sig
.header
.coroutine_kind
.map(|coroutine_kind| coroutine_kind.return_id())
{
this.record_lifetime_params_for_impl_trait(coro_node_id);
}
},
);
return;
}
FnKind::Fn(..) => {
self.diag_metadata.current_function = Some((fn_kind, sp));
}
// Do not update `current_function` for closures: it suggests `self` parameters.
FnKind::Closure(..) => {}
};
debug!("(resolving function) entering function");
// Create a value rib for the function.
self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
// Create a label rib for the function.
this.with_label_rib(RibKind::FnOrCoroutine, |this| {
match fn_kind {
FnKind::Fn(_, _, sig, _, generics, body) => {
this.visit_generics(generics);
let declaration = &sig.decl;
let coro_node_id = sig
.header
.coroutine_kind
.map(|coroutine_kind| coroutine_kind.return_id());
this.with_lifetime_rib(
LifetimeRibKind::AnonymousCreateParameter {
binder: fn_id,
report_in_path: coro_node_id.is_some(),
},
|this| {
this.resolve_fn_signature(
fn_id,
declaration.has_self(),
declaration
.inputs
.iter()
.map(|Param { pat, ty, .. }| (Some(&**pat), &**ty)),
&declaration.output,
);
if let Some((async_node_id, _)) = coro_node_id {
this.record_lifetime_params_for_impl_trait(async_node_id);
}
},
);
if let Some(body) = body {
// Ignore errors in function bodies if this is rustdoc
// Be sure not to set this until the function signature has been resolved.
let previous_state = replace(&mut this.in_func_body, true);
// We only care block in the same function
this.last_block_rib = None;
// Resolve the function body, potentially inside the body of an async closure
this.with_lifetime_rib(
LifetimeRibKind::Elided(LifetimeRes::Infer),
|this| this.visit_block(body),
);
debug!("(resolving function) leaving function");
this.in_func_body = previous_state;
}
}
FnKind::Closure(binder, _, declaration, body) => {
this.visit_closure_binder(binder);
this.with_lifetime_rib(
match binder {
// We do not have any explicit generic lifetime parameter.
ClosureBinder::NotPresent => {
LifetimeRibKind::AnonymousCreateParameter {
binder: fn_id,
report_in_path: false,
}
}
ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
},
// Add each argument to the rib.
|this| this.resolve_params(&declaration.inputs),
);
this.with_lifetime_rib(
match binder {
ClosureBinder::NotPresent => {
LifetimeRibKind::Elided(LifetimeRes::Infer)
}
ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
},
|this| visit::walk_fn_ret_ty(this, &declaration.output),
);
// Ignore errors in function bodies if this is rustdoc
// Be sure not to set this until the function signature has been resolved.
let previous_state = replace(&mut this.in_func_body, true);
// Resolve the function body, potentially inside the body of an async closure
this.with_lifetime_rib(
LifetimeRibKind::Elided(LifetimeRes::Infer),
|this| this.visit_expr(body),
);
debug!("(resolving function) leaving function");
this.in_func_body = previous_state;
}
}
})
});
self.diag_metadata.current_function = previous_value;
}
fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
self.resolve_lifetime(lifetime, use_ctxt)
}
fn visit_precise_capturing_arg(&mut self, arg: &'ast PreciseCapturingArg) {
match arg {
// Lower the lifetime regularly; we'll resolve the lifetime and check
// it's a parameter later on in HIR lowering.
PreciseCapturingArg::Lifetime(_) => {}
PreciseCapturingArg::Arg(path, id) => {
// we want `impl use<C>` to try to resolve `C` as both a type parameter or
// a const parameter. Since the resolver specifically doesn't allow having
// two generic params with the same name, even if they're a different namespace,
// it doesn't really matter which we try resolving first, but just like
// `Ty::Param` we just fall back to the value namespace only if it's missing
// from the type namespace.
let mut check_ns = |ns| {
self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns).is_some()
};
// Like `Ty::Param`, we try resolving this as both a const and a type.
if !check_ns(TypeNS) && check_ns(ValueNS) {
self.smart_resolve_path(
*id,
&None,
path,
PathSource::PreciseCapturingArg(ValueNS),
);
} else {
self.smart_resolve_path(
*id,
&None,
path,
PathSource::PreciseCapturingArg(TypeNS),
);
}
}
}
visit::walk_precise_capturing_arg(self, arg)
}
fn visit_generics(&mut self, generics: &'ast Generics) {
self.visit_generic_params(&generics.params, self.diag_metadata.current_self_item.is_some());
for p in &generics.where_clause.predicates {
self.visit_where_predicate(p);
}
}
fn visit_closure_binder(&mut self, b: &'ast ClosureBinder) {
match b {
ClosureBinder::NotPresent => {}
ClosureBinder::For { generic_params, .. } => {
self.visit_generic_params(
generic_params,
self.diag_metadata.current_self_item.is_some(),
);
}
}
}
fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
debug!("visit_generic_arg({:?})", arg);
let prev = replace(&mut self.diag_metadata.currently_processing_generic_args, true);
match arg {
GenericArg::Type(ref ty) => {
// We parse const arguments as path types as we cannot distinguish them during
// parsing. We try to resolve that ambiguity by attempting resolution the type
// namespace first, and if that fails we try again in the value namespace. If
// resolution in the value namespace succeeds, we have an generic const argument on
// our hands.
if let TyKind::Path(None, ref path) = ty.kind {
// We cannot disambiguate multi-segment paths right now as that requires type
// checking.
if path.is_potential_trivial_const_arg() {
let mut check_ns = |ns| {
self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
.is_some()
};
if !check_ns(TypeNS) && check_ns(ValueNS) {
self.resolve_anon_const_manual(
true,
AnonConstKind::ConstArg(IsRepeatExpr::No),
|this| {
this.smart_resolve_path(
ty.id,
&None,
path,
PathSource::Expr(None),
);
this.visit_path(path, ty.id);
},
);
self.diag_metadata.currently_processing_generic_args = prev;
return;
}
}
}
self.visit_ty(ty);
}
GenericArg::Lifetime(lt) => self.visit_lifetime(lt, visit::LifetimeCtxt::GenericArg),
GenericArg::Const(ct) => {
self.resolve_anon_const(ct, AnonConstKind::ConstArg(IsRepeatExpr::No))
}
}
self.diag_metadata.currently_processing_generic_args = prev;
}
fn visit_assoc_item_constraint(&mut self, constraint: &'ast AssocItemConstraint) {
self.visit_ident(constraint.ident);
if let Some(ref gen_args) = constraint.gen_args {
// Forbid anonymous lifetimes in GAT parameters until proper semantics are decided.
self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
this.visit_generic_args(gen_args)
});
}
match constraint.kind {
AssocItemConstraintKind::Equality { ref term } => match term {
Term::Ty(ty) => self.visit_ty(ty),
Term::Const(c) => {
self.resolve_anon_const(c, AnonConstKind::ConstArg(IsRepeatExpr::No))
}
},
AssocItemConstraintKind::Bound { ref bounds } => {
self.record_lifetime_params_for_impl_trait(constraint.id);
walk_list!(self, visit_param_bound, bounds, BoundKind::Bound);
}
}
}
fn visit_path_segment(&mut self, path_segment: &'ast PathSegment) {
if let Some(ref args) = path_segment.args {
match &**args {
GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, args),
GenericArgs::Parenthesized(p_args) => {
// Probe the lifetime ribs to know how to behave.
for rib in self.lifetime_ribs.iter().rev() {
match rib.kind {
// We are inside a `PolyTraitRef`. The lifetimes are
// to be introduced in that (maybe implicit) `for<>` binder.
LifetimeRibKind::Generics {
binder,
kind: LifetimeBinderKind::PolyTrait,
..
} => {
self.with_lifetime_rib(
LifetimeRibKind::AnonymousCreateParameter {
binder,
report_in_path: false,
},
|this| {
this.resolve_fn_signature(
binder,
false,
p_args.inputs.iter().map(|ty| (None, &**ty)),
&p_args.output,
)
},
);
break;
}
// We have nowhere to introduce generics. Code is malformed,
// so use regular lifetime resolution to avoid spurious errors.
LifetimeRibKind::Item | LifetimeRibKind::Generics { .. } => {
visit::walk_generic_args(self, args);
break;
}
LifetimeRibKind::AnonymousCreateParameter { .. }
| LifetimeRibKind::AnonymousReportError
| LifetimeRibKind::StaticIfNoLifetimeInScope { .. }
| LifetimeRibKind::Elided(_)
| LifetimeRibKind::ElisionFailure
| LifetimeRibKind::ConcreteAnonConst(_)
| LifetimeRibKind::ConstParamTy => {}
}
}
}
GenericArgs::ParenthesizedElided(_) => {}
}
}
}
fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
debug!("visit_where_predicate {:?}", p);
let previous_value = replace(&mut self.diag_metadata.current_where_predicate, Some(p));
self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
if let WherePredicate::BoundPredicate(WhereBoundPredicate {
ref bounded_ty,
ref bounds,
ref bound_generic_params,
span: predicate_span,
..
}) = p
{
let span = predicate_span.shrink_to_lo().to(bounded_ty.span.shrink_to_lo());
this.with_generic_param_rib(
bound_generic_params,
RibKind::Normal,
LifetimeRibKind::Generics {
binder: bounded_ty.id,
kind: LifetimeBinderKind::WhereBound,
span,
},
|this| {
this.visit_generic_params(bound_generic_params, false);
this.visit_ty(bounded_ty);
for bound in bounds {
this.visit_param_bound(bound, BoundKind::Bound)
}
},
);
} else {
visit::walk_where_predicate(this, p);
}
});
self.diag_metadata.current_where_predicate = previous_value;
}
fn visit_inline_asm(&mut self, asm: &'ast InlineAsm) {
for (op, _) in &asm.operands {
match op {
InlineAsmOperand::In { expr, .. }
| InlineAsmOperand::Out { expr: Some(expr), .. }
| InlineAsmOperand::InOut { expr, .. } => self.visit_expr(expr),
InlineAsmOperand::Out { expr: None, .. } => {}
InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
self.visit_expr(in_expr);
if let Some(out_expr) = out_expr {
self.visit_expr(out_expr);
}
}
InlineAsmOperand::Const { anon_const, .. } => {
// Although this is `DefKind::AnonConst`, it is allowed to reference outer
// generic parameters like an inline const.
self.resolve_anon_const(anon_const, AnonConstKind::InlineConst);
}
InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym),
InlineAsmOperand::Label { block } => self.visit_block(block),
}
}
}
fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
// This is similar to the code for AnonConst.
self.with_rib(ValueNS, RibKind::InlineAsmSym, |this| {
this.with_rib(TypeNS, RibKind::InlineAsmSym, |this| {
this.with_label_rib(RibKind::InlineAsmSym, |this| {
this.smart_resolve_path(sym.id, &sym.qself, &sym.path, PathSource::Expr(None));
visit::walk_inline_asm_sym(this, sym);
});
})
});
}
fn visit_variant(&mut self, v: &'ast Variant) {
self.resolve_doc_links(&v.attrs, MaybeExported::Ok(v.id));
visit::walk_variant(self, v)
}
fn visit_variant_discr(&mut self, discr: &'ast AnonConst) {
self.resolve_anon_const(discr, AnonConstKind::EnumDiscriminant);
}
fn visit_field_def(&mut self, f: &'ast FieldDef) {
self.resolve_doc_links(&f.attrs, MaybeExported::Ok(f.id));
visit::walk_field_def(self, f)
}
}
impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
fn new(resolver: &'a mut Resolver<'ra, 'tcx>) -> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
// During late resolution we only track the module component of the parent scope,
// although it may be useful to track other components as well for diagnostics.
let graph_root = resolver.graph_root;
let parent_scope = ParentScope::module(graph_root, resolver);
let start_rib_kind = RibKind::Module(graph_root);
LateResolutionVisitor {
r: resolver,
parent_scope,
ribs: PerNS {
value_ns: vec![Rib::new(start_rib_kind)],
type_ns: vec![Rib::new(start_rib_kind)],
macro_ns: vec![Rib::new(start_rib_kind)],
},
last_block_rib: None,
label_ribs: Vec::new(),
lifetime_ribs: Vec::new(),
lifetime_elision_candidates: None,
current_trait_ref: None,
diag_metadata: Default::default(),
// errors at module scope should always be reported
in_func_body: false,
lifetime_uses: Default::default(),
}
}
fn maybe_resolve_ident_in_lexical_scope(
&mut self,
ident: Ident,
ns: Namespace,
) -> Option<LexicalScopeBinding<'ra>> {
self.r.resolve_ident_in_lexical_scope(
ident,
ns,
&self.parent_scope,
None,
&self.ribs[ns],
None,
)
}
fn resolve_ident_in_lexical_scope(
&mut self,
ident: Ident,
ns: Namespace,
finalize: Option<Finalize>,
ignore_binding: Option<NameBinding<'ra>>,
) -> Option<LexicalScopeBinding<'ra>> {
self.r.resolve_ident_in_lexical_scope(
ident,
ns,
&self.parent_scope,
finalize,
&self.ribs[ns],
ignore_binding,
)
}
fn resolve_path(
&mut self,
path: &[Segment],
opt_ns: Option<Namespace>, // `None` indicates a module path in import
finalize: Option<Finalize>,
) -> PathResult<'ra> {
self.r.resolve_path_with_ribs(
path,
opt_ns,
&self.parent_scope,
finalize,
Some(&self.ribs),
None,
None,
)
}
// AST resolution
//
// We maintain a list of value ribs and type ribs.
//
// Simultaneously, we keep track of the current position in the module
// graph in the `parent_scope.module` pointer. When we go to resolve a name in
// the value or type namespaces, we first look through all the ribs and
// then query the module graph. When we resolve a name in the module
// namespace, we can skip all the ribs (since nested modules are not
// allowed within blocks in Rust) and jump straight to the current module
// graph node.
//
// Named implementations are handled separately. When we find a method
// call, we consult the module node to find all of the implementations in
// scope. This information is lazily cached in the module node. We then
// generate a fake "implementation scope" containing all the
// implementations thus found, for compatibility with old resolve pass.
/// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
fn with_rib<T>(
&mut self,
ns: Namespace,
kind: RibKind<'ra>,
work: impl FnOnce(&mut Self) -> T,
) -> T {
self.ribs[ns].push(Rib::new(kind));
let ret = work(self);
self.ribs[ns].pop();
ret
}
fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
// Move down in the graph.
let orig_module = replace(&mut self.parent_scope.module, module);
self.with_rib(ValueNS, RibKind::Module(module), |this| {
this.with_rib(TypeNS, RibKind::Module(module), |this| {
let ret = f(this);
this.parent_scope.module = orig_module;
ret
})
})
} else {
f(self)
}
}
fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) {
// For type parameter defaults, we have to ban access
// to following type parameters, as the GenericArgs can only
// provide previous type parameters as they're built. We
// put all the parameters on the ban list and then remove
// them one by one as they are processed and become available.
let mut forward_ty_ban_rib = Rib::new(RibKind::ForwardGenericParamBan);
let mut forward_const_ban_rib = Rib::new(RibKind::ForwardGenericParamBan);
for param in params.iter() {
match param.kind {
GenericParamKind::Type { .. } => {
forward_ty_ban_rib
.bindings
.insert(Ident::with_dummy_span(param.ident.name), Res::Err);
}
GenericParamKind::Const { .. } => {
forward_const_ban_rib
.bindings
.insert(Ident::with_dummy_span(param.ident.name), Res::Err);
}
GenericParamKind::Lifetime => {}
}
}
// rust-lang/rust#61631: The type `Self` is essentially
// another type parameter. For ADTs, we consider it
// well-defined only after all of the ADT type parameters have
// been provided. Therefore, we do not allow use of `Self`
// anywhere in ADT type parameter defaults.
//
// (We however cannot ban `Self` for defaults on *all* generic
// lists; e.g. trait generics can usefully refer to `Self`,
// such as in the case of `trait Add<Rhs = Self>`.)
if add_self_upper {
// (`Some` if + only if we are in ADT's generics.)
forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
}
self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
for param in params {
match param.kind {
GenericParamKind::Lifetime => {
for bound in &param.bounds {
this.visit_param_bound(bound, BoundKind::Bound);
}
}
GenericParamKind::Type { ref default } => {
for bound in &param.bounds {
this.visit_param_bound(bound, BoundKind::Bound);
}
if let Some(ref ty) = default {
this.ribs[TypeNS].push(forward_ty_ban_rib);
this.ribs[ValueNS].push(forward_const_ban_rib);
this.visit_ty(ty);
forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
}
// Allow all following defaults to refer to this type parameter.
forward_ty_ban_rib
.bindings
.remove(&Ident::with_dummy_span(param.ident.name));
}
GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
// Const parameters can't have param bounds.
assert!(param.bounds.is_empty());
this.ribs[TypeNS].push(Rib::new(RibKind::ConstParamTy));
this.ribs[ValueNS].push(Rib::new(RibKind::ConstParamTy));
this.with_lifetime_rib(LifetimeRibKind::ConstParamTy, |this| {
this.visit_ty(ty)
});
this.ribs[TypeNS].pop().unwrap();
this.ribs[ValueNS].pop().unwrap();
if let Some(ref expr) = default {
this.ribs[TypeNS].push(forward_ty_ban_rib);
this.ribs[ValueNS].push(forward_const_ban_rib);
this.resolve_anon_const(
expr,
AnonConstKind::ConstArg(IsRepeatExpr::No),
);
forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
}
// Allow all following defaults to refer to this const parameter.
forward_const_ban_rib
.bindings
.remove(&Ident::with_dummy_span(param.ident.name));
}
}
}
})
}
#[instrument(level = "debug", skip(self, work))]
fn with_lifetime_rib<T>(
&mut self,
kind: LifetimeRibKind,
work: impl FnOnce(&mut Self) -> T,
) -> T {
self.lifetime_ribs.push(LifetimeRib::new(kind));
let outer_elision_candidates = self.lifetime_elision_candidates.take();
let ret = work(self);
self.lifetime_elision_candidates = outer_elision_candidates;
self.lifetime_ribs.pop();
ret
}
#[instrument(level = "debug", skip(self))]
fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
let ident = lifetime.ident;
if ident.name == kw::StaticLifetime {
self.record_lifetime_res(
lifetime.id,
LifetimeRes::Static { suppress_elision_warning: false },
LifetimeElisionCandidate::Named,
);
return;
}
if ident.name == kw::UnderscoreLifetime {
return self.resolve_anonymous_lifetime(lifetime, lifetime.id, false);
}
let mut lifetime_rib_iter = self.lifetime_ribs.iter().rev();
while let Some(rib) = lifetime_rib_iter.next() {
let normalized_ident = ident.normalize_to_macros_2_0();
if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
if let LifetimeRes::Param { param, binder } = res {
match self.lifetime_uses.entry(param) {
Entry::Vacant(v) => {
debug!("First use of {:?} at {:?}", res, ident.span);
let use_set = self
.lifetime_ribs
.iter()
.rev()
.find_map(|rib| match rib.kind {
// Do not suggest eliding a lifetime where an anonymous
// lifetime would be illegal.
LifetimeRibKind::Item
| LifetimeRibKind::AnonymousReportError
| LifetimeRibKind::StaticIfNoLifetimeInScope { .. }
| LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
// An anonymous lifetime is legal here, and bound to the right
// place, go ahead.
LifetimeRibKind::AnonymousCreateParameter {
binder: anon_binder,
..
} => Some(if binder == anon_binder {
LifetimeUseSet::One { use_span: ident.span, use_ctxt }
} else {
LifetimeUseSet::Many
}),
// Only report if eliding the lifetime would have the same
// semantics.
LifetimeRibKind::Elided(r) => Some(if res == r {
LifetimeUseSet::One { use_span: ident.span, use_ctxt }
} else {
LifetimeUseSet::Many
}),
LifetimeRibKind::Generics { .. }
| LifetimeRibKind::ConstParamTy => None,
LifetimeRibKind::ConcreteAnonConst(_) => {
span_bug!(ident.span, "unexpected rib kind: {:?}", rib.kind)
}
})
.unwrap_or(LifetimeUseSet::Many);
debug!(?use_ctxt, ?use_set);
v.insert(use_set);
}
Entry::Occupied(mut o) => {
debug!("Many uses of {:?} at {:?}", res, ident.span);
*o.get_mut() = LifetimeUseSet::Many;
}
}
}
return;
}
match rib.kind {
LifetimeRibKind::Item => break,
LifetimeRibKind::ConstParamTy => {
self.emit_non_static_lt_in_const_param_ty_error(lifetime);
self.record_lifetime_res(
lifetime.id,
LifetimeRes::Error,
LifetimeElisionCandidate::Ignore,
);
return;
}
LifetimeRibKind::ConcreteAnonConst(cause) => {
self.emit_forbidden_non_static_lifetime_error(cause, lifetime);
self.record_lifetime_res(
lifetime.id,
LifetimeRes::Error,
LifetimeElisionCandidate::Ignore,
);
return;
}
LifetimeRibKind::AnonymousCreateParameter { .. }
| LifetimeRibKind::Elided(_)
| LifetimeRibKind::Generics { .. }
| LifetimeRibKind::ElisionFailure
| LifetimeRibKind::AnonymousReportError
| LifetimeRibKind::StaticIfNoLifetimeInScope { .. } => {}
}
}
let mut outer_res = None;
for rib in lifetime_rib_iter {
let normalized_ident = ident.normalize_to_macros_2_0();
if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
outer_res = Some(outer);
break;
}
}
self.emit_undeclared_lifetime_error(lifetime, outer_res);
self.record_lifetime_res(lifetime.id, LifetimeRes::Error, LifetimeElisionCandidate::Named);
}
#[instrument(level = "debug", skip(self))]
fn resolve_anonymous_lifetime(
&mut self,
lifetime: &Lifetime,
id_for_lint: NodeId,
elided: bool,
) {
debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
let kind =
if elided { MissingLifetimeKind::Ampersand } else { MissingLifetimeKind::Underscore };
let missing_lifetime = MissingLifetime {
id: lifetime.id,
span: lifetime.ident.span,
kind,
count: 1,
id_for_lint,
};
let elision_candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
for (i, rib) in self.lifetime_ribs.iter().enumerate().rev() {
debug!(?rib.kind);
match rib.kind {
LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
let res = self.create_fresh_lifetime(lifetime.ident, binder, kind);
self.record_lifetime_res(lifetime.id, res, elision_candidate);
return;
}
LifetimeRibKind::StaticIfNoLifetimeInScope { lint_id: node_id, emit_lint } => {
let mut lifetimes_in_scope = vec![];
for rib in &self.lifetime_ribs[..i] {
lifetimes_in_scope.extend(rib.bindings.iter().map(|(ident, _)| ident.span));
// Consider any anonymous lifetimes, too
if let LifetimeRibKind::AnonymousCreateParameter { binder, .. } = rib.kind
&& let Some(extra) = self.r.extra_lifetime_params_map.get(&binder)
{
lifetimes_in_scope.extend(extra.iter().map(|(ident, _, _)| ident.span));
}
}
if lifetimes_in_scope.is_empty() {
self.record_lifetime_res(
lifetime.id,
// We are inside a const item, so do not warn.
LifetimeRes::Static { suppress_elision_warning: true },
elision_candidate,
);
return;
} else if emit_lint {
self.r.lint_buffer.buffer_lint(
lint::builtin::ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
node_id,
lifetime.ident.span,
lint::BuiltinLintDiag::AssociatedConstElidedLifetime {
elided,
span: lifetime.ident.span,
lifetimes_in_scope: lifetimes_in_scope.into(),
},
);
}
}
LifetimeRibKind::AnonymousReportError => {
if elided {
let mut suggestion = None;
for rib in self.lifetime_ribs[i..].iter().rev() {
if let LifetimeRibKind::Generics {
span,
kind: LifetimeBinderKind::PolyTrait | LifetimeBinderKind::WhereBound,
..
} = &rib.kind
{
suggestion =
Some(errors::ElidedAnonymousLivetimeReportErrorSuggestion {
lo: span.shrink_to_lo(),
hi: lifetime.ident.span.shrink_to_hi(),
});
break;
}
}
// are we trying to use an anonymous lifetime
// on a non GAT associated trait type?
if !self.in_func_body
&& let Some((module, _)) = &self.current_trait_ref
&& let Some(ty) = &self.diag_metadata.current_self_type
&& Some(true) == self.diag_metadata.in_non_gat_assoc_type
&& let crate::ModuleKind::Def(DefKind::Trait, trait_id, _) = module.kind
{
if def_id_matches_path(self.r.tcx, trait_id, &[
"core", "iter", "traits", "iterator", "Iterator",
]) {
self.r.dcx().emit_err(errors::LendingIteratorReportError {
lifetime: lifetime.ident.span,
ty: ty.span,
});
} else {
self.r.dcx().emit_err(errors::AnonymousLivetimeNonGatReportError {
lifetime: lifetime.ident.span,
});
}
} else {
self.r.dcx().emit_err(errors::ElidedAnonymousLivetimeReportError {
span: lifetime.ident.span,
suggestion,
});
}
} else {
self.r.dcx().emit_err(errors::ExplicitAnonymousLivetimeReportError {
span: lifetime.ident.span,
});
};
self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
return;
}
LifetimeRibKind::Elided(res) => {
self.record_lifetime_res(lifetime.id, res, elision_candidate);
return;
}
LifetimeRibKind::ElisionFailure => {
self.diag_metadata.current_elision_failures.push(missing_lifetime);
self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
return;
}
LifetimeRibKind::Item => break,
LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstParamTy => {}
LifetimeRibKind::ConcreteAnonConst(_) => {
// There is always an `Elided(LifetimeRes::Infer)` inside an `AnonConst`.
span_bug!(lifetime.ident.span, "unexpected rib kind: {:?}", rib.kind)
}
}
}
self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
}
#[instrument(level = "debug", skip(self))]
fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
let id = self.r.next_node_id();
let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
self.record_lifetime_res(
anchor_id,
LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
LifetimeElisionCandidate::Ignore,
);
self.resolve_anonymous_lifetime(&lt, anchor_id, true);
}
#[instrument(level = "debug", skip(self))]
fn create_fresh_lifetime(
&mut self,
ident: Ident,
binder: NodeId,
kind: MissingLifetimeKind,
) -> LifetimeRes {
debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
debug!(?ident.span);
// Leave the responsibility to create the `LocalDefId` to lowering.
let param = self.r.next_node_id();
let res = LifetimeRes::Fresh { param, binder, kind };
self.record_lifetime_param(param, res);
// Record the created lifetime parameter so lowering can pick it up and add it to HIR.
self.r
.extra_lifetime_params_map
.entry(binder)
.or_insert_with(Vec::new)
.push((ident, param, res));
res
}
#[instrument(level = "debug", skip(self))]
fn resolve_elided_lifetimes_in_path(
&mut self,
partial_res: PartialRes,
path: &[Segment],
source: PathSource<'_>,
path_span: Span,
) {
let proj_start = path.len() - partial_res.unresolved_segments();
for (i, segment) in path.iter().enumerate() {
if segment.has_lifetime_args {
continue;
}
let Some(segment_id) = segment.id else {
continue;
};
// Figure out if this is a type/trait segment,
// which may need lifetime elision performed.
let type_def_id = match partial_res.base_res() {
Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => {
self.r.tcx.parent(def_id)
}
Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => {
self.r.tcx.parent(def_id)
}
Res::Def(DefKind::Struct, def_id)
| Res::Def(DefKind::Union, def_id)
| Res::Def(DefKind::Enum, def_id)
| Res::Def(DefKind::TyAlias, def_id)
| Res::Def(DefKind::Trait, def_id)
if i + 1 == proj_start =>
{
def_id
}
_ => continue,
};
let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
if expected_lifetimes == 0 {
continue;
}
let node_ids = self.r.next_node_ids(expected_lifetimes);
self.record_lifetime_res(
segment_id,
LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
LifetimeElisionCandidate::Ignore,
);
let inferred = match source {
PathSource::Trait(..)
| PathSource::TraitItem(..)
| PathSource::Type
| PathSource::PreciseCapturingArg(..)
| PathSource::ReturnTypeNotation => false,
PathSource::Expr(..)
| PathSource::Pat
| PathSource::Struct
| PathSource::TupleStruct(..)
| PathSource::Delegation => true,
};
if inferred {
// Do not create a parameter for patterns and expressions: type checking can infer
// the appropriate lifetime for us.
for id in node_ids {
self.record_lifetime_res(
id,
LifetimeRes::Infer,
LifetimeElisionCandidate::Named,
);
}
continue;
}
let elided_lifetime_span = if segment.has_generic_args {
// If there are brackets, but not generic arguments, then use the opening bracket
segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
} else {
// If there are no brackets, use the identifier span.
// HACK: we use find_ancestor_inside to properly suggest elided spans in paths
// originating from macros, since the segment's span might be from a macro arg.
segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
};
let ident = Ident::new(kw::UnderscoreLifetime, elided_lifetime_span);
let kind = if segment.has_generic_args {
MissingLifetimeKind::Comma
} else {
MissingLifetimeKind::Brackets
};
let missing_lifetime = MissingLifetime {
id: node_ids.start,
id_for_lint: segment_id,
span: elided_lifetime_span,
kind,
count: expected_lifetimes,
};
let mut should_lint = true;
for rib in self.lifetime_ribs.iter().rev() {
match rib.kind {
// In create-parameter mode we error here because we don't want to support
// deprecated impl elision in new features like impl elision and `async fn`,
// both of which work using the `CreateParameter` mode:
//
// impl Foo for std::cell::Ref<u32> // note lack of '_
// async fn foo(_: std::cell::Ref<u32>) { ... }
LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. }
| LifetimeRibKind::StaticIfNoLifetimeInScope { .. } => {
let sess = self.r.tcx.sess;
let subdiag = rustc_errors::elided_lifetime_in_path_suggestion(
sess.source_map(),
expected_lifetimes,
path_span,
!segment.has_generic_args,
elided_lifetime_span,
);
self.r.dcx().emit_err(errors::ImplicitElidedLifetimeNotAllowedHere {
span: path_span,
subdiag,
});
should_lint = false;
for id in node_ids {
self.record_lifetime_res(
id,
LifetimeRes::Error,
LifetimeElisionCandidate::Named,
);
}
break;
}
// Do not create a parameter for patterns and expressions.
LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
// Group all suggestions into the first record.
let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
for id in node_ids {
let res = self.create_fresh_lifetime(ident, binder, kind);
self.record_lifetime_res(
id,
res,
replace(&mut candidate, LifetimeElisionCandidate::Named),
);
}
break;
}
LifetimeRibKind::Elided(res) => {
let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
for id in node_ids {
self.record_lifetime_res(
id,
res,
replace(&mut candidate, LifetimeElisionCandidate::Ignore),
);
}
break;
}
LifetimeRibKind::ElisionFailure => {
self.diag_metadata.current_elision_failures.push(missing_lifetime);
for id in node_ids {
self.record_lifetime_res(
id,
LifetimeRes::Error,
LifetimeElisionCandidate::Ignore,
);
}
break;
}
// `LifetimeRes::Error`, which would usually be used in the case of
// `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
// we simply resolve to an implicit lifetime, which will be checked later, at
// which point a suitable error will be emitted.
LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
for id in node_ids {
self.record_lifetime_res(
id,
LifetimeRes::Error,
LifetimeElisionCandidate::Ignore,
);
}
self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
break;
}
LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstParamTy => {}
LifetimeRibKind::ConcreteAnonConst(_) => {
// There is always an `Elided(LifetimeRes::Infer)` inside an `AnonConst`.
span_bug!(elided_lifetime_span, "unexpected rib kind: {:?}", rib.kind)
}
}
}
if should_lint {
self.r.lint_buffer.buffer_lint(
lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
segment_id,
elided_lifetime_span,
lint::BuiltinLintDiag::ElidedLifetimesInPaths(
expected_lifetimes,
path_span,
!segment.has_generic_args,
elided_lifetime_span,
),
);
}
}
}
#[instrument(level = "debug", skip(self))]
fn record_lifetime_res(
&mut self,
id: NodeId,
res: LifetimeRes,
candidate: LifetimeElisionCandidate,
) {
if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
panic!("lifetime {id:?} resolved multiple times ({prev_res:?} before, {res:?} now)")
}
match candidate {
LifetimeElisionCandidate::Missing(missing @ MissingLifetime { .. }) => {
debug_assert_eq!(id, missing.id);
match res {
LifetimeRes::Static { suppress_elision_warning } => {
if !suppress_elision_warning {
self.r.lint_buffer.buffer_lint(
lint::builtin::ELIDED_NAMED_LIFETIMES,
missing.id_for_lint,
missing.span,
BuiltinLintDiag::ElidedNamedLifetimes {
elided: (missing.span, missing.kind),
resolution: lint::ElidedLifetimeResolution::Static,
},
);
}
}
LifetimeRes::Param { param, binder: _ } => {
let tcx = self.r.tcx();
self.r.lint_buffer.buffer_lint(
lint::builtin::ELIDED_NAMED_LIFETIMES,
missing.id_for_lint,
missing.span,
BuiltinLintDiag::ElidedNamedLifetimes {
elided: (missing.span, missing.kind),
resolution: lint::ElidedLifetimeResolution::Param(
tcx.item_name(param.into()),
tcx.source_span(param),
),
},
);
}
LifetimeRes::Fresh { .. }
| LifetimeRes::Infer
| LifetimeRes::Error
| LifetimeRes::ElidedAnchor { .. } => {}
}
}
LifetimeElisionCandidate::Ignore | LifetimeElisionCandidate::Named => {}
}
match res {
LifetimeRes::Param { .. } | LifetimeRes::Fresh { .. } | LifetimeRes::Static { .. } => {
if let Some(ref mut candidates) = self.lifetime_elision_candidates {
candidates.push((res, candidate));
}
}
LifetimeRes::Infer | LifetimeRes::Error | LifetimeRes::ElidedAnchor { .. } => {}
}
}
#[instrument(level = "debug", skip(self))]
fn record_lifetime_param(&mut self, id: NodeId, res: LifetimeRes) {
if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
panic!(
"lifetime parameter {id:?} resolved multiple times ({prev_res:?} before, {res:?} now)"
)
}
}
/// Perform resolution of a function signature, accounting for lifetime elision.
#[instrument(level = "debug", skip(self, inputs))]
fn resolve_fn_signature(
&mut self,
fn_id: NodeId,
has_self: bool,
inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)> + Clone,
output_ty: &'ast FnRetTy,
) {
// Add each argument to the rib.
let elision_lifetime = self.resolve_fn_params(has_self, inputs);
debug!(?elision_lifetime);
let outer_failures = take(&mut self.diag_metadata.current_elision_failures);
let output_rib = if let Ok(res) = elision_lifetime.as_ref() {
self.r.lifetime_elision_allowed.insert(fn_id);
LifetimeRibKind::Elided(*res)
} else {
LifetimeRibKind::ElisionFailure
};
self.with_lifetime_rib(output_rib, |this| visit::walk_fn_ret_ty(this, output_ty));
let elision_failures =
replace(&mut self.diag_metadata.current_elision_failures, outer_failures);
if !elision_failures.is_empty() {
let Err(failure_info) = elision_lifetime else { bug!() };
self.report_missing_lifetime_specifiers(elision_failures, Some(failure_info));
}
}
/// Resolve inside function parameters and parameter types.
/// Returns the lifetime for elision in fn return type,
/// or diagnostic information in case of elision failure.
fn resolve_fn_params(
&mut self,
has_self: bool,
inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)>,
) -> Result<LifetimeRes, (Vec<MissingLifetime>, Vec<ElisionFnParameter>)> {
enum Elision {
/// We have not found any candidate.
None,
/// We have a candidate bound to `self`.
Self_(LifetimeRes),
/// We have a candidate bound to a parameter.
Param(LifetimeRes),
/// We failed elision.
Err,
}
// Save elision state to reinstate it later.
let outer_candidates = self.lifetime_elision_candidates.take();
// Result of elision.
let mut elision_lifetime = Elision::None;
// Information for diagnostics.
let mut parameter_info = Vec::new();
let mut all_candidates = Vec::new();
let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
for (index, (pat, ty)) in inputs.enumerate() {
debug!(?pat, ?ty);
self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
if let Some(pat) = pat {
this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
}
});
// Record elision candidates only for this parameter.
debug_assert_matches!(self.lifetime_elision_candidates, None);
self.lifetime_elision_candidates = Some(Default::default());
self.visit_ty(ty);
let local_candidates = self.lifetime_elision_candidates.take();
if let Some(candidates) = local_candidates {
let distinct: FxHashSet<_> = candidates.iter().map(|(res, _)| *res).collect();
let lifetime_count = distinct.len();
if lifetime_count != 0 {
parameter_info.push(ElisionFnParameter {
index,
ident: if let Some(pat) = pat
&& let PatKind::Ident(_, ident, _) = pat.kind
{
Some(ident)
} else {
None
},
lifetime_count,
span: ty.span,
});
all_candidates.extend(candidates.into_iter().filter_map(|(_, candidate)| {
match candidate {
LifetimeElisionCandidate::Ignore | LifetimeElisionCandidate::Named => {
None
}
LifetimeElisionCandidate::Missing(missing) => Some(missing),
}
}));
}
let mut distinct_iter = distinct.into_iter();
if let Some(res) = distinct_iter.next() {
match elision_lifetime {
// We are the first parameter to bind lifetimes.
Elision::None => {
if distinct_iter.next().is_none() {
// We have a single lifetime => success.
elision_lifetime = Elision::Param(res)
} else {
// We have multiple lifetimes => error.
elision_lifetime = Elision::Err;
}
}
// We have 2 parameters that bind lifetimes => error.
Elision::Param(_) => elision_lifetime = Elision::Err,
// `self` elision takes precedence over everything else.
Elision::Self_(_) | Elision::Err => {}
}
}
}
// Handle `self` specially.
if index == 0 && has_self {
let self_lifetime = self.find_lifetime_for_self(ty);
elision_lifetime = match self_lifetime {
// We found `self` elision.
Set1::One(lifetime) => Elision::Self_(lifetime),
// `self` itself had ambiguous lifetimes, e.g.
// &Box<&Self>. In this case we won't consider
// taking an alternative parameter lifetime; just avoid elision
// entirely.
Set1::Many => Elision::Err,
// We do not have `self` elision: disregard the `Elision::Param` that we may
// have found.
Set1::Empty => Elision::None,
}
}
debug!("(resolving function / closure) recorded parameter");
}
// Reinstate elision state.
debug_assert_matches!(self.lifetime_elision_candidates, None);
self.lifetime_elision_candidates = outer_candidates;
if let Elision::Param(res) | Elision::Self_(res) = elision_lifetime {
return Ok(res);
}
// We do not have a candidate.
Err((all_candidates, parameter_info))
}
/// List all the lifetimes that appear in the provided type.
fn find_lifetime_for_self(&self, ty: &'ast Ty) -> Set1<LifetimeRes> {
/// Visits a type to find all the &references, and determines the
/// set of lifetimes for all of those references where the referent
/// contains Self.
struct FindReferenceVisitor<'a, 'ra, 'tcx> {
r: &'a Resolver<'ra, 'tcx>,
impl_self: Option<Res>,
lifetime: Set1<LifetimeRes>,
}
impl<'ra> Visitor<'ra> for FindReferenceVisitor<'_, '_, '_> {
fn visit_ty(&mut self, ty: &'ra Ty) {
trace!("FindReferenceVisitor considering ty={:?}", ty);
if let TyKind::Ref(lt, _) | TyKind::PinnedRef(lt, _) = ty.kind {
// See if anything inside the &thing contains Self
let mut visitor =
SelfVisitor { r: self.r, impl_self: self.impl_self, self_found: false };
visitor.visit_ty(ty);
trace!("FindReferenceVisitor: SelfVisitor self_found={:?}", visitor.self_found);
if visitor.self_found {
let lt_id = if let Some(lt) = lt {
lt.id
} else {
let res = self.r.lifetimes_res_map[&ty.id];
let LifetimeRes::ElidedAnchor { start, .. } = res else { bug!() };
start
};
let lt_res = self.r.lifetimes_res_map[&lt_id];
trace!("FindReferenceVisitor inserting res={:?}", lt_res);
self.lifetime.insert(lt_res);
}
}
visit::walk_ty(self, ty)
}
// A type may have an expression as a const generic argument.
// We do not want to recurse into those.
fn visit_expr(&mut self, _: &'ra Expr) {}
}
/// Visitor which checks the referent of a &Thing to see if the
/// Thing contains Self
struct SelfVisitor<'a, 'ra, 'tcx> {
r: &'a Resolver<'ra, 'tcx>,
impl_self: Option<Res>,
self_found: bool,
}
impl SelfVisitor<'_, '_, '_> {
// Look for `self: &'a Self` - also desugared from `&'a self`
fn is_self_ty(&self, ty: &Ty) -> bool {
match ty.kind {
TyKind::ImplicitSelf => true,
TyKind::Path(None, _) => {
let path_res = self.r.partial_res_map[&ty.id].full_res();
if let Some(Res::SelfTyParam { .. } | Res::SelfTyAlias { .. }) = path_res {
return true;
}
self.impl_self.is_some() && path_res == self.impl_self
}
_ => false,
}
}
}
impl<'ra> Visitor<'ra> for SelfVisitor<'_, '_, '_> {
fn visit_ty(&mut self, ty: &'ra Ty) {
trace!("SelfVisitor considering ty={:?}", ty);
if self.is_self_ty(ty) {
trace!("SelfVisitor found Self");
self.self_found = true;
}
visit::walk_ty(self, ty)
}
// A type may have an expression as a const generic argument.
// We do not want to recurse into those.
fn visit_expr(&mut self, _: &'ra Expr) {}
}
let impl_self = self
.diag_metadata
.current_self_type
.as_ref()
.and_then(|ty| {
if let TyKind::Path(None, _) = ty.kind {
self.r.partial_res_map.get(&ty.id)
} else {
None
}
})
.and_then(|res| res.full_res())
.filter(|res| {
// Permit the types that unambiguously always
// result in the same type constructor being used
// (it can't differ between `Self` and `self`).
matches!(
res,
Res::Def(DefKind::Struct | DefKind::Union | DefKind::Enum, _,) | Res::PrimTy(_)
)
});
let mut visitor = FindReferenceVisitor { r: self.r, impl_self, lifetime: Set1::Empty };
visitor.visit_ty(ty);
trace!("FindReferenceVisitor found={:?}", visitor.lifetime);
visitor.lifetime
}
/// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
/// label and reports an error if the label is not found or is unreachable.
fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'ra>> {
let mut suggestion = None;
for i in (0..self.label_ribs.len()).rev() {
let rib = &self.label_ribs[i];
if let RibKind::MacroDefinition(def) = rib.kind {
// If an invocation of this macro created `ident`, give up on `ident`
// and switch to `ident`'s source from the macro definition.
if def == self.r.macro_def(label.span.ctxt()) {
label.span.remove_mark();
}
}
let ident = label.normalize_to_macro_rules();
if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
let definition_span = ident.span;
return if self.is_label_valid_from_rib(i) {
Ok((*id, definition_span))
} else {
Err(ResolutionError::UnreachableLabel {
name: label.name,
definition_span,
suggestion,
})
};
}
// Diagnostics: Check if this rib contains a label with a similar name, keep track of
// the first such label that is encountered.
suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
}
Err(ResolutionError::UndeclaredLabel { name: label.name, suggestion })
}
/// Determine whether or not a label from the `rib_index`th label rib is reachable.
fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
let ribs = &self.label_ribs[rib_index + 1..];
for rib in ribs {
if rib.kind.is_label_barrier() {
return false;
}
}
true
}
fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
debug!("resolve_adt");
let kind = self.r.local_def_kind(item.id);
self.with_current_self_item(item, |this| {
this.with_generic_param_rib(
&generics.params,
RibKind::Item(HasGenericParams::Yes(generics.span), kind),
LifetimeRibKind::Generics {
binder: item.id,
kind: LifetimeBinderKind::Item,
span: generics.span,
},
|this| {
let item_def_id = this.r.local_def_id(item.id).to_def_id();
this.with_self_rib(
Res::SelfTyAlias {
alias_to: item_def_id,
forbid_generic: false,
is_trait_impl: false,
},
|this| {
visit::walk_item(this, item);
},
);
},
);
});
}
fn future_proof_import(&mut self, use_tree: &UseTree) {
if let [segment, rest @ ..] = use_tree.prefix.segments.as_slice() {
let ident = segment.ident;
if ident.is_path_segment_keyword() || ident.span.is_rust_2015() {
return;
}
let nss = match use_tree.kind {
UseTreeKind::Simple(..) if rest.is_empty() => &[TypeNS, ValueNS][..],
_ => &[TypeNS],
};
let report_error = |this: &Self, ns| {
if this.should_report_errs() {
let what = if ns == TypeNS { "type parameters" } else { "local variables" };
this.r.dcx().emit_err(errors::ImportsCannotReferTo { span: ident.span, what });
}
};
for &ns in nss {
match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
Some(LexicalScopeBinding::Res(..)) => {
report_error(self, ns);
}
Some(LexicalScopeBinding::Item(binding)) => {
if let Some(LexicalScopeBinding::Res(..)) =
self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
{
report_error(self, ns);
}
}
None => {}
}
}
} else if let UseTreeKind::Nested { items, .. } = &use_tree.kind {
for (use_tree, _) in items {
self.future_proof_import(use_tree);
}
}
}
fn resolve_item(&mut self, item: &'ast Item) {
let mod_inner_docs =
matches!(item.kind, ItemKind::Mod(..)) && rustdoc::inner_docs(&item.attrs);
if !mod_inner_docs && !matches!(item.kind, ItemKind::Impl(..) | ItemKind::Use(..)) {
self.resolve_doc_links(&item.attrs, MaybeExported::Ok(item.id));
}
let name = item.ident.name;
debug!("(resolving item) resolving {} ({:?})", name, item.kind);
let def_kind = self.r.local_def_kind(item.id);
match item.kind {
ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
self.with_generic_param_rib(
&generics.params,
RibKind::Item(HasGenericParams::Yes(generics.span), def_kind),
LifetimeRibKind::Generics {
binder: item.id,
kind: LifetimeBinderKind::Item,
span: generics.span,
},
|this| visit::walk_item(this, item),
);
}
ItemKind::Fn(box Fn { ref generics, .. }) => {
self.with_generic_param_rib(
&generics.params,
RibKind::Item(HasGenericParams::Yes(generics.span), def_kind),
LifetimeRibKind::Generics {
binder: item.id,
kind: LifetimeBinderKind::Function,
span: generics.span,
},
|this| visit::walk_item(this, item),
);
}
ItemKind::Enum(_, ref generics)
| ItemKind::Struct(_, ref generics)
| ItemKind::Union(_, ref generics) => {
self.resolve_adt(item, generics);
}
ItemKind::Impl(box Impl {
ref generics,
ref of_trait,
ref self_ty,
items: ref impl_items,
..
}) => {
self.diag_metadata.current_impl_items = Some(impl_items);
self.resolve_implementation(
&item.attrs,
generics,
of_trait,
self_ty,
item.id,
impl_items,
);
self.diag_metadata.current_impl_items = None;
}
ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
// Create a new rib for the trait-wide type parameters.
self.with_generic_param_rib(
&generics.params,
RibKind::Item(HasGenericParams::Yes(generics.span), def_kind),
LifetimeRibKind::Generics {
binder: item.id,
kind: LifetimeBinderKind::Item,
span: generics.span,
},
|this| {
let local_def_id = this.r.local_def_id(item.id).to_def_id();
this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
this.visit_generics(generics);
walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
this.resolve_trait_items(items);
});
},
);
}
ItemKind::TraitAlias(ref generics, ref bounds) => {
// Create a new rib for the trait-wide type parameters.
self.with_generic_param_rib(
&generics.params,
RibKind::Item(HasGenericParams::Yes(generics.span), def_kind),
LifetimeRibKind::Generics {
binder: item.id,
kind: LifetimeBinderKind::Item,
span: generics.span,
},
|this| {
let local_def_id = this.r.local_def_id(item.id).to_def_id();
this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
this.visit_generics(generics);
walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
});
},
);
}
ItemKind::Mod(..) => {
self.with_scope(item.id, |this| {
if mod_inner_docs {
this.resolve_doc_links(&item.attrs, MaybeExported::Ok(item.id));
}
let old_macro_rules = this.parent_scope.macro_rules;
visit::walk_item(this, item);
// Maintain macro_rules scopes in the same way as during early resolution
// for diagnostics and doc links.
if item.attrs.iter().all(|attr| {
!attr.has_name(sym::macro_use) && !attr.has_name(sym::macro_escape)
}) {
this.parent_scope.macro_rules = old_macro_rules;
}
});
}
ItemKind::Static(box ast::StaticItem { ref ty, ref expr, .. }) => {
self.with_static_rib(def_kind, |this| {
this.with_lifetime_rib(
LifetimeRibKind::Elided(LifetimeRes::Static {
suppress_elision_warning: true,
}),
|this| {
this.visit_ty(ty);
},
);
if let Some(expr) = expr {
// We already forbid generic params because of the above item rib,
// so it doesn't matter whether this is a trivial constant.
this.resolve_const_body(expr, Some((item.ident, ConstantItemKind::Static)));
}
});
}
ItemKind::Const(box ast::ConstItem { ref generics, ref ty, ref expr, .. }) => {
self.with_generic_param_rib(
&generics.params,
RibKind::Item(
if self.r.tcx.features().generic_const_items {
HasGenericParams::Yes(generics.span)
} else {
HasGenericParams::No
},
def_kind,
),
LifetimeRibKind::Generics {
binder: item.id,
kind: LifetimeBinderKind::ConstItem,
span: generics.span,
},
|this| {
this.visit_generics(generics);
this.with_lifetime_rib(
LifetimeRibKind::Elided(LifetimeRes::Static {
suppress_elision_warning: true,
}),
|this| this.visit_ty(ty),
);
if let Some(expr) = expr {
this.resolve_const_body(
expr,
Some((item.ident, ConstantItemKind::Const)),
);
}
},
);
}
ItemKind::Use(ref use_tree) => {
let maybe_exported = match use_tree.kind {
UseTreeKind::Simple(_) | UseTreeKind::Glob => MaybeExported::Ok(item.id),
UseTreeKind::Nested { .. } => MaybeExported::NestedUse(&item.vis),
};
self.resolve_doc_links(&item.attrs, maybe_exported);
self.future_proof_import(use_tree);
}
ItemKind::MacroDef(ref macro_def) => {
// Maintain macro_rules scopes in the same way as during early resolution
// for diagnostics and doc links.
if macro_def.macro_rules {
let def_id = self.r.local_def_id(item.id);
self.parent_scope.macro_rules = self.r.macro_rules_scopes[&def_id];
}
}
ItemKind::ForeignMod(_) | ItemKind::GlobalAsm(_) => {
visit::walk_item(self, item);
}
ItemKind::Delegation(ref delegation) => {
let span = delegation.path.segments.last().unwrap().ident.span;
self.with_generic_param_rib(
&[],
RibKind::Item(HasGenericParams::Yes(span), def_kind),
LifetimeRibKind::Generics {
binder: item.id,
kind: LifetimeBinderKind::Function,
span,
},
|this| this.resolve_delegation(delegation),
);
}
ItemKind::ExternCrate(..) => {}
ItemKind::MacCall(_) | ItemKind::DelegationMac(..) => {
panic!("unexpanded macro in resolve!")
}
}
}
fn with_generic_param_rib<'c, F>(
&'c mut self,
params: &'c [GenericParam],
kind: RibKind<'ra>,
lifetime_kind: LifetimeRibKind,
f: F,
) where
F: FnOnce(&mut Self),
{
debug!("with_generic_param_rib");
let LifetimeRibKind::Generics { binder, span: generics_span, kind: generics_kind, .. } =
lifetime_kind
else {
panic!()
};
let mut function_type_rib = Rib::new(kind);
let mut function_value_rib = Rib::new(kind);
let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
// Only check for shadowed bindings if we're declaring new params.
if !params.is_empty() {
let mut seen_bindings = FxHashMap::default();
// Store all seen lifetimes names from outer scopes.
let mut seen_lifetimes = FxHashSet::default();
// We also can't shadow bindings from associated parent items.
for ns in [ValueNS, TypeNS] {
for parent_rib in self.ribs[ns].iter().rev() {
// Break at mod level, to account for nested items which are
// allowed to shadow generic param names.
if matches!(parent_rib.kind, RibKind::Module(..)) {
break;
}
seen_bindings
.extend(parent_rib.bindings.keys().map(|ident| (*ident, ident.span)));
}
}
// Forbid shadowing lifetime bindings
for rib in self.lifetime_ribs.iter().rev() {
seen_lifetimes.extend(rib.bindings.iter().map(|(ident, _)| *ident));
if let LifetimeRibKind::Item = rib.kind {
break;
}
}
for param in params {
let ident = param.ident.normalize_to_macros_2_0();
debug!("with_generic_param_rib: {}", param.id);
if let GenericParamKind::Lifetime = param.kind
&& let Some(&original) = seen_lifetimes.get(&ident)
{
diagnostics::signal_lifetime_shadowing(self.r.tcx.sess, original, param.ident);
// Record lifetime res, so lowering knows there is something fishy.
self.record_lifetime_param(param.id, LifetimeRes::Error);
continue;
}
match seen_bindings.entry(ident) {
Entry::Occupied(entry) => {
let span = *entry.get();
let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
self.report_error(param.ident.span, err);
let rib = match param.kind {
GenericParamKind::Lifetime => {
// Record lifetime res, so lowering knows there is something fishy.
self.record_lifetime_param(param.id, LifetimeRes::Error);
continue;
}
GenericParamKind::Type { .. } => &mut function_type_rib,
GenericParamKind::Const { .. } => &mut function_value_rib,
};
// Taint the resolution in case of errors to prevent follow up errors in typeck
self.r.record_partial_res(param.id, PartialRes::new(Res::Err));
rib.bindings.insert(ident, Res::Err);
continue;
}
Entry::Vacant(entry) => {
entry.insert(param.ident.span);
}
}
if param.ident.name == kw::UnderscoreLifetime {
self.r
.dcx()
.emit_err(errors::UnderscoreLifetimeIsReserved { span: param.ident.span });
// Record lifetime res, so lowering knows there is something fishy.
self.record_lifetime_param(param.id, LifetimeRes::Error);
continue;
}
if param.ident.name == kw::StaticLifetime {
self.r.dcx().emit_err(errors::StaticLifetimeIsReserved {
span: param.ident.span,
lifetime: param.ident,
});
// Record lifetime res, so lowering knows there is something fishy.
self.record_lifetime_param(param.id, LifetimeRes::Error);
continue;
}
let def_id = self.r.local_def_id(param.id);
// Plain insert (no renaming).
let (rib, def_kind) = match param.kind {
GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
GenericParamKind::Const { .. } => {
(&mut function_value_rib, DefKind::ConstParam)
}
GenericParamKind::Lifetime => {
let res = LifetimeRes::Param { param: def_id, binder };
self.record_lifetime_param(param.id, res);
function_lifetime_rib.bindings.insert(ident, (param.id, res));
continue;
}
};
let res = match kind {
RibKind::Item(..) | RibKind::AssocItem => {
Res::Def(def_kind, def_id.to_def_id())
}
RibKind::Normal => {
// FIXME(non_lifetime_binders): Stop special-casing
// const params to error out here.
if self.r.tcx.features().non_lifetime_binders
&& matches!(param.kind, GenericParamKind::Type { .. })
{
Res::Def(def_kind, def_id.to_def_id())
} else {
Res::Err
}
}
_ => span_bug!(param.ident.span, "Unexpected rib kind {:?}", kind),
};
self.r.record_partial_res(param.id, PartialRes::new(res));
rib.bindings.insert(ident, res);
}
}
self.lifetime_ribs.push(function_lifetime_rib);
self.ribs[ValueNS].push(function_value_rib);
self.ribs[TypeNS].push(function_type_rib);
f(self);
self.ribs[TypeNS].pop();
self.ribs[ValueNS].pop();
let function_lifetime_rib = self.lifetime_ribs.pop().unwrap();
// Do not account for the parameters we just bound for function lifetime elision.
if let Some(ref mut candidates) = self.lifetime_elision_candidates {
for (_, res) in function_lifetime_rib.bindings.values() {
candidates.retain(|(r, _)| r != res);
}
}
if let LifetimeBinderKind::BareFnType
| LifetimeBinderKind::WhereBound
| LifetimeBinderKind::Function
| LifetimeBinderKind::ImplBlock = generics_kind
{
self.maybe_report_lifetime_uses(generics_span, params)
}
}
fn with_label_rib(&mut self, kind: RibKind<'ra>, f: impl FnOnce(&mut Self)) {
self.label_ribs.push(Rib::new(kind));
f(self);
self.label_ribs.pop();
}
fn with_static_rib(&mut self, def_kind: DefKind, f: impl FnOnce(&mut Self)) {
let kind = RibKind::Item(HasGenericParams::No, def_kind);
self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
}
// HACK(min_const_generics, generic_const_exprs): We
// want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
// with a future compat lint for now. We do this by adding an
// additional special case for repeat expressions.
//
// Note that we intentionally still forbid `[0; N + 1]` during
// name resolution so that we don't extend the future
// compat lint to new cases.
#[instrument(level = "debug", skip(self, f))]
fn with_constant_rib(
&mut self,
is_repeat: IsRepeatExpr,
may_use_generics: ConstantHasGenerics,
item: Option<(Ident, ConstantItemKind)>,
f: impl FnOnce(&mut Self),
) {
let f = |this: &mut Self| {
this.with_rib(ValueNS, RibKind::ConstantItem(may_use_generics, item), |this| {
this.with_rib(
TypeNS,
RibKind::ConstantItem(
may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
item,
),
|this| {
this.with_label_rib(RibKind::ConstantItem(may_use_generics, item), f);
},
)
})
};
if let ConstantHasGenerics::No(cause) = may_use_generics {
self.with_lifetime_rib(LifetimeRibKind::ConcreteAnonConst(cause), f)
} else {
f(self)
}
}
fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
// Handle nested impls (inside fn bodies)
let previous_value =
replace(&mut self.diag_metadata.current_self_type, Some(self_type.clone()));
let result = f(self);
self.diag_metadata.current_self_type = previous_value;
result
}
fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
let previous_value = replace(&mut self.diag_metadata.current_self_item, Some(self_item.id));
let result = f(self);
self.diag_metadata.current_self_item = previous_value;
result
}
/// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
fn resolve_trait_items(&mut self, trait_items: &'ast [P<AssocItem>]) {
let trait_assoc_items =
replace(&mut self.diag_metadata.current_trait_assoc_items, Some(trait_items));
let walk_assoc_item =
|this: &mut Self, generics: &Generics, kind, item: &'ast AssocItem| {
this.with_generic_param_rib(
&generics.params,
RibKind::AssocItem,
LifetimeRibKind::Generics { binder: item.id, span: generics.span, kind },
|this| visit::walk_assoc_item(this, item, AssocCtxt::Trait),
);
};
for item in trait_items {
self.resolve_doc_links(&item.attrs, MaybeExported::Ok(item.id));
match &item.kind {
AssocItemKind::Const(box ast::ConstItem { generics, ty, expr, .. }) => {
self.with_generic_param_rib(
&generics.params,
RibKind::AssocItem,
LifetimeRibKind::Generics {
binder: item.id,
span: generics.span,
kind: LifetimeBinderKind::ConstItem,
},
|this| {
this.with_lifetime_rib(
LifetimeRibKind::StaticIfNoLifetimeInScope {
lint_id: item.id,
emit_lint: false,
},
|this| {
this.visit_generics(generics);
this.visit_ty(ty);
// Only impose the restrictions of `ConstRibKind` for an
// actual constant expression in a provided default.
if let Some(expr) = expr {
// We allow arbitrary const expressions inside of associated consts,
// even if they are potentially not const evaluatable.
//
// Type parameters can already be used and as associated consts are
// not used as part of the type system, this is far less surprising.
this.resolve_const_body(expr, None);
}
},
)
},
);
}
AssocItemKind::Fn(box Fn { generics, .. }) => {
walk_assoc_item(self, generics, LifetimeBinderKind::Function, item);
}
AssocItemKind::Delegation(delegation) => {
self.with_generic_param_rib(
&[],
RibKind::AssocItem,
LifetimeRibKind::Generics {
binder: item.id,
kind: LifetimeBinderKind::Function,
span: delegation.path.segments.last().unwrap().ident.span,
},
|this| this.resolve_delegation(delegation),
);
}
AssocItemKind::Type(box TyAlias { generics, .. }) => self
.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
walk_assoc_item(this, generics, LifetimeBinderKind::Item, item)
}),
AssocItemKind::MacCall(_) | AssocItemKind::DelegationMac(..) => {
panic!("unexpanded macro in resolve!")
}
};
}
self.diag_metadata.current_trait_assoc_items = trait_assoc_items;
}
/// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
fn with_optional_trait_ref<T>(
&mut self,
opt_trait_ref: Option<&TraitRef>,
self_type: &'ast Ty,
f: impl FnOnce(&mut Self, Option<DefId>) -> T,
) -> T {
let mut new_val = None;
let mut new_id = None;
if let Some(trait_ref) = opt_trait_ref {
let path: Vec<_> = Segment::from_path(&trait_ref.path);
self.diag_metadata.currently_processing_impl_trait =
Some((trait_ref.clone(), self_type.clone()));
let res = self.smart_resolve_path_fragment(
&None,
&path,
PathSource::Trait(AliasPossibility::No),
Finalize::new(trait_ref.ref_id, trait_ref.path.span),
RecordPartialRes::Yes,
);
self.diag_metadata.currently_processing_impl_trait = None;
if let Some(def_id) = res.expect_full_res().opt_def_id() {
new_id = Some(def_id);
new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
}
}
let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
let result = f(self, new_id);
self.current_trait_ref = original_trait_ref;
result
}
fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
let mut self_type_rib = Rib::new(RibKind::Normal);
// Plain insert (no renaming, since types are not currently hygienic)
self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
self.ribs[ns].push(self_type_rib);
f(self);
self.ribs[ns].pop();
}
fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
self.with_self_rib_ns(TypeNS, self_res, f)
}
fn resolve_implementation(
&mut self,
attrs: &[ast::Attribute],
generics: &'ast Generics,
opt_trait_reference: &'ast Option<TraitRef>,
self_type: &'ast Ty,
item_id: NodeId,
impl_items: &'ast [P<AssocItem>],
) {
debug!("resolve_implementation");
// If applicable, create a rib for the type parameters.
self.with_generic_param_rib(
&generics.params,
RibKind::Item(HasGenericParams::Yes(generics.span), self.r.local_def_kind(item_id)),
LifetimeRibKind::Generics {
span: generics.span,
binder: item_id,
kind: LifetimeBinderKind::ImplBlock,
},
|this| {
// Dummy self type for better errors if `Self` is used in the trait path.
this.with_self_rib(Res::SelfTyParam { trait_: LOCAL_CRATE.as_def_id() }, |this| {
this.with_lifetime_rib(
LifetimeRibKind::AnonymousCreateParameter {
binder: item_id,
report_in_path: true
},
|this| {
// Resolve the trait reference, if necessary.
this.with_optional_trait_ref(
opt_trait_reference.as_ref(),
self_type,
|this, trait_id| {
this.resolve_doc_links(attrs, MaybeExported::Impl(trait_id));
let item_def_id = this.r.local_def_id(item_id);
// Register the trait definitions from here.
if let Some(trait_id) = trait_id {
this.r
.trait_impls
.entry(trait_id)
.or_default()
.push(item_def_id);
}
let item_def_id = item_def_id.to_def_id();
let res = Res::SelfTyAlias {
alias_to: item_def_id,
forbid_generic: false,
is_trait_impl: trait_id.is_some()
};
this.with_self_rib(res, |this| {
if let Some(trait_ref) = opt_trait_reference.as_ref() {
// Resolve type arguments in the trait path.
visit::walk_trait_ref(this, trait_ref);
}
// Resolve the self type.
this.visit_ty(self_type);
// Resolve the generic parameters.
this.visit_generics(generics);
// Resolve the items within the impl.
this.with_current_self_type(self_type, |this| {
this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
let mut seen_trait_items = Default::default();
for item in impl_items {
this.resolve_impl_item(&**item, &mut seen_trait_items, trait_id);
}
});
});
});
},
)
},
);
});
},
);
}
fn resolve_impl_item(
&mut self,
item: &'ast AssocItem,
seen_trait_items: &mut FxHashMap<DefId, Span>,
trait_id: Option<DefId>,
) {
use crate::ResolutionError::*;
self.resolve_doc_links(&item.attrs, MaybeExported::ImplItem(trait_id.ok_or(&item.vis)));
match &item.kind {
AssocItemKind::Const(box ast::ConstItem { generics, ty, expr, .. }) => {
debug!("resolve_implementation AssocItemKind::Const");
self.with_generic_param_rib(
&generics.params,
RibKind::AssocItem,
LifetimeRibKind::Generics {
binder: item.id,
span: generics.span,
kind: LifetimeBinderKind::ConstItem,
},
|this| {
this.with_lifetime_rib(
LifetimeRibKind::StaticIfNoLifetimeInScope {
lint_id: item.id,
// In impls, it's not a hard error yet due to backcompat.
emit_lint: true,
},
|this| {
// If this is a trait impl, ensure the const
// exists in trait
this.check_trait_item(
item.id,
item.ident,
&item.kind,
ValueNS,
item.span,
seen_trait_items,
|i, s, c| ConstNotMemberOfTrait(i, s, c),
);
this.visit_generics(generics);
this.visit_ty(ty);
if let Some(expr) = expr {
// We allow arbitrary const expressions inside of associated consts,
// even if they are potentially not const evaluatable.
//
// Type parameters can already be used and as associated consts are
// not used as part of the type system, this is far less surprising.
this.resolve_const_body(expr, None);
}
},
);
},
);
}
AssocItemKind::Fn(box Fn { generics, .. }) => {
debug!("resolve_implementation AssocItemKind::Fn");
// We also need a new scope for the impl item type parameters.
self.with_generic_param_rib(
&generics.params,
RibKind::AssocItem,
LifetimeRibKind::Generics {
binder: item.id,
span: generics.span,
kind: LifetimeBinderKind::Function,
},
|this| {
// If this is a trait impl, ensure the method
// exists in trait
this.check_trait_item(
item.id,
item.ident,
&item.kind,
ValueNS,
item.span,
seen_trait_items,
|i, s, c| MethodNotMemberOfTrait(i, s, c),
);
visit::walk_assoc_item(this, item, AssocCtxt::Impl)
},
);
}
AssocItemKind::Type(box TyAlias { generics, .. }) => {
self.diag_metadata.in_non_gat_assoc_type = Some(generics.params.is_empty());
debug!("resolve_implementation AssocItemKind::Type");
// We also need a new scope for the impl item type parameters.
self.with_generic_param_rib(
&generics.params,
RibKind::AssocItem,
LifetimeRibKind::Generics {
binder: item.id,
span: generics.span,
kind: LifetimeBinderKind::Item,
},
|this| {
this.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
// If this is a trait impl, ensure the type
// exists in trait
this.check_trait_item(
item.id,
item.ident,
&item.kind,
TypeNS,
item.span,
seen_trait_items,
|i, s, c| TypeNotMemberOfTrait(i, s, c),
);
visit::walk_assoc_item(this, item, AssocCtxt::Impl)
});
},
);
self.diag_metadata.in_non_gat_assoc_type = None;
}
AssocItemKind::Delegation(box delegation) => {
debug!("resolve_implementation AssocItemKind::Delegation");
self.with_generic_param_rib(
&[],
RibKind::AssocItem,
LifetimeRibKind::Generics {
binder: item.id,
kind: LifetimeBinderKind::Function,
span: delegation.path.segments.last().unwrap().ident.span,
},
|this| {
this.check_trait_item(
item.id,
item.ident,
&item.kind,
ValueNS,
item.span,
seen_trait_items,
|i, s, c| MethodNotMemberOfTrait(i, s, c),
);
this.resolve_delegation(delegation)
},
);
}
AssocItemKind::MacCall(_) | AssocItemKind::DelegationMac(..) => {
panic!("unexpanded macro in resolve!")
}
}
}
fn check_trait_item<F>(
&mut self,
id: NodeId,
mut ident: Ident,
kind: &AssocItemKind,
ns: Namespace,
span: Span,
seen_trait_items: &mut FxHashMap<DefId, Span>,
err: F,
) where
F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'ra>,
{
// If there is a TraitRef in scope for an impl, then the method must be in the trait.
let Some((module, _)) = self.current_trait_ref else {
return;
};
ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
let key = BindingKey::new(ident, ns);
let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
debug!(?binding);
if binding.is_none() {
// We could not find the trait item in the correct namespace.
// Check the other namespace to report an error.
let ns = match ns {
ValueNS => TypeNS,
TypeNS => ValueNS,
_ => ns,
};
let key = BindingKey::new(ident, ns);
binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
debug!(?binding);
}
let feed_visibility = |this: &mut Self, def_id| {
let vis = this.r.tcx.visibility(def_id);
let vis = if vis.is_visible_locally() {
vis.expect_local()
} else {
this.r.dcx().span_delayed_bug(
span,
"error should be emitted when an unexpected trait item is used",
);
rustc_middle::ty::Visibility::Public
};
this.r.feed_visibility(this.r.feed(id), vis);
};
let Some(binding) = binding else {
// We could not find the method: report an error.
let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
let path = &self.current_trait_ref.as_ref().unwrap().1.path;
let path_names = path_names_to_string(path);
self.report_error(span, err(ident, path_names, candidate));
feed_visibility(self, module.def_id());
return;
};
let res = binding.res();
let Res::Def(def_kind, id_in_trait) = res else { bug!() };
feed_visibility(self, id_in_trait);
match seen_trait_items.entry(id_in_trait) {
Entry::Occupied(entry) => {
self.report_error(span, ResolutionError::TraitImplDuplicate {
name: ident.name,
old_span: *entry.get(),
trait_item_span: binding.span,
});
return;
}
Entry::Vacant(entry) => {
entry.insert(span);
}
};
match (def_kind, kind) {
(DefKind::AssocTy, AssocItemKind::Type(..))
| (DefKind::AssocFn, AssocItemKind::Fn(..))
| (DefKind::AssocConst, AssocItemKind::Const(..))
| (DefKind::AssocFn, AssocItemKind::Delegation(..)) => {
self.r.record_partial_res(id, PartialRes::new(res));
return;
}
_ => {}
}
// The method kind does not correspond to what appeared in the trait, report.
let path = &self.current_trait_ref.as_ref().unwrap().1.path;
let (code, kind) = match kind {
AssocItemKind::Const(..) => (E0323, "const"),
AssocItemKind::Fn(..) => (E0324, "method"),
AssocItemKind::Type(..) => (E0325, "type"),
AssocItemKind::Delegation(..) => (E0324, "method"),
AssocItemKind::MacCall(..) | AssocItemKind::DelegationMac(..) => {
span_bug!(span, "unexpanded macro")
}
};
let trait_path = path_names_to_string(path);
self.report_error(span, ResolutionError::TraitImplMismatch {
name: ident.name,
kind,
code,
trait_path,
trait_item_span: binding.span,
});
}
fn resolve_const_body(&mut self, expr: &'ast Expr, item: Option<(Ident, ConstantItemKind)>) {
self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
this.with_constant_rib(IsRepeatExpr::No, ConstantHasGenerics::Yes, item, |this| {
this.visit_expr(expr)
});
})
}
fn resolve_delegation(&mut self, delegation: &'ast Delegation) {
self.smart_resolve_path(
delegation.id,
&delegation.qself,
&delegation.path,
PathSource::Delegation,
);
if let Some(qself) = &delegation.qself {
self.visit_ty(&qself.ty);
}
self.visit_path(&delegation.path, delegation.id);
if let Some(body) = &delegation.body {
self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
// `PatBoundCtx` is not necessary in this context
let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
let span = delegation.path.segments.last().unwrap().ident.span;
this.fresh_binding(
Ident::new(kw::SelfLower, span),
delegation.id,
PatternSource::FnParam,
&mut bindings,
);
this.visit_block(body);
});
}
}
fn resolve_params(&mut self, params: &'ast [Param]) {
let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
for Param { pat, .. } in params {
this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
}
});
for Param { ty, .. } in params {
self.visit_ty(ty);
}
}
fn resolve_local(&mut self, local: &'ast Local) {
debug!("resolving local ({:?})", local);
// Resolve the type.
visit_opt!(self, visit_ty, &local.ty);
// Resolve the initializer.
if let Some((init, els)) = local.kind.init_else_opt() {
self.visit_expr(init);
// Resolve the `else` block
if let Some(els) = els {
self.visit_block(els);
}
}
// Resolve the pattern.
self.resolve_pattern_top(&local.pat, PatternSource::Let);
}
/// Build a map from pattern identifiers to binding-info's, and check the bindings are
/// consistent when encountering or-patterns and never patterns.
/// This is done hygienically: this could arise for a macro that expands into an or-pattern
/// where one 'x' was from the user and one 'x' came from the macro.
///
/// A never pattern by definition indicates an unreachable case. For example, matching on
/// `Result<T, &!>` could look like:
/// ```rust
/// # #![feature(never_type)]
/// # #![feature(never_patterns)]
/// # fn bar(_x: u32) {}
/// let foo: Result<u32, &!> = Ok(0);
/// match foo {
/// Ok(x) => bar(x),
/// Err(&!),
/// }
/// ```
/// This extends to product types: `(x, !)` is likewise unreachable. So it doesn't make sense to
/// have a binding here, and we tell the user to use `_` instead.
fn compute_and_check_binding_map(
&mut self,
pat: &Pat,
) -> Result<FxIndexMap<Ident, BindingInfo>, IsNeverPattern> {
let mut binding_map = FxIndexMap::default();
let mut is_never_pat = false;
pat.walk(&mut |pat| {
match pat.kind {
PatKind::Ident(annotation, ident, ref sub_pat)
if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
{
binding_map.insert(ident, BindingInfo { span: ident.span, annotation });
}
PatKind::Or(ref ps) => {
// Check the consistency of this or-pattern and
// then add all bindings to the larger map.
match self.compute_and_check_or_pat_binding_map(ps) {
Ok(bm) => binding_map.extend(bm),
Err(IsNeverPattern) => is_never_pat = true,
}
return false;
}
PatKind::Never => is_never_pat = true,
_ => {}
}
true
});
if is_never_pat {
for (_, binding) in binding_map {
self.report_error(binding.span, ResolutionError::BindingInNeverPattern);
}
Err(IsNeverPattern)
} else {
Ok(binding_map)
}
}
fn is_base_res_local(&self, nid: NodeId) -> bool {
matches!(
self.r.partial_res_map.get(&nid).map(|res| res.expect_full_res()),
Some(Res::Local(..))
)
}
/// Compute the binding map for an or-pattern. Checks that all of the arms in the or-pattern
/// have exactly the same set of bindings, with the same binding modes for each.
/// Returns the computed binding map and a boolean indicating whether the pattern is a never
/// pattern.
///
/// A never pattern by definition indicates an unreachable case. For example, destructuring a
/// `Result<T, &!>` could look like:
/// ```rust
/// # #![feature(never_type)]
/// # #![feature(never_patterns)]
/// # fn foo() -> Result<bool, &'static !> { Ok(true) }
/// let (Ok(x) | Err(&!)) = foo();
/// # let _ = x;
/// ```
/// Because the `Err(&!)` branch is never reached, it does not need to have the same bindings as
/// the other branches of the or-pattern. So we must ignore never pattern when checking the
/// bindings of an or-pattern.
/// Moreover, if all the subpatterns are never patterns (e.g. `Ok(!) | Err(!)`), then the
/// pattern as a whole counts as a never pattern (since it's definitionallly unreachable).
fn compute_and_check_or_pat_binding_map(
&mut self,
pats: &[P<Pat>],
) -> Result<FxIndexMap<Ident, BindingInfo>, IsNeverPattern> {
let mut missing_vars = FxIndexMap::default();
let mut inconsistent_vars = FxIndexMap::default();
// 1) Compute the binding maps of all arms; we must ignore never patterns here.
let not_never_pats = pats
.iter()
.filter_map(|pat| {
let binding_map = self.compute_and_check_binding_map(pat).ok()?;
Some((binding_map, pat))
})
.collect::<Vec<_>>();
// 2) Record any missing bindings or binding mode inconsistencies.
for (map_outer, pat_outer) in not_never_pats.iter() {
// Check against all arms except for the same pattern which is always self-consistent.
let inners = not_never_pats
.iter()
.filter(|(_, pat)| pat.id != pat_outer.id)
.flat_map(|(map, _)| map);
for (key, binding_inner) in inners {
let name = key.name;
match map_outer.get(key) {
None => {
// The inner binding is missing in the outer.
let binding_error =
missing_vars.entry(name).or_insert_with(|| BindingError {
name,
origin: BTreeSet::new(),
target: BTreeSet::new(),
could_be_path: name.as_str().starts_with(char::is_uppercase),
});
binding_error.origin.insert(binding_inner.span);
binding_error.target.insert(pat_outer.span);
}
Some(binding_outer) => {
if binding_outer.annotation != binding_inner.annotation {
// The binding modes in the outer and inner bindings differ.
inconsistent_vars
.entry(name)
.or_insert((binding_inner.span, binding_outer.span));
}
}
}
}
}
// 3) Report all missing variables we found.
for (name, mut v) in missing_vars {
if inconsistent_vars.contains_key(&name) {
v.could_be_path = false;
}
self.report_error(
*v.origin.iter().next().unwrap(),
ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
);
}
// 4) Report all inconsistencies in binding modes we found.
for (name, v) in inconsistent_vars {
self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(name, v.1));
}
// 5) Bubble up the final binding map.
if not_never_pats.is_empty() {
// All the patterns are never patterns, so the whole or-pattern is one too.
Err(IsNeverPattern)
} else {
let mut binding_map = FxIndexMap::default();
for (bm, _) in not_never_pats {
binding_map.extend(bm);
}
Ok(binding_map)
}
}
/// Check the consistency of bindings wrt or-patterns and never patterns.
fn check_consistent_bindings(&mut self, pat: &'ast Pat) {
let mut is_or_or_never = false;
pat.walk(&mut |pat| match pat.kind {
PatKind::Or(..) | PatKind::Never => {
is_or_or_never = true;
false
}
_ => true,
});
if is_or_or_never {
let _ = self.compute_and_check_binding_map(pat);
}
}
fn resolve_arm(&mut self, arm: &'ast Arm) {
self.with_rib(ValueNS, RibKind::Normal, |this| {
this.resolve_pattern_top(&arm.pat, PatternSource::Match);
visit_opt!(this, visit_expr, &arm.guard);
visit_opt!(this, visit_expr, &arm.body);
});
}
/// Arising from `source`, resolve a top level pattern.
fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
self.resolve_pattern(pat, pat_src, &mut bindings);
}
fn resolve_pattern(
&mut self,
pat: &'ast Pat,
pat_src: PatternSource,
bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
) {
// We walk the pattern before declaring the pattern's inner bindings,
// so that we avoid resolving a literal expression to a binding defined
// by the pattern.
visit::walk_pat(self, pat);
self.resolve_pattern_inner(pat, pat_src, bindings);
// This has to happen *after* we determine which pat_idents are variants:
self.check_consistent_bindings(pat);
}
/// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
///
/// ### `bindings`
///
/// A stack of sets of bindings accumulated.
///
/// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
/// be interpreted as re-binding an already bound binding. This results in an error.
/// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
/// in reusing this binding rather than creating a fresh one.
///
/// When called at the top level, the stack must have a single element
/// with `PatBound::Product`. Otherwise, pushing to the stack happens as
/// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
/// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
/// When each `p_i` has been dealt with, the top set is merged with its parent.
/// When a whole or-pattern has been dealt with, the thing happens.
///
/// See the implementation and `fresh_binding` for more details.
fn resolve_pattern_inner(
&mut self,
pat: &Pat,
pat_src: PatternSource,
bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
) {
// Visit all direct subpatterns of this pattern.
pat.walk(&mut |pat| {
debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
match pat.kind {
PatKind::Ident(bmode, ident, ref sub) => {
// First try to resolve the identifier as some existing entity,
// then fall back to a fresh binding.
let has_sub = sub.is_some();
let res = self
.try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
.unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
self.r.record_partial_res(pat.id, PartialRes::new(res));
self.r.record_pat_span(pat.id, pat.span);
}
PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
self.smart_resolve_path(
pat.id,
qself,
path,
PathSource::TupleStruct(
pat.span,
self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
),
);
}
PatKind::Path(ref qself, ref path) => {
self.smart_resolve_path(pat.id, qself, path, PathSource::Pat);
}
PatKind::Struct(ref qself, ref path, ..) => {
self.smart_resolve_path(pat.id, qself, path, PathSource::Struct);
}
PatKind::Or(ref ps) => {
// Add a new set of bindings to the stack. `Or` here records that when a
// binding already exists in this set, it should not result in an error because
// `V1(a) | V2(a)` must be allowed and are checked for consistency later.
bindings.push((PatBoundCtx::Or, Default::default()));
for p in ps {
// Now we need to switch back to a product context so that each
// part of the or-pattern internally rejects already bound names.
// For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
bindings.push((PatBoundCtx::Product, Default::default()));
self.resolve_pattern_inner(p, pat_src, bindings);
// Move up the non-overlapping bindings to the or-pattern.
// Existing bindings just get "merged".
let collected = bindings.pop().unwrap().1;
bindings.last_mut().unwrap().1.extend(collected);
}
// This or-pattern itself can itself be part of a product,
// e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
// Both cases bind `a` again in a product pattern and must be rejected.
let collected = bindings.pop().unwrap().1;
bindings.last_mut().unwrap().1.extend(collected);
// Prevent visiting `ps` as we've already done so above.
return false;
}
_ => {}
}
true
});
}
fn fresh_binding(
&mut self,
ident: Ident,
pat_id: NodeId,
pat_src: PatternSource,
bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
) -> Res {
// Add the binding to the local ribs, if it doesn't already exist in the bindings map.
// (We must not add it if it's in the bindings map because that breaks the assumptions
// later passes make about or-patterns.)
let ident = ident.normalize_to_macro_rules();
let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
// Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
// Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
// This is *required* for consistency which is checked later.
let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
if already_bound_and {
// Overlap in a product pattern somewhere; report an error.
use ResolutionError::*;
let error = match pat_src {
// `fn f(a: u8, a: u8)`:
PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
// `Variant(a, a)`:
_ => IdentifierBoundMoreThanOnceInSamePattern,
};
self.report_error(ident.span, error(ident.name));
}
// Record as bound if it's valid:
let ident_valid = ident.name != kw::Empty;
if ident_valid {
bindings.last_mut().unwrap().1.insert(ident);
}
if already_bound_or {
// `Variant1(a) | Variant2(a)`, ok
// Reuse definition from the first `a`.
self.innermost_rib_bindings(ValueNS)[&ident]
} else {
let res = Res::Local(pat_id);
if ident_valid {
// A completely fresh binding add to the set if it's valid.
self.innermost_rib_bindings(ValueNS).insert(ident, res);
}
res
}
}
fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
&mut self.ribs[ns].last_mut().unwrap().bindings
}
fn try_resolve_as_non_binding(
&mut self,
pat_src: PatternSource,
ann: BindingMode,
ident: Ident,
has_sub: bool,
) -> Option<Res> {
// An immutable (no `mut`) by-value (no `ref`) binding pattern without
// a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
// also be interpreted as a path to e.g. a constant, variant, etc.
let is_syntactic_ambiguity = !has_sub && ann == BindingMode::NONE;
let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
let (res, binding) = match ls_binding {
LexicalScopeBinding::Item(binding)
if is_syntactic_ambiguity && binding.is_ambiguity_recursive() =>
{
// For ambiguous bindings we don't know all their definitions and cannot check
// whether they can be shadowed by fresh bindings or not, so force an error.
// issues/33118#issuecomment-233962221 (see below) still applies here,
// but we have to ignore it for backward compatibility.
self.r.record_use(ident, binding, Used::Other);
return None;
}
LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
LexicalScopeBinding::Res(res) => (res, None),
};
match res {
Res::SelfCtor(_) // See #70549.
| Res::Def(
DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
_,
) if is_syntactic_ambiguity => {
// Disambiguate in favor of a unit struct/variant or constant pattern.
if let Some(binding) = binding {
self.r.record_use(ident, binding, Used::Other);
}
Some(res)
}
Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static { .. }, _) => {
// This is unambiguously a fresh binding, either syntactically
// (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
// to something unusable as a pattern (e.g., constructor function),
// but we still conservatively report an error, see
// issues/33118#issuecomment-233962221 for one reason why.
let binding = binding.expect("no binding for a ctor or static");
self.report_error(
ident.span,
ResolutionError::BindingShadowsSomethingUnacceptable {
shadowing_binding: pat_src,
name: ident.name,
participle: if binding.is_import() { "imported" } else { "defined" },
article: binding.res().article(),
shadowed_binding: binding.res(),
shadowed_binding_span: binding.span,
},
);
None
}
Res::Def(DefKind::ConstParam, def_id) => {
// Same as for DefKind::Const above, but here, `binding` is `None`, so we
// have to construct the error differently
self.report_error(
ident.span,
ResolutionError::BindingShadowsSomethingUnacceptable {
shadowing_binding: pat_src,
name: ident.name,
participle: "defined",
article: res.article(),
shadowed_binding: res,
shadowed_binding_span: self.r.def_span(def_id),
}
);
None
}
Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
// These entities are explicitly allowed to be shadowed by fresh bindings.
None
}
Res::SelfCtor(_) => {
// We resolve `Self` in pattern position as an ident sometimes during recovery,
// so delay a bug instead of ICEing. (Note: is this no longer true? We now ICE. If
// this triggers, please convert to a delayed bug and add a test.)
self.r.dcx().span_bug(
ident.span,
"unexpected `SelfCtor` in pattern, expected identifier"
);
}
_ => span_bug!(
ident.span,
"unexpected resolution for an identifier in pattern: {:?}",
res,
),
}
}
// High-level and context dependent path resolution routine.
// Resolves the path and records the resolution into definition map.
// If resolution fails tries several techniques to find likely
// resolution candidates, suggest imports or other help, and report
// errors in user friendly way.
fn smart_resolve_path(
&mut self,
id: NodeId,
qself: &Option<P<QSelf>>,
path: &Path,
source: PathSource<'ast>,
) {
self.smart_resolve_path_fragment(
qself,
&Segment::from_path(path),
source,
Finalize::new(id, path.span),
RecordPartialRes::Yes,
);
}
#[instrument(level = "debug", skip(self))]
fn smart_resolve_path_fragment(
&mut self,
qself: &Option<P<QSelf>>,
path: &[Segment],
source: PathSource<'ast>,
finalize: Finalize,
record_partial_res: RecordPartialRes,
) -> PartialRes {
let ns = source.namespace();
let Finalize { node_id, path_span, .. } = finalize;
let report_errors = |this: &mut Self, res: Option<Res>| {
if this.should_report_errs() {
let (err, candidates) =
this.smart_resolve_report_errors(path, None, path_span, source, res);
let def_id = this.parent_scope.module.nearest_parent_mod();
let instead = res.is_some();
let suggestion = if let Some((start, end)) = this.diag_metadata.in_range
&& path[0].ident.span.lo() == end.span.lo()
&& !matches!(start.kind, ExprKind::Lit(_))
{
let mut sugg = ".";
let mut span = start.span.between(end.span);
if span.lo() + BytePos(2) == span.hi() {
// There's no space between the start, the range op and the end, suggest
// removal which will look better.
span = span.with_lo(span.lo() + BytePos(1));
sugg = "";
}
Some((
span,
"you might have meant to write `.` instead of `..`",
sugg.to_string(),
Applicability::MaybeIncorrect,
))
} else if res.is_none()
&& let PathSource::Type
| PathSource::Expr(_)
| PathSource::PreciseCapturingArg(..) = source
{
this.suggest_adding_generic_parameter(path, source)
} else {
None
};
let ue = UseError {
err,
candidates,
def_id,
instead,
suggestion,
path: path.into(),
is_call: source.is_call(),
};
this.r.use_injections.push(ue);
}
PartialRes::new(Res::Err)
};
// For paths originating from calls (like in `HashMap::new()`), tries
// to enrich the plain `failed to resolve: ...` message with hints
// about possible missing imports.
//
// Similar thing, for types, happens in `report_errors` above.
let report_errors_for_call =
|this: &mut Self, parent_err: Spanned<ResolutionError<'ra>>| {
// Before we start looking for candidates, we have to get our hands
// on the type user is trying to perform invocation on; basically:
// we're transforming `HashMap::new` into just `HashMap`.
let (following_seg, prefix_path) = match path.split_last() {
Some((last, path)) if !path.is_empty() => (Some(last), path),
_ => return Some(parent_err),
};
let (mut err, candidates) = this.smart_resolve_report_errors(
prefix_path,
following_seg,
path_span,
PathSource::Type,
None,
);
// There are two different error messages user might receive at
// this point:
// - E0412 cannot find type `{}` in this scope
// - E0433 failed to resolve: use of undeclared type or module `{}`
//
// The first one is emitted for paths in type-position, and the
// latter one - for paths in expression-position.
//
// Thus (since we're in expression-position at this point), not to
// confuse the user, we want to keep the *message* from E0433 (so
// `parent_err`), but we want *hints* from E0412 (so `err`).
//
// And that's what happens below - we're just mixing both messages
// into a single one.
let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
// overwrite all properties with the parent's error message
err.messages = take(&mut parent_err.messages);
err.code = take(&mut parent_err.code);
swap(&mut err.span, &mut parent_err.span);
err.children = take(&mut parent_err.children);
err.sort_span = parent_err.sort_span;
err.is_lint = parent_err.is_lint.clone();
// merge the parent_err's suggestions with the typo (err's) suggestions
match &mut err.suggestions {
Suggestions::Enabled(typo_suggestions) => match &mut parent_err.suggestions {
Suggestions::Enabled(parent_suggestions) => {
// If both suggestions are enabled, append parent_err's suggestions to err's suggestions.
typo_suggestions.append(parent_suggestions)
}
Suggestions::Sealed(_) | Suggestions::Disabled => {
// If the parent's suggestions are either sealed or disabled, it signifies that
// new suggestions cannot be added or removed from the diagnostic. Therefore,
// we assign both types of suggestions to err's suggestions and discard the
// existing suggestions in err.
err.suggestions = std::mem::take(&mut parent_err.suggestions);
}
},
Suggestions::Sealed(_) | Suggestions::Disabled => (),
}
parent_err.cancel();
let def_id = this.parent_scope.module.nearest_parent_mod();
if this.should_report_errs() {
if candidates.is_empty() {
if path.len() == 2
&& let [segment] = prefix_path
{
// Delay to check whether methond name is an associated function or not
// ```
// let foo = Foo {};
// foo::bar(); // possibly suggest to foo.bar();
//```
err.stash(segment.ident.span, rustc_errors::StashKey::CallAssocMethod);
} else {
// When there is no suggested imports, we can just emit the error
// and suggestions immediately. Note that we bypass the usually error
// reporting routine (ie via `self.r.report_error`) because we need
// to post-process the `ResolutionError` above.
err.emit();
}
} else {
// If there are suggested imports, the error reporting is delayed
this.r.use_injections.push(UseError {
err,
candidates,
def_id,
instead: false,
suggestion: None,
path: prefix_path.into(),
is_call: source.is_call(),
});
}
} else {
err.cancel();
}
// We don't return `Some(parent_err)` here, because the error will
// be already printed either immediately or as part of the `use` injections
None
};
let partial_res = match self.resolve_qpath_anywhere(
qself,
path,
ns,
path_span,
source.defer_to_typeck(),
finalize,
) {
Ok(Some(partial_res)) if let Some(res) = partial_res.full_res() => {
// if we also have an associated type that matches the ident, stash a suggestion
if let Some(items) = self.diag_metadata.current_trait_assoc_items
&& let [Segment { ident, .. }] = path
&& items.iter().any(|item| {
item.ident == *ident && matches!(item.kind, AssocItemKind::Type(_))
})
{
let mut diag = self.r.tcx.dcx().struct_allow("");
diag.span_suggestion_verbose(
path_span.shrink_to_lo(),
"there is an associated type with the same name",
"Self::",
Applicability::MaybeIncorrect,
);
diag.stash(path_span, StashKey::AssociatedTypeSuggestion);
}
if source.is_expected(res) || res == Res::Err {
partial_res
} else {
report_errors(self, Some(res))
}
}
Ok(Some(partial_res)) if source.defer_to_typeck() => {
// Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
// or `<T>::A::B`. If `B` should be resolved in value namespace then
// it needs to be added to the trait map.
if ns == ValueNS {
let item_name = path.last().unwrap().ident;
let traits = self.traits_in_scope(item_name, ns);
self.r.trait_map.insert(node_id, traits);
}
if PrimTy::from_name(path[0].ident.name).is_some() {
let mut std_path = Vec::with_capacity(1 + path.len());
std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
std_path.extend(path);
if let PathResult::Module(_) | PathResult::NonModule(_) =
self.resolve_path(&std_path, Some(ns), None)
{
// Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
let item_span =
path.iter().last().map_or(path_span, |segment| segment.ident.span);
self.r.confused_type_with_std_module.insert(item_span, path_span);
self.r.confused_type_with_std_module.insert(path_span, path_span);
}
}
partial_res
}
Err(err) => {
if let Some(err) = report_errors_for_call(self, err) {
self.report_error(err.span, err.node);
}
PartialRes::new(Res::Err)
}
_ => report_errors(self, None),
};
if record_partial_res == RecordPartialRes::Yes {
// Avoid recording definition of `A::B` in `<T as A>::B::C`.
self.r.record_partial_res(node_id, partial_res);
self.resolve_elided_lifetimes_in_path(partial_res, path, source, path_span);
self.lint_unused_qualifications(path, ns, finalize);
}
partial_res
}
fn self_type_is_available(&mut self) -> bool {
let binding = self
.maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
}
fn self_value_is_available(&mut self, self_span: Span) -> bool {
let ident = Ident::new(kw::SelfLower, self_span);
let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
}
/// A wrapper around [`Resolver::report_error`].
///
/// This doesn't emit errors for function bodies if this is rustdoc.
fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'ra>) {
if self.should_report_errs() {
self.r.report_error(span, resolution_error);
}
}
#[inline]
/// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items or
// an invalid `use foo::*;` was found, which can cause unbounded ammounts of "item not found"
// errors. We silence them all.
fn should_report_errs(&self) -> bool {
!(self.r.tcx.sess.opts.actually_rustdoc && self.in_func_body)
&& !self.r.glob_error.is_some()
}
// Resolve in alternative namespaces if resolution in the primary namespace fails.
fn resolve_qpath_anywhere(
&mut self,
qself: &Option<P<QSelf>>,
path: &[Segment],
primary_ns: Namespace,
span: Span,
defer_to_typeck: bool,
finalize: Finalize,
) -> Result<Option<PartialRes>, Spanned<ResolutionError<'ra>>> {
let mut fin_res = None;
for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
if i == 0 || ns != primary_ns {
match self.resolve_qpath(qself, path, ns, finalize)? {
Some(partial_res)
if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
{
return Ok(Some(partial_res));
}
partial_res => {
if fin_res.is_none() {
fin_res = partial_res;
}
}
}
}
}
assert!(primary_ns != MacroNS);
if qself.is_none() {
let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
if let Ok((_, res)) =
self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false, None)
{
return Ok(Some(PartialRes::new(res)));
}
}
Ok(fin_res)
}
/// Handles paths that may refer to associated items.
fn resolve_qpath(
&mut self,
qself: &Option<P<QSelf>>,
path: &[Segment],
ns: Namespace,
finalize: Finalize,
) -> Result<Option<PartialRes>, Spanned<ResolutionError<'ra>>> {
debug!(
"resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
qself, path, ns, finalize,
);
if let Some(qself) = qself {
if qself.position == 0 {
// This is a case like `<T>::B`, where there is no
// trait to resolve. In that case, we leave the `B`
// segment to be resolved by type-check.
return Ok(Some(PartialRes::with_unresolved_segments(
Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
path.len(),
)));
}
let num_privacy_errors = self.r.privacy_errors.len();
// Make sure that `A` in `<T as A>::B::C` is a trait.
let trait_res = self.smart_resolve_path_fragment(
&None,
&path[..qself.position],
PathSource::Trait(AliasPossibility::No),
Finalize::new(finalize.node_id, qself.path_span),
RecordPartialRes::No,
);
if trait_res.expect_full_res() == Res::Err {
return Ok(Some(trait_res));
}
// Truncate additional privacy errors reported above,
// because they'll be recomputed below.
self.r.privacy_errors.truncate(num_privacy_errors);
// Make sure `A::B` in `<T as A>::B::C` is a trait item.
//
// Currently, `path` names the full item (`A::B::C`, in
// our example). so we extract the prefix of that that is
// the trait (the slice upto and including
// `qself.position`). And then we recursively resolve that,
// but with `qself` set to `None`.
let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
let partial_res = self.smart_resolve_path_fragment(
&None,
&path[..=qself.position],
PathSource::TraitItem(ns),
Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
RecordPartialRes::No,
);
// The remaining segments (the `C` in our example) will
// have to be resolved by type-check, since that requires doing
// trait resolution.
return Ok(Some(PartialRes::with_unresolved_segments(
partial_res.base_res(),
partial_res.unresolved_segments() + path.len() - qself.position - 1,
)));
}
let result = match self.resolve_path(path, Some(ns), Some(finalize)) {
PathResult::NonModule(path_res) => path_res,
PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
PartialRes::new(module.res().unwrap())
}
// In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
// don't report an error right away, but try to fallback to a primitive type.
// So, we are still able to successfully resolve something like
//
// use std::u8; // bring module u8 in scope
// fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
// u8::max_value() // OK, resolves to associated function <u8>::max_value,
// // not to nonexistent std::u8::max_value
// }
//
// Such behavior is required for backward compatibility.
// The same fallback is used when `a` resolves to nothing.
PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
if (ns == TypeNS || path.len() > 1)
&& PrimTy::from_name(path[0].ident.name).is_some() =>
{
let prim = PrimTy::from_name(path[0].ident.name).unwrap();
let tcx = self.r.tcx();
let gate_err_sym_msg = match prim {
PrimTy::Float(FloatTy::F16) if !tcx.features().f16 => {
Some((sym::f16, "the type `f16` is unstable"))
}
PrimTy::Float(FloatTy::F128) if !tcx.features().f128 => {
Some((sym::f128, "the type `f128` is unstable"))
}
_ => None,
};
if let Some((sym, msg)) = gate_err_sym_msg {
let span = path[0].ident.span;
if !span.allows_unstable(sym) {
feature_err(tcx.sess, sym, span, msg).emit();
}
};
PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
}
PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
PartialRes::new(module.res().unwrap())
}
PathResult::Failed {
is_error_from_last_segment: false,
span,
label,
suggestion,
module,
segment_name,
} => {
return Err(respan(span, ResolutionError::FailedToResolve {
segment: Some(segment_name),
label,
suggestion,
module,
}));
}
PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
};
Ok(Some(result))
}
fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
if let Some(label) = label {
if label.ident.as_str().as_bytes()[1] != b'_' {
self.diag_metadata.unused_labels.insert(id, label.ident.span);
}
if let Ok((_, orig_span)) = self.resolve_label(label.ident) {
diagnostics::signal_label_shadowing(self.r.tcx.sess, orig_span, label.ident)
}
self.with_label_rib(RibKind::Normal, |this| {
let ident = label.ident.normalize_to_macro_rules();
this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
f(this);
});
} else {
f(self);
}
}
fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
self.with_resolved_label(label, id, |this| this.visit_block(block));
}
fn resolve_block(&mut self, block: &'ast Block) {
debug!("(resolving block) entering block");
// Move down in the graph, if there's an anonymous module rooted here.
let orig_module = self.parent_scope.module;
let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
let mut num_macro_definition_ribs = 0;
if let Some(anonymous_module) = anonymous_module {
debug!("(resolving block) found anonymous module, moving down");
self.ribs[ValueNS].push(Rib::new(RibKind::Module(anonymous_module)));
self.ribs[TypeNS].push(Rib::new(RibKind::Module(anonymous_module)));
self.parent_scope.module = anonymous_module;
} else {
self.ribs[ValueNS].push(Rib::new(RibKind::Normal));
}
let prev = self.diag_metadata.current_block_could_be_bare_struct_literal.take();
if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
(block.could_be_bare_literal, &block.stmts[..])
&& let ExprKind::Type(..) = expr.kind
{
self.diag_metadata.current_block_could_be_bare_struct_literal = Some(block.span);
}
// Descend into the block.
for stmt in &block.stmts {
if let StmtKind::Item(ref item) = stmt.kind
&& let ItemKind::MacroDef(..) = item.kind
{
num_macro_definition_ribs += 1;
let res = self.r.local_def_id(item.id).to_def_id();
self.ribs[ValueNS].push(Rib::new(RibKind::MacroDefinition(res)));
self.label_ribs.push(Rib::new(RibKind::MacroDefinition(res)));
}
self.visit_stmt(stmt);
}
self.diag_metadata.current_block_could_be_bare_struct_literal = prev;
// Move back up.
self.parent_scope.module = orig_module;
for _ in 0..num_macro_definition_ribs {
self.ribs[ValueNS].pop();
self.label_ribs.pop();
}
self.last_block_rib = self.ribs[ValueNS].pop();
if anonymous_module.is_some() {
self.ribs[TypeNS].pop();
}
debug!("(resolving block) leaving block");
}
fn resolve_anon_const(&mut self, constant: &'ast AnonConst, anon_const_kind: AnonConstKind) {
debug!(
"resolve_anon_const(constant: {:?}, anon_const_kind: {:?})",
constant, anon_const_kind
);
self.resolve_anon_const_manual(
constant.value.is_potential_trivial_const_arg(true),
anon_const_kind,
|this| this.resolve_expr(&constant.value, None),
)
}
/// There are a few places that we need to resolve an anon const but we did not parse an
/// anon const so cannot provide an `&'ast AnonConst`. Right now this is just unbraced
/// const arguments that were parsed as type arguments, and `legacy_const_generics` which
/// parse as normal function argument expressions. To avoid duplicating the code for resolving
/// an anon const we have this function which lets the caller manually call `resolve_expr` or
/// `smart_resolve_path`.
fn resolve_anon_const_manual(
&mut self,
is_trivial_const_arg: bool,
anon_const_kind: AnonConstKind,
resolve_expr: impl FnOnce(&mut Self),
) {
let is_repeat_expr = match anon_const_kind {
AnonConstKind::ConstArg(is_repeat_expr) => is_repeat_expr,
_ => IsRepeatExpr::No,
};
let may_use_generics = match anon_const_kind {
AnonConstKind::EnumDiscriminant => {
ConstantHasGenerics::No(NoConstantGenericsReason::IsEnumDiscriminant)
}
AnonConstKind::InlineConst => ConstantHasGenerics::Yes,
AnonConstKind::ConstArg(_) => {
if self.r.tcx.features().generic_const_exprs || is_trivial_const_arg {
ConstantHasGenerics::Yes
} else {
ConstantHasGenerics::No(NoConstantGenericsReason::NonTrivialConstArg)
}
}
};
self.with_constant_rib(is_repeat_expr, may_use_generics, None, |this| {
this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
resolve_expr(this);
});
});
}
fn resolve_expr_field(&mut self, f: &'ast ExprField, e: &'ast Expr) {
self.resolve_expr(&f.expr, Some(e));
self.visit_ident(f.ident);
walk_list!(self, visit_attribute, f.attrs.iter());
}
fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
// First, record candidate traits for this expression if it could
// result in the invocation of a method call.
self.record_candidate_traits_for_expr_if_necessary(expr);
// Next, resolve the node.
match expr.kind {
ExprKind::Path(ref qself, ref path) => {
self.smart_resolve_path(expr.id, qself, path, PathSource::Expr(parent));
visit::walk_expr(self, expr);
}
ExprKind::Struct(ref se) => {
self.smart_resolve_path(expr.id, &se.qself, &se.path, PathSource::Struct);
// This is the same as `visit::walk_expr(self, expr);`, but we want to pass the
// parent in for accurate suggestions when encountering `Foo { bar }` that should
// have been `Foo { bar: self.bar }`.
if let Some(qself) = &se.qself {
self.visit_ty(&qself.ty);
}
self.visit_path(&se.path, expr.id);
walk_list!(self, resolve_expr_field, &se.fields, expr);
match &se.rest {
StructRest::Base(expr) => self.visit_expr(expr),
StructRest::Rest(_span) => {}
StructRest::None => {}
}
}
ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
match self.resolve_label(label.ident) {
Ok((node_id, _)) => {
// Since this res is a label, it is never read.
self.r.label_res_map.insert(expr.id, node_id);
self.diag_metadata.unused_labels.remove(&node_id);
}
Err(error) => {
self.report_error(label.ident.span, error);
}
}
// visit `break` argument if any
visit::walk_expr(self, expr);
}
ExprKind::Break(None, Some(ref e)) => {
// We use this instead of `visit::walk_expr` to keep the parent expr around for
// better diagnostics.
self.resolve_expr(e, Some(expr));
}
ExprKind::Let(ref pat, ref scrutinee, _, _) => {
self.visit_expr(scrutinee);
self.resolve_pattern_top(pat, PatternSource::Let);
}
ExprKind::If(ref cond, ref then, ref opt_else) => {
self.with_rib(ValueNS, RibKind::Normal, |this| {
let old = this.diag_metadata.in_if_condition.replace(cond);
this.visit_expr(cond);
this.diag_metadata.in_if_condition = old;
this.visit_block(then);
});
if let Some(expr) = opt_else {
self.visit_expr(expr);
}
}
ExprKind::Loop(ref block, label, _) => {
self.resolve_labeled_block(label, expr.id, block)
}
ExprKind::While(ref cond, ref block, label) => {
self.with_resolved_label(label, expr.id, |this| {
this.with_rib(ValueNS, RibKind::Normal, |this| {
let old = this.diag_metadata.in_if_condition.replace(cond);
this.visit_expr(cond);
this.diag_metadata.in_if_condition = old;
this.visit_block(block);
})
});
}
ExprKind::ForLoop { ref pat, ref iter, ref body, label, kind: _ } => {
self.visit_expr(iter);
self.with_rib(ValueNS, RibKind::Normal, |this| {
this.resolve_pattern_top(pat, PatternSource::For);
this.resolve_labeled_block(label, expr.id, body);
});
}
ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
// Equivalent to `visit::walk_expr` + passing some context to children.
ExprKind::Field(ref subexpression, _) => {
self.resolve_expr(subexpression, Some(expr));
}
ExprKind::MethodCall(box MethodCall { ref seg, ref receiver, ref args, .. }) => {
self.resolve_expr(receiver, Some(expr));
for arg in args {
self.resolve_expr(arg, None);
}
self.visit_path_segment(seg);
}
ExprKind::Call(ref callee, ref arguments) => {
self.resolve_expr(callee, Some(expr));
let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
for (idx, argument) in arguments.iter().enumerate() {
// Constant arguments need to be treated as AnonConst since
// that is how they will be later lowered to HIR.
if const_args.contains(&idx) {
self.resolve_anon_const_manual(
argument.is_potential_trivial_const_arg(true),
AnonConstKind::ConstArg(IsRepeatExpr::No),
|this| this.resolve_expr(argument, None),
);
} else {
self.resolve_expr(argument, None);
}
}
}
ExprKind::Type(ref _type_expr, ref _ty) => {
visit::walk_expr(self, expr);
}
// For closures, RibKind::FnOrCoroutine is added in visit_fn
ExprKind::Closure(box ast::Closure {
binder: ClosureBinder::For { ref generic_params, span },
..
}) => {
self.with_generic_param_rib(
generic_params,
RibKind::Normal,
LifetimeRibKind::Generics {
binder: expr.id,
kind: LifetimeBinderKind::Closure,
span,
},
|this| visit::walk_expr(this, expr),
);
}
ExprKind::Closure(..) => visit::walk_expr(self, expr),
ExprKind::Gen(..) => {
self.with_label_rib(RibKind::FnOrCoroutine, |this| visit::walk_expr(this, expr));
}
ExprKind::Repeat(ref elem, ref ct) => {
self.visit_expr(elem);
self.resolve_anon_const(ct, AnonConstKind::ConstArg(IsRepeatExpr::Yes));
}
ExprKind::ConstBlock(ref ct) => {
self.resolve_anon_const(ct, AnonConstKind::InlineConst);
}
ExprKind::Index(ref elem, ref idx, _) => {
self.resolve_expr(elem, Some(expr));
self.visit_expr(idx);
}
ExprKind::Assign(ref lhs, ref rhs, _) => {
if !self.diag_metadata.is_assign_rhs {
self.diag_metadata.in_assignment = Some(expr);
}
self.visit_expr(lhs);
self.diag_metadata.is_assign_rhs = true;
self.diag_metadata.in_assignment = None;
self.visit_expr(rhs);
self.diag_metadata.is_assign_rhs = false;
}
ExprKind::Range(Some(ref start), Some(ref end), RangeLimits::HalfOpen) => {
self.diag_metadata.in_range = Some((start, end));
self.resolve_expr(start, Some(expr));
self.resolve_expr(end, Some(expr));
self.diag_metadata.in_range = None;
}
_ => {
visit::walk_expr(self, expr);
}
}
}
fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
match expr.kind {
ExprKind::Field(_, ident) => {
// #6890: Even though you can't treat a method like a field,
// we need to add any trait methods we find that match the
// field name so that we can do some nice error reporting
// later on in typeck.
let traits = self.traits_in_scope(ident, ValueNS);
self.r.trait_map.insert(expr.id, traits);
}
ExprKind::MethodCall(ref call) => {
debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
let traits = self.traits_in_scope(call.seg.ident, ValueNS);
self.r.trait_map.insert(expr.id, traits);
}
_ => {
// Nothing to do.
}
}
}
fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
self.r.traits_in_scope(
self.current_trait_ref.as_ref().map(|(module, _)| *module),
&self.parent_scope,
ident.span.ctxt(),
Some((ident.name, ns)),
)
}
/// Construct the list of in-scope lifetime parameters for impl trait lowering.
/// We include all lifetime parameters, either named or "Fresh".
/// The order of those parameters does not matter, as long as it is
/// deterministic.
fn record_lifetime_params_for_impl_trait(&mut self, impl_trait_node_id: NodeId) {
let mut extra_lifetime_params = vec![];
for rib in self.lifetime_ribs.iter().rev() {
extra_lifetime_params
.extend(rib.bindings.iter().map(|(&ident, &(node_id, res))| (ident, node_id, res)));
match rib.kind {
LifetimeRibKind::Item => break,
LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
if let Some(earlier_fresh) = self.r.extra_lifetime_params_map.get(&binder) {
extra_lifetime_params.extend(earlier_fresh);
}
}
_ => {}
}
}
self.r.extra_lifetime_params_map.insert(impl_trait_node_id, extra_lifetime_params);
}
fn resolve_and_cache_rustdoc_path(&mut self, path_str: &str, ns: Namespace) -> Option<Res> {
// FIXME: This caching may be incorrect in case of multiple `macro_rules`
// items with the same name in the same module.
// Also hygiene is not considered.
let mut doc_link_resolutions = std::mem::take(&mut self.r.doc_link_resolutions);
let res = *doc_link_resolutions
.entry(self.parent_scope.module.nearest_parent_mod().expect_local())
.or_default()
.entry((Symbol::intern(path_str), ns))
.or_insert_with_key(|(path, ns)| {
let res = self.r.resolve_rustdoc_path(path.as_str(), *ns, self.parent_scope);
if let Some(res) = res
&& let Some(def_id) = res.opt_def_id()
&& !def_id.is_local()
&& self.r.tcx.crate_types().contains(&CrateType::ProcMacro)
&& matches!(
self.r.tcx.sess.opts.resolve_doc_links,
ResolveDocLinks::ExportedMetadata
)
{
// Encoding foreign def ids in proc macro crate metadata will ICE.
return None;
}
res
});
self.r.doc_link_resolutions = doc_link_resolutions;
res
}
fn resolve_doc_links(&mut self, attrs: &[Attribute], maybe_exported: MaybeExported<'_>) {
match self.r.tcx.sess.opts.resolve_doc_links {
ResolveDocLinks::None => return,
ResolveDocLinks::ExportedMetadata
if !self.r.tcx.crate_types().iter().copied().any(CrateType::has_metadata)
|| !maybe_exported.eval(self.r) =>
{
return;
}
ResolveDocLinks::Exported
if !maybe_exported.eval(self.r)
&& !rustdoc::has_primitive_or_keyword_docs(attrs) =>
{
return;
}
ResolveDocLinks::ExportedMetadata
| ResolveDocLinks::Exported
| ResolveDocLinks::All => {}
}
if !attrs.iter().any(|attr| attr.may_have_doc_links()) {
return;
}
let mut need_traits_in_scope = false;
for path_str in rustdoc::attrs_to_preprocessed_links(attrs) {
// Resolve all namespaces due to no disambiguator or for diagnostics.
let mut any_resolved = false;
let mut need_assoc = false;
for ns in [TypeNS, ValueNS, MacroNS] {
if let Some(res) = self.resolve_and_cache_rustdoc_path(&path_str, ns) {
// Rustdoc ignores tool attribute resolutions and attempts
// to resolve their prefixes for diagnostics.
any_resolved = !matches!(res, Res::NonMacroAttr(NonMacroAttrKind::Tool));
} else if ns != MacroNS {
need_assoc = true;
}
}
// Resolve all prefixes for type-relative resolution or for diagnostics.
if need_assoc || !any_resolved {
let mut path = &path_str[..];
while let Some(idx) = path.rfind("::") {
path = &path[..idx];
need_traits_in_scope = true;
for ns in [TypeNS, ValueNS, MacroNS] {
self.resolve_and_cache_rustdoc_path(path, ns);
}
}
}
}
if need_traits_in_scope {
// FIXME: hygiene is not considered.
let mut doc_link_traits_in_scope = std::mem::take(&mut self.r.doc_link_traits_in_scope);
doc_link_traits_in_scope
.entry(self.parent_scope.module.nearest_parent_mod().expect_local())
.or_insert_with(|| {
self.r
.traits_in_scope(None, &self.parent_scope, SyntaxContext::root(), None)
.into_iter()
.filter_map(|tr| {
if !tr.def_id.is_local()
&& self.r.tcx.crate_types().contains(&CrateType::ProcMacro)
&& matches!(
self.r.tcx.sess.opts.resolve_doc_links,
ResolveDocLinks::ExportedMetadata
)
{
// Encoding foreign def ids in proc macro crate metadata will ICE.
return None;
}
Some(tr.def_id)
})
.collect()
});
self.r.doc_link_traits_in_scope = doc_link_traits_in_scope;
}
}
fn lint_unused_qualifications(&mut self, path: &[Segment], ns: Namespace, finalize: Finalize) {
// Don't lint on global paths because the user explicitly wrote out the full path.
if let Some(seg) = path.first()
&& seg.ident.name == kw::PathRoot
{
return;
}
if finalize.path_span.from_expansion()
|| path.iter().any(|seg| seg.ident.span.from_expansion())
{
return;
}
let end_pos =
path.iter().position(|seg| seg.has_generic_args).map_or(path.len(), |pos| pos + 1);
let unqualified = path[..end_pos].iter().enumerate().skip(1).rev().find_map(|(i, seg)| {
// Preserve the current namespace for the final path segment, but use the type
// namespace for all preceding segments
//
// e.g. for `std::env::args` check the `ValueNS` for `args` but the `TypeNS` for
// `std` and `env`
//
// If the final path segment is beyond `end_pos` all the segments to check will
// use the type namespace
let ns = if i + 1 == path.len() { ns } else { TypeNS };
let res = self.r.partial_res_map.get(&seg.id?)?.full_res()?;
let binding = self.resolve_ident_in_lexical_scope(seg.ident, ns, None, None)?;
(res == binding.res()).then_some((seg, binding))
});
if let Some((seg, binding)) = unqualified {
self.r.potentially_unnecessary_qualifications.push(UnnecessaryQualification {
binding,
node_id: finalize.node_id,
path_span: finalize.path_span,
removal_span: path[0].ident.span.until(seg.ident.span),
});
}
}
}
/// Walks the whole crate in DFS order, visiting each item, counting the declared number of
/// lifetime generic parameters and function parameters.
struct ItemInfoCollector<'a, 'ra, 'tcx> {
r: &'a mut Resolver<'ra, 'tcx>,
}
impl ItemInfoCollector<'_, '_, '_> {
fn collect_fn_info(&mut self, sig: &FnSig, id: NodeId) {
let sig = DelegationFnSig {
header: sig.header,
param_count: sig.decl.inputs.len(),
has_self: sig.decl.has_self(),
c_variadic: sig.decl.c_variadic(),
};
self.r.delegation_fn_sigs.insert(self.r.local_def_id(id), sig);
}
}
impl<'ast> Visitor<'ast> for ItemInfoCollector<'_, '_, '_> {
fn visit_item(&mut self, item: &'ast Item) {
match &item.kind {
ItemKind::TyAlias(box TyAlias { ref generics, .. })
| ItemKind::Const(box ConstItem { ref generics, .. })
| ItemKind::Fn(box Fn { ref generics, .. })
| ItemKind::Enum(_, ref generics)
| ItemKind::Struct(_, ref generics)
| ItemKind::Union(_, ref generics)
| ItemKind::Impl(box Impl { ref generics, .. })
| ItemKind::Trait(box Trait { ref generics, .. })
| ItemKind::TraitAlias(ref generics, _) => {
if let ItemKind::Fn(box Fn { ref sig, .. }) = &item.kind {
self.collect_fn_info(sig, item.id);
}
let def_id = self.r.local_def_id(item.id);
let count = generics
.params
.iter()
.filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
.count();
self.r.item_generics_num_lifetimes.insert(def_id, count);
}
ItemKind::Mod(..)
| ItemKind::ForeignMod(..)
| ItemKind::Static(..)
| ItemKind::Use(..)
| ItemKind::ExternCrate(..)
| ItemKind::MacroDef(..)
| ItemKind::GlobalAsm(..)
| ItemKind::MacCall(..)
| ItemKind::DelegationMac(..) => {}
ItemKind::Delegation(..) => {
// Delegated functions have lifetimes, their count is not necessarily zero.
// But skipping the delegation items here doesn't mean that the count will be considered zero,
// it means there will be a panic when retrieving the count,
// but for delegation items we are never actually retrieving that count in practice.
}
}
visit::walk_item(self, item)
}
fn visit_assoc_item(&mut self, item: &'ast AssocItem, ctxt: AssocCtxt) {
if let AssocItemKind::Fn(box Fn { ref sig, .. }) = &item.kind {
self.collect_fn_info(sig, item.id);
}
visit::walk_assoc_item(self, item, ctxt);
}
}
impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
visit::walk_crate(&mut ItemInfoCollector { r: self }, krate);
let mut late_resolution_visitor = LateResolutionVisitor::new(self);
late_resolution_visitor.resolve_doc_links(&krate.attrs, MaybeExported::Ok(CRATE_NODE_ID));
visit::walk_crate(&mut late_resolution_visitor, krate);
for (id, span) in late_resolution_visitor.diag_metadata.unused_labels.iter() {
self.lint_buffer.buffer_lint(
lint::builtin::UNUSED_LABELS,
*id,
*span,
BuiltinLintDiag::UnusedLabel,
);
}
}
}
/// Check if definition matches a path
fn def_id_matches_path(tcx: TyCtxt<'_>, mut def_id: DefId, expected_path: &[&str]) -> bool {
let mut path = expected_path.iter().rev();
while let (Some(parent), Some(next_step)) = (tcx.opt_parent(def_id), path.next()) {
if !tcx.opt_item_name(def_id).map_or(false, |n| n.as_str() == *next_step) {
return false;
}
def_id = parent;
}
true
}