Struct rustc_resolve::late::lifetimes::LifetimeContext

pub(crate) struct LifetimeContext<'a, 'tcx> {
    pub(crate) tcx: TyCtxt<'tcx>,
    map: &'a mut NamedRegionMap,
    scope: &'a Scope<'a>,
    trait_ref_hack: bool,
    is_in_fn_syntax: bool,
    is_in_const_generic: bool,
    labels_in_fn: Vec<Ident>,
    xcrate_object_lifetime_defaults: DefIdMap<Vec<ObjectLifetimeDefault>>,
    lifetime_uses: &'a mut DefIdMap<LifetimeUseSet<'tcx>>,
    pub(crate) missing_named_lifetime_spots: Vec<MissingLifetimeSpot<'tcx>>,
}

Fields

tcx: TyCtxt<'tcx>

map: &'a mut NamedRegionMap

scope: &'a Scope<'a>

trait_ref_hack: bool

This is slightly complicated. Our representation for poly-trait-refs contains a single binder and thus we only allow a single level of quantification. However, the syntax of Rust permits quantification in two places, e.g., T: for <'a> Foo<'a> and for <'a, 'b> &'b T: Foo<'a>. In order to get the De Bruijn indices correct when representing these constraints, we should only introduce one scope. However, we want to support both locations for the quantifier and during lifetime resolution we want precise information (so we can't desugar in an earlier phase).

So, if we encounter a quantifier at the outer scope, we set trait_ref_hack to true (and introduce a scope), and then if we encounter a quantifier at the inner scope, we error. If trait_ref_hack is false, then we introduce the scope at the inner quantifier.

is_in_fn_syntax: bool

Used to disallow the use of in-band lifetimes in fn or Fn syntax.

is_in_const_generic: bool

labels_in_fn: Vec<Ident>

List of labels in the function/method currently under analysis.

xcrate_object_lifetime_defaults: DefIdMap<Vec<ObjectLifetimeDefault>>

Cache for cross-crate per-definition object lifetime defaults.

lifetime_uses: &'a mut DefIdMap<LifetimeUseSet<'tcx>>

missing_named_lifetime_spots: Vec<MissingLifetimeSpot<'tcx>>

When encountering an undefined named lifetime, we will suggest introducing it in these places.

Implementations

impl<'tcx, '_> LifetimeContext<'_, 'tcx>

pub(crate) fn report_missing_lifetime_specifiers(
    &self,
    span: Span,
    count: usize
) -> DiagnosticBuilder<'tcx>

pub(crate) fn emit_undeclared_lifetime_error(&self, lifetime_ref: &Lifetime)

pub(crate) fn emit_non_static_lt_in_const_generic_error(
    &self,
    lifetime_ref: &Lifetime
)

pub(crate) fn is_trait_ref_fn_scope(
    &mut self,
    trait_ref: &'tcx PolyTraitRef<'tcx>
) -> bool

pub(crate) fn add_missing_lifetime_specifiers_label(
    &self,
    err: &mut DiagnosticBuilder<'_>,
    span: Span,
    count: usize,
    lifetime_names: &FxHashSet<Symbol>,
    lifetime_spans: Vec<Span>,
    params: &[ElisionFailureInfo]
)

pub(crate) fn maybe_emit_forbidden_non_static_lifetime_error(
    &self,
    body_id: BodyId,
    lifetime_ref: &'tcx Lifetime
)

Non-static lifetimes are prohibited in anonymous constants under min_const_generics so this function will emit an error if min_const_generics is enabled, the body identified by body_id is an anonymous constant and lifetime_ref is non-static.

impl<'a, 'tcx> LifetimeContext<'a, 'tcx>

pub(in late::lifetimes) fn hack<F>(
    &mut self,
    f: F
) where
    F: for<'b> FnOnce(&mut LifetimeContext<'b, 'tcx>), 

pub(in late::lifetimes) fn with<F>(
    &mut self,
    wrap_scope: Scope<'_>,
    f: F
) where
    F: for<'b> FnOnce(&'_ Scope<'_>, &mut LifetimeContext<'b, 'tcx>), 

pub(in late::lifetimes) fn lifetime_deletion_span(
    &self,
    name: Ident,
    generics: &Generics<'_>
) -> Option<Span>

helper method to determine the span to remove when suggesting the deletion of a lifetime

pub(in late::lifetimes) fn suggest_eliding_single_use_lifetime(
    &self,
    err: &mut DiagnosticBuilder<'_>,
    def_id: DefId,
    lifetime: &Lifetime
)

pub(in late::lifetimes) fn check_uses_for_lifetimes_defined_by_scope(
    &mut self
)

pub(in late::lifetimes) fn visit_early_late<F>(
    &mut self,
    parent_id: Option<HirId>,
    decl: &'tcx FnDecl<'tcx>,
    generics: &'tcx Generics<'tcx>,
    walk: F
) where
    F: for<'b, 'c> FnOnce(&'b mut LifetimeContext<'c, 'tcx>), 

Visits self by adding a scope and handling recursive walk over the contents with walk.

Handles visiting fns and methods. These are a bit complicated because we must distinguish early- vs late-bound lifetime parameters. We do this by checking which lifetimes appear within type bounds; those are early bound lifetimes, and the rest are late bound.

For example:

fn foo<'a,'b,'c,T:Trait<'b>>(...)

Here 'a and 'c are late bound but 'b is early bound. Note that early- and late-bound lifetimes may be interspersed together.

If early bound lifetimes are present, we separate them into their own list (and likewise for late bound). They will be numbered sequentially, starting from the lowest index that is already in scope (for a fn item, that will be 0, but for a method it might not be). Late bound lifetimes are resolved by name and associated with a binder ID (binder_id), so the ordering is not important there.

pub(in late::lifetimes) fn next_early_index_helper(
    &self,
    only_opaque_type_parent: bool
) -> u32

pub(in late::lifetimes) fn next_early_index(
    &self
) -> u32

Returns the next index one would use for an early-bound-region if extending the current scope.

pub(in late::lifetimes) fn next_early_index_for_opaque_type(
    &self
) -> u32

Returns the next index one would use for an impl Trait that is being converted into an opaque type alias impl Trait. This will be the next early index from the enclosing item, for the most part. See the opaque_type_parent field for more info.

pub(in late::lifetimes) fn resolve_lifetime_ref(
    &mut self,
    lifetime_ref: &'tcx Lifetime
)

pub(in late::lifetimes) fn visit_segment_args(
    &mut self,
    res: Res,
    depth: usize,
    generic_args: &'tcx GenericArgs<'tcx>
)

pub(in late::lifetimes) fn visit_fn_like_elision(
    &mut self,
    inputs: &'tcx [Ty<'tcx>],
    output: Option<&'tcx Ty<'tcx>>
)

pub(in late::lifetimes) fn resolve_elided_lifetimes(
    &mut self,
    lifetime_refs: Vec<&'tcx Lifetime>
)

pub(in late::lifetimes) fn report_elision_failure(
    &mut self,
    db: &mut DiagnosticBuilder<'_>,
    params: &[ElisionFailureInfo]
) -> bool

pub(in late::lifetimes) fn resolve_object_lifetime_default(
    &mut self,
    lifetime_ref: &'tcx Lifetime
)

pub(in late::lifetimes) fn check_lifetime_params(
    &mut self,
    old_scope: &'_ Scope<'_>,
    params: &'tcx [GenericParam<'tcx>]
)

pub(in late::lifetimes) fn check_lifetime_param_for_shadowing(
    &self,
    old_scope: &'_ Scope<'_>,
    param: &'tcx GenericParam<'tcx>
)

pub(in late::lifetimes) fn track_lifetime_uses(
    &self
) -> bool

Returns true if, in the current scope, replacing '_ would be equivalent to a single-use lifetime.

pub(in late::lifetimes) fn insert_lifetime(
    &mut self,
    lifetime_ref: &'tcx Lifetime,
    def: Region
)

pub(in late::lifetimes) fn uninsert_lifetime_on_error(
    &mut self,
    lifetime_ref: &'tcx Lifetime,
    bad_def: Region
)

Sometimes we resolve a lifetime, but later find that it is an error (esp. around impl trait). In that case, we remove the entry into map.defs so as not to confuse later code.

Trait Implementations

impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx>

type Map = Map<'tcx>

pub fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map>

The default versions of the visit_nested_XXX routines invoke this method to get a map to use. By selecting an enum variant, you control which kinds of nested HIR are visited; see NestedVisitorMap for details. By "nested HIR", we are referring to bits of HIR that are not directly embedded within one another but rather indirectly, through a table in the crate. This is done to control dependencies during incremental compilation: the non-inline bits of HIR can be tracked and hashed separately.

pub fn visit_nested_item(&mut self, _: ItemId)

Invoked when a nested item is encountered. By default does nothing unless you override nested_visit_map to return other than None, in which case it will walk the item. You probably don't want to override this method -- instead, override nested_visit_map or use the "shallow" or "deep" visit patterns described on itemlikevisit::ItemLikeVisitor. The only reason to override this method is if you want a nested pattern but cannot supply a Map; see nested_visit_map for advice.

pub fn visit_nested_body(&mut self, body: BodyId)

Invoked to visit the body of a function, method or closure. Like visit_nested_item, does nothing by default unless you override nested_visit_map to return other than None, in which case it will walk the body.

pub fn visit_item(&mut self, item: &'tcx Item<'tcx>)

Visits the top-level item and (optionally) nested items / impl items. See visit_nested_item for details.

pub fn visit_foreign_item(&mut self, item: &'tcx ForeignItem<'tcx>)

pub fn visit_ty(&mut self, ty: &'tcx Ty<'tcx>)

pub fn visit_trait_item(&mut self, trait_item: &'tcx TraitItem<'tcx>)

pub fn visit_impl_item(&mut self, impl_item: &'tcx ImplItem<'tcx>)

pub fn visit_lifetime(&mut self, lifetime_ref: &'tcx Lifetime)

pub fn visit_path(&mut self, path: &'tcx Path<'tcx>, _: HirId)

pub fn visit_fn_decl(&mut self, fd: &'tcx FnDecl<'tcx>)

pub fn visit_generics(&mut self, generics: &'tcx Generics<'tcx>)

pub fn visit_param_bound(&mut self, bound: &'tcx GenericBound<'tcx>)

pub fn visit_poly_trait_ref(
    &mut self,
    trait_ref: &'tcx PolyTraitRef<'tcx>,
    _modifier: TraitBoundModifier
)

pub fn visit_nested_trait_item(&mut self, id: TraitItemId)

Like visit_nested_item(), but for trait items. See visit_nested_item() for advice on when to override this method.

pub fn visit_nested_impl_item(&mut self, id: ImplItemId)

Like visit_nested_item(), but for impl items. See visit_nested_item() for advice on when to override this method.

pub fn visit_param(&mut self, param: &'v Param<'v>)

pub fn visit_body(&mut self, b: &'v Body<'v>)

pub fn as_deep_visitor(&mut self) -> DeepVisitor<'_, Self>

When invoking visit_all_item_likes(), you need to supply an item-like visitor. This method converts a "intra-visit" visitor into an item-like visitor that walks the entire tree. If you use this, you probably don't want to process the contents of nested item-like things, since the outer loop will visit them as well.

pub fn visit_id(&mut self, _hir_id: HirId)

pub fn visit_name(&mut self, _span: Span, _name: Symbol)

pub fn visit_ident(&mut self, ident: Ident)

pub fn visit_mod(&mut self, m: &'v Mod<'v>, _s: Span, n: HirId)

pub fn visit_local(&mut self, l: &'v Local<'v>)

pub fn visit_block(&mut self, b: &'v Block<'v>)

pub fn visit_stmt(&mut self, s: &'v Stmt<'v>)

pub fn visit_arm(&mut self, a: &'v Arm<'v>)

pub fn visit_pat(&mut self, p: &'v Pat<'v>)

pub fn visit_anon_const(&mut self, c: &'v AnonConst)

pub fn visit_expr(&mut self, ex: &'v Expr<'v>)

pub fn visit_generic_param(&mut self, p: &'v GenericParam<'v>)

pub fn visit_where_predicate(&mut self, predicate: &'v WherePredicate<'v>)

pub fn visit_fn(
    &mut self,
    fk: FnKind<'v>,
    fd: &'v FnDecl<'v>,
    b: BodyId,
    s: Span,
    id: HirId
)

pub fn visit_use(&mut self, path: &'v Path<'v>, hir_id: HirId)

pub fn visit_trait_item_ref(&mut self, ii: &'v TraitItemRef)

pub fn visit_impl_item_ref(&mut self, ii: &'v ImplItemRef<'v>)

pub fn visit_trait_ref(&mut self, t: &'v TraitRef<'v>)

pub fn visit_variant_data(
    &mut self,
    s: &'v VariantData<'v>,
    Symbol,
    &'v Generics<'v>,
    _parent_id: HirId,
    Span
)

pub fn visit_struct_field(&mut self, s: &'v StructField<'v>)

pub fn visit_enum_def(
    &mut self,
    enum_definition: &'v EnumDef<'v>,
    generics: &'v Generics<'v>,
    item_id: HirId,
    Span
)

pub fn visit_variant(
    &mut self,
    v: &'v Variant<'v>,
    g: &'v Generics<'v>,
    item_id: HirId
)

pub fn visit_label(&mut self, label: &'v Label)

pub fn visit_generic_arg(&mut self, generic_arg: &'v GenericArg<'v>)

pub fn visit_qpath(&mut self, qpath: &'v QPath<'v>, id: HirId, span: Span)

pub fn visit_path_segment(
    &mut self,
    path_span: Span,
    path_segment: &'v PathSegment<'v>
)

pub fn visit_generic_args(
    &mut self,
    path_span: Span,
    generic_args: &'v GenericArgs<'v>
)

pub fn visit_assoc_type_binding(&mut self, type_binding: &'v TypeBinding<'v>)

pub fn visit_attribute(&mut self, _attr: &'v Attribute)

pub fn visit_macro_def(&mut self, macro_def: &'v MacroDef<'v>)

pub fn visit_vis(&mut self, vis: &'v Spanned<VisibilityKind<'v>>)

pub fn visit_associated_item_kind(&mut self, kind: &'v AssocItemKind)

pub fn visit_defaultness(&mut self, defaultness: &'v Defaultness)