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//! "Collection" is the process of determining the type and other external
//! details of each item in Rust. Collection is specifically concerned
//! with *inter-procedural* things -- for example, for a function
//! definition, collection will figure out the type and signature of the
//! function, but it will not visit the *body* of the function in any way,
//! nor examine type annotations on local variables (that's the job of
//! type *checking*).
//!
//! Collecting is ultimately defined by a bundle of queries that
//! inquire after various facts about the items in the crate (e.g.,
//! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
//! for the full set.
//!
//! At present, however, we do run collection across all items in the
//! crate as a kind of pass. This should eventually be factored away.
use crate::astconv::{AstConv, Bounds, SizedByDefault};
use crate::check::intrinsic::intrinsic_operation_unsafety;
use crate::constrained_generic_params as cgp;
use crate::middle::resolve_lifetime as rl;
use rustc_ast::ast;
use rustc_ast::ast::MetaItemKind;
use rustc_attr::{list_contains_name, mark_used, InlineAttr, OptimizeAttr};
use rustc_data_structures::captures::Captures;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_errors::{struct_span_err, Applicability};
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, DefKind, Res};
use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_hir::weak_lang_items;
use rustc_hir::{GenericParamKind, Node};
use rustc_middle::hir::map::blocks::FnLikeNode;
use rustc_middle::hir::map::Map;
use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
use rustc_middle::mir::mono::Linkage;
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::subst::InternalSubsts;
use rustc_middle::ty::util::Discr;
use rustc_middle::ty::util::IntTypeExt;
use rustc_middle::ty::{self, AdtKind, Const, ToPolyTraitRef, Ty, TyCtxt};
use rustc_middle::ty::{ReprOptions, ToPredicate, WithConstness};
use rustc_session::config::SanitizerSet;
use rustc_session::lint;
use rustc_session::parse::feature_err;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{Span, DUMMY_SP};
use rustc_target::spec::abi;
use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
mod type_of;
struct OnlySelfBounds(bool);
///////////////////////////////////////////////////////////////////////////
// Main entry point
fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
tcx.hir().visit_item_likes_in_module(
module_def_id,
&mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
);
}
pub fn provide(providers: &mut Providers) {
*providers = Providers {
type_of: type_of::type_of,
generics_of,
predicates_of,
predicates_defined_on,
explicit_predicates_of,
super_predicates_of,
type_param_predicates,
trait_def,
adt_def,
fn_sig,
impl_trait_ref,
impl_polarity,
is_foreign_item,
static_mutability,
generator_kind,
codegen_fn_attrs,
collect_mod_item_types,
..*providers
};
}
///////////////////////////////////////////////////////////////////////////
/// Context specific to some particular item. This is what implements
/// `AstConv`. It has information about the predicates that are defined
/// on the trait. Unfortunately, this predicate information is
/// available in various different forms at various points in the
/// process. So we can't just store a pointer to e.g., the AST or the
/// parsed ty form, we have to be more flexible. To this end, the
/// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
/// `get_type_parameter_bounds` requests, drawing the information from
/// the AST (`hir::Generics`), recursively.
pub struct ItemCtxt<'tcx> {
tcx: TyCtxt<'tcx>,
item_def_id: DefId,
}
///////////////////////////////////////////////////////////////////////////
#[derive(Default)]
crate struct PlaceholderHirTyCollector(crate Vec<Span>);
impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
type Map = intravisit::ErasedMap<'v>;
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
if let hir::TyKind::Infer = t.kind {
self.0.push(t.span);
}
intravisit::walk_ty(self, t)
}
}
struct CollectItemTypesVisitor<'tcx> {
tcx: TyCtxt<'tcx>,
}
/// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
/// and suggest adding type parameters in the appropriate place, taking into consideration any and
/// all already existing generic type parameters to avoid suggesting a name that is already in use.
crate fn placeholder_type_error(
tcx: TyCtxt<'tcx>,
span: Span,
generics: &[hir::GenericParam<'_>],
placeholder_types: Vec<Span>,
suggest: bool,
) {
if placeholder_types.is_empty() {
return;
}
let type_name = generics.next_type_param_name(None);
let mut sugg: Vec<_> =
placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
if generics.is_empty() {
sugg.push((span, format!("<{}>", type_name)));
} else if let Some(arg) = generics.iter().find(|arg| match arg.name {
hir::ParamName::Plain(Ident { name: kw::Underscore, .. }) => true,
_ => false,
}) {
// Account for `_` already present in cases like `struct S<_>(_);` and suggest
// `struct S<T>(T);` instead of `struct S<_, T>(T);`.
sugg.push((arg.span, (*type_name).to_string()));
} else {
let last = generics.iter().last().unwrap();
sugg.push((
// Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
last.bounds_span().unwrap_or(last.span).shrink_to_hi(),
format!(", {}", type_name),
));
}
let mut err = bad_placeholder_type(tcx, placeholder_types);
if suggest {
err.multipart_suggestion(
"use type parameters instead",
sugg,
Applicability::HasPlaceholders,
);
}
err.emit();
}
fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
let (generics, suggest) = match &item.kind {
hir::ItemKind::Union(_, generics)
| hir::ItemKind::Enum(_, generics)
| hir::ItemKind::TraitAlias(generics, _)
| hir::ItemKind::Trait(_, _, generics, ..)
| hir::ItemKind::Impl { generics, .. }
| hir::ItemKind::Struct(_, generics) => (generics, true),
hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
| hir::ItemKind::TyAlias(_, generics) => (generics, false),
// `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
_ => return,
};
let mut visitor = PlaceholderHirTyCollector::default();
visitor.visit_item(item);
placeholder_type_error(tcx, generics.span, &generics.params[..], visitor.0, suggest);
}
impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
type Map = Map<'tcx>;
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::OnlyBodies(self.tcx.hir())
}
fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
convert_item(self.tcx, item.hir_id);
reject_placeholder_type_signatures_in_item(self.tcx, item);
intravisit::walk_item(self, item);
}
fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
for param in generics.params {
match param.kind {
hir::GenericParamKind::Lifetime { .. } => {}
hir::GenericParamKind::Type { default: Some(_), .. } => {
let def_id = self.tcx.hir().local_def_id(param.hir_id);
self.tcx.ensure().type_of(def_id);
}
hir::GenericParamKind::Type { .. } => {}
hir::GenericParamKind::Const { .. } => {
let def_id = self.tcx.hir().local_def_id(param.hir_id);
self.tcx.ensure().type_of(def_id);
}
}
}
intravisit::walk_generics(self, generics);
}
fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
if let hir::ExprKind::Closure(..) = expr.kind {
let def_id = self.tcx.hir().local_def_id(expr.hir_id);
self.tcx.ensure().generics_of(def_id);
self.tcx.ensure().type_of(def_id);
}
intravisit::walk_expr(self, expr);
}
fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
convert_trait_item(self.tcx, trait_item.hir_id);
intravisit::walk_trait_item(self, trait_item);
}
fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
convert_impl_item(self.tcx, impl_item.hir_id);
intravisit::walk_impl_item(self, impl_item);
}
}
///////////////////////////////////////////////////////////////////////////
// Utility types and common code for the above passes.
fn bad_placeholder_type(
tcx: TyCtxt<'tcx>,
mut spans: Vec<Span>,
) -> rustc_errors::DiagnosticBuilder<'tcx> {
spans.sort();
let mut err = struct_span_err!(
tcx.sess,
spans.clone(),
E0121,
"the type placeholder `_` is not allowed within types on item signatures",
);
for span in spans {
err.span_label(span, "not allowed in type signatures");
}
err
}
impl ItemCtxt<'tcx> {
pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
ItemCtxt { tcx, item_def_id }
}
pub fn to_ty(&self, ast_ty: &'tcx hir::Ty<'tcx>) -> Ty<'tcx> {
AstConv::ast_ty_to_ty(self, ast_ty)
}
pub fn hir_id(&self) -> hir::HirId {
self.tcx.hir().as_local_hir_id(self.item_def_id.expect_local())
}
pub fn node(&self) -> hir::Node<'tcx> {
self.tcx.hir().get(self.hir_id())
}
}
impl AstConv<'tcx> for ItemCtxt<'tcx> {
fn tcx(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn item_def_id(&self) -> Option<DefId> {
Some(self.item_def_id)
}
fn default_constness_for_trait_bounds(&self) -> hir::Constness {
if let Some(fn_like) = FnLikeNode::from_node(self.node()) {
fn_like.constness()
} else {
hir::Constness::NotConst
}
}
fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
self.tcx.at(span).type_param_predicates((self.item_def_id, def_id.expect_local()))
}
fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
None
}
fn allow_ty_infer(&self) -> bool {
false
}
fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
self.tcx().ty_error_with_message(span, "bad_placeholder_type")
}
fn ct_infer(
&self,
ty: Ty<'tcx>,
_: Option<&ty::GenericParamDef>,
span: Span,
) -> &'tcx Const<'tcx> {
bad_placeholder_type(self.tcx(), vec![span]).emit();
self.tcx().const_error(ty)
}
fn projected_ty_from_poly_trait_ref(
&self,
span: Span,
item_def_id: DefId,
item_segment: &hir::PathSegment<'_>,
poly_trait_ref: ty::PolyTraitRef<'tcx>,
) -> Ty<'tcx> {
if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
self,
self.tcx,
span,
item_def_id,
item_segment,
trait_ref.substs,
);
self.tcx().mk_projection(item_def_id, item_substs)
} else {
// There are no late-bound regions; we can just ignore the binder.
let mut err = struct_span_err!(
self.tcx().sess,
span,
E0212,
"cannot extract an associated type from a higher-ranked trait bound \
in this context"
);
match self.node() {
hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
let item =
self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
match &item.kind {
hir::ItemKind::Enum(_, generics)
| hir::ItemKind::Struct(_, generics)
| hir::ItemKind::Union(_, generics) => {
let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
let (lt_sp, sugg) = match &generics.params[..] {
[] => (generics.span, format!("<{}>", lt_name)),
[bound, ..] => {
(bound.span.shrink_to_lo(), format!("{}, ", lt_name))
}
};
let suggestions = vec![
(lt_sp, sugg),
(
span,
format!(
"{}::{}",
// Replace the existing lifetimes with a new named lifetime.
self.tcx
.replace_late_bound_regions(&poly_trait_ref, |_| {
self.tcx.mk_region(ty::ReEarlyBound(
ty::EarlyBoundRegion {
def_id: item_def_id,
index: 0,
name: Symbol::intern(&lt_name),
},
))
})
.0,
item_segment.ident
),
),
];
err.multipart_suggestion(
"use a fully qualified path with explicit lifetimes",
suggestions,
Applicability::MaybeIncorrect,
);
}
_ => {}
}
}
hir::Node::Item(hir::Item {
kind:
hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
..
}) => {}
hir::Node::Item(_)
| hir::Node::ForeignItem(_)
| hir::Node::TraitItem(_)
| hir::Node::ImplItem(_) => {
err.span_suggestion(
span,
"use a fully qualified path with inferred lifetimes",
format!(
"{}::{}",
// Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
self.tcx.anonymize_late_bound_regions(&poly_trait_ref).skip_binder(),
item_segment.ident
),
Applicability::MaybeIncorrect,
);
}
_ => {}
}
err.emit();
self.tcx().ty_error()
}
}
fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
// Types in item signatures are not normalized to avoid undue dependencies.
ty
}
fn set_tainted_by_errors(&self) {
// There's no obvious place to track this, so just let it go.
}
fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
// There's no place to record types from signatures?
}
}
/// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
fn get_new_lifetime_name<'tcx>(
tcx: TyCtxt<'tcx>,
poly_trait_ref: ty::PolyTraitRef<'tcx>,
generics: &hir::Generics<'tcx>,
) -> String {
let existing_lifetimes = tcx
.collect_referenced_late_bound_regions(&poly_trait_ref)
.into_iter()
.filter_map(|lt| {
if let ty::BoundRegion::BrNamed(_, name) = lt {
Some(name.as_str().to_string())
} else {
None
}
})
.chain(generics.params.iter().filter_map(|param| {
if let hir::GenericParamKind::Lifetime { .. } = &param.kind {
Some(param.name.ident().as_str().to_string())
} else {
None
}
}))
.collect::<FxHashSet<String>>();
let a_to_z_repeat_n = |n| {
(b'a'..=b'z').map(move |c| {
let mut s = '\''.to_string();
s.extend(std::iter::repeat(char::from(c)).take(n));
s
})
};
// If all single char lifetime names are present, we wrap around and double the chars.
(1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
}
/// Returns the predicates defined on `item_def_id` of the form
/// `X: Foo` where `X` is the type parameter `def_id`.
fn type_param_predicates(
tcx: TyCtxt<'_>,
(item_def_id, def_id): (DefId, LocalDefId),
) -> ty::GenericPredicates<'_> {
use rustc_hir::*;
// In the AST, bounds can derive from two places. Either
// written inline like `<T: Foo>` or in a where-clause like
// `where T: Foo`.
let param_id = tcx.hir().as_local_hir_id(def_id);
let param_owner = tcx.hir().ty_param_owner(param_id);
let param_owner_def_id = tcx.hir().local_def_id(param_owner);
let generics = tcx.generics_of(param_owner_def_id);
let index = generics.param_def_id_to_index[&def_id.to_def_id()];
let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
// Don't look for bounds where the type parameter isn't in scope.
let parent = if item_def_id == param_owner_def_id.to_def_id() {
None
} else {
tcx.generics_of(item_def_id).parent
};
let mut result = parent
.map(|parent| {
let icx = ItemCtxt::new(tcx, parent);
icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id())
})
.unwrap_or_default();
let mut extend = None;
let item_hir_id = tcx.hir().as_local_hir_id(item_def_id.expect_local());
let ast_generics = match tcx.hir().get(item_hir_id) {
Node::TraitItem(item) => &item.generics,
Node::ImplItem(item) => &item.generics,
Node::Item(item) => {
match item.kind {
ItemKind::Fn(.., ref generics, _)
| ItemKind::Impl { ref generics, .. }
| ItemKind::TyAlias(_, ref generics)
| ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
| ItemKind::Enum(_, ref generics)
| ItemKind::Struct(_, ref generics)
| ItemKind::Union(_, ref generics) => generics,
ItemKind::Trait(_, _, ref generics, ..) => {
// Implied `Self: Trait` and supertrait bounds.
if param_id == item_hir_id {
let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
extend =
Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
}
generics
}
_ => return result,
}
}
Node::ForeignItem(item) => match item.kind {
ForeignItemKind::Fn(_, _, ref generics) => generics,
_ => return result,
},
_ => return result,
};
let icx = ItemCtxt::new(tcx, item_def_id);
let extra_predicates = extend.into_iter().chain(
icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))
.into_iter()
.filter(|(predicate, _)| match predicate.kind() {
ty::PredicateKind::Trait(ref data, _) => {
data.skip_binder().self_ty().is_param(index)
}
_ => false,
}),
);
result.predicates =
tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
result
}
impl ItemCtxt<'tcx> {
/// Finds bounds from `hir::Generics`. This requires scanning through the
/// AST. We do this to avoid having to convert *all* the bounds, which
/// would create artificial cycles. Instead, we can only convert the
/// bounds for a type parameter `X` if `X::Foo` is used.
fn type_parameter_bounds_in_generics(
&self,
ast_generics: &'tcx hir::Generics<'tcx>,
param_id: hir::HirId,
ty: Ty<'tcx>,
only_self_bounds: OnlySelfBounds,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
let constness = self.default_constness_for_trait_bounds();
let from_ty_params = ast_generics
.params
.iter()
.filter_map(|param| match param.kind {
GenericParamKind::Type { .. } if param.hir_id == param_id => Some(&param.bounds),
_ => None,
})
.flat_map(|bounds| bounds.iter())
.flat_map(|b| predicates_from_bound(self, ty, b, constness));
let from_where_clauses = ast_generics
.where_clause
.predicates
.iter()
.filter_map(|wp| match *wp {
hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
_ => None,
})
.flat_map(|bp| {
let bt = if is_param(self.tcx, &bp.bounded_ty, param_id) {
Some(ty)
} else if !only_self_bounds.0 {
Some(self.to_ty(&bp.bounded_ty))
} else {
None
};
bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
})
.flat_map(|(bt, b)| predicates_from_bound(self, bt, b, constness));
from_ty_params.chain(from_where_clauses).collect()
}
}
/// Tests whether this is the AST for a reference to the type
/// parameter with ID `param_id`. We use this so as to avoid running
/// `ast_ty_to_ty`, because we want to avoid triggering an all-out
/// conversion of the type to avoid inducing unnecessary cycles.
fn is_param(tcx: TyCtxt<'_>, ast_ty: &hir::Ty<'_>, param_id: hir::HirId) -> bool {
if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = ast_ty.kind {
match path.res {
Res::SelfTy(Some(def_id), None) | Res::Def(DefKind::TyParam, def_id) => {
def_id == tcx.hir().local_def_id(param_id).to_def_id()
}
_ => false,
}
} else {
false
}
}
fn convert_item(tcx: TyCtxt<'_>, item_id: hir::HirId) {
let it = tcx.hir().expect_item(item_id);
debug!("convert: item {} with id {}", it.ident, it.hir_id);
let def_id = tcx.hir().local_def_id(item_id);
match it.kind {
// These don't define types.
hir::ItemKind::ExternCrate(_)
| hir::ItemKind::Use(..)
| hir::ItemKind::Mod(_)
| hir::ItemKind::GlobalAsm(_) => {}
hir::ItemKind::ForeignMod(ref foreign_mod) => {
for item in foreign_mod.items {
let def_id = tcx.hir().local_def_id(item.hir_id);
tcx.ensure().generics_of(def_id);
tcx.ensure().type_of(def_id);
tcx.ensure().predicates_of(def_id);
if let hir::ForeignItemKind::Fn(..) = item.kind {
tcx.ensure().fn_sig(def_id);
}
}
}
hir::ItemKind::Enum(ref enum_definition, _) => {
tcx.ensure().generics_of(def_id);
tcx.ensure().type_of(def_id);
tcx.ensure().predicates_of(def_id);
convert_enum_variant_types(tcx, def_id.to_def_id(), &enum_definition.variants);
}
hir::ItemKind::Impl { .. } => {
tcx.ensure().generics_of(def_id);
tcx.ensure().type_of(def_id);
tcx.ensure().impl_trait_ref(def_id);
tcx.ensure().predicates_of(def_id);
}
hir::ItemKind::Trait(..) => {
tcx.ensure().generics_of(def_id);
tcx.ensure().trait_def(def_id);
tcx.at(it.span).super_predicates_of(def_id);
tcx.ensure().predicates_of(def_id);
}
hir::ItemKind::TraitAlias(..) => {
tcx.ensure().generics_of(def_id);
tcx.at(it.span).super_predicates_of(def_id);
tcx.ensure().predicates_of(def_id);
}
hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
tcx.ensure().generics_of(def_id);
tcx.ensure().type_of(def_id);
tcx.ensure().predicates_of(def_id);
for f in struct_def.fields() {
let def_id = tcx.hir().local_def_id(f.hir_id);
tcx.ensure().generics_of(def_id);
tcx.ensure().type_of(def_id);
tcx.ensure().predicates_of(def_id);
}
if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
convert_variant_ctor(tcx, ctor_hir_id);
}
}
// Desugared from `impl Trait`, so visited by the function's return type.
hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(_), .. }) => {}
hir::ItemKind::OpaqueTy(..)
| hir::ItemKind::TyAlias(..)
| hir::ItemKind::Static(..)
| hir::ItemKind::Const(..)
| hir::ItemKind::Fn(..) => {
tcx.ensure().generics_of(def_id);
tcx.ensure().type_of(def_id);
tcx.ensure().predicates_of(def_id);
if let hir::ItemKind::Fn(..) = it.kind {
tcx.ensure().fn_sig(def_id);
}
}
}
}
fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::HirId) {
let trait_item = tcx.hir().expect_trait_item(trait_item_id);
let def_id = tcx.hir().local_def_id(trait_item.hir_id);
tcx.ensure().generics_of(def_id);
match trait_item.kind {
hir::TraitItemKind::Fn(..) => {
tcx.ensure().type_of(def_id);
tcx.ensure().fn_sig(def_id);
}
hir::TraitItemKind::Const(.., Some(_)) => {
tcx.ensure().type_of(def_id);
}
hir::TraitItemKind::Const(..) | hir::TraitItemKind::Type(_, Some(_)) => {
tcx.ensure().type_of(def_id);
// Account for `const C: _;` and `type T = _;`.
let mut visitor = PlaceholderHirTyCollector::default();
visitor.visit_trait_item(trait_item);
placeholder_type_error(tcx, DUMMY_SP, &[], visitor.0, false);
}
hir::TraitItemKind::Type(_, None) => {}
};
tcx.ensure().predicates_of(def_id);
}
fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::HirId) {
let def_id = tcx.hir().local_def_id(impl_item_id);
tcx.ensure().generics_of(def_id);
tcx.ensure().type_of(def_id);
tcx.ensure().predicates_of(def_id);
let impl_item = tcx.hir().expect_impl_item(impl_item_id);
match impl_item.kind {
hir::ImplItemKind::Fn(..) => {
tcx.ensure().fn_sig(def_id);
}
hir::ImplItemKind::TyAlias(_) => {
// Account for `type T = _;`
let mut visitor = PlaceholderHirTyCollector::default();
visitor.visit_impl_item(impl_item);
placeholder_type_error(tcx, DUMMY_SP, &[], visitor.0, false);
}
hir::ImplItemKind::Const(..) => {}
}
}
fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
let def_id = tcx.hir().local_def_id(ctor_id);
tcx.ensure().generics_of(def_id);
tcx.ensure().type_of(def_id);
tcx.ensure().predicates_of(def_id);
}
fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
let def = tcx.adt_def(def_id);
let repr_type = def.repr.discr_type();
let initial = repr_type.initial_discriminant(tcx);
let mut prev_discr = None::<Discr<'_>>;
// fill the discriminant values and field types
for variant in variants {
let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
prev_discr = Some(
if let Some(ref e) = variant.disr_expr {
let expr_did = tcx.hir().local_def_id(e.hir_id);
def.eval_explicit_discr(tcx, expr_did.to_def_id())
} else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
Some(discr)
} else {
struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
.span_label(
variant.span,
format!("overflowed on value after {}", prev_discr.unwrap()),
)
.note(&format!(
"explicitly set `{} = {}` if that is desired outcome",
variant.ident, wrapped_discr
))
.emit();
None
}
.unwrap_or(wrapped_discr),
);
for f in variant.data.fields() {
let def_id = tcx.hir().local_def_id(f.hir_id);
tcx.ensure().generics_of(def_id);
tcx.ensure().type_of(def_id);
tcx.ensure().predicates_of(def_id);
}
// Convert the ctor, if any. This also registers the variant as
// an item.
if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
convert_variant_ctor(tcx, ctor_hir_id);
}
}
}
fn convert_variant(
tcx: TyCtxt<'_>,
variant_did: Option<LocalDefId>,
ctor_did: Option<LocalDefId>,
ident: Ident,
discr: ty::VariantDiscr,
def: &hir::VariantData<'_>,
adt_kind: ty::AdtKind,
parent_did: LocalDefId,
) -> ty::VariantDef {
let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did));
let fields = def
.fields()
.iter()
.map(|f| {
let fid = tcx.hir().local_def_id(f.hir_id);
let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
if let Some(prev_span) = dup_span {
struct_span_err!(
tcx.sess,
f.span,
E0124,
"field `{}` is already declared",
f.ident
)
.span_label(f.span, "field already declared")
.span_label(prev_span, format!("`{}` first declared here", f.ident))
.emit();
} else {
seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
}
ty::FieldDef {
did: fid.to_def_id(),
ident: f.ident,
vis: ty::Visibility::from_hir(&f.vis, hir_id, tcx),
}
})
.collect();
let recovered = match def {
hir::VariantData::Struct(_, r) => *r,
_ => false,
};
ty::VariantDef::new(
tcx,
ident,
variant_did.map(LocalDefId::to_def_id),
ctor_did.map(LocalDefId::to_def_id),
discr,
fields,
CtorKind::from_hir(def),
adt_kind,
parent_did.to_def_id(),
recovered,
)
}
fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
use rustc_hir::*;
let def_id = def_id.expect_local();
let hir_id = tcx.hir().as_local_hir_id(def_id);
let item = match tcx.hir().get(hir_id) {
Node::Item(item) => item,
_ => bug!(),
};
let repr = ReprOptions::new(tcx, def_id.to_def_id());
let (kind, variants) = match item.kind {
ItemKind::Enum(ref def, _) => {
let mut distance_from_explicit = 0;
let variants = def
.variants
.iter()
.map(|v| {
let variant_did = Some(tcx.hir().local_def_id(v.id));
let ctor_did =
v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
let discr = if let Some(ref e) = v.disr_expr {
distance_from_explicit = 0;
ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
} else {
ty::VariantDiscr::Relative(distance_from_explicit)
};
distance_from_explicit += 1;
convert_variant(
tcx,
variant_did,
ctor_did,
v.ident,
discr,
&v.data,
AdtKind::Enum,
def_id,
)
})
.collect();
(AdtKind::Enum, variants)
}
ItemKind::Struct(ref def, _) => {
let variant_did = None::<LocalDefId>;
let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
let variants = std::iter::once(convert_variant(
tcx,
variant_did,
ctor_did,
item.ident,
ty::VariantDiscr::Relative(0),
def,
AdtKind::Struct,
def_id,
))
.collect();
(AdtKind::Struct, variants)
}
ItemKind::Union(ref def, _) => {
let variant_did = None;
let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
let variants = std::iter::once(convert_variant(
tcx,
variant_did,
ctor_did,
item.ident,
ty::VariantDiscr::Relative(0),
def,
AdtKind::Union,
def_id,
))
.collect();
(AdtKind::Union, variants)
}
_ => bug!(),
};
tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
}
/// Ensures that the super-predicates of the trait with a `DefId`
/// of `trait_def_id` are converted and stored. This also ensures that
/// the transitive super-predicates are converted.
fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
debug!("super_predicates(trait_def_id={:?})", trait_def_id);
let trait_hir_id = tcx.hir().as_local_hir_id(trait_def_id.expect_local());
let item = match tcx.hir().get(trait_hir_id) {
Node::Item(item) => item,
_ => bug!("trait_node_id {} is not an item", trait_hir_id),
};
let (generics, bounds) = match item.kind {
hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
_ => span_bug!(item.span, "super_predicates invoked on non-trait"),
};
let icx = ItemCtxt::new(tcx, trait_def_id);
// Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
let self_param_ty = tcx.types.self_param;
let superbounds1 =
AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
// Convert any explicit superbounds in the where-clause,
// e.g., `trait Foo where Self: Bar`.
// In the case of trait aliases, however, we include all bounds in the where-clause,
// so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
// as one of its "superpredicates".
let is_trait_alias = tcx.is_trait_alias(trait_def_id);
let superbounds2 = icx.type_parameter_bounds_in_generics(
generics,
item.hir_id,
self_param_ty,
OnlySelfBounds(!is_trait_alias),
);
// Combine the two lists to form the complete set of superbounds:
let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
// Now require that immediate supertraits are converted,
// which will, in turn, reach indirect supertraits.
for &(pred, span) in superbounds {
debug!("superbound: {:?}", pred);
if let ty::PredicateKind::Trait(bound, _) = pred.kind() {
tcx.at(span).super_predicates_of(bound.def_id());
}
}
ty::GenericPredicates { parent: None, predicates: superbounds }
}
fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
let item = tcx.hir().expect_item(hir_id);
let (is_auto, unsafety) = match item.kind {
hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
_ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
};
let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
if paren_sugar && !tcx.features().unboxed_closures {
tcx.sess
.struct_span_err(
item.span,
"the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
which traits can use parenthetical notation",
)
.help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
.emit();
}
let is_marker = tcx.has_attr(def_id, sym::marker);
let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
ty::trait_def::TraitSpecializationKind::Marker
} else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
ty::trait_def::TraitSpecializationKind::AlwaysApplicable
} else {
ty::trait_def::TraitSpecializationKind::None
};
let def_path_hash = tcx.def_path_hash(def_id);
ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, spec_kind, def_path_hash)
}
fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
struct LateBoundRegionsDetector<'tcx> {
tcx: TyCtxt<'tcx>,
outer_index: ty::DebruijnIndex,
has_late_bound_regions: Option<Span>,
}
impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
type Map = intravisit::ErasedMap<'tcx>;
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
if self.has_late_bound_regions.is_some() {
return;
}
match ty.kind {
hir::TyKind::BareFn(..) => {
self.outer_index.shift_in(1);
intravisit::walk_ty(self, ty);
self.outer_index.shift_out(1);
}
_ => intravisit::walk_ty(self, ty),
}
}
fn visit_poly_trait_ref(
&mut self,
tr: &'tcx hir::PolyTraitRef<'tcx>,
m: hir::TraitBoundModifier,
) {
if self.has_late_bound_regions.is_some() {
return;
}
self.outer_index.shift_in(1);
intravisit::walk_poly_trait_ref(self, tr, m);
self.outer_index.shift_out(1);
}
fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
if self.has_late_bound_regions.is_some() {
return;
}
match self.tcx.named_region(lt.hir_id) {
Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
Some(
rl::Region::LateBound(debruijn, _, _) | rl::Region::LateBoundAnon(debruijn, _),
) if debruijn < self.outer_index => {}
Some(
rl::Region::LateBound(..)
| rl::Region::LateBoundAnon(..)
| rl::Region::Free(..),
)
| None => {
self.has_late_bound_regions = Some(lt.span);
}
}
}
}
fn has_late_bound_regions<'tcx>(
tcx: TyCtxt<'tcx>,
generics: &'tcx hir::Generics<'tcx>,
decl: &'tcx hir::FnDecl<'tcx>,
) -> Option<Span> {
let mut visitor = LateBoundRegionsDetector {
tcx,
outer_index: ty::INNERMOST,
has_late_bound_regions: None,
};
for param in generics.params {
if let GenericParamKind::Lifetime { .. } = param.kind {
if tcx.is_late_bound(param.hir_id) {
return Some(param.span);
}
}
}
visitor.visit_fn_decl(decl);
visitor.has_late_bound_regions
}
match node {
Node::TraitItem(item) => match item.kind {
hir::TraitItemKind::Fn(ref sig, _) => {
has_late_bound_regions(tcx, &item.generics, &sig.decl)
}
_ => None,
},
Node::ImplItem(item) => match item.kind {
hir::ImplItemKind::Fn(ref sig, _) => {
has_late_bound_regions(tcx, &item.generics, &sig.decl)
}
_ => None,
},
Node::ForeignItem(item) => match item.kind {
hir::ForeignItemKind::Fn(ref fn_decl, _, ref generics) => {
has_late_bound_regions(tcx, generics, fn_decl)
}
_ => None,
},
Node::Item(item) => match item.kind {
hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
has_late_bound_regions(tcx, generics, &sig.decl)
}
_ => None,
},
_ => None,
}
}
fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
use rustc_hir::*;
let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
let node = tcx.hir().get(hir_id);
let parent_def_id = match node {
Node::ImplItem(_)
| Node::TraitItem(_)
| Node::Variant(_)
| Node::Ctor(..)
| Node::Field(_) => {
let parent_id = tcx.hir().get_parent_item(hir_id);
Some(tcx.hir().local_def_id(parent_id).to_def_id())
}
// FIXME(#43408) always enable this once `lazy_normalization` is
// stable enough and does not need a feature gate anymore.
Node::AnonConst(_) => {
let parent_id = tcx.hir().get_parent_item(hir_id);
let parent_def_id = tcx.hir().local_def_id(parent_id);
// HACK(eddyb) this provides the correct generics when
// `feature(const_generics)` is enabled, so that const expressions
// used with const generics, e.g. `Foo<{N+1}>`, can work at all.
if tcx.lazy_normalization() {
Some(parent_def_id.to_def_id())
} else {
let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
match parent_node {
// HACK(eddyb) this provides the correct generics for repeat
// expressions' count (i.e. `N` in `[x; N]`), and explicit
// `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
// as they shouldn't be able to cause query cycle errors.
Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
| Node::Variant(Variant { disr_expr: Some(ref constant), .. })
if constant.hir_id == hir_id =>
{
Some(parent_def_id.to_def_id())
}
_ => None,
}
}
}
Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
Some(tcx.closure_base_def_id(def_id))
}
Node::Item(item) => match item.kind {
ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => {
impl_trait_fn.or_else(|| {
let parent_id = tcx.hir().get_parent_item(hir_id);
assert!(parent_id != hir_id && parent_id != CRATE_HIR_ID);
debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
// Opaque types are always nested within another item, and
// inherit the generics of the item.
Some(tcx.hir().local_def_id(parent_id).to_def_id())
})
}
_ => None,
},
_ => None,
};
let mut opt_self = None;
let mut allow_defaults = false;
let no_generics = hir::Generics::empty();
let ast_generics = match node {
Node::TraitItem(item) => &item.generics,
Node::ImplItem(item) => &item.generics,
Node::Item(item) => {
match item.kind {
ItemKind::Fn(.., ref generics, _) | ItemKind::Impl { ref generics, .. } => generics,
ItemKind::TyAlias(_, ref generics)
| ItemKind::Enum(_, ref generics)
| ItemKind::Struct(_, ref generics)
| ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
| ItemKind::Union(_, ref generics) => {
allow_defaults = true;
generics
}
ItemKind::Trait(_, _, ref generics, ..)
| ItemKind::TraitAlias(ref generics, ..) => {
// Add in the self type parameter.
//
// Something of a hack: use the node id for the trait, also as
// the node id for the Self type parameter.
let param_id = item.hir_id;
opt_self = Some(ty::GenericParamDef {
index: 0,
name: kw::SelfUpper,
def_id: tcx.hir().local_def_id(param_id).to_def_id(),
pure_wrt_drop: false,
kind: ty::GenericParamDefKind::Type {
has_default: false,
object_lifetime_default: rl::Set1::Empty,
synthetic: None,
},
});
allow_defaults = true;
generics
}
_ => &no_generics,
}
}
Node::ForeignItem(item) => match item.kind {
ForeignItemKind::Static(..) => &no_generics,
ForeignItemKind::Fn(_, _, ref generics) => generics,
ForeignItemKind::Type => &no_generics,
},
_ => &no_generics,
};
let has_self = opt_self.is_some();
let mut parent_has_self = false;
let mut own_start = has_self as u32;
let parent_count = parent_def_id.map_or(0, |def_id| {
let generics = tcx.generics_of(def_id);
assert_eq!(has_self, false);
parent_has_self = generics.has_self;
own_start = generics.count() as u32;
generics.parent_count + generics.params.len()
});
let mut params: Vec<_> = opt_self.into_iter().collect();
let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
name: param.name.ident().name,
index: own_start + i as u32,
def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
pure_wrt_drop: param.pure_wrt_drop,
kind: ty::GenericParamDefKind::Lifetime,
}));
let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
// Now create the real type and const parameters.
let type_start = own_start - has_self as u32 + params.len() as u32;
let mut i = 0;
// FIXME(const_generics): a few places in the compiler expect generic params
// to be in the order lifetimes, then type params, then const params.
//
// To prevent internal errors in case const parameters are supplied before
// type parameters we first add all type params, then all const params.
params.extend(ast_generics.params.iter().filter_map(|param| {
if let GenericParamKind::Type { ref default, synthetic, .. } = param.kind {
if !allow_defaults && default.is_some() {
if !tcx.features().default_type_parameter_fallback {
tcx.struct_span_lint_hir(
lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
param.hir_id,
param.span,
|lint| {
lint.build(
"defaults for type parameters are only allowed in \
`struct`, `enum`, `type`, or `trait` definitions.",
)
.emit();
},
);
}
}
let kind = ty::GenericParamDefKind::Type {
has_default: default.is_some(),
object_lifetime_default: object_lifetime_defaults
.as_ref()
.map_or(rl::Set1::Empty, |o| o[i]),
synthetic,
};
let param_def = ty::GenericParamDef {
index: type_start + i as u32,
name: param.name.ident().name,
def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
pure_wrt_drop: param.pure_wrt_drop,
kind,
};
i += 1;
Some(param_def)
} else {
None
}
}));
params.extend(ast_generics.params.iter().filter_map(|param| {
if let GenericParamKind::Const { .. } = param.kind {
let param_def = ty::GenericParamDef {
index: type_start + i as u32,
name: param.name.ident().name,
def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
pure_wrt_drop: param.pure_wrt_drop,
kind: ty::GenericParamDefKind::Const,
};
i += 1;
Some(param_def)
} else {
None
}
}));
// provide junk type parameter defs - the only place that
// cares about anything but the length is instantiation,
// and we don't do that for closures.
if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
let dummy_args = if gen.is_some() {
&["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
} else {
&["<closure_kind>", "<closure_signature>", "<upvars>"][..]
};
params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
index: type_start + i as u32,
name: Symbol::intern(arg),
def_id,
pure_wrt_drop: false,
kind: ty::GenericParamDefKind::Type {
has_default: false,
object_lifetime_default: rl::Set1::Empty,
synthetic: None,
},
}));
}
let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
ty::Generics {
parent: parent_def_id,
parent_count,
params,
param_def_id_to_index,
has_self: has_self || parent_has_self,
has_late_bound_regions: has_late_bound_regions(tcx, node),
}
}
fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
generic_args
.iter()
.filter_map(|arg| match arg {
hir::GenericArg::Type(ty) => Some(ty),
_ => None,
})
.any(is_suggestable_infer_ty)
}
/// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
/// use inference to provide suggestions for the appropriate type if possible.
fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
use hir::TyKind::*;
match &ty.kind {
Infer => true,
Slice(ty) | Array(ty, _) => is_suggestable_infer_ty(ty),
Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
Path(hir::QPath::TypeRelative(ty, segment)) => {
is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.generic_args().args)
}
Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
ty_opt.map_or(false, is_suggestable_infer_ty)
|| segments
.iter()
.any(|segment| are_suggestable_generic_args(segment.generic_args().args))
}
_ => false,
}
}
pub fn get_infer_ret_ty(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
if let hir::FnRetTy::Return(ref ty) = output {
if is_suggestable_infer_ty(ty) {
return Some(&**ty);
}
}
None
}
fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
use rustc_hir::Node::*;
use rustc_hir::*;
let def_id = def_id.expect_local();
let hir_id = tcx.hir().as_local_hir_id(def_id);
let icx = ItemCtxt::new(tcx, def_id.to_def_id());
match tcx.hir().get(hir_id) {
TraitItem(hir::TraitItem {
kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
ident,
generics,
..
})
| ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. })
| Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
match get_infer_ret_ty(&sig.decl.output) {
Some(ty) => {
let fn_sig = tcx.typeck_tables_of(def_id).liberated_fn_sigs()[hir_id];
let mut visitor = PlaceholderHirTyCollector::default();
visitor.visit_ty(ty);
let mut diag = bad_placeholder_type(tcx, visitor.0);
let ret_ty = fn_sig.output();
if ret_ty != tcx.ty_error() {
diag.span_suggestion(
ty.span,
"replace with the correct return type",
ret_ty.to_string(),
Applicability::MaybeIncorrect,
);
}
diag.emit();
ty::Binder::bind(fn_sig)
}
None => AstConv::ty_of_fn(
&icx,
sig.header.unsafety,
sig.header.abi,
&sig.decl,
&generics,
Some(ident.span),
),
}
}
TraitItem(hir::TraitItem {
kind: TraitItemKind::Fn(FnSig { header, decl }, _),
ident,
generics,
..
}) => {
AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl, &generics, Some(ident.span))
}
ForeignItem(&hir::ForeignItem {
kind: ForeignItemKind::Fn(ref fn_decl, _, _),
ident,
..
}) => {
let abi = tcx.hir().get_foreign_abi(hir_id);
compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
}
Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id).to_def_id());
let inputs =
data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
ty::Binder::bind(tcx.mk_fn_sig(
inputs,
ty,
false,
hir::Unsafety::Normal,
abi::Abi::Rust,
))
}
Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
// Closure signatures are not like other function
// signatures and cannot be accessed through `fn_sig`. For
// example, a closure signature excludes the `self`
// argument. In any case they are embedded within the
// closure type as part of the `ClosureSubsts`.
//
// To get the signature of a closure, you should use the
// `sig` method on the `ClosureSubsts`:
//
// substs.as_closure().sig(def_id, tcx)
bug!(
"to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
);
}
x => {
bug!("unexpected sort of node in fn_sig(): {:?}", x);
}
}
}
fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
let icx = ItemCtxt::new(tcx, def_id);
let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
match tcx.hir().expect_item(hir_id).kind {
hir::ItemKind::Impl { ref of_trait, .. } => of_trait.as_ref().map(|ast_trait_ref| {
let selfty = tcx.type_of(def_id);
AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
}),
_ => bug!(),
}
}
fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
let item = tcx.hir().expect_item(hir_id);
match &item.kind {
hir::ItemKind::Impl { polarity: hir::ImplPolarity::Negative(span), of_trait, .. } => {
if is_rustc_reservation {
let span = span.to(of_trait.as_ref().map(|t| t.path.span).unwrap_or(*span));
tcx.sess.span_err(span, "reservation impls can't be negative");
}
ty::ImplPolarity::Negative
}
hir::ItemKind::Impl { polarity: hir::ImplPolarity::Positive, of_trait: None, .. } => {
if is_rustc_reservation {
tcx.sess.span_err(item.span, "reservation impls can't be inherent");
}
ty::ImplPolarity::Positive
}
hir::ItemKind::Impl {
polarity: hir::ImplPolarity::Positive, of_trait: Some(_), ..
} => {
if is_rustc_reservation {
ty::ImplPolarity::Reservation
} else {
ty::ImplPolarity::Positive
}
}
ref item => bug!("impl_polarity: {:?} not an impl", item),
}
}
/// Returns the early-bound lifetimes declared in this generics
/// listing. For anything other than fns/methods, this is just all
/// the lifetimes that are declared. For fns or methods, we have to
/// screen out those that do not appear in any where-clauses etc using
/// `resolve_lifetime::early_bound_lifetimes`.
fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
tcx: TyCtxt<'tcx>,
generics: &'a hir::Generics<'a>,
) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
generics.params.iter().filter(move |param| match param.kind {
GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
_ => false,
})
}
/// Returns a list of type predicates for the definition with ID `def_id`, including inferred
/// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
/// inferred constraints concerning which regions outlive other regions.
fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
debug!("predicates_defined_on({:?})", def_id);
let mut result = tcx.explicit_predicates_of(def_id);
debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
let inferred_outlives = tcx.inferred_outlives_of(def_id);
if !inferred_outlives.is_empty() {
debug!(
"predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
def_id, inferred_outlives,
);
if result.predicates.is_empty() {
result.predicates = inferred_outlives;
} else {
result.predicates = tcx
.arena
.alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
}
}
debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
result
}
/// Returns a list of all type predicates (explicit and implicit) for the definition with
/// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
/// `Self: Trait` predicates for traits.
fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
let mut result = tcx.predicates_defined_on(def_id);
if tcx.is_trait(def_id) {
// For traits, add `Self: Trait` predicate. This is
// not part of the predicates that a user writes, but it
// is something that one must prove in order to invoke a
// method or project an associated type.
//
// In the chalk setup, this predicate is not part of the
// "predicates" for a trait item. But it is useful in
// rustc because if you directly (e.g.) invoke a trait
// method like `Trait::method(...)`, you must naturally
// prove that the trait applies to the types that were
// used, and adding the predicate into this list ensures
// that this is done.
let span = tcx.sess.source_map().guess_head_span(tcx.def_span(def_id));
result.predicates =
tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
span,
))));
}
debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
result
}
/// Returns a list of user-specified type predicates for the definition with ID `def_id`.
/// N.B., this does not include any implied/inferred constraints.
fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
use rustc_hir::*;
debug!("explicit_predicates_of(def_id={:?})", def_id);
/// A data structure with unique elements, which preserves order of insertion.
/// Preserving the order of insertion is important here so as not to break
/// compile-fail UI tests.
// FIXME(eddyb) just use `IndexSet` from `indexmap`.
struct UniquePredicates<'tcx> {
predicates: Vec<(ty::Predicate<'tcx>, Span)>,
uniques: FxHashSet<(ty::Predicate<'tcx>, Span)>,
}
impl<'tcx> UniquePredicates<'tcx> {
fn new() -> Self {
UniquePredicates { predicates: vec![], uniques: FxHashSet::default() }
}
fn push(&mut self, value: (ty::Predicate<'tcx>, Span)) {
if self.uniques.insert(value) {
self.predicates.push(value);
}
}
fn extend<I: IntoIterator<Item = (ty::Predicate<'tcx>, Span)>>(&mut self, iter: I) {
for value in iter {
self.push(value);
}
}
}
let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
let node = tcx.hir().get(hir_id);
let mut is_trait = None;
let mut is_default_impl_trait = None;
let mut is_trait_associated_type = None;
let icx = ItemCtxt::new(tcx, def_id);
let constness = icx.default_constness_for_trait_bounds();
const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
let mut predicates = UniquePredicates::new();
let ast_generics = match node {
Node::TraitItem(item) => {
if let hir::TraitItemKind::Type(bounds, _) = item.kind {
is_trait_associated_type = Some((bounds, item.span));
}
&item.generics
}
Node::ImplItem(item) => &item.generics,
Node::Item(item) => {
match item.kind {
ItemKind::Impl { defaultness, ref generics, .. } => {
if defaultness.is_default() {
is_default_impl_trait = tcx.impl_trait_ref(def_id);
}
generics
}
ItemKind::Fn(.., ref generics, _)
| ItemKind::TyAlias(_, ref generics)
| ItemKind::Enum(_, ref generics)
| ItemKind::Struct(_, ref generics)
| ItemKind::Union(_, ref generics) => generics,
ItemKind::Trait(_, _, ref generics, .., items) => {
is_trait = Some((ty::TraitRef::identity(tcx, def_id), items));
generics
}
ItemKind::TraitAlias(ref generics, _) => {
is_trait = Some((ty::TraitRef::identity(tcx, def_id), &[]));
generics
}
ItemKind::OpaqueTy(OpaqueTy {
ref bounds,
impl_trait_fn,
ref generics,
origin: _,
}) => {
let bounds_predicates = ty::print::with_no_queries(|| {
let substs = InternalSubsts::identity_for_item(tcx, def_id);
let opaque_ty = tcx.mk_opaque(def_id, substs);
// Collect the bounds, i.e., the `A + B + 'c` in `impl A + B + 'c`.
let bounds = AstConv::compute_bounds(
&icx,
opaque_ty,
bounds,
SizedByDefault::Yes,
tcx.def_span(def_id),
);
bounds.predicates(tcx, opaque_ty)
});
if impl_trait_fn.is_some() {
// opaque types
return ty::GenericPredicates {
parent: None,
predicates: tcx.arena.alloc_from_iter(bounds_predicates),
};
} else {
// named opaque types
predicates.extend(bounds_predicates);
generics
}
}
_ => NO_GENERICS,
}
}
Node::ForeignItem(item) => match item.kind {
ForeignItemKind::Static(..) => NO_GENERICS,
ForeignItemKind::Fn(_, _, ref generics) => generics,
ForeignItemKind::Type => NO_GENERICS,
},
_ => NO_GENERICS,
};
let generics = tcx.generics_of(def_id);
let parent_count = generics.parent_count as u32;
let has_own_self = generics.has_self && parent_count == 0;
// Below we'll consider the bounds on the type parameters (including `Self`)
// and the explicit where-clauses, but to get the full set of predicates
// on a trait we need to add in the supertrait bounds and bounds found on
// associated types.
if let Some((_trait_ref, _)) = is_trait {
predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
}
// In default impls, we can assume that the self type implements
// the trait. So in:
//
// default impl Foo for Bar { .. }
//
// we add a default where clause `Foo: Bar`. We do a similar thing for traits
// (see below). Recall that a default impl is not itself an impl, but rather a
// set of defaults that can be incorporated into another impl.
if let Some(trait_ref) = is_default_impl_trait {
predicates.push((
trait_ref.to_poly_trait_ref().without_const().to_predicate(tcx),
tcx.def_span(def_id),
));
}
// Collect the region predicates that were declared inline as
// well. In the case of parameters declared on a fn or method, we
// have to be careful to only iterate over early-bound regions.
let mut index = parent_count + has_own_self as u32;
for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
index,
name: param.name.ident().name,
}));
index += 1;
match param.kind {
GenericParamKind::Lifetime { .. } => {
param.bounds.iter().for_each(|bound| match bound {
hir::GenericBound::Outlives(lt) => {
let bound = AstConv::ast_region_to_region(&icx, &lt, None);
let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
predicates.push((outlives.to_predicate(tcx), lt.span));
}
_ => bug!(),
});
}
_ => bug!(),
}
}
// Collect the predicates that were written inline by the user on each
// type parameter (e.g., `<T: Foo>`).
for param in ast_generics.params {
if let GenericParamKind::Type { .. } = param.kind {
let name = param.name.ident().name;
let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
index += 1;
let sized = SizedByDefault::Yes;
let bounds = AstConv::compute_bounds(&icx, param_ty, &param.bounds, sized, param.span);
predicates.extend(bounds.predicates(tcx, param_ty));
}
}
// Add in the bounds that appear in the where-clause.
let where_clause = &ast_generics.where_clause;
for predicate in where_clause.predicates {
match predicate {
&hir::WherePredicate::BoundPredicate(ref bound_pred) => {
let ty = icx.to_ty(&bound_pred.bounded_ty);
// Keep the type around in a dummy predicate, in case of no bounds.
// That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
// is still checked for WF.
if bound_pred.bounds.is_empty() {
if let ty::Param(_) = ty.kind {
// This is a `where T:`, which can be in the HIR from the
// transformation that moves `?Sized` to `T`'s declaration.
// We can skip the predicate because type parameters are
// trivially WF, but also we *should*, to avoid exposing
// users who never wrote `where Type:,` themselves, to
// compiler/tooling bugs from not handling WF predicates.
} else {
let span = bound_pred.bounded_ty.span;
let re_root_empty = tcx.lifetimes.re_root_empty;
let predicate = ty::OutlivesPredicate(ty, re_root_empty);
predicates.push((
ty::PredicateKind::TypeOutlives(ty::Binder::dummy(predicate))
.to_predicate(tcx),
span,
));
}
}
for bound in bound_pred.bounds.iter() {
match bound {
&hir::GenericBound::Trait(ref poly_trait_ref, modifier) => {
let constness = match modifier {
hir::TraitBoundModifier::MaybeConst => hir::Constness::NotConst,
hir::TraitBoundModifier::None => constness,
hir::TraitBoundModifier::Maybe => bug!("this wasn't handled"),
};
let mut bounds = Bounds::default();
let _ = AstConv::instantiate_poly_trait_ref(
&icx,
poly_trait_ref,
constness,
ty,
&mut bounds,
);
predicates.extend(bounds.predicates(tcx, ty));
}
&hir::GenericBound::Outlives(ref lifetime) => {
let region = AstConv::ast_region_to_region(&icx, lifetime, None);
let pred = ty::Binder::bind(ty::OutlivesPredicate(ty, region));
predicates.push((
ty::PredicateKind::TypeOutlives(pred).to_predicate(tcx),
lifetime.span,
))
}
}
}
}
&hir::WherePredicate::RegionPredicate(ref region_pred) => {
let r1 = AstConv::ast_region_to_region(&icx, &region_pred.lifetime, None);
predicates.extend(region_pred.bounds.iter().map(|bound| {
let (r2, span) = match bound {
hir::GenericBound::Outlives(lt) => {
(AstConv::ast_region_to_region(&icx, lt, None), lt.span)
}
_ => bug!(),
};
let pred = ty::Binder::bind(ty::OutlivesPredicate(r1, r2));
(ty::PredicateKind::RegionOutlives(pred).to_predicate(icx.tcx), span)
}))
}
&hir::WherePredicate::EqPredicate(..) => {
// FIXME(#20041)
}
}
}
// Add predicates from associated type bounds (`type X: Bound`)
if tcx.features().generic_associated_types {
// New behavior: bounds declared on associate type are predicates of that
// associated type. Not the default because it needs more testing.
if let Some((bounds, span)) = is_trait_associated_type {
let projection_ty =
tcx.mk_projection(def_id, InternalSubsts::identity_for_item(tcx, def_id));
predicates.extend(associated_item_bounds(tcx, def_id, bounds, projection_ty, span))
}
} else if let Some((self_trait_ref, trait_items)) = is_trait {
// Current behavior: bounds declared on associate type are predicates
// of its parent trait.
predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
trait_associated_item_predicates(tcx, def_id, self_trait_ref, trait_item_ref)
}))
}
let mut predicates = predicates.predicates;
// Subtle: before we store the predicates into the tcx, we
// sort them so that predicates like `T: Foo<Item=U>` come
// before uses of `U`. This avoids false ambiguity errors
// in trait checking. See `setup_constraining_predicates`
// for details.
if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
let self_ty = tcx.type_of(def_id);
let trait_ref = tcx.impl_trait_ref(def_id);
cgp::setup_constraining_predicates(
tcx,
&mut predicates,
trait_ref,
&mut cgp::parameters_for_impl(self_ty, trait_ref),
);
}
let result = ty::GenericPredicates {
parent: generics.parent,
predicates: tcx.arena.alloc_from_iter(predicates),
};
debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
result
}
fn trait_associated_item_predicates(
tcx: TyCtxt<'tcx>,
def_id: DefId,
self_trait_ref: ty::TraitRef<'tcx>,
trait_item_ref: &hir::TraitItemRef,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
let trait_item = tcx.hir().trait_item(trait_item_ref.id);
let item_def_id = tcx.hir().local_def_id(trait_item_ref.id.hir_id);
let bounds = match trait_item.kind {
hir::TraitItemKind::Type(ref bounds, _) => bounds,
_ => return Vec::new(),
};
if !tcx.generics_of(item_def_id).params.is_empty() {
// For GATs the substs provided to the mk_projection call below are
// wrong. We should emit a feature gate error if we get here so skip
// this type.
tcx.sess.delay_span_bug(trait_item.span, "gats used without feature gate");
return Vec::new();
}
let assoc_ty = tcx.mk_projection(
tcx.hir().local_def_id(trait_item.hir_id).to_def_id(),
self_trait_ref.substs,
);
associated_item_bounds(tcx, def_id, bounds, assoc_ty, trait_item.span)
}
fn associated_item_bounds(
tcx: TyCtxt<'tcx>,
def_id: DefId,
bounds: &'tcx [hir::GenericBound<'tcx>],
projection_ty: Ty<'tcx>,
span: Span,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
let bounds = AstConv::compute_bounds(
&ItemCtxt::new(tcx, def_id),
projection_ty,
bounds,
SizedByDefault::Yes,
span,
);
let predicates = bounds.predicates(tcx, projection_ty);
predicates
}
/// Converts a specific `GenericBound` from the AST into a set of
/// predicates that apply to the self type. A vector is returned
/// because this can be anywhere from zero predicates (`T: ?Sized` adds no
/// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
/// and `<T as Bar>::X == i32`).
fn predicates_from_bound<'tcx>(
astconv: &dyn AstConv<'tcx>,
param_ty: Ty<'tcx>,
bound: &'tcx hir::GenericBound<'tcx>,
constness: hir::Constness,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
match *bound {
hir::GenericBound::Trait(ref tr, modifier) => {
let constness = match modifier {
hir::TraitBoundModifier::Maybe => return vec![],
hir::TraitBoundModifier::MaybeConst => hir::Constness::NotConst,
hir::TraitBoundModifier::None => constness,
};
let mut bounds = Bounds::default();
let _ = astconv.instantiate_poly_trait_ref(tr, constness, param_ty, &mut bounds);
bounds.predicates(astconv.tcx(), param_ty)
}
hir::GenericBound::Outlives(ref lifetime) => {
let region = astconv.ast_region_to_region(lifetime, None);
let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
vec![(ty::PredicateKind::TypeOutlives(pred).to_predicate(astconv.tcx()), lifetime.span)]
}
}
}
fn compute_sig_of_foreign_fn_decl<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: DefId,
decl: &'tcx hir::FnDecl<'tcx>,
abi: abi::Abi,
ident: Ident,
) -> ty::PolyFnSig<'tcx> {
let unsafety = if abi == abi::Abi::RustIntrinsic {
intrinsic_operation_unsafety(tcx.item_name(def_id))
} else {
hir::Unsafety::Unsafe
};
let fty = AstConv::ty_of_fn(
&ItemCtxt::new(tcx, def_id),
unsafety,
abi,
decl,
&hir::Generics::empty(),
Some(ident.span),
);
// Feature gate SIMD types in FFI, since I am not sure that the
// ABIs are handled at all correctly. -huonw
if abi != abi::Abi::RustIntrinsic
&& abi != abi::Abi::PlatformIntrinsic
&& !tcx.features().simd_ffi
{
let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
if ty.is_simd() {
let snip = tcx
.sess
.source_map()
.span_to_snippet(ast_ty.span)
.map_or(String::new(), |s| format!(" `{}`", s));
tcx.sess
.struct_span_err(
ast_ty.span,
&format!(
"use of SIMD type{} in FFI is highly experimental and \
may result in invalid code",
snip
),
)
.help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
.emit();
}
};
for (input, ty) in decl.inputs.iter().zip(fty.inputs().skip_binder()) {
check(&input, ty)
}
if let hir::FnRetTy::Return(ref ty) = decl.output {
check(&ty, fty.output().skip_binder())
}
}
fty
}
fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
match tcx.hir().get_if_local(def_id) {
Some(Node::ForeignItem(..)) => true,
Some(_) => false,
_ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
}
}
fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
match tcx.hir().get_if_local(def_id) {
Some(
Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. })
| Node::ForeignItem(&hir::ForeignItem {
kind: hir::ForeignItemKind::Static(_, mutbl),
..
}),
) => Some(mutbl),
Some(_) => None,
_ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
}
}
fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
match tcx.hir().get_if_local(def_id) {
Some(Node::Expr(&rustc_hir::Expr {
kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
..
})) => tcx.hir().body(body_id).generator_kind(),
Some(_) => None,
_ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
}
}
fn from_target_feature(
tcx: TyCtxt<'_>,
id: DefId,
attr: &ast::Attribute,
supported_target_features: &FxHashMap<String, Option<Symbol>>,
target_features: &mut Vec<Symbol>,
) {
let list = match attr.meta_item_list() {
Some(list) => list,
None => return,
};
let bad_item = |span| {
let msg = "malformed `target_feature` attribute input";
let code = "enable = \"..\"".to_owned();
tcx.sess
.struct_span_err(span, &msg)
.span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
.emit();
};
let rust_features = tcx.features();
for item in list {
// Only `enable = ...` is accepted in the meta-item list.
if !item.check_name(sym::enable) {
bad_item(item.span());
continue;
}
// Must be of the form `enable = "..."` (a string).
let value = match item.value_str() {
Some(value) => value,
None => {
bad_item(item.span());
continue;
}
};
// We allow comma separation to enable multiple features.
target_features.extend(value.as_str().split(',').filter_map(|feature| {
let feature_gate = match supported_target_features.get(feature) {
Some(g) => g,
None => {
let msg =
format!("the feature named `{}` is not valid for this target", feature);
let mut err = tcx.sess.struct_span_err(item.span(), &msg);
err.span_label(
item.span(),
format!("`{}` is not valid for this target", feature),
);
if feature.starts_with('+') {
let valid = supported_target_features.contains_key(&feature[1..]);
if valid {
err.help("consider removing the leading `+` in the feature name");
}
}
err.emit();
return None;
}
};
// Only allow features whose feature gates have been enabled.
let allowed = match feature_gate.as_ref().copied() {
Some(sym::arm_target_feature) => rust_features.arm_target_feature,
Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
Some(sym::mips_target_feature) => rust_features.mips_target_feature,
Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
Some(sym::adx_target_feature) => rust_features.adx_target_feature,
Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
Some(name) => bug!("unknown target feature gate {}", name),
None => true,
};
if !allowed && id.is_local() {
feature_err(
&tcx.sess.parse_sess,
feature_gate.unwrap(),
item.span(),
&format!("the target feature `{}` is currently unstable", feature),
)
.emit();
}
Some(Symbol::intern(feature))
}));
}
}
fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
use rustc_middle::mir::mono::Linkage::*;
// Use the names from src/llvm/docs/LangRef.rst here. Most types are only
// applicable to variable declarations and may not really make sense for
// Rust code in the first place but allow them anyway and trust that the
// user knows what s/he's doing. Who knows, unanticipated use cases may pop
// up in the future.
//
// ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
// and don't have to be, LLVM treats them as no-ops.
match name {
"appending" => Appending,
"available_externally" => AvailableExternally,
"common" => Common,
"extern_weak" => ExternalWeak,
"external" => External,
"internal" => Internal,
"linkonce" => LinkOnceAny,
"linkonce_odr" => LinkOnceODR,
"private" => Private,
"weak" => WeakAny,
"weak_odr" => WeakODR,
_ => {
let span = tcx.hir().span_if_local(def_id);
if let Some(span) = span {
tcx.sess.span_fatal(span, "invalid linkage specified")
} else {
tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
}
}
}
}
fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
let attrs = tcx.get_attrs(id);
let mut codegen_fn_attrs = CodegenFnAttrs::new();
if should_inherit_track_caller(tcx, id) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
}
let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
let mut inline_span = None;
let mut link_ordinal_span = None;
let mut no_sanitize_span = None;
for attr in attrs.iter() {
if attr.check_name(sym::cold) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
} else if attr.check_name(sym::rustc_allocator) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
} else if attr.check_name(sym::unwind) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;
} else if attr.check_name(sym::ffi_returns_twice) {
if tcx.is_foreign_item(id) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
} else {
// `#[ffi_returns_twice]` is only allowed `extern fn`s.
struct_span_err!(
tcx.sess,
attr.span,
E0724,
"`#[ffi_returns_twice]` may only be used on foreign functions"
)
.emit();
}
} else if attr.check_name(sym::ffi_pure) {
if tcx.is_foreign_item(id) {
if attrs.iter().any(|a| a.check_name(sym::ffi_const)) {
// `#[ffi_const]` functions cannot be `#[ffi_pure]`
struct_span_err!(
tcx.sess,
attr.span,
E0757,
"`#[ffi_const]` function cannot be `#[ffi_pure]`"
)
.emit();
} else {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
}
} else {
// `#[ffi_pure]` is only allowed on foreign functions
struct_span_err!(
tcx.sess,
attr.span,
E0755,
"`#[ffi_pure]` may only be used on foreign functions"
)
.emit();
}
} else if attr.check_name(sym::ffi_const) {
if tcx.is_foreign_item(id) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
} else {
// `#[ffi_const]` is only allowed on foreign functions
struct_span_err!(
tcx.sess,
attr.span,
E0756,
"`#[ffi_const]` may only be used on foreign functions"
)
.emit();
}
} else if attr.check_name(sym::rustc_allocator_nounwind) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND;
} else if attr.check_name(sym::naked) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
} else if attr.check_name(sym::no_mangle) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
} else if attr.check_name(sym::rustc_std_internal_symbol) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
} else if attr.check_name(sym::used) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
} else if attr.check_name(sym::thread_local) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
} else if attr.check_name(sym::track_caller) {
if tcx.is_closure(id) || tcx.fn_sig(id).abi() != abi::Abi::Rust {
struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
.emit();
}
codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
} else if attr.check_name(sym::export_name) {
if let Some(s) = attr.value_str() {
if s.as_str().contains('\0') {
// `#[export_name = ...]` will be converted to a null-terminated string,
// so it may not contain any null characters.
struct_span_err!(
tcx.sess,
attr.span,
E0648,
"`export_name` may not contain null characters"
)
.emit();
}
codegen_fn_attrs.export_name = Some(s);
}
} else if attr.check_name(sym::target_feature) {
if !tcx.features().target_feature_11 {
check_target_feature_safe_fn(tcx, id, attr.span);
} else if let Some(local_id) = id.as_local() {
if tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
check_target_feature_trait_unsafe(tcx, local_id, attr.span);
}
}
from_target_feature(
tcx,
id,
attr,
&supported_target_features,
&mut codegen_fn_attrs.target_features,
);
} else if attr.check_name(sym::linkage) {
if let Some(val) = attr.value_str() {
codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
}
} else if attr.check_name(sym::link_section) {
if let Some(val) = attr.value_str() {
if val.as_str().bytes().any(|b| b == 0) {
let msg = format!(
"illegal null byte in link_section \
value: `{}`",
&val
);