Google Git
Sign in
fuchsia / third_party / rust / 03222c037142e915e9ea75f681ab98a5a46b8739 / . / src / librustc_typeck / collect.rs
blob: 6d6e7685fa05338cde3082f0fe1f17f86e5651a6 [file] [log] [blame]
//! "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::constrained_generic_params as cgp;
use crate::check::intrinsic::intrinsic_operation_unsafety;
use crate::lint;
use crate::middle::resolve_lifetime as rl;
use crate::middle::weak_lang_items;
use rustc::mir::mono::Linkage;
use rustc::ty::query::Providers;
use rustc::ty::subst::{Subst, InternalSubsts};
use rustc::ty::util::Discr;
use rustc::ty::util::IntTypeExt;
use rustc::ty::subst::GenericArgKind;
use rustc::ty::{self, AdtKind, DefIdTree, ToPolyTraitRef, Ty, TyCtxt, Const};
use rustc::ty::{ReprOptions, ToPredicate};
use rustc::util::captures::Captures;
use rustc::util::nodemap::FxHashMap;
use rustc_target::spec::abi;
use syntax::ast;
use syntax::ast::{Ident, MetaItemKind};
use syntax::attr::{InlineAttr, OptimizeAttr, list_contains_name, mark_used};
use syntax::feature_gate;
use syntax::symbol::{kw, Symbol, sym};
use syntax_pos::{Span, DUMMY_SP};
use rustc::hir::def::{CtorKind, Res, DefKind};
use rustc::hir::Node;
use rustc::hir::def_id::{DefId, LOCAL_CRATE};
use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc::hir::GenericParamKind;
use rustc::hir::{self, CodegenFnAttrFlags, CodegenFnAttrs, Unsafety};
use errors::{Applicability, StashKey};
use rustc_error_codes::*;
struct OnlySelfBounds(bool);
///////////////////////////////////////////////////////////////////////////
// Main entry point
fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: DefId) {
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,
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,
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,
}
///////////////////////////////////////////////////////////////////////////
struct CollectItemTypesVisitor<'tcx> {
tcx: TyCtxt<'tcx>,
}
impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
NestedVisitorMap::OnlyBodies(&self.tcx.hir())
}
fn visit_item(&mut self, item: &'tcx hir::Item) {
convert_item(self.tcx, item.hir_id);
intravisit::walk_item(self, item);
}
fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
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.type_of(def_id);
}
hir::GenericParamKind::Type { .. } => {}
hir::GenericParamKind::Const { .. } => {
let def_id = self.tcx.hir().local_def_id(param.hir_id);
self.tcx.type_of(def_id);
}
}
}
intravisit::walk_generics(self, generics);
}
fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
if let hir::ExprKind::Closure(..) = expr.kind {
let def_id = self.tcx.hir().local_def_id(expr.hir_id);
self.tcx.generics_of(def_id);
self.tcx.type_of(def_id);
}
intravisit::walk_expr(self, expr);
}
fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
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) {
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>, span: Span) -> errors::DiagnosticBuilder<'tcx> {
let mut diag = struct_span_err!(
tcx.sess,
span,
E0121,
"the type placeholder `_` is not allowed within types on item signatures",
);
diag.span_label(span, "not allowed in type signatures");
diag
}
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) -> Ty<'tcx> {
AstConv::ast_ty_to_ty(self, ast_ty)
}
}
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 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))
}
fn re_infer(
&self,
_: Option<&ty::GenericParamDef>,
_: Span,
) -> Option<ty::Region<'tcx>> {
None
}
fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
bad_placeholder_type(self.tcx(), span).emit();
self.tcx().types.err
}
fn ct_infer(
&self,
_: Ty<'tcx>,
_: Option<&ty::GenericParamDef>,
span: Span,
) -> &'tcx Const<'tcx> {
bad_placeholder_type(self.tcx(), span).emit();
self.tcx().consts.err
}
fn projected_ty_from_poly_trait_ref(
&self,
span: Span,
item_def_id: DefId,
poly_trait_ref: ty::PolyTraitRef<'tcx>,
) -> Ty<'tcx> {
if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
self.tcx().mk_projection(item_def_id, trait_ref.substs)
} else {
// There are no late-bound regions; we can just ignore the binder.
span_err!(
self.tcx().sess,
span,
E0212,
"cannot extract an associated type from a higher-ranked trait bound \
in this context"
);
self.tcx().types.err
}
}
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?
}
}
/// 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, DefId),
) -> 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).unwrap();
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];
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 {
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)
}).unwrap_or_default();
let mut extend = None;
let item_hir_id = tcx.hir().as_local_hir_id(item_def_id).unwrap();
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.to_predicate(), 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 {
ty::Predicate::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,
param_id: hir::HirId,
ty: Ty<'tcx>,
only_self_bounds: OnlySelfBounds,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
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));
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));
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)
}
_ => 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.generics_of(def_id);
tcx.type_of(def_id);
tcx.predicates_of(def_id);
if let hir::ForeignItemKind::Fn(..) = item.kind {
tcx.fn_sig(def_id);
}
}
}
hir::ItemKind::Enum(ref enum_definition, _) => {
tcx.generics_of(def_id);
tcx.type_of(def_id);
tcx.predicates_of(def_id);
convert_enum_variant_types(tcx, def_id, &enum_definition.variants);
}
hir::ItemKind::Impl(..) => {
tcx.generics_of(def_id);
tcx.type_of(def_id);
tcx.impl_trait_ref(def_id);
tcx.predicates_of(def_id);
}
hir::ItemKind::Trait(..) => {
tcx.generics_of(def_id);
tcx.trait_def(def_id);
tcx.at(it.span).super_predicates_of(def_id);
tcx.predicates_of(def_id);
}
hir::ItemKind::TraitAlias(..) => {
tcx.generics_of(def_id);
tcx.at(it.span).super_predicates_of(def_id);
tcx.predicates_of(def_id);
}
hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
tcx.generics_of(def_id);
tcx.type_of(def_id);
tcx.predicates_of(def_id);
for f in struct_def.fields() {
let def_id = tcx.hir().local_def_id(f.hir_id);
tcx.generics_of(def_id);
tcx.type_of(def_id);
tcx.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.generics_of(def_id);
tcx.type_of(def_id);
tcx.predicates_of(def_id);
if let hir::ItemKind::Fn(..) = it.kind {
tcx.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.generics_of(def_id);
match trait_item.kind {
hir::TraitItemKind::Const(..)
| hir::TraitItemKind::Type(_, Some(_))
| hir::TraitItemKind::Method(..) => {
tcx.type_of(def_id);
if let hir::TraitItemKind::Method(..) = trait_item.kind {
tcx.fn_sig(def_id);
}
}
hir::TraitItemKind::Type(_, None) => {}
};
tcx.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.generics_of(def_id);
tcx.type_of(def_id);
tcx.predicates_of(def_id);
if let hir::ImplItemKind::Method(..) = tcx.hir().expect_impl_item(impl_item_id).kind {
tcx.fn_sig(def_id);
}
}
fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
let def_id = tcx.hir().local_def_id(ctor_id);
tcx.generics_of(def_id);
tcx.type_of(def_id);
tcx.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)
} 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.generics_of(def_id);
tcx.type_of(def_id);
tcx.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<DefId>,
ctor_did: Option<DefId>,
ident: Ident,
discr: ty::VariantDiscr,
def: &hir::VariantData,
adt_kind: ty::AdtKind,
parent_did: DefId,
) -> ty::VariantDef {
let mut seen_fields: FxHashMap<ast::Ident, Span> = Default::default();
let hir_id = tcx.hir().as_local_hir_id(variant_did.unwrap_or(parent_did)).unwrap();
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.modern()).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.modern(), f.span);
}
ty::FieldDef {
did: fid,
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,
ctor_did,
discr,
fields,
CtorKind::from_hir(def),
adt_kind,
parent_did,
recovered,
)
}
fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
use rustc::hir::*;
let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
let item = match tcx.hir().get(hir_id) {
Node::Item(item) => item,
_ => bug!(),
};
let repr = ReprOptions::new(tcx, 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))
} 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;
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, 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).unwrap();
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::Predicate::Trait(bound) = pred {
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).unwrap();
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 {
let mut err = 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!(
&mut err,
"add `#![feature(unboxed_closures)]` to \
the crate attributes to use it"
);
err.emit();
}
let is_marker = tcx.has_attr(def_id, sym::marker);
let def_path_hash = tcx.def_path_hash(def_id);
let def = ty::TraitDef::new(def_id, unsafety, paren_sugar, is_auto, is_marker, def_path_hash);
tcx.arena.alloc(def)
}
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> {
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
NestedVisitorMap::None
}
fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
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,
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) | Some(rl::Region::EarlyBound(..)) => {}
Some(rl::Region::LateBound(debruijn, _, _))
| Some(rl::Region::LateBoundAnon(debruijn, _)) if debruijn < self.outer_index => {}
Some(rl::Region::LateBound(..))
| Some(rl::Region::LateBoundAnon(..))
| Some(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,
decl: &'tcx hir::FnDecl,
) -> 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::Method(ref sig, _) => {
has_late_bound_regions(tcx, &item.generics, &sig.decl)
}
_ => None,
},
Node::ImplItem(item) => match item.kind {
hir::ImplItemKind::Method(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).unwrap();
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))
}
// FIXME(#43408) enable this always when we get lazy normalization.
Node::AnonConst(_) => {
// 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.features().const_generics {
let parent_id = tcx.hir().get_parent_item(hir_id);
Some(tcx.hir().local_def_id(parent_id))
} else {
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,
_ => 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),
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),
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 parameters.
let type_start = own_start - has_self as u32 + params.len() as u32;
let mut i = 0;
params.extend(
ast_generics
.params
.iter()
.filter_map(|param| {
let kind = match param.kind {
GenericParamKind::Type {
ref default,
synthetic,
..
} => {
if !allow_defaults && default.is_some() {
if !tcx.features().default_type_parameter_fallback {
tcx.lint_hir(
lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
param.hir_id,
param.span,
&format!(
"defaults for type parameters are only allowed in \
`struct`, `enum`, `type`, or `trait` definitions."
),
);
}
}
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,
}
}
GenericParamKind::Const { .. } => {
ty::GenericParamDefKind::Const
}
_ => return None,
};
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),
pure_wrt_drop: param.pure_wrt_drop,
kind,
};
i += 1;
Some(param_def)
})
);
// 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() {
&["<yield_ty>", "<return_ty>", "<witness>"][..]
} else {
&["<closure_kind>", "<closure_signature>"][..]
};
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,
},
}),
);
if let Some(upvars) = tcx.upvars(def_id) {
params.extend(upvars.iter().zip((dummy_args.len() as u32)..).map(|(_, i)| {
ty::GenericParamDef {
index: type_start + i,
name: Symbol::intern("<upvar>"),
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();
tcx.arena.alloc(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 report_assoc_ty_on_inherent_impl(tcx: TyCtxt<'_>, span: Span) {
span_err!(
tcx.sess,
span,
E0202,
"associated types are not yet supported in inherent impls (see #8995)"
);
}
fn infer_placeholder_type(
tcx: TyCtxt<'_>,
def_id: DefId,
body_id: hir::BodyId,
span: Span,
item_ident: Ident,
) -> Ty<'_> {
let ty = tcx.typeck_tables_of(def_id).node_type(body_id.hir_id);
// If this came from a free `const` or `static mut?` item,
// then the user may have written e.g. `const A = 42;`.
// In this case, the parser has stashed a diagnostic for
// us to improve in typeck so we do that now.
match tcx.sess.diagnostic().steal_diagnostic(span, StashKey::ItemNoType) {
Some(mut err) => {
// The parser provided a sub-optimal `HasPlaceholders` suggestion for the type.
// We are typeck and have the real type, so remove that and suggest the actual type.
err.suggestions.clear();
err.span_suggestion(
span,
"provide a type for the item",
format!("{}: {}", item_ident, ty),
Applicability::MachineApplicable,
)
.emit();
}
None => {
let mut diag = bad_placeholder_type(tcx, span);
if ty != tcx.types.err {
diag.span_suggestion(
span,
"replace `_` with the correct type",
ty.to_string(),
Applicability::MaybeIncorrect,
);
}
diag.emit();
}
}
ty
}
fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
use rustc::hir::*;
let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
let icx = ItemCtxt::new(tcx, def_id);
match tcx.hir().get(hir_id) {
Node::TraitItem(item) => match item.kind {
TraitItemKind::Method(..) => {
let substs = InternalSubsts::identity_for_item(tcx, def_id);
tcx.mk_fn_def(def_id, substs)
}
TraitItemKind::Const(ref ty, body_id) => {
body_id.and_then(|body_id| {
if let hir::TyKind::Infer = ty.kind {
Some(infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident))
} else {
None
}
}).unwrap_or_else(|| icx.to_ty(ty))
},
TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
TraitItemKind::Type(_, None) => {
span_bug!(item.span, "associated type missing default");
}
},
Node::ImplItem(item) => match item.kind {
ImplItemKind::Method(..) => {
let substs = InternalSubsts::identity_for_item(tcx, def_id);
tcx.mk_fn_def(def_id, substs)
}
ImplItemKind::Const(ref ty, body_id) => {
if let hir::TyKind::Infer = ty.kind {
infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
} else {
icx.to_ty(ty)
}
},
ImplItemKind::OpaqueTy(_) => {
if tcx
.impl_trait_ref(tcx.hir().get_parent_did(hir_id))
.is_none()
{
report_assoc_ty_on_inherent_impl(tcx, item.span);
}
find_opaque_ty_constraints(tcx, def_id)
}
ImplItemKind::TyAlias(ref ty) => {
if tcx
.impl_trait_ref(tcx.hir().get_parent_did(hir_id))
.is_none()
{
report_assoc_ty_on_inherent_impl(tcx, item.span);
}
icx.to_ty(ty)
}
},
Node::Item(item) => {
match item.kind {
ItemKind::Static(ref ty, .., body_id)
| ItemKind::Const(ref ty, body_id) => {
if let hir::TyKind::Infer = ty.kind {
infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
} else {
icx.to_ty(ty)
}
},
ItemKind::TyAlias(ref ty, _)
| ItemKind::Impl(.., ref ty, _) => icx.to_ty(ty),
ItemKind::Fn(..) => {
let substs = InternalSubsts::identity_for_item(tcx, def_id);
tcx.mk_fn_def(def_id, substs)
}
ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
let def = tcx.adt_def(def_id);
let substs = InternalSubsts::identity_for_item(tcx, def_id);
tcx.mk_adt(def, substs)
}
ItemKind::OpaqueTy(hir::OpaqueTy {
impl_trait_fn: None,
..
}) => find_opaque_ty_constraints(tcx, def_id),
// Opaque types desugared from `impl Trait`.
ItemKind::OpaqueTy(hir::OpaqueTy {
impl_trait_fn: Some(owner),
..
}) => {
tcx.typeck_tables_of(owner)
.concrete_opaque_types
.get(&def_id)
.map(|opaque| opaque.concrete_type)
.unwrap_or_else(|| {
// This can occur if some error in the
// owner fn prevented us from populating
// the `concrete_opaque_types` table.
tcx.sess.delay_span_bug(
DUMMY_SP,
&format!(
"owner {:?} has no opaque type for {:?} in its tables",
owner, def_id,
),
);
tcx.types.err
})
}
ItemKind::Trait(..)
| ItemKind::TraitAlias(..)
| ItemKind::Mod(..)
| ItemKind::ForeignMod(..)
| ItemKind::GlobalAsm(..)
| ItemKind::ExternCrate(..)
| ItemKind::Use(..) => {
span_bug!(
item.span,
"compute_type_of_item: unexpected item type: {:?}",
item.kind
);
}
}
}
Node::ForeignItem(foreign_item) => match foreign_item.kind {
ForeignItemKind::Fn(..) => {
let substs = InternalSubsts::identity_for_item(tcx, def_id);
tcx.mk_fn_def(def_id, substs)
}
ForeignItemKind::Static(ref t, _) => icx.to_ty(t),
ForeignItemKind::Type => tcx.mk_foreign(def_id),
},
Node::Ctor(&ref def) | Node::Variant(
hir::Variant { data: ref def, .. }
) => match *def {
VariantData::Unit(..) | VariantData::Struct(..) => {
tcx.type_of(tcx.hir().get_parent_did(hir_id))
}
VariantData::Tuple(..) => {
let substs = InternalSubsts::identity_for_item(tcx, def_id);
tcx.mk_fn_def(def_id, substs)
}
},
Node::Field(field) => icx.to_ty(&field.ty),
Node::Expr(&hir::Expr {
kind: hir::ExprKind::Closure(.., gen),
..
}) => {
if gen.is_some() {
return tcx.typeck_tables_of(def_id).node_type(hir_id);
}
let substs = InternalSubsts::identity_for_item(tcx, def_id);
tcx.mk_closure(def_id, substs)
}
Node::AnonConst(_) => {
let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
match parent_node {
Node::Ty(&hir::Ty {
kind: hir::TyKind::Array(_, ref constant),
..
})
| Node::Ty(&hir::Ty {
kind: hir::TyKind::Typeof(ref constant),
..
})
| Node::Expr(&hir::Expr {
kind: ExprKind::Repeat(_, ref constant),
..
}) if constant.hir_id == hir_id =>
{
tcx.types.usize
}
Node::Variant(Variant {
disr_expr: Some(ref e),
..
}) if e.hir_id == hir_id =>
{
tcx.adt_def(tcx.hir().get_parent_did(hir_id))
.repr
.discr_type()
.to_ty(tcx)
}
Node::Ty(&hir::Ty { kind: hir::TyKind::Path(_), .. }) |
Node::Expr(&hir::Expr { kind: ExprKind::Struct(..), .. }) |
Node::Expr(&hir::Expr { kind: ExprKind::Path(_), .. }) |
Node::TraitRef(..) => {
let path = match parent_node {
Node::Ty(&hir::Ty {
kind: hir::TyKind::Path(QPath::Resolved(_, ref path)),
..
})
| Node::Expr(&hir::Expr {
kind: ExprKind::Path(QPath::Resolved(_, ref path)),
..
}) => {
Some(&**path)
}
Node::Expr(&hir::Expr { kind: ExprKind::Struct(ref path, ..), .. }) => {
if let QPath::Resolved(_, ref path) = **path {
Some(&**path)
} else {
None
}
}
Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(&**path),
_ => None,
};
if let Some(path) = path {
let arg_index = path.segments.iter()
.filter_map(|seg| seg.args.as_ref())
.map(|generic_args| generic_args.args.as_ref())
.find_map(|args| {
args.iter()
.filter(|arg| arg.is_const())
.enumerate()
.filter(|(_, arg)| arg.id() == hir_id)
.map(|(index, _)| index)
.next()
})
.unwrap_or_else(|| {
bug!("no arg matching AnonConst in path");
});
// We've encountered an `AnonConst` in some path, so we need to
// figure out which generic parameter it corresponds to and return
// the relevant type.
let generics = match path.res {
Res::Def(DefKind::Ctor(..), def_id) => {
tcx.generics_of(tcx.parent(def_id).unwrap())
}
Res::Def(_, def_id) => tcx.generics_of(def_id),
Res::Err => return tcx.types.err,
res => {
tcx.sess.delay_span_bug(
DUMMY_SP,
&format!(
"unexpected const parent path def {:?}",
res,
),
);
return tcx.types.err;
}
};
generics.params.iter()
.filter(|param| {
if let ty::GenericParamDefKind::Const = param.kind {
true
} else {
false
}
})
.nth(arg_index)
.map(|param| tcx.type_of(param.def_id))
// This is no generic parameter associated with the arg. This is
// probably from an extra arg where one is not needed.
.unwrap_or(tcx.types.err)
} else {
tcx.sess.delay_span_bug(
DUMMY_SP,
&format!(
"unexpected const parent path {:?}",
parent_node,
),
);
return tcx.types.err;
}
}
x => {
tcx.sess.delay_span_bug(
DUMMY_SP,
&format!(
"unexpected const parent in type_of_def_id(): {:?}", x
),
);
tcx.types.err
}
}
}
Node::GenericParam(param) => match &param.kind {
hir::GenericParamKind::Type { default: Some(ref ty), .. } => icx.to_ty(ty),
hir::GenericParamKind::Const { ty: ref hir_ty, .. } => {
let ty = icx.to_ty(hir_ty);
if !tcx.features().const_compare_raw_pointers {
let err = match ty.peel_refs().kind {
ty::FnPtr(_) => Some("function pointers"),
ty::RawPtr(_) => Some("raw pointers"),
_ => None,
};
if let Some(unsupported_type) = err {
feature_gate::feature_err(
&tcx.sess.parse_sess,
sym::const_compare_raw_pointers,
hir_ty.span,
&format!(
"using {} as const generic parameters is unstable",
unsupported_type
),
)
.emit();
};
}
if ty::search_for_structural_match_violation(
param.hir_id, param.span, tcx, ty).is_some()
{
struct_span_err!(
tcx.sess,
hir_ty.span,
E0741,
"the types of const generic parameters must derive `PartialEq` and `Eq`",
).span_label(
hir_ty.span,
format!("`{}` doesn't derive both `PartialEq` and `Eq`", ty),
).emit();
}
ty
}
x => bug!("unexpected non-type Node::GenericParam: {:?}", x),
},
x => {
bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
}
}
}
fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
use rustc::hir::{ImplItem, Item, TraitItem};
debug!("find_opaque_ty_constraints({:?})", def_id);
struct ConstraintLocator<'tcx> {
tcx: TyCtxt<'tcx>,
def_id: DefId,
// (first found type span, actual type, mapping from the opaque type's generic
// parameters to the concrete type's generic parameters)
//
// The mapping is an index for each use site of a generic parameter in the concrete type
//
// The indices index into the generic parameters on the opaque type.
found: Option<(Span, Ty<'tcx>, Vec<usize>)>,
}
impl ConstraintLocator<'tcx> {
fn check(&mut self, def_id: DefId) {
// Don't try to check items that cannot possibly constrain the type.
if !self.tcx.has_typeck_tables(def_id) {
debug!(
"find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`: no tables",
self.def_id,
def_id,
);
return;
}
let ty = self
.tcx
.typeck_tables_of(def_id)
.concrete_opaque_types
.get(&self.def_id);
if let Some(ty::ResolvedOpaqueTy { concrete_type, substs }) = ty {
debug!(
"find_opaque_ty_constraints: found constraint for `{:?}` at `{:?}`: {:?}",
self.def_id,
def_id,
ty,
);
// FIXME(oli-obk): trace the actual span from inference to improve errors.
let span = self.tcx.def_span(def_id);
// used to quickly look up the position of a generic parameter
let mut index_map: FxHashMap<ty::ParamTy, usize> = FxHashMap::default();
// Skipping binder is ok, since we only use this to find generic parameters and
// their positions.
for (idx, subst) in substs.iter().enumerate() {
if let GenericArgKind::Type(ty) = subst.unpack() {
if let ty::Param(p) = ty.kind {
if index_map.insert(p, idx).is_some() {
// There was already an entry for `p`, meaning a generic parameter
// was used twice.
self.tcx.sess.span_err(
span,
&format!(
"defining opaque type use restricts opaque \
type by using the generic parameter `{}` twice",
p,
),
);
return;
}
} else {
self.tcx.sess.delay_span_bug(
span,
&format!(
"non-defining opaque ty use in defining scope: {:?}, {:?}",
concrete_type, substs,
),
);
}
}
}
// Compute the index within the opaque type for each generic parameter used in
// the concrete type.
let indices = concrete_type
.subst(self.tcx, substs)
.walk()
.filter_map(|t| match &t.kind {
ty::Param(p) => Some(*index_map.get(p).unwrap()),
_ => None,
}).collect();
let is_param = |ty: Ty<'_>| match ty.kind {
ty::Param(_) => true,
_ => false,
};
let bad_substs: Vec<_> = substs.types().enumerate()
.filter(|(_, ty)| !is_param(ty)).collect();
if !bad_substs.is_empty() {
let identity_substs = InternalSubsts::identity_for_item(self.tcx, self.def_id);
for (i, bad_subst) in bad_substs {
self.tcx.sess.span_err(
span,
&format!("defining opaque type use does not fully define opaque type: \
generic parameter `{}` is specified as concrete type `{}`",
identity_substs.type_at(i), bad_subst)
);
}
} else if let Some((prev_span, prev_ty, ref prev_indices)) = self.found {
let mut ty = concrete_type.walk().fuse();
let mut p_ty = prev_ty.walk().fuse();
let iter_eq = (&mut ty).zip(&mut p_ty).all(|(t, p)| match (&t.kind, &p.kind) {
// Type parameters are equal to any other type parameter for the purpose of
// concrete type equality, as it is possible to obtain the same type just
// by passing matching parameters to a function.
(ty::Param(_), ty::Param(_)) => true,
_ => t == p,
});
if !iter_eq || ty.next().is_some() || p_ty.next().is_some() {
debug!("find_opaque_ty_constraints: span={:?}", span);
// Found different concrete types for the opaque type.
let mut err = self.tcx.sess.struct_span_err(
span,
"concrete type differs from previous defining opaque type use",
);
err.span_label(
span,
format!("expected `{}`, got `{}`", prev_ty, concrete_type),
);
err.span_note(prev_span, "previous use here");
err.emit();
} else if indices != *prev_indices {
// Found "same" concrete types, but the generic parameter order differs.
let mut err = self.tcx.sess.struct_span_err(
span,
"concrete type's generic parameters differ from previous defining use",
);
use std::fmt::Write;
let mut s = String::new();
write!(s, "expected [").unwrap();
let list = |s: &mut String, indices: &Vec<usize>| {
let mut indices = indices.iter().cloned();
if let Some(first) = indices.next() {
write!(s, "`{}`", substs[first]).unwrap();
for i in indices {
write!(s, ", `{}`", substs[i]).unwrap();
}
}
};
list(&mut s, prev_indices);
write!(s, "], got [").unwrap();
list(&mut s, &indices);
write!(s, "]").unwrap();
err.span_label(span, s);
err.span_note(prev_span, "previous use here");
err.emit();
}
} else {
self.found = Some((span, concrete_type, indices));
}
} else {
debug!(
"find_opaque_ty_constraints: no constraint for `{:?}` at `{:?}`",
self.def_id,
def_id,
);
}
}
}
impl<'tcx> intravisit::Visitor<'tcx> for ConstraintLocator<'tcx> {
fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
intravisit::NestedVisitorMap::All(&self.tcx.hir())
}
fn visit_item(&mut self, it: &'tcx Item) {
debug!("find_existential_constraints: visiting {:?}", it);
let def_id = self.tcx.hir().local_def_id(it.hir_id);
// The opaque type itself or its children are not within its reveal scope.
if def_id != self.def_id {
self.check(def_id);
intravisit::walk_item(self, it);
}
}
fn visit_impl_item(&mut self, it: &'tcx ImplItem) {
debug!("find_existential_constraints: visiting {:?}", it);
let def_id = self.tcx.hir().local_def_id(it.hir_id);
// The opaque type itself or its children are not within its reveal scope.
if def_id != self.def_id {
self.check(def_id);
intravisit::walk_impl_item(self, it);
}
}
fn visit_trait_item(&mut self, it: &'tcx TraitItem) {
debug!("find_existential_constraints: visiting {:?}", it);
let def_id = self.tcx.hir().local_def_id(it.hir_id);
self.check(def_id);
intravisit::walk_trait_item(self, it);
}
}
let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
let scope = tcx.hir().get_defining_scope(hir_id);
let mut locator = ConstraintLocator {
def_id,
tcx,
found: None,
};
debug!("find_opaque_ty_constraints: scope={:?}", scope);
if scope == hir::CRATE_HIR_ID {
intravisit::walk_crate(&mut locator, tcx.hir().krate());
} else {
debug!("find_opaque_ty_constraints: scope={:?}", tcx.hir().get(scope));
match tcx.hir().get(scope) {
// We explicitly call `visit_*` methods, instead of using `intravisit::walk_*` methods
// This allows our visitor to process the defining item itself, causing
// it to pick up any 'sibling' defining uses.
//
// For example, this code:
// ```
// fn foo() {
// type Blah = impl Debug;
// let my_closure = || -> Blah { true };
// }
// ```
//
// requires us to explicitly process `foo()` in order
// to notice the defining usage of `Blah`.
Node::Item(ref it) => locator.visit_item(it),
Node::ImplItem(ref it) => locator.visit_impl_item(it),
Node::TraitItem(ref it) => locator.visit_trait_item(it),
other => bug!(
"{:?} is not a valid scope for an opaque type item",
other
),
}
}
match locator.found {
Some((_, ty, _)) => ty,
None => {
let span = tcx.def_span(def_id);
tcx.sess.span_err(span, "could not find defining uses");
tcx.types.err
}
}
}
pub fn get_infer_ret_ty(output: &'_ hir::FunctionRetTy) -> Option<&hir::Ty> {
if let hir::FunctionRetTy::Return(ref ty) = output {
if let hir::TyKind::Infer = ty.kind {
return Some(&**ty)
}
}
None
}
fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
use rustc::hir::*;
use rustc::hir::Node::*;
let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
let icx = ItemCtxt::new(tcx, def_id);
match tcx.hir().get(hir_id) {
TraitItem(hir::TraitItem {
kind: TraitItemKind::Method(sig, TraitMethod::Provided(_)),
..
})
| ImplItem(hir::ImplItem {
kind: ImplItemKind::Method(sig, _),
..
})
| Item(hir::Item {
kind: ItemKind::Fn(sig, _, _),
..
}) => 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 diag = bad_placeholder_type(tcx, ty.span);
let ret_ty = fn_sig.output();
if ret_ty != tcx.types.err {
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)
},
TraitItem(hir::TraitItem {
kind: TraitItemKind::Method(FnSig { header, decl }, _),
..
}) => {
AstConv::ty_of_fn(&icx, header.unsafety, header.abi, decl)
},
ForeignItem(&hir::ForeignItem {
kind: ForeignItemKind::Fn(ref fn_decl, _, _),
..
}) => {
let abi = tcx.hir().get_foreign_abi(hir_id);
compute_sig_of_foreign_fn_decl(tcx, def_id, fn_decl, abi)
}
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));
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
// `closure_sig` method on the `ClosureSubsts`:
//
// closure_substs.sig(def_id, tcx)
//
// or, inside of an inference context, you can use
//
// infcx.closure_sig(def_id, closure_substs)
bug!("to get the signature of a closure, use `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).unwrap();
match tcx.hir().expect_item(hir_id).kind {
hir::ItemKind::Impl(.., ref opt_trait_ref, _, _) => {
opt_trait_ref.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).unwrap();
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(_, hir::ImplPolarity::Negative, ..) => {
if is_rustc_reservation {
tcx.sess.span_err(item.span, "reservation impls can't be negative");
}
ty::ImplPolarity::Negative
}
hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, None, _, _) => {
if is_rustc_reservation {
tcx.sess.span_err(item.span, "reservation impls can't be inherent");
}
ty::ImplPolarity::Positive
}
hir::ItemKind::Impl(_, hir::ImplPolarity::Positive, _, _, Some(_tr), _, _) => {
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,
) -> impl Iterator<Item = &'a hir::GenericParam> + 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.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).to_predicate(), 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::*;
use rustc_data_structures::fx::FxHashSet;
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).unwrap();
let node = tcx.hir().get(hir_id);
let mut is_trait = None;
let mut is_default_impl_trait = None;
let icx = ItemCtxt::new(tcx, def_id);
const NO_GENERICS: &hir::Generics = &hir::Generics::empty();
let empty_trait_items = HirVec::new();
let mut predicates = UniquePredicates::new();
let ast_generics = match node {
Node::TraitItem(item) => &item.generics,
Node::ImplItem(item) => match item.kind {
ImplItemKind::OpaqueTy(ref bounds) => {
ty::print::with_no_queries(|| {
let substs = InternalSubsts::identity_for_item(tcx, def_id);
let opaque_ty = tcx.mk_opaque(def_id, substs);
debug!("explicit_predicates_of({:?}): created opaque type {:?}",
def_id, opaque_ty);
// 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),
);
predicates.extend(bounds.predicates(tcx, opaque_ty));
&item.generics
})
}
_ => &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, .., ref 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), &empty_trait_items));
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().to_predicate(), 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),
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(), 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 predicate = ty::OutlivesPredicate(ty, tcx.mk_region(ty::ReEmpty));
predicates.push(
(ty::Predicate::TypeOutlives(ty::Binder::dummy(predicate)), span)
);
}
}
for bound in bound_pred.bounds.iter() {
match bound {
&hir::GenericBound::Trait(ref poly_trait_ref, _) => {
let mut bounds = Bounds::default();
let _ = AstConv::instantiate_poly_trait_ref(
&icx,
poly_trait_ref,
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::Predicate::TypeOutlives(pred), 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::Predicate::RegionOutlives(pred), span)
}))
}
&hir::WherePredicate::EqPredicate(..) => {
// FIXME(#20041)
}
}
}
// Add predicates from associated type bounds.
if let Some((self_trait_ref, trait_items)) = is_trait {
predicates.extend(trait_items.iter().flat_map(|trait_item_ref| {
let trait_item = tcx.hir().trait_item(trait_item_ref.id);
let bounds = match trait_item.kind {
hir::TraitItemKind::Type(ref bounds, _) => bounds,
_ => return Vec::new().into_iter()
};
let assoc_ty =
tcx.mk_projection(tcx.hir().local_def_id(trait_item.hir_id),
self_trait_ref.substs);
let bounds = AstConv::compute_bounds(
&ItemCtxt::new(tcx, def_id),
assoc_ty,
bounds,
SizedByDefault::Yes,
trait_item.span,
);
bounds.predicates(tcx, assoc_ty).into_iter()
}))
}
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
}
/// 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,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
match *bound {
hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
let mut bounds = Bounds::default();
let _ = astconv.instantiate_poly_trait_ref(
tr,
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::Predicate::TypeOutlives(pred), lifetime.span)]
}
hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
}
}
fn compute_sig_of_foreign_fn_decl<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: DefId,
decl: &'tcx hir::FnDecl,
abi: abi::Abi,
) -> ty::PolyFnSig<'tcx> {
let unsafety = if abi == abi::Abi::RustIntrinsic {
intrinsic_operation_unsafety(&tcx.item_name(def_id).as_str())
} else {
hir::Unsafety::Unsafe
};
let fty = AstConv::ty_of_fn(&ItemCtxt::new(tcx, def_id), unsafety, abi, decl);
// 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() {
tcx.sess
.struct_span_err(
ast_ty.span,
&format!(
"use of SIMD type `{}` in FFI is highly experimental and \
may result in invalid code",
tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
),
)
.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::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, _), ..
})) |
Some(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 from_target_feature(
tcx: TyCtxt<'_>,
id: DefId,
attr: &ast::Attribute,
whitelist: &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| {
// Only allow whitelisted features per platform.
let feature_gate = match whitelist.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 = whitelist.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().map(|s| *s) {
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::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_gate::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::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 whitelist 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();
let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
let mut inline_span = None;
let mut link_ordinal_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::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::no_debug) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_DEBUG;
} 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.fn_sig(id).abi() != abi::Abi::Rust {
struct_span_err!(
tcx.sess,
attr.span,
E0737,
"Rust ABI is required to use `#[track_caller]`"
).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.fn_sig(id).unsafety() == Unsafety::Normal {
let msg = "`#[target_feature(..)]` can only be applied to `unsafe` functions";
tcx.sess.struct_span_err(attr.span, msg)
.span_label(attr.span, "can only be applied to `unsafe` functions")
.span_label(tcx.def_span(id), "not an `unsafe` function")
.emit();
}
from_target_feature(
tcx,
id,
attr,
&whitelist,
&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
);
tcx.sess.span_err(attr.span, &msg);
} else {
codegen_fn_attrs.link_section = Some(val);
}
}
} else if attr.check_name(sym::link_name) {
codegen_fn_attrs.link_name = attr.value_str();
} else if attr.check_name(sym::link_ordinal) {
link_ordinal_span = Some(attr.span);
if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
codegen_fn_attrs.link_ordinal = ordinal;
}
}
}
codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
if !attr.has_name(sym::inline) {
return ia;
}
match attr.meta().map(|i| i.kind) {
Some(MetaItemKind::Word) => {
mark_used(attr);
InlineAttr::Hint
}
Some(MetaItemKind::List(ref items)) => {
mark_used(attr);
inline_span = Some(attr.span);
if items.len() != 1 {
span_err!(
tcx.sess.diagnostic(),
attr.span,
E0534,
"expected one argument"
);
InlineAttr::None
} else if list_contains_name(&items[..], sym::always) {
InlineAttr::Always
} else if list_contains_name(&items[..], sym::never) {
InlineAttr::Never
} else {
span_err!(
tcx.sess.diagnostic(),
items[0].span(),
E0535,
"invalid argument"
);
InlineAttr::None
}
}
Some(MetaItemKind::NameValue(_)) => ia,
None => ia,
}
});
codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
if !attr.has_name(sym::optimize) {
return ia;
}
let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
match attr.meta().map(|i| i.kind) {
Some(MetaItemKind::Word) => {
err(attr.span, "expected one argument");
ia
}
Some(MetaItemKind::List(ref items)) => {
mark_used(attr);
inline_span = Some(attr.span);
if items.len() != 1 {
err(attr.span, "expected one argument");
OptimizeAttr::None
} else if list_contains_name(&items[..], sym::size) {
OptimizeAttr::Size
} else if list_contains_name(&items[..], sym::speed) {
OptimizeAttr::Speed
} else {
err(items[0].span(), "invalid argument");
OptimizeAttr::None
}
}
Some(MetaItemKind::NameValue(_)) => ia,
None => ia,
}
});
// If a function uses #[target_feature] it can't be inlined into general
// purpose functions as they wouldn't have the right target features
// enabled. For that reason we also forbid #[inline(always)] as it can't be
// respected.
if codegen_fn_attrs.target_features.len() > 0 {
if codegen_fn_attrs.inline == InlineAttr::Always {
if let Some(span) = inline_span {
tcx.sess.span_err(
span,
"cannot use `#[inline(always)]` with \
`#[target_feature]`",
);
}
}
}
// Weak lang items have the same semantics as "std internal" symbols in the
// sense that they're preserved through all our LTO passes and only
// strippable by the linker.
//
// Additionally weak lang items have predetermined symbol names.
if tcx.is_weak_lang_item(id) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
}
if let Some(name) = weak_lang_items::link_name(&attrs) {
codegen_fn_attrs.export_name = Some(name);
codegen_fn_attrs.link_name = Some(name);
}
check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
// Internal symbols to the standard library all have no_mangle semantics in
// that they have defined symbol names present in the function name. This
// also applies to weak symbols where they all have known symbol names.
if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
}
codegen_fn_attrs
}
fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
use syntax::ast::{Lit, LitIntType, LitKind};
let meta_item_list = attr.meta_item_list();
let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
let sole_meta_list = match meta_item_list {
Some([item]) => item.literal(),
_ => None,
};
if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
if *ordinal <= std::usize::MAX as u128 {
Some(*ordinal as usize)
} else {
let msg = format!(
"ordinal value in `link_ordinal` is too large: `{}`",
&ordinal
);
tcx.sess.struct_span_err(attr.span, &msg)
.note("the value may not exceed `std::usize::MAX`")
.emit();
None
}
} else {
tcx.sess.struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
.note("an unsuffixed integer value, e.g., `1`, is expected")
.emit();
None
}
}
fn check_link_name_xor_ordinal(
tcx: TyCtxt<'_>,
codegen_fn_attrs: &CodegenFnAttrs,
inline_span: Option<Span>,
) {
if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
return;
}
let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
if let Some(span) = inline_span {
tcx.sess.span_err(span, msg);
} else {
tcx.sess.err(msg);
}
}