use crate::namespace::Namespace;
use rustc::lint::builtin::AMBIGUOUS_ASSOCIATED_ITEMS;
use rustc::traits;
-use rustc::ty::{self, DefIdTree, Ty, TyCtxt, ToPredicate, TypeFoldable};
+use rustc::ty::{self, DefIdTree, Ty, TyCtxt, Const, ToPredicate, TypeFoldable};
use rustc::ty::{GenericParamDef, GenericParamDefKind};
use rustc::ty::subst::{Kind, Subst, InternalSubsts, SubstsRef};
use rustc::ty::wf::object_region_bounds;
pub struct PathSeg(pub DefId, pub usize);
pub trait AstConv<'gcx, 'tcx> {
- fn tcx<'a>(&'a self) -> TyCtxt<'a, 'gcx, 'tcx>;
+ fn tcx<'a>(&'a self) -> TyCtxt<'gcx, 'tcx>;
/// Returns the set of bounds in scope for the type parameter with
/// the given id.
-> &'tcx ty::GenericPredicates<'tcx>;
/// Returns the lifetime to use when a lifetime is omitted (and not elided).
- fn re_infer(&self, span: Span, _def: Option<&ty::GenericParamDef>)
+ fn re_infer(
+ &self,
+ param: Option<&ty::GenericParamDef>,
+ span: Span,
+ )
-> Option<ty::Region<'tcx>>;
/// Returns the type to use when a type is omitted.
- fn ty_infer(&self, span: Span) -> Ty<'tcx>;
+ fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx>;
- /// Same as `ty_infer`, but with a known type parameter definition.
- fn ty_infer_for_def(&self,
- _def: &ty::GenericParamDef,
- span: Span) -> Ty<'tcx> {
- self.ty_infer(span)
- }
+ /// Returns the const to use when a const is omitted.
+ fn ct_infer(
+ &self,
+ ty: Ty<'tcx>,
+ param: Option<&ty::GenericParamDef>,
+ span: Span,
+ ) -> &'tcx Const<'tcx>;
/// Projecting an associated type from a (potentially)
/// higher-ranked trait reference is more complicated, because of
}
None => {
- self.re_infer(lifetime.span, def)
+ self.re_infer(def, lifetime.span)
.unwrap_or_else(|| {
// This indicates an illegal lifetime
// elision. `resolve_lifetime` should have
span,
def_id,
generic_args,
- item_segment.infer_types,
+ item_segment.infer_args,
None,
)
});
/// Report error if there is an explicit type parameter when using `impl Trait`.
fn check_impl_trait(
- tcx: TyCtxt<'_, '_, '_>,
+ tcx: TyCtxt<'_, '_>,
span: Span,
seg: &hir::PathSegment,
generics: &ty::Generics,
) -> bool {
- let explicit = !seg.infer_types;
+ let explicit = !seg.infer_args;
let impl_trait = generics.params.iter().any(|param| match param.kind {
ty::GenericParamDefKind::Type {
synthetic: Some(hir::SyntheticTyParamKind::ImplTrait), ..
/// Checks that the correct number of generic arguments have been provided.
/// Used specifically for function calls.
pub fn check_generic_arg_count_for_call(
- tcx: TyCtxt<'_, '_, '_>,
+ tcx: TyCtxt<'_, '_>,
span: Span,
def: &ty::Generics,
seg: &hir::PathSegment,
GenericArgPosition::Value
},
def.parent.is_none() && def.has_self, // `has_self`
- seg.infer_types || suppress_mismatch, // `infer_types`
+ seg.infer_args || suppress_mismatch, // `infer_args`
).0
}
/// Checks that the correct number of generic arguments have been provided.
/// This is used both for datatypes and function calls.
fn check_generic_arg_count(
- tcx: TyCtxt<'_, '_, '_>,
+ tcx: TyCtxt<'_, '_>,
span: Span,
def: &ty::Generics,
args: &hir::GenericArgs,
position: GenericArgPosition,
has_self: bool,
- infer_types: bool,
+ infer_args: bool,
) -> (bool, Option<Vec<Span>>) {
// At this stage we are guaranteed that the generic arguments are in the correct order, e.g.
// that lifetimes will proceed types. So it suffices to check the number of each generic
let param_counts = def.own_counts();
let arg_counts = args.own_counts();
let infer_lifetimes = position != GenericArgPosition::Type && arg_counts.lifetimes == 0;
- let infer_consts = position != GenericArgPosition::Type && arg_counts.consts == 0;
let mut defaults: ty::GenericParamCount = Default::default();
for param in &def.params {
offset
);
// We enforce the following: `required` <= `provided` <= `permitted`.
- // For kinds without defaults (i.e., lifetimes), `required == permitted`.
+ // For kinds without defaults (e.g.., lifetimes), `required == permitted`.
// For other kinds (i.e., types), `permitted` may be greater than `required`.
if required <= provided && provided <= permitted {
return (reported_late_bound_region_err.unwrap_or(false), None);
);
}
// FIXME(const_generics:defaults)
- if !infer_consts || arg_counts.consts > param_counts.consts {
+ if !infer_args || arg_counts.consts > param_counts.consts {
check_kind_count(
"const",
param_counts.consts,
);
}
// Note that type errors are currently be emitted *after* const errors.
- if !infer_types
+ if !infer_args
|| arg_counts.types > param_counts.types - defaults.types - has_self as usize {
check_kind_count(
"type",
/// instantiate a `Kind`.
/// - `inferred_kind`: if no parameter was provided, and inference is enabled, then
/// creates a suitable inference variable.
- pub fn create_substs_for_generic_args<'a, 'b>(
- tcx: TyCtxt<'a, 'gcx, 'tcx>,
+ pub fn create_substs_for_generic_args<'b>(
+ tcx: TyCtxt<'gcx, 'tcx>,
def_id: DefId,
parent_substs: &[Kind<'tcx>],
has_self: bool,
}
// Check whether this segment takes generic arguments and the user has provided any.
- let (generic_args, infer_types) = args_for_def_id(def_id);
+ let (generic_args, infer_args) = args_for_def_id(def_id);
let mut args = generic_args.iter().flat_map(|generic_args| generic_args.args.iter())
.peekable();
| (GenericArg::Const(_), GenericParamDefKind::Lifetime) => {
// We expected a lifetime argument, but got a type or const
// argument. That means we're inferring the lifetimes.
- substs.push(inferred_kind(None, param, infer_types));
+ substs.push(inferred_kind(None, param, infer_args));
params.next();
}
(_, _) => {
(None, Some(¶m)) => {
// If there are fewer arguments than parameters, it means
// we're inferring the remaining arguments.
- substs.push(inferred_kind(Some(&substs), param, infer_types));
+ substs.push(inferred_kind(Some(&substs), param, infer_args));
args.next();
params.next();
}
/// Given the type/lifetime/const arguments provided to some path (along with
/// an implicit `Self`, if this is a trait reference), returns the complete
/// set of substitutions. This may involve applying defaulted type parameters.
+ /// Also returns back constriants on associated types.
+ ///
+ /// Example:
+ ///
+ /// ```
+ /// T: std::ops::Index<usize, Output = u32>
+ /// ^1 ^^^^^^^^^^^^^^2 ^^^^3 ^^^^^^^^^^^4
+ /// ```
+ ///
+ /// 1. The `self_ty` here would refer to the type `T`.
+ /// 2. The path in question is the path to the trait `std::ops::Index`,
+ /// which will have been resolved to a `def_id`
+ /// 3. The `generic_args` contains info on the `<...>` contents. The `usize` type
+ /// parameters are returned in the `SubstsRef`, the associated type bindings like
+ /// `Output = u32` are returned in the `Vec<ConvertedBinding...>` result.
///
/// Note that the type listing given here is *exactly* what the user provided.
fn create_substs_for_ast_path<'a>(&self,
span: Span,
def_id: DefId,
generic_args: &'a hir::GenericArgs,
- infer_types: bool,
+ infer_args: bool,
self_ty: Option<Ty<'tcx>>)
-> (SubstsRef<'tcx>, Vec<ConvertedBinding<'tcx>>, Option<Vec<Span>>)
{
&generic_args,
GenericArgPosition::Type,
has_self,
- infer_types,
+ infer_args,
);
let is_object = self_ty.map_or(false, |ty| {
self_ty.is_some(),
self_ty,
// Provide the generic args, and whether types should be inferred.
- |_| (Some(generic_args), infer_types),
+ |_| (Some(generic_args), infer_args),
// Provide substitutions for parameters for which (valid) arguments have been provided.
|param, arg| {
match (¶m.kind, arg) {
}
},
// Provide substitutions for parameters for which arguments are inferred.
- |substs, param, infer_types| {
+ |substs, param, infer_args| {
match param.kind {
GenericParamDefKind::Lifetime => tcx.lifetimes.re_static.into(),
GenericParamDefKind::Type { has_default, .. } => {
- if !infer_types && has_default {
+ if !infer_args && has_default {
// No type parameter provided, but a default exists.
// If we are converting an object type, then the
.subst_spanned(tcx, substs.unwrap(), Some(span))
).into()
}
- } else if infer_types {
+ } else if infer_args {
// No type parameters were provided, we can infer all.
- if !default_needs_object_self(param) {
- self.ty_infer_for_def(param, span).into()
+ let param = if !default_needs_object_self(param) {
+ Some(param)
} else {
- self.ty_infer(span).into()
- }
+ None
+ };
+ self.ty_infer(param, span).into()
} else {
// We've already errored above about the mismatch.
tcx.types.err.into()
}
GenericParamDefKind::Const => {
// FIXME(const_generics:defaults)
- // We've already errored above about the mismatch.
- tcx.consts.err.into()
+ if infer_args {
+ // No const parameters were provided, we can infer all.
+ let ty = tcx.at(span).type_of(param.def_id);
+ self.ct_infer(ty, Some(param), span).into()
+ } else {
+ // We've already errored above about the mismatch.
+ tcx.consts.err.into()
+ }
}
}
},
// back separately.
let assoc_bindings = generic_args.bindings.iter()
.map(|binding| {
- let kind = if let hir::TyKind::AssocTyExistential(ref bounds) = binding.ty.node {
- ConvertedBindingKind::Constraint(bounds.clone())
- } else {
- ConvertedBindingKind::Equality(self.ast_ty_to_ty(&binding.ty))
+ let kind = match binding.kind {
+ hir::TypeBindingKind::Equality { ref ty } =>
+ ConvertedBindingKind::Equality(self.ast_ty_to_ty(ty)),
+ hir::TypeBindingKind::Constraint { ref bounds } =>
+ ConvertedBindingKind::Constraint(bounds.clone()),
};
ConvertedBinding {
item_name: binding.ident,
(poly_trait_ref, potential_assoc_types)
}
+ /// Given a trait bound like `Debug`, applies that trait bound the given self-type to construct
+ /// a full trait reference. The resulting trait reference is returned. This may also generate
+ /// auxiliary bounds, which are added to `bounds`.
+ ///
+ /// Example:
+ ///
+ /// ```
+ /// poly_trait_ref = Iterator<Item = u32>
+ /// self_ty = Foo
+ /// ```
+ ///
+ /// this would return `Foo: Iterator` and add `<Foo as Iterator>::Item = u32` into `bounds`.
+ ///
+ /// **A note on binders:** against our usual convention, there is an implied bounder around
+ /// the `self_ty` and `poly_trait_ref` parameters here. So they may reference bound regions.
+ /// If for example you had `for<'a> Foo<'a>: Bar<'a>`, then the `self_ty` would be `Foo<'a>`
+ /// where `'a` is a bound region at depth 0. Similarly, the `poly_trait_ref` would be
+ /// `Bar<'a>`. The returned poly-trait-ref will have this binder instantiated explicitly,
+ /// however.
pub fn instantiate_poly_trait_ref(&self,
poly_trait_ref: &hir::PolyTraitRef,
self_ty: Ty<'tcx>,
self.create_substs_for_ast_path(span,
trait_def_id,
generic_args,
- trait_segment.infer_types,
+ trait_segment.infer_args,
Some(self_ty))
})
}
true
}
+ /// This helper takes a *converted* parameter type (`param_ty`)
+ /// and an *unconverted* list of bounds:
+ ///
+ /// ```
+ /// fn foo<T: Debug>
+ /// ^ ^^^^^ `ast_bounds` parameter, in HIR form
+ /// |
+ /// `param_ty`, in ty form
+ /// ```
+ ///
+ /// It adds these `ast_bounds` into the `bounds` structure.
+ ///
+ /// **A note on binders:** there is an implied binder around
+ /// `param_ty` and `ast_bounds`. See `instantiate_poly_trait_ref`
+ /// for more details.
fn add_bounds(&self,
param_ty: Ty<'tcx>,
ast_bounds: &[hir::GenericBound],
);
}
- /// Translates the AST's notion of ty param bounds (which are an enum consisting of a newtyped
- /// `Ty` or a region) to ty's notion of ty param bounds (which can either be user-defined traits
- /// or the built-in trait `Sized`).
+ /// Translates a list of bounds from the HIR into the `Bounds` data structure.
+ /// The self-type for the bounds is given by `param_ty`.
+ ///
+ /// Example:
+ ///
+ /// ```
+ /// fn foo<T: Bar + Baz>() { }
+ /// ^ ^^^^^^^^^ ast_bounds
+ /// param_ty
+ /// ```
+ ///
+ /// The `sized_by_default` parameter indicates if, in this context, the `param_ty` should be
+ /// considered `Sized` unless there is an explicit `?Sized` bound. This would be true in the
+ /// example above, but is not true in supertrait listings like `trait Foo: Bar + Baz`.
+ ///
+ /// `span` should be the declaration size of the parameter.
pub fn compute_bounds(&self,
param_ty: Ty<'tcx>,
ast_bounds: &[hir::GenericBound],
bounds
}
+ /// Given an HIR binding like `Item = Foo` or `Item: Foo`, pushes the corresponding predicates
+ /// onto `bounds`.
+ ///
+ /// **A note on binders:** given something like `T: for<'a> Iterator<Item = &'a u32>`, the
+ /// `trait_ref` here will be `for<'a> T: Iterator`. The `binding` data however is from *inside*
+ /// the binder (e.g., `&'a u32`) and hence may reference bound regions.
fn add_predicates_for_ast_type_binding(
&self,
hir_ref_id: hir::HirId,
}), binding.span));
}
ConvertedBindingKind::Constraint(ref ast_bounds) => {
- // Calling `skip_binder` is okay, because the predicates are re-bound later by
- // `instantiate_poly_trait_ref`.
+ // "Desugar" a constraint like `T: Iterator<Item: Debug>` to
+ //
+ // `<T as Iterator>::Item: Debug`
+ //
+ // Calling `skip_binder` is okay, because `add_bounds` expects the `param_ty`
+ // parameter to have a skipped binder.
let param_ty = tcx.mk_projection(assoc_ty.def_id, candidate.skip_binder().substs);
self.add_bounds(
param_ty,
if tcx.named_region(lifetime.hir_id).is_some() {
self.ast_region_to_region(lifetime, None)
} else {
- self.re_infer(span, None).unwrap_or_else(|| {
+ self.re_infer(None, span).unwrap_or_else(|| {
span_err!(tcx.sess, span, E0228,
"the lifetime bound for this object type cannot be deduced \
from context; please supply an explicit bound");
has_err
}
- pub fn prohibit_assoc_ty_binding(tcx: TyCtxt<'_, '_, '_>, span: Span) {
+ pub fn prohibit_assoc_ty_binding(tcx: TyCtxt<'_, '_>, span: Span) {
let mut err = struct_span_err!(tcx.sess, span, E0229,
"associated type bindings are not allowed here");
err.span_label(span, "associated type not allowed here").emit();
// values in a ExprKind::Closure, or as
// the type of local variables. Both of these cases are
// handled specially and will not descend into this routine.
- self.ty_infer(ast_ty.span)
+ self.ty_infer(None, ast_ty.span)
}
hir::TyKind::CVarArgs(lt) => {
let va_list_did = match tcx.lang_items().va_list() {
let region = self.ast_region_to_region(<, None);
tcx.type_of(va_list_did).subst(tcx, &[region.into()])
}
- hir::TyKind::AssocTyExistential(..) => {
- // Type is never actually used.
- tcx.types.err
- }
hir::TyKind::Err => {
tcx.types.err
}
result_ty
}
+ /// Returns the `DefId` of the constant parameter that the provided expression is a path to.
+ pub fn const_param_def_id(&self, expr: &hir::Expr) -> Option<DefId> {
+ match &expr.node {
+ ExprKind::Path(hir::QPath::Resolved(_, path)) => match path.res {
+ Res::Def(DefKind::ConstParam, did) => Some(did),
+ _ => None,
+ },
+ _ => None,
+ }
+ }
+
pub fn ast_const_to_const(
&self,
ast_const: &hir::AnonConst,
}
}
- if let ExprKind::Path(ref qpath) = expr.node {
- if let hir::QPath::Resolved(_, ref path) = qpath {
- if let Res::Def(DefKind::ConstParam, def_id) = path.res {
- let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
- let item_id = tcx.hir().get_parent_node(node_id);
- let item_def_id = tcx.hir().local_def_id(item_id);
- let generics = tcx.generics_of(item_def_id);
- let index = generics.param_def_id_to_index[&tcx.hir().local_def_id(node_id)];
- let name = tcx.hir().name(node_id).as_interned_str();
- const_.val = ConstValue::Param(ty::ParamConst::new(index, name));
- }
- }
- };
+ if let Some(def_id) = self.const_param_def_id(expr) {
+ // Find the name and index of the const parameter by indexing the generics of the
+ // parent item and construct a `ParamConst`.
+ let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
+ let item_id = tcx.hir().get_parent_node(node_id);
+ let item_def_id = tcx.hir().local_def_id(item_id);
+ let generics = tcx.generics_of(item_def_id);
+ let index = generics.param_def_id_to_index[&tcx.hir().local_def_id(node_id)];
+ let name = tcx.hir().name(node_id).as_interned_str();
+ const_.val = ConstValue::Param(ty::ParamConst::new(index, name));
+ }
tcx.mk_const(const_)
}
}
}
-// A helper struct for conveniently grouping a set of bounds which we pass to
-// and return from functions in multiple places.
+/// Collects together a list of bounds that are applied to some type,
+/// after they've been converted into `ty` form (from the HIR
+/// representations). These lists of bounds occur in many places in
+/// Rust's syntax:
+///
+/// ```
+/// trait Foo: Bar + Baz { }
+/// ^^^^^^^^^ supertrait list bounding the `Self` type parameter
+///
+/// fn foo<T: Bar + Baz>() { }
+/// ^^^^^^^^^ bounding the type parameter `T`
+///
+/// impl dyn Bar + Baz
+/// ^^^^^^^^^ bounding the forgotten dynamic type
+/// ```
+///
+/// Our representation is a bit mixed here -- in some cases, we
+/// include the self type (e.g., `trait_bounds`) but in others we do
#[derive(Default, PartialEq, Eq, Clone, Debug)]
pub struct Bounds<'tcx> {
+ /// A list of region bounds on the (implicit) self type. So if you
+ /// had `T: 'a + 'b` this might would be a list `['a, 'b]` (but
+ /// the `T` is not explicitly included).
pub region_bounds: Vec<(ty::Region<'tcx>, Span)>,
+
+ /// A list of trait bounds. So if you had `T: Debug` this would be
+ /// `T: Debug`. Note that the self-type is explicit here.
pub trait_bounds: Vec<(ty::PolyTraitRef<'tcx>, Span)>,
+
+ /// A list of projection equality bounds. So if you had `T:
+ /// Iterator<Item = u32>` this would include `<T as
+ /// Iterator>::Item => u32`. Note that the self-type is explicit
+ /// here.
pub projection_bounds: Vec<(ty::PolyProjectionPredicate<'tcx>, Span)>,
+
+ /// `Some` if there is *no* `?Sized` predicate. The `span`
+ /// is the location in the source of the `T` declaration which can
+ /// be cited as the source of the `T: Sized` requirement.
pub implicitly_sized: Option<Span>,
}
-impl<'a, 'gcx, 'tcx> Bounds<'tcx> {
- pub fn predicates(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, param_ty: Ty<'tcx>)
- -> Vec<(ty::Predicate<'tcx>, Span)>
- {
+impl<'gcx, 'tcx> Bounds<'tcx> {
+ /// Converts a bounds list into a flat set of predicates (like
+ /// where-clauses). Because some of our bounds listings (e.g.,
+ /// regions) don't include the self-type, you must supply the
+ /// self-type here (the `param_ty` parameter).
+ pub fn predicates(
+ &self,
+ tcx: TyCtxt<'gcx, 'tcx>,
+ param_ty: Ty<'tcx>,
+ ) -> Vec<(ty::Predicate<'tcx>, Span)> {
// If it could be sized, and is, add the `Sized` predicate.
let sized_predicate = self.implicitly_sized.and_then(|span| {
tcx.lang_items().sized_trait().map(|sized| {
projects / rust.git / blobdiff