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Split collect.rs

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This commit is contained in:
Oli Scherer 2022-09-29 09:31:46 +00:00
parent 1536a53ea4
commit 6367e69929
3 changed files with 1204 additions and 1178 deletions
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1194
compiler/rustc_hir_analysis/src/collect.rs
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compiler/rustc_hir_analysis/src/collect/generics_of.rs Normal file
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use crate::middle::resolve_lifetime as rl;
use hir::{
intravisit::{self, Visitor},
GenericParamKind, HirId, Node,
};
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::DefId;
use rustc_middle::ty::{self, TyCtxt};
use rustc_session::lint;
use rustc_span::symbol::{kw, Symbol};
use rustc_span::Span;
pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
use rustc_hir::*;
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
let node = tcx.hir().get(hir_id);
let parent_def_id = match node {
Node::ImplItem(_)
| Node::TraitItem(_)
| Node::Variant(_)
| Node::Ctor(..)
| Node::Field(_) => {
let parent_id = tcx.hir().get_parent_item(hir_id);
Some(parent_id.to_def_id())
}
// FIXME(#43408) always enable this once `lazy_normalization` is
// stable enough and does not need a feature gate anymore.
Node::AnonConst(_) => {
let parent_def_id = tcx.hir().get_parent_item(hir_id);
let mut in_param_ty = false;
for (_parent, node) in tcx.hir().parent_iter(hir_id) {
if let Some(generics) = node.generics() {
let mut visitor = AnonConstInParamTyDetector {
in_param_ty: false,
found_anon_const_in_param_ty: false,
ct: hir_id,
};
visitor.visit_generics(generics);
in_param_ty = visitor.found_anon_const_in_param_ty;
break;
}
}
if in_param_ty {
// We do not allow generic parameters in anon consts if we are inside
// of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
None
} else if tcx.lazy_normalization() {
if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
// If the def_id we are calling generics_of on is an anon ct default i.e:
//
// struct Foo<const N: usize = { .. }>;
// ^^^ ^ ^^^^^^ def id of this anon const
// ^ ^ param_id
// ^ parent_def_id
//
// then we only want to return generics for params to the left of `N`. If we don't do that we
// end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
//
// This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
// we substitute the defaults with the partially built substs when we build the substs. Subst'ing
// the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
//
// We fix this by having this function return the parent's generics ourselves and truncating the
// generics to only include non-forward declared params (with the exception of the `Self` ty)
//
// For the above code example that means we want `substs: []`
// For the following struct def we want `substs: [N#0]` when generics_of is called on
// the def id of the `{ N + 1 }` anon const
// struct Foo<const N: usize, const M: usize = { N + 1 }>;
//
// This has some implications for how we get the predicates available to the anon const
// see `explicit_predicates_of` for more information on this
let generics = tcx.generics_of(parent_def_id.to_def_id());
let param_def = tcx.hir().local_def_id(param_id).to_def_id();
let param_def_idx = generics.param_def_id_to_index[&param_def];
// In the above example this would be .params[..N#0]
let params = generics.params[..param_def_idx as usize].to_owned();
let param_def_id_to_index =
params.iter().map(|param| (param.def_id, param.index)).collect();
return ty::Generics {
// we set the parent of these generics to be our parent's parent so that we
// dont end up with substs: [N, M, N] for the const default on a struct like this:
// struct Foo<const N: usize, const M: usize = { ... }>;
parent: generics.parent,
parent_count: generics.parent_count,
params,
param_def_id_to_index,
has_self: generics.has_self,
has_late_bound_regions: generics.has_late_bound_regions,
};
}
// HACK(eddyb) this provides the correct generics when
// `feature(generic_const_expressions)` is enabled, so that const expressions
// used with const generics, e.g. `Foo<{N+1}>`, can work at all.
//
// Note that we do not supply the parent generics when using
// `min_const_generics`.
Some(parent_def_id.to_def_id())
} else {
let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
match parent_node {
// HACK(eddyb) this provides the correct generics for repeat
// expressions' count (i.e. `N` in `[x; N]`), and explicit
// `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
// as they shouldn't be able to cause query cycle errors.
Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
if constant.hir_id() == hir_id =>
{
Some(parent_def_id.to_def_id())
}
Node::Variant(Variant { disr_expr: Some(ref constant), .. })
if constant.hir_id == hir_id =>
{
Some(parent_def_id.to_def_id())
}
Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
Some(tcx.typeck_root_def_id(def_id))
}
// Exclude `GlobalAsm` here which cannot have generics.
Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. })
if asm.operands.iter().any(|(op, _op_sp)| match op {
hir::InlineAsmOperand::Const { anon_const }
| hir::InlineAsmOperand::SymFn { anon_const } => {
anon_const.hir_id == hir_id
}
_ => false,
}) =>
{
Some(parent_def_id.to_def_id())
}
_ => None,
}
}
}
Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => {
Some(tcx.typeck_root_def_id(def_id))
}
Node::Item(item) => match item.kind {
ItemKind::OpaqueTy(hir::OpaqueTy {
origin:
hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
in_trait,
..
}) => {
if in_trait {
assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn))
} else {
assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn | DefKind::Fn))
}
Some(fn_def_id.to_def_id())
}
ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
let parent_id = tcx.hir().get_parent_item(hir_id);
assert_ne!(parent_id, hir::CRATE_OWNER_ID);
debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
// Opaque types are always nested within another item, and
// inherit the generics of the item.
Some(parent_id.to_def_id())
}
_ => None,
},
_ => None,
};
enum Defaults {
Allowed,
// See #36887
FutureCompatDisallowed,
Deny,
}
let no_generics = hir::Generics::empty();
let ast_generics = node.generics().unwrap_or(&no_generics);
let (opt_self, allow_defaults) = match node {
Node::Item(item) => {
match item.kind {
ItemKind::Trait(..) | ItemKind::TraitAlias(..) => {
// 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 opt_self = Some(ty::GenericParamDef {
index: 0,
name: kw::SelfUpper,
def_id,
pure_wrt_drop: false,
kind: ty::GenericParamDefKind::Type {
has_default: false,
synthetic: false,
},
});
(opt_self, Defaults::Allowed)
}
ItemKind::TyAlias(..)
| ItemKind::Enum(..)
| ItemKind::Struct(..)
| ItemKind::OpaqueTy(..)
| ItemKind::Union(..) => (None, Defaults::Allowed),
_ => (None, Defaults::FutureCompatDisallowed),
}
}
// GATs
Node::TraitItem(item) if matches!(item.kind, TraitItemKind::Type(..)) => {
(None, Defaults::Deny)
}
Node::ImplItem(item) if matches!(item.kind, ImplItemKind::TyAlias(..)) => {
(None, Defaults::Deny)
}
_ => (None, Defaults::FutureCompatDisallowed),
};
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!(!has_self);
parent_has_self = generics.has_self;
own_start = generics.count() as u32;
generics.parent_count + generics.params.len()
});
let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
if let Some(opt_self) = opt_self {
params.push(opt_self);
}
let early_lifetimes = super::early_bound_lifetimes_from_generics(tcx, ast_generics);
params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
name: param.name.ident().name,
index: own_start + i as u32,
def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
pure_wrt_drop: param.pure_wrt_drop,
kind: ty::GenericParamDefKind::Lifetime,
}));
// Now create the real type and const parameters.
let type_start = own_start - has_self as u32 + params.len() as u32;
let mut i = 0;
const TYPE_DEFAULT_NOT_ALLOWED: &'static str = "defaults for type parameters are only allowed in \
`struct`, `enum`, `type`, or `trait` definitions";
params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
GenericParamKind::Lifetime { .. } => None,
GenericParamKind::Type { ref default, synthetic, .. } => {
if default.is_some() {
match allow_defaults {
Defaults::Allowed => {}
Defaults::FutureCompatDisallowed
if tcx.features().default_type_parameter_fallback => {}
Defaults::FutureCompatDisallowed => {
tcx.struct_span_lint_hir(
lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
param.hir_id,
param.span,
|lint| {
lint.build(TYPE_DEFAULT_NOT_ALLOWED).emit();
},
);
}
Defaults::Deny => {
tcx.sess.span_err(param.span, TYPE_DEFAULT_NOT_ALLOWED);
}
}
}
let kind = ty::GenericParamDefKind::Type { has_default: default.is_some(), synthetic };
let param_def = ty::GenericParamDef {
index: type_start + i as u32,
name: param.name.ident().name,
def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
pure_wrt_drop: param.pure_wrt_drop,
kind,
};
i += 1;
Some(param_def)
}
GenericParamKind::Const { default, .. } => {
if !matches!(allow_defaults, Defaults::Allowed) && default.is_some() {
tcx.sess.span_err(
param.span,
"defaults for const parameters are only allowed in \
`struct`, `enum`, `type`, or `trait` definitions",
);
}
let param_def = ty::GenericParamDef {
index: type_start + i as u32,
name: param.name.ident().name,
def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
pure_wrt_drop: param.pure_wrt_drop,
kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
};
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(hir::Closure { movability: gen, .. }),
..
}) = node
{
let dummy_args = if gen.is_some() {
&["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
} else {
&["<closure_kind>", "<closure_signature>", "<upvars>"][..]
};
params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
index: type_start + i as u32,
name: Symbol::intern(arg),
def_id,
pure_wrt_drop: false,
kind: ty::GenericParamDefKind::Type { has_default: false, synthetic: false },
}));
}
// provide junk type parameter defs for const blocks.
if let Node::AnonConst(_) = node {
let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
params.push(ty::GenericParamDef {
index: type_start,
name: Symbol::intern("<const_ty>"),
def_id,
pure_wrt_drop: false,
kind: ty::GenericParamDefKind::Type { has_default: false, synthetic: false },
});
}
}
let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
ty::Generics {
parent: parent_def_id,
parent_count,
params,
param_def_id_to_index,
has_self: has_self || parent_has_self,
has_late_bound_regions: has_late_bound_regions(tcx, node),
}
}
fn 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<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
if self.has_late_bound_regions.is_some() {
return;
}
match ty.kind {
hir::TyKind::BareFn(..) => {
self.outer_index.shift_in(1);
intravisit::walk_ty(self, ty);
self.outer_index.shift_out(1);
}
_ => intravisit::walk_ty(self, ty),
}
}
fn visit_poly_trait_ref(&mut self, tr: &'tcx hir::PolyTraitRef<'tcx>) {
if self.has_late_bound_regions.is_some() {
return;
}
self.outer_index.shift_in(1);
intravisit::walk_poly_trait_ref(self, tr);
self.outer_index.shift_out(1);
}
fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
if self.has_late_bound_regions.is_some() {
return;
}
match self.tcx.named_region(lt.hir_id) {
Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
Some(rl::Region::LateBound(debruijn, _, _)) if debruijn < self.outer_index => {}
Some(rl::Region::LateBound(..) | rl::Region::Free(..)) | None => {
self.has_late_bound_regions = Some(lt.span);
}
}
}
}
fn has_late_bound_regions<'tcx>(
tcx: TyCtxt<'tcx>,
generics: &'tcx hir::Generics<'tcx>,
decl: &'tcx hir::FnDecl<'tcx>,
) -> Option<Span> {
let mut visitor = LateBoundRegionsDetector {
tcx,
outer_index: ty::INNERMOST,
has_late_bound_regions: None,
};
for param in generics.params {
if let GenericParamKind::Lifetime { .. } = param.kind {
if tcx.is_late_bound(param.hir_id) {
return Some(param.span);
}
}
}
visitor.visit_fn_decl(decl);
visitor.has_late_bound_regions
}
match node {
Node::TraitItem(item) => match item.kind {
hir::TraitItemKind::Fn(ref sig, _) => {
has_late_bound_regions(tcx, &item.generics, sig.decl)
}
_ => None,
},
Node::ImplItem(item) => match item.kind {
hir::ImplItemKind::Fn(ref sig, _) => {
has_late_bound_regions(tcx, &item.generics, sig.decl)
}
_ => None,
},
Node::ForeignItem(item) => match item.kind {
hir::ForeignItemKind::Fn(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,
}
}
struct AnonConstInParamTyDetector {
in_param_ty: bool,
found_anon_const_in_param_ty: bool,
ct: HirId,
}
impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
if let GenericParamKind::Const { ty, default: _ } = p.kind {
let prev = self.in_param_ty;
self.in_param_ty = true;
self.visit_ty(ty);
self.in_param_ty = prev;
}
}
fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
if self.in_param_ty && self.ct == c.hir_id {
self.found_anon_const_in_param_ty = true;
} else {
intravisit::walk_anon_const(self, c)
}
}
}

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compiler/rustc_hir_analysis/src/collect/predicates_of.rs Normal file
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use crate::astconv::AstConv;
use crate::bounds::Bounds;
use crate::collect::ItemCtxt;
use crate::constrained_generic_params as cgp;
use hir::{HirId, Node};
use rustc_data_structures::fx::FxIndexSet;
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::intravisit::{self, Visitor};
use rustc_middle::ty::subst::InternalSubsts;
use rustc_middle::ty::ToPredicate;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_span::symbol::{sym, Ident};
use rustc_span::{Span, DUMMY_SP};
#[derive(Debug)]
struct OnlySelfBounds(bool);
/// 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.
pub(super) 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.
//
// We use a DUMMY_SP here as a way to signal trait bounds that come
// from the trait itself that *shouldn't* be shown as the source of
// an obligation and instead be skipped. Otherwise we'd use
// `tcx.def_span(def_id);`
let constness = if tcx.has_attr(def_id, sym::const_trait) {
ty::BoundConstness::ConstIfConst
} else {
ty::BoundConstness::NotConst
};
let span = rustc_span::DUMMY_SP;
result.predicates =
tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
ty::TraitRef::identity(tcx, def_id).with_constness(constness).to_predicate(tcx),
span,
))));
}
debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
result
}
/// Returns a list of user-specified type predicates for the definition with ID `def_id`.
/// N.B., this does not include any implied/inferred constraints.
#[instrument(level = "trace", skip(tcx), ret)]
fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
use rustc_hir::*;
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
let node = tcx.hir().get(hir_id);
let mut is_trait = None;
let mut is_default_impl_trait = None;
let icx = ItemCtxt::new(tcx, def_id);
const NO_GENERICS: &hir::Generics<'_> = hir::Generics::empty();
// We use an `IndexSet` to preserves order of insertion.
// Preserving the order of insertion is important here so as not to break UI tests.
let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
let ast_generics = match node {
Node::TraitItem(item) => item.generics,
Node::ImplItem(item) => item.generics,
Node::Item(item) => {
match item.kind {
ItemKind::Impl(ref impl_) => {
if impl_.defaultness.is_default() {
is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
}
&impl_.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, ..) => {
is_trait = Some(ty::TraitRef::identity(tcx, def_id));
*generics
}
ItemKind::TraitAlias(ref generics, _) => {
is_trait = Some(ty::TraitRef::identity(tcx, def_id));
*generics
}
ItemKind::OpaqueTy(OpaqueTy {
origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
..
}) => {
// return-position impl trait
//
// We don't inherit predicates from the parent here:
// If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
// then the return type is `f::<'static, T>::{{opaque}}`.
//
// If we inherited the predicates of `f` then we would
// require that `T: 'static` to show that the return
// type is well-formed.
//
// The only way to have something with this opaque type
// is from the return type of the containing function,
// which will ensure that the function's predicates
// hold.
return ty::GenericPredicates { parent: None, predicates: &[] };
}
ItemKind::OpaqueTy(OpaqueTy {
ref generics,
origin: hir::OpaqueTyOrigin::TyAlias,
..
}) => {
// type-alias impl trait
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.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
}
// Collect the region predicates that were declared inline as
// well. In the case of parameters declared on a fn or method, we
// have to be careful to only iterate over early-bound regions.
let mut index = parent_count
+ has_own_self as u32
+ super::early_bound_lifetimes_from_generics(tcx, ast_generics).count() as u32;
trace!(?predicates);
trace!(?ast_generics);
// Collect the predicates that were written inline by the user on each
// type parameter (e.g., `<T: Foo>`).
for param in ast_generics.params {
match param.kind {
// We already dealt with early bound lifetimes above.
GenericParamKind::Lifetime { .. } => (),
GenericParamKind::Type { .. } => {
let name = param.name.ident().name;
let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
index += 1;
let mut bounds = Bounds::default();
// Params are implicitly sized unless a `?Sized` bound is found
<dyn AstConv<'_>>::add_implicitly_sized(
&icx,
&mut bounds,
&[],
Some((param.hir_id, ast_generics.predicates)),
param.span,
);
trace!(?bounds);
predicates.extend(bounds.predicates(tcx, param_ty));
trace!(?predicates);
}
GenericParamKind::Const { .. } => {
// Bounds on const parameters are currently not possible.
index += 1;
}
}
}
trace!(?predicates);
// Add in the bounds that appear in the where-clause.
for predicate in ast_generics.predicates {
match predicate {
hir::WherePredicate::BoundPredicate(bound_pred) => {
let ty = icx.to_ty(bound_pred.bounded_ty);
let bound_vars = icx.tcx.late_bound_vars(bound_pred.hir_id);
// 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::Binder::bind_with_vars(
ty::PredicateKind::WellFormed(ty.into()),
bound_vars,
);
predicates.insert((predicate.to_predicate(tcx), span));
}
}
let mut bounds = Bounds::default();
<dyn AstConv<'_>>::add_bounds(
&icx,
ty,
bound_pred.bounds.iter(),
&mut bounds,
bound_vars,
);
predicates.extend(bounds.predicates(tcx, ty));
}
hir::WherePredicate::RegionPredicate(region_pred) => {
let r1 = <dyn 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) => {
(<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
}
_ => bug!(),
};
let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
ty::OutlivesPredicate(r1, r2),
))
.to_predicate(icx.tcx);
(pred, span)
}))
}
hir::WherePredicate::EqPredicate(..) => {
// FIXME(#20041)
}
}
}
if tcx.features().generic_const_exprs {
predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
}
let mut predicates: Vec<_> = predicates.into_iter().collect();
// 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),
);
}
ty::GenericPredicates {
parent: generics.parent,
predicates: tcx.arena.alloc_from_iter(predicates),
}
}
fn const_evaluatable_predicates_of<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: LocalDefId,
) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
struct ConstCollector<'tcx> {
tcx: TyCtxt<'tcx>,
preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
}
impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
let def_id = self.tcx.hir().local_def_id(c.hir_id);
let ct = ty::Const::from_anon_const(self.tcx, def_id);
if let ty::ConstKind::Unevaluated(uv) = ct.kind() {
let span = self.tcx.hir().span(c.hir_id);
self.preds.insert((
ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv))
.to_predicate(self.tcx),
span,
));
}
}
fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
// Do not look into const param defaults,
// these get checked when they are actually instantiated.
//
// We do not want the following to error:
//
// struct Foo<const N: usize, const M: usize = { N + 1 }>;
// struct Bar<const N: usize>(Foo<N, 3>);
}
}
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
let node = tcx.hir().get(hir_id);
let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
if let hir::Node::Item(item) = node && let hir::ItemKind::Impl(ref impl_) = item.kind {
if let Some(of_trait) = &impl_.of_trait {
debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
collector.visit_trait_ref(of_trait);
}
debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
collector.visit_ty(impl_.self_ty);
}
if let Some(generics) = node.generics() {
debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
collector.visit_generics(generics);
}
if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
collector.visit_fn_decl(fn_sig.decl);
}
debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
collector.preds
}
pub(super) fn trait_explicit_predicates_and_bounds(
tcx: TyCtxt<'_>,
def_id: LocalDefId,
) -> ty::GenericPredicates<'_> {
assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
gather_explicit_predicates_of(tcx, def_id.to_def_id())
}
pub(super) fn explicit_predicates_of<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: DefId,
) -> ty::GenericPredicates<'tcx> {
let def_kind = tcx.def_kind(def_id);
if let DefKind::Trait = def_kind {
// Remove bounds on associated types from the predicates, they will be
// returned by `explicit_item_bounds`.
let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
let is_assoc_item_ty = |ty: Ty<'tcx>| {
// For a predicate from a where clause to become a bound on an
// associated type:
// * It must use the identity substs of the item.
// * Since any generic parameters on the item are not in scope,
// this means that the item is not a GAT, and its identity
// substs are the same as the trait's.
// * It must be an associated type for this trait (*not* a
// supertrait).
if let ty::Projection(projection) = ty.kind() {
projection.substs == trait_identity_substs
&& tcx.associated_item(projection.item_def_id).container_id(tcx) == def_id
} else {
false
}
};
let predicates: Vec<_> = predicates_and_bounds
.predicates
.iter()
.copied()
.filter(|(pred, _)| match pred.kind().skip_binder() {
ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
ty::PredicateKind::Projection(proj) => {
!is_assoc_item_ty(proj.projection_ty.self_ty())
}
ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
_ => true,
})
.collect();
if predicates.len() == predicates_and_bounds.predicates.len() {
predicates_and_bounds
} else {
ty::GenericPredicates {
parent: predicates_and_bounds.parent,
predicates: tcx.arena.alloc_slice(&predicates),
}
}
} else {
if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
// In `generics_of` we set the generics' parent to be our parent's parent which means that
// we lose out on the predicates of our actual parent if we dont return those predicates here.
// (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
//
// struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
// ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
// ^^^ explicit_predicates_of on
// parent item we dont have set as the
// parent of generics returned by `generics_of`
//
// In the above code we want the anon const to have predicates in its param env for `T: Trait`
let item_def_id = tcx.hir().get_parent_item(hir_id);
// In the above code example we would be calling `explicit_predicates_of(Foo)` here
return tcx.explicit_predicates_of(item_def_id);
}
}
gather_explicit_predicates_of(tcx, def_id)
}
}
/// 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.
pub(super) fn super_predicates_of(
tcx: TyCtxt<'_>,
trait_def_id: DefId,
) -> ty::GenericPredicates<'_> {
tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
}
/// 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.
pub(super) fn super_predicates_that_define_assoc_type(
tcx: TyCtxt<'_>,
(trait_def_id, assoc_name): (DefId, Option<Ident>),
) -> ty::GenericPredicates<'_> {
if trait_def_id.is_local() {
debug!("local trait");
let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
let Node::Item(item) = tcx.hir().get(trait_hir_id) else {
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 = if let Some(assoc_name) = assoc_name {
<dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
&icx,
self_param_ty,
bounds,
assoc_name,
)
} else {
<dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
};
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),
assoc_name,
);
// Combine the two lists to form the complete set of superbounds:
let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
debug!(?superbounds);
// Now require that immediate supertraits are converted,
// which will, in turn, reach indirect supertraits.
if assoc_name.is_none() {
// Now require that immediate supertraits are converted,
// which will, in turn, reach indirect supertraits.
for &(pred, span) in superbounds {
debug!("superbound: {:?}", pred);
if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
tcx.at(span).super_predicates_of(bound.def_id());
}
}
}
ty::GenericPredicates { parent: None, predicates: superbounds }
} else {
// if `assoc_name` is None, then the query should've been redirected to an
// external provider
assert!(assoc_name.is_some());
tcx.super_predicates_of(trait_def_id)
}
}
/// Returns the predicates defined on `item_def_id` of the form
/// `X: Foo` where `X` is the type parameter `def_id`.
#[instrument(level = "trace", skip(tcx))]
pub(super) fn type_param_predicates(
tcx: TyCtxt<'_>,
(item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
) -> 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().local_def_id_to_hir_id(def_id);
let param_owner = tcx.hir().ty_param_owner(def_id);
let generics = tcx.generics_of(param_owner);
let index = generics.param_def_id_to_index[&def_id.to_def_id()];
let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id));
// Don't look for bounds where the type parameter isn't in scope.
let parent = if item_def_id == param_owner.to_def_id() {
None
} else {
tcx.generics_of(item_def_id).parent
};
let mut result = parent
.map(|parent| {
let icx = ItemCtxt::new(tcx, parent);
icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
})
.unwrap_or_default();
let mut extend = None;
let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
let ast_generics = match tcx.hir().get(item_hir_id) {
Node::TraitItem(item) => &item.generics,
Node::ImplItem(item) => &item.generics,
Node::Item(item) => {
match item.kind {
ItemKind::Fn(.., ref generics, _)
| ItemKind::Impl(hir::Impl { ref generics, .. })
| ItemKind::TyAlias(_, ref generics)
| ItemKind::OpaqueTy(OpaqueTy {
ref generics,
origin: hir::OpaqueTyOrigin::TyAlias,
..
})
| ItemKind::Enum(_, ref generics)
| ItemKind::Struct(_, ref generics)
| ItemKind::Union(_, ref generics) => generics,
ItemKind::Trait(_, _, ref generics, ..) => {
// Implied `Self: Trait` and supertrait bounds.
if param_id == item_hir_id {
let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
extend =
Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
}
generics
}
_ => return result,
}
}
Node::ForeignItem(item) => match item.kind {
ForeignItemKind::Fn(_, _, ref generics) => generics,
_ => return result,
},
_ => return result,
};
let icx = ItemCtxt::new(tcx, item_def_id);
let extra_predicates = extend.into_iter().chain(
icx.type_parameter_bounds_in_generics(
ast_generics,
param_id,
ty,
OnlySelfBounds(true),
Some(assoc_name),
)
.into_iter()
.filter(|(predicate, _)| match predicate.kind().skip_binder() {
ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
_ => false,
}),
);
result.predicates =
tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
result
}
impl<'tcx> 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.
#[instrument(level = "trace", skip(self, ast_generics))]
fn type_parameter_bounds_in_generics(
&self,
ast_generics: &'tcx hir::Generics<'tcx>,
param_id: hir::HirId,
ty: Ty<'tcx>,
only_self_bounds: OnlySelfBounds,
assoc_name: Option<Ident>,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
trace!(?param_def_id);
ast_generics
.predicates
.iter()
.filter_map(|wp| match *wp {
hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
_ => None,
})
.flat_map(|bp| {
let bt = if bp.is_param_bound(param_def_id) {
Some(ty)
} else if !only_self_bounds.0 {
Some(self.to_ty(bp.bounded_ty))
} else {
None
};
let bvars = self.tcx.late_bound_vars(bp.hir_id);
bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b, bvars))).filter(
|(_, b, _)| match assoc_name {
Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
None => true,
},
)
})
.flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars))
.collect()
}
#[instrument(level = "trace", skip(self))]
fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
match b {
hir::GenericBound::Trait(poly_trait_ref, _) => {
let trait_ref = &poly_trait_ref.trait_ref;
if let Some(trait_did) = trait_ref.trait_def_id() {
self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
} else {
false
}
}
_ => false,
}
}
}
/// Converts a specific `GenericBound` from the AST into a set of
/// predicates that apply to the self type. A vector is returned
/// because this can be anywhere from zero predicates (`T: ?Sized` adds no
/// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
/// and `<T as Bar>::X == i32`).
fn predicates_from_bound<'tcx>(
astconv: &dyn AstConv<'tcx>,
param_ty: Ty<'tcx>,
bound: &'tcx hir::GenericBound<'tcx>,
bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
let mut bounds = Bounds::default();
astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
bounds.predicates(astconv.tcx(), param_ty).collect()
}