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use super::callee::DeferredCallResolution;
use rustc_data_structures::fx::FxHashSet;
use rustc_data_structures::sync::Lrc;
use rustc_hir as hir;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::HirIdMap;
use rustc_infer::infer;
use rustc_infer::infer::{InferCtxt, InferOk, TyCtxtInferExt};
use rustc_middle::ty::fold::TypeFoldable;
use rustc_middle::ty::visit::TypeVisitable;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_span::def_id::LocalDefIdMap;
use rustc_span::{self, Span};
use rustc_trait_selection::infer::InferCtxtExt as _;
use rustc_trait_selection::traits::{
self, ObligationCause, ObligationCtxt, TraitEngine, TraitEngineExt as _,
};
use std::cell::RefCell;
use std::ops::Deref;
/// Closures defined within the function. For example:
/// ```ignore (illustrative)
/// fn foo() {
/// bar(move|| { ... })
/// }
/// ```
/// Here, the function `foo()` and the closure passed to
/// `bar()` will each have their own `FnCtxt`, but they will
/// share the inherited fields.
pub struct Inherited<'a, 'tcx> {
pub(super) infcx: InferCtxt<'a, 'tcx>,
pub(super) typeck_results: &'a RefCell<ty::TypeckResults<'tcx>>,
pub(super) locals: RefCell<HirIdMap<super::LocalTy<'tcx>>>,
pub(super) fulfillment_cx: RefCell<Box<dyn TraitEngine<'tcx>>>,
// Some additional `Sized` obligations badly affect type inference.
// These obligations are added in a later stage of typeck.
// Removing these may also cause additional complications, see #101066.
pub(super) deferred_sized_obligations:
RefCell<Vec<(Ty<'tcx>, Span, traits::ObligationCauseCode<'tcx>)>>,
// When we process a call like `c()` where `c` is a closure type,
// we may not have decided yet whether `c` is a `Fn`, `FnMut`, or
// `FnOnce` closure. In that case, we defer full resolution of the
// call until upvar inference can kick in and make the
// decision. We keep these deferred resolutions grouped by the
// def-id of the closure, so that once we decide, we can easily go
// back and process them.
pub(super) deferred_call_resolutions: RefCell<LocalDefIdMap<Vec<DeferredCallResolution<'tcx>>>>,
pub(super) deferred_cast_checks: RefCell<Vec<super::cast::CastCheck<'tcx>>>,
pub(super) deferred_transmute_checks: RefCell<Vec<(Ty<'tcx>, Ty<'tcx>, Span)>>,
pub(super) deferred_asm_checks: RefCell<Vec<(&'tcx hir::InlineAsm<'tcx>, hir::HirId)>>,
pub(super) deferred_generator_interiors:
RefCell<Vec<(hir::BodyId, Ty<'tcx>, hir::GeneratorKind)>>,
pub(super) body_id: Option<hir::BodyId>,
/// Whenever we introduce an adjustment from `!` into a type variable,
/// we record that type variable here. This is later used to inform
/// fallback. See the `fallback` module for details.
pub(super) diverging_type_vars: RefCell<FxHashSet<Ty<'tcx>>>,
}
impl<'a, 'tcx> Deref for Inherited<'a, 'tcx> {
type Target = InferCtxt<'a, 'tcx>;
fn deref(&self) -> &Self::Target {
&self.infcx
}
}
/// A temporary returned by `Inherited::build(...)`. This is necessary
/// for multiple `InferCtxt` to share the same `in_progress_typeck_results`
/// without using `Rc` or something similar.
pub struct InheritedBuilder<'tcx> {
infcx: infer::InferCtxtBuilder<'tcx>,
def_id: LocalDefId,
}
impl<'tcx> Inherited<'_, 'tcx> {
pub fn build(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> InheritedBuilder<'tcx> {
let hir_owner = tcx.hir().local_def_id_to_hir_id(def_id).owner;
InheritedBuilder {
infcx: tcx
.infer_ctxt()
.ignoring_regions()
.with_fresh_in_progress_typeck_results(hir_owner)
.with_normalize_fn_sig_for_diagnostic(Lrc::new(move |infcx, fn_sig| {
if fn_sig.has_escaping_bound_vars() {
return fn_sig;
}
infcx.probe(|_| {
let ocx = ObligationCtxt::new_in_snapshot(infcx);
let normalized_fn_sig = ocx.normalize(
ObligationCause::dummy(),
// FIXME(compiler-errors): This is probably not the right param-env...
infcx.tcx.param_env(def_id),
fn_sig,
);
if ocx.select_all_or_error().is_empty() {
let normalized_fn_sig =
infcx.resolve_vars_if_possible(normalized_fn_sig);
if !normalized_fn_sig.needs_infer() {
return normalized_fn_sig;
}
}
fn_sig
})
})),
def_id,
}
}
}
impl<'tcx> InheritedBuilder<'tcx> {
pub fn enter<F, R>(&mut self, f: F) -> R
where
F: for<'a> FnOnce(Inherited<'a, 'tcx>) -> R,
{
let def_id = self.def_id;
self.infcx.enter(|infcx| f(Inherited::new(infcx, def_id)))
}
}
impl<'a, 'tcx> Inherited<'a, 'tcx> {
fn new(infcx: InferCtxt<'a, 'tcx>, def_id: LocalDefId) -> Self {
let tcx = infcx.tcx;
let body_id = tcx.hir().maybe_body_owned_by(def_id);
let typeck_results =
infcx.in_progress_typeck_results.expect("building `FnCtxt` without typeck results");
Inherited {
typeck_results,
infcx,
fulfillment_cx: RefCell::new(<dyn TraitEngine<'_>>::new(tcx)),
locals: RefCell::new(Default::default()),
deferred_sized_obligations: RefCell::new(Vec::new()),
deferred_call_resolutions: RefCell::new(Default::default()),
deferred_cast_checks: RefCell::new(Vec::new()),
deferred_transmute_checks: RefCell::new(Vec::new()),
deferred_asm_checks: RefCell::new(Vec::new()),
deferred_generator_interiors: RefCell::new(Vec::new()),
diverging_type_vars: RefCell::new(Default::default()),
body_id,
}
}
#[instrument(level = "debug", skip(self))]
pub(super) fn register_predicate(&self, obligation: traits::PredicateObligation<'tcx>) {
if obligation.has_escaping_bound_vars() {
span_bug!(obligation.cause.span, "escaping bound vars in predicate {:?}", obligation);
}
self.fulfillment_cx.borrow_mut().register_predicate_obligation(self, obligation);
}
pub(super) fn register_predicates<I>(&self, obligations: I)
where
I: IntoIterator<Item = traits::PredicateObligation<'tcx>>,
{
for obligation in obligations {
self.register_predicate(obligation);
}
}
pub(super) fn register_infer_ok_obligations<T>(&self, infer_ok: InferOk<'tcx, T>) -> T {
self.register_predicates(infer_ok.obligations);
infer_ok.value
}
pub(super) fn normalize_associated_types_in<T>(
&self,
span: Span,
body_id: hir::HirId,
param_env: ty::ParamEnv<'tcx>,
value: T,
) -> T
where
T: TypeFoldable<'tcx>,
{
self.normalize_associated_types_in_with_cause(
ObligationCause::misc(span, body_id),
param_env,
value,
)
}
pub(super) fn normalize_associated_types_in_with_cause<T>(
&self,
cause: ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
value: T,
) -> T
where
T: TypeFoldable<'tcx>,
{
let ok = self.partially_normalize_associated_types_in(cause, param_env, value);
debug!(?ok);
self.register_infer_ok_obligations(ok)
}
}
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