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Auto merge of #91354 - fee1-dead:const_env, r=spastorino
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Cleanup: Eliminate ConstnessAnd

This is almost a behaviour-free change and purely a refactoring. "almost" because we appear to be using the wrong ParamEnv somewhere already, and this is now exposed by failing a test using the unstable `~const` feature.

We most definitely need to review all `without_const` and at some point should probably get rid of many of them by using `TraitPredicate` instead of `TraitRef`.

This is a continuation of #90274.

r? `@oli-obk`

cc `@spastorino` `@ecstatic-morse`
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bors committed Dec 2, 2021
2 parents d9baa36 + 5ebc99e commit 18bb8c6
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Showing 49 changed files with 380 additions and 430 deletions.
2 changes: 1 addition & 1 deletion compiler/rustc_borrowck/src/type_check/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ use rustc_middle::ty::fold::TypeFoldable;
use rustc_middle::ty::subst::{GenericArgKind, SubstsRef, UserSubsts};
use rustc_middle::ty::{
self, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, OpaqueTypeKey, RegionVid,
ToPredicate, Ty, TyCtxt, UserType, UserTypeAnnotationIndex, WithConstness,
ToPredicate, Ty, TyCtxt, UserType, UserTypeAnnotationIndex,
};
use rustc_span::def_id::CRATE_DEF_ID;
use rustc_span::{Span, DUMMY_SP};
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3 changes: 3 additions & 0 deletions compiler/rustc_const_eval/src/const_eval/eval_queries.rs
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ use crate::interpret::{
};

use rustc_errors::ErrorReported;
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_middle::mir;
use rustc_middle::mir::interpret::ErrorHandled;
Expand Down Expand Up @@ -215,6 +216,7 @@ pub fn eval_to_const_value_raw_provider<'tcx>(
tcx: TyCtxt<'tcx>,
key: ty::ParamEnvAnd<'tcx, GlobalId<'tcx>>,
) -> ::rustc_middle::mir::interpret::EvalToConstValueResult<'tcx> {
assert!(key.param_env.constness() == hir::Constness::Const);
// see comment in eval_to_allocation_raw_provider for what we're doing here
if key.param_env.reveal() == Reveal::All {
let mut key = key;
Expand Down Expand Up @@ -249,6 +251,7 @@ pub fn eval_to_allocation_raw_provider<'tcx>(
tcx: TyCtxt<'tcx>,
key: ty::ParamEnvAnd<'tcx, GlobalId<'tcx>>,
) -> ::rustc_middle::mir::interpret::EvalToAllocationRawResult<'tcx> {
assert!(key.param_env.constness() == hir::Constness::Const);
// Because the constant is computed twice (once per value of `Reveal`), we are at risk of
// reporting the same error twice here. To resolve this, we check whether we can evaluate the
// constant in the more restrictive `Reveal::UserFacing`, which most likely already was
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1 change: 1 addition & 0 deletions compiler/rustc_const_eval/src/interpret/eval_context.rs
Original file line number Diff line number Diff line change
Expand Up @@ -918,6 +918,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
} else {
self.param_env
};
let param_env = param_env.with_const();
let val = self.tcx.eval_to_allocation_raw(param_env.and(gid))?;
self.raw_const_to_mplace(val)
}
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Original file line number Diff line number Diff line change
Expand Up @@ -817,8 +817,7 @@ impl Visitor<'tcx> for Checker<'mir, 'tcx> {
);

let implsrc = tcx.infer_ctxt().enter(|infcx| {
let mut selcx =
SelectionContext::with_constness(&infcx, hir::Constness::Const);
let mut selcx = SelectionContext::new(&infcx);
selcx.select(&obligation)
});

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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,6 @@
//! See the `Qualif` trait for more info.

use rustc_errors::ErrorReported;
use rustc_hir as hir;
use rustc_infer::infer::TyCtxtInferExt;
use rustc_middle::mir::*;
use rustc_middle::ty::{self, subst::SubstsRef, AdtDef, Ty};
Expand Down Expand Up @@ -167,7 +166,7 @@ impl Qualif for NeedsNonConstDrop {
);

let implsrc = cx.tcx.infer_ctxt().enter(|infcx| {
let mut selcx = SelectionContext::with_constness(&infcx, hir::Constness::Const);
let mut selcx = SelectionContext::new(&infcx);
selcx.select(&obligation)
});
!matches!(
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25 changes: 0 additions & 25 deletions compiler/rustc_hir/src/hir.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3230,31 +3230,6 @@ impl<'hir> Node<'hir> {
}
}

/// Returns `Constness::Const` when this node is a const fn/impl/item.
pub fn constness_for_typeck(&self) -> Constness {
match self {
Node::Item(Item {
kind: ItemKind::Fn(FnSig { header: FnHeader { constness, .. }, .. }, ..),
..
})
| Node::TraitItem(TraitItem {
kind: TraitItemKind::Fn(FnSig { header: FnHeader { constness, .. }, .. }, ..),
..
})
| Node::ImplItem(ImplItem {
kind: ImplItemKind::Fn(FnSig { header: FnHeader { constness, .. }, .. }, ..),
..
})
| Node::Item(Item { kind: ItemKind::Impl(Impl { constness, .. }), .. }) => *constness,

Node::Item(Item { kind: ItemKind::Const(..), .. })
| Node::TraitItem(TraitItem { kind: TraitItemKind::Const(..), .. })
| Node::ImplItem(ImplItem { kind: ImplItemKind::Const(..), .. }) => Constness::Const,

_ => Constness::NotConst,
}
}

pub fn as_owner(self) -> Option<OwnerNode<'hir>> {
match self {
Node::Item(i) => Some(OwnerNode::Item(i)),
Expand Down
20 changes: 1 addition & 19 deletions compiler/rustc_infer/src/traits/engine.rs
Original file line number Diff line number Diff line change
@@ -1,9 +1,8 @@
use crate::infer::InferCtxt;
use crate::traits::Obligation;
use rustc_data_structures::fx::FxHashMap;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_middle::ty::{self, ToPredicate, Ty, WithConstness};
use rustc_middle::ty::{self, ToPredicate, Ty};

use super::FulfillmentError;
use super::{ObligationCause, PredicateObligation};
Expand Down Expand Up @@ -48,26 +47,9 @@ pub trait TraitEngine<'tcx>: 'tcx {

fn select_all_or_error(&mut self, infcx: &InferCtxt<'_, 'tcx>) -> Vec<FulfillmentError<'tcx>>;

fn select_all_with_constness_or_error(
&mut self,
infcx: &InferCtxt<'_, 'tcx>,
_constness: hir::Constness,
) -> Vec<FulfillmentError<'tcx>> {
self.select_all_or_error(infcx)
}

fn select_where_possible(&mut self, infcx: &InferCtxt<'_, 'tcx>)
-> Vec<FulfillmentError<'tcx>>;

// FIXME(fee1-dead) this should not provide a default body for chalk as chalk should be updated
fn select_with_constness_where_possible(
&mut self,
infcx: &InferCtxt<'_, 'tcx>,
_constness: hir::Constness,
) -> Vec<FulfillmentError<'tcx>> {
self.select_where_possible(infcx)
}

fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>>;

fn relationships(&mut self) -> &mut FxHashMap<ty::TyVid, ty::FoundRelationships>;
Expand Down
10 changes: 10 additions & 0 deletions compiler/rustc_infer/src/traits/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,16 @@ impl PredicateObligation<'tcx> {
}
}

impl TraitObligation<'tcx> {
/// Returns `true` if the trait predicate is considered `const` in its ParamEnv.
pub fn is_const(&self) -> bool {
match (self.predicate.skip_binder().constness, self.param_env.constness()) {
(ty::BoundConstness::ConstIfConst, hir::Constness::Const) => true,
_ => false,
}
}
}

// `PredicateObligation` is used a lot. Make sure it doesn't unintentionally get bigger.
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
static_assert_size!(PredicateObligation<'_>, 32);
Expand Down
10 changes: 5 additions & 5 deletions compiler/rustc_infer/src/traits/util.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ use smallvec::smallvec;
use crate::infer::outlives::components::{push_outlives_components, Component};
use crate::traits::{Obligation, ObligationCause, PredicateObligation};
use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
use rustc_middle::ty::{self, ToPredicate, TyCtxt, WithConstness};
use rustc_middle::ty::{self, ToPredicate, TyCtxt};
use rustc_span::symbol::Ident;
use rustc_span::Span;

Expand Down Expand Up @@ -328,8 +328,8 @@ pub fn transitive_bounds_that_define_assoc_type<'tcx>(
));
for (super_predicate, _) in super_predicates.predicates {
let subst_predicate = super_predicate.subst_supertrait(tcx, &trait_ref);
if let Some(binder) = subst_predicate.to_opt_poly_trait_ref() {
stack.push(binder.value);
if let Some(binder) = subst_predicate.to_opt_poly_trait_pred() {
stack.push(binder.map_bound(|t| t.trait_ref));
}
}

Expand Down Expand Up @@ -362,8 +362,8 @@ impl<'tcx, I: Iterator<Item = PredicateObligation<'tcx>>> Iterator for FilterToT

fn next(&mut self) -> Option<ty::PolyTraitRef<'tcx>> {
while let Some(obligation) = self.base_iterator.next() {
if let Some(data) = obligation.predicate.to_opt_poly_trait_ref() {
return Some(data.value);
if let Some(data) = obligation.predicate.to_opt_poly_trait_pred() {
return Some(data.map_bound(|t| t.trait_ref));
}
}
None
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3 changes: 2 additions & 1 deletion compiler/rustc_middle/src/hir/map/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -474,7 +474,8 @@ impl<'hir> Map<'hir> {
/// Panics if `LocalDefId` does not have an associated body.
///
/// This should only be used for determining the context of a body, a return
/// value of `Some` does not always suggest that the owner of the body is `const`.
/// value of `Some` does not always suggest that the owner of the body is `const`,
/// just that it has to be checked as if it were.
pub fn body_const_context(&self, did: LocalDefId) -> Option<ConstContext> {
let hir_id = self.local_def_id_to_hir_id(did);
let ccx = match self.body_owner_kind(hir_id) {
Expand Down
2 changes: 2 additions & 0 deletions compiler/rustc_middle/src/mir/interpret/queries.rs
Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,7 @@ impl<'tcx> TyCtxt<'tcx> {
cid: GlobalId<'tcx>,
span: Option<Span>,
) -> EvalToConstValueResult<'tcx> {
let param_env = param_env.with_const();
// Const-eval shouldn't depend on lifetimes at all, so we can erase them, which should
// improve caching of queries.
let inputs = self.erase_regions(param_env.and(cid));
Expand Down Expand Up @@ -92,6 +93,7 @@ impl<'tcx> TyCtxt<'tcx> {
gid: GlobalId<'tcx>,
param_env: ty::ParamEnv<'tcx>,
) -> Result<&'tcx mir::Allocation, ErrorHandled> {
let param_env = param_env.with_const();
trace!("eval_to_allocation: Need to compute {:?}", gid);
let raw_const = self.eval_to_allocation_raw(param_env.and(gid))?;
Ok(self.global_alloc(raw_const.alloc_id).unwrap_memory())
Expand Down
10 changes: 4 additions & 6 deletions compiler/rustc_middle/src/traits/select.rs
Original file line number Diff line number Diff line change
Expand Up @@ -12,14 +12,12 @@ use rustc_hir::def_id::DefId;
use rustc_query_system::cache::Cache;

pub type SelectionCache<'tcx> = Cache<
(ty::ConstnessAnd<ty::ParamEnvAnd<'tcx, ty::TraitRef<'tcx>>>, ty::ImplPolarity),
ty::ParamEnvAnd<'tcx, ty::TraitPredicate<'tcx>>,
SelectionResult<'tcx, SelectionCandidate<'tcx>>,
>;

pub type EvaluationCache<'tcx> = Cache<
(ty::ParamEnvAnd<'tcx, ty::ConstnessAnd<ty::PolyTraitRef<'tcx>>>, ty::ImplPolarity),
EvaluationResult,
>;
pub type EvaluationCache<'tcx> =
Cache<ty::ParamEnvAnd<'tcx, ty::PolyTraitPredicate<'tcx>>, EvaluationResult>;

/// The selection process begins by considering all impls, where
/// clauses, and so forth that might resolve an obligation. Sometimes
Expand Down Expand Up @@ -103,7 +101,7 @@ pub enum SelectionCandidate<'tcx> {
/// `false` if there are no *further* obligations.
has_nested: bool,
},
ParamCandidate((ty::ConstnessAnd<ty::PolyTraitRef<'tcx>>, ty::ImplPolarity)),
ParamCandidate(ty::PolyTraitPredicate<'tcx>),
ImplCandidate(DefId),
AutoImplCandidate(DefId),

Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_middle/src/traits/util.rs
Original file line number Diff line number Diff line change
Expand Up @@ -26,9 +26,9 @@ impl<'tcx> Elaborator<'tcx> {
.predicates
.into_iter()
.flat_map(|(pred, _)| {
pred.subst_supertrait(self.tcx, &trait_ref).to_opt_poly_trait_ref()
pred.subst_supertrait(self.tcx, &trait_ref).to_opt_poly_trait_pred()
})
.map(|t| t.value)
.map(|t| t.map_bound(|pred| pred.trait_ref))
.filter(|supertrait_ref| self.visited.insert(*supertrait_ref));

self.stack.extend(supertrait_refs);
Expand Down
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