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Use the constness from the param env instead of having a separate dimension for it

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This breaks a ~const test that will be fixed in a follow up commit of this PR
This commit is contained in:
Oli Scherer 2021-10-21 16:07:37 +00:00 • committed by Deadbeef
parent 19f2101272
commit d51068ca28
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GPG key ID: 6D017A96D8E6C2F9
12 changed files with 25 additions and 142 deletions
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39
compiler/rustc_trait_selection/src/traits/fulfill.rs
View file

@ -4,7 +4,6 @@ use rustc_data_structures::obligation_forest::ProcessResult;
use rustc_data_structures::obligation_forest::{Error, ForestObligation, Outcome};
use rustc_data_structures::obligation_forest::{ObligationForest, ObligationProcessor};
use rustc_errors::ErrorReported;
use rustc_hir as hir;
use rustc_infer::traits::{SelectionError, TraitEngine, TraitEngineExt as _, TraitObligation};
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::thir::abstract_const::NotConstEvaluatable;
@ -231,21 +230,6 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentContext<'tcx> {
self.predicates.to_errors(CodeAmbiguity).into_iter().map(to_fulfillment_error).collect()
}
fn select_all_with_constness_or_error(
&mut self,
infcx: &InferCtxt<'_, 'tcx>,
constness: rustc_hir::Constness,
) -> Vec<FulfillmentError<'tcx>> {
{
let errors = self.select_with_constness_where_possible(infcx, constness);
if !errors.is_empty() {
return errors;
}
}
self.predicates.to_errors(CodeAmbiguity).into_iter().map(to_fulfillment_error).collect()
}
fn select_where_possible(
&mut self,
infcx: &InferCtxt<'_, 'tcx>,
@ -254,15 +238,6 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentContext<'tcx> {
self.select(&mut selcx)
}
fn select_with_constness_where_possible(
&mut self,
infcx: &InferCtxt<'_, 'tcx>,
constness: hir::Constness,
) -> Vec<FulfillmentError<'tcx>> {
let mut selcx = SelectionContext::with_constness(infcx, constness);
self.select(&mut selcx)
}
fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>> {
self.predicates.map_pending_obligations(|o| o.obligation.clone())
}
@ -679,12 +654,7 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
if obligation.predicate.is_known_global() {
// no type variables present, can use evaluation for better caching.
// FIXME: consider caching errors too.
//
// If the predicate is considered const, then we cannot use this because
// it will cause false negatives in the ui tests.
if !self.selcx.is_predicate_const(obligation.predicate)
&& infcx.predicate_must_hold_considering_regions(obligation)
{
if infcx.predicate_must_hold_considering_regions(obligation) {
debug!(
"selecting trait at depth {} evaluated to holds",
obligation.recursion_depth
@ -738,12 +708,7 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
if obligation.predicate.is_global(tcx) {
// no type variables present, can use evaluation for better caching.
// FIXME: consider caching errors too.
//
// If the predicate is considered const, then we cannot use this because
// it will cause false negatives in the ui tests.
if !self.selcx.is_predicate_const(obligation.predicate)
&& self.selcx.infcx().predicate_must_hold_considering_regions(obligation)
{
if self.selcx.infcx().predicate_must_hold_considering_regions(obligation) {
return ProcessResult::Changed(vec![]);
} else {
tracing::debug!("Does NOT hold: {:?}", obligation);

2
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
View file

@ -303,7 +303,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
} else if lang_items.drop_trait() == Some(def_id)
&& obligation.predicate.skip_binder().constness == ty::BoundConstness::ConstIfConst
{
if self.is_in_const_context {
if obligation.param_env.constness() == hir::Constness::Const {
self.assemble_const_drop_candidates(obligation, stack, &mut candidates)?;
} else {
debug!("passing ~const Drop bound; in non-const context");

38
compiler/rustc_trait_selection/src/traits/select/mod.rs
View file

@ -128,9 +128,6 @@ pub struct SelectionContext<'cx, 'tcx> {
/// and a negative impl
allow_negative_impls: bool,
/// Are we in a const context that needs `~const` bounds to be const?
is_in_const_context: bool,
/// The mode that trait queries run in, which informs our error handling
/// policy. In essence, canonicalized queries need their errors propagated
/// rather than immediately reported because we do not have accurate spans.
@ -222,7 +219,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
intercrate: false,
intercrate_ambiguity_causes: None,
allow_negative_impls: false,
is_in_const_context: false,
query_mode: TraitQueryMode::Standard,
}
}
@ -234,7 +230,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
intercrate: true,
intercrate_ambiguity_causes: None,
allow_negative_impls: false,
is_in_const_context: false,
query_mode: TraitQueryMode::Standard,
}
}
@ -250,7 +245,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
intercrate: false,
intercrate_ambiguity_causes: None,
allow_negative_impls,
is_in_const_context: false,
query_mode: TraitQueryMode::Standard,
}
}
@ -266,26 +260,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
intercrate: false,
intercrate_ambiguity_causes: None,
allow_negative_impls: false,
is_in_const_context: false,
query_mode,
}
}
pub fn with_constness(
infcx: &'cx InferCtxt<'cx, 'tcx>,
constness: hir::Constness,
) -> SelectionContext<'cx, 'tcx> {
SelectionContext {
infcx,
freshener: infcx.freshener_keep_static(),
intercrate: false,
intercrate_ambiguity_causes: None,
allow_negative_impls: false,
is_in_const_context: matches!(constness, hir::Constness::Const),
query_mode: TraitQueryMode::Standard,
}
}
/// Enables tracking of intercrate ambiguity causes. These are
/// used in coherence to give improved diagnostics. We don't do
/// this until we detect a coherence error because it can lead to
@ -318,20 +296,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
self.intercrate
}
/// Returns `true` if the trait predicate is considerd `const` to this selection context.
pub fn is_trait_predicate_const(&self, pred: ty::TraitPredicate<'_>) -> bool {
matches!(pred.constness, ty::BoundConstness::ConstIfConst) && self.is_in_const_context
}
/// Returns `true` if the predicate is considered `const` to
/// this selection context.
pub fn is_predicate_const(&self, pred: ty::Predicate<'_>) -> bool {
match pred.kind().skip_binder() {
ty::PredicateKind::Trait(pred) => self.is_trait_predicate_const(pred),
_ => false,
}
}
///////////////////////////////////////////////////////////////////////////
// Selection
//
@ -1138,7 +1102,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
for candidate in candidates {
// Respect const trait obligations
if self.is_trait_predicate_const(obligation.predicate.skip_binder()) {
if obligation.is_const() {
match candidate {
// const impl
ImplCandidate(def_id)