Auto merge of #118689 - compiler-errors:const-drop, r=fee1-dead

Fix const drop checking Fixes confirmation of `~const Destruct` and const drops. r? fee1-dead
rust-lang · Dec 8, 2023 · ae612be · ae612be
2 parents 5ea6256 efe8ae7
commit ae612be
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Showing 10 changed files with 57 additions and 67 deletions.
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -22,7  22,7 @@ use std::mem;
 use std::ops::{ControlFlow, Deref};
 
 use super::ops::{self, NonConstOp, Status};
-use super::qualifs::{self, CustomEq, HasMutInterior, NeedsDrop};
 use super::qualifs::{self, CustomEq, HasMutInterior, NeedsDrop, NeedsNonConstDrop};
 use super::resolver::FlowSensitiveAnalysis;
 use super::{ConstCx, Qualif};
 use crate::const_eval::is_unstable_const_fn;
@@ -35,7  35,7 @@ type QualifResults<'mir, 'tcx, Q> =
 pub struct Qualifs<'mir, 'tcx> {
     has_mut_interior: Option<QualifResults<'mir, 'tcx, HasMutInterior>>,
     needs_drop: Option<QualifResults<'mir, 'tcx, NeedsDrop>>,
-    // needs_non_const_drop: Option<QualifResults<'mir, 'tcx, NeedsNonConstDrop>>,
     needs_non_const_drop: Option<QualifResults<'mir, 'tcx, NeedsNonConstDrop>>,
 }
 
 impl<'mir, 'tcx> Qualifs<'mir, 'tcx> {
@@ -78,27  78,25 @@ impl<'mir, 'tcx> Qualifs<'mir, 'tcx> {
         local: Local,
         location: Location,
     ) -> bool {
-        // FIXME(effects) replace with `NeedsNonconstDrop` after const traits work again
-        /*
         let ty = ccx.body.local_decls[local].ty;
-        if !NeedsDrop::in_any_value_of_ty(ccx, ty) {
         // Peeking into opaque types causes cycles if the current function declares said opaque
         // type. Thus we avoid short circuiting on the type and instead run the more expensive
         // analysis that looks at the actual usage within this function
         if !ty.has_opaque_types() && !NeedsNonConstDrop::in_any_value_of_ty(ccx, ty) {
             return false;
         }
 
         let needs_non_const_drop = self.needs_non_const_drop.get_or_insert_with(|| {
             let ConstCx { tcx, body, .. } = *ccx;
 
-            FlowSensitiveAnalysis::new(NeedsDrop, ccx)
-                .into_engine(tcx, &body)
             FlowSensitiveAnalysis::new(NeedsNonConstDrop, ccx)
                 .into_engine(tcx, body)
                 .iterate_to_fixpoint()
-                .into_results_cursor(&body)
                 .into_results_cursor(body)
         });
 
         needs_non_const_drop.seek_before_primary_effect(location);
         needs_non_const_drop.get().contains(local)
-        */
-
-        self.needs_drop(ccx, local, location)
     }
 
     /// Returns `true` if `local` is `HasMutInterior` at the given `Location`.
@@ -1013,9  1011,8 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                 let mut err_span = self.span;
                 let ty_of_dropped_place = dropped_place.ty(self.body, self.tcx).ty;
 
-                // FIXME(effects) replace with `NeedsNonConstDrop` once we fix const traits
                 let ty_needs_non_const_drop =
-                    qualifs::NeedsDrop::in_any_value_of_ty(self.ccx, ty_of_dropped_place);
                     qualifs::NeedsNonConstDrop::in_any_value_of_ty(self.ccx, ty_of_dropped_place);
 
                 debug!(?ty_of_dropped_place, ?ty_needs_non_const_drop);
 

diff --git a/compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs b/compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs
@@ -5,7  5,7 @@ use rustc_span::{symbol::sym, Span};
 
 use super::check::Qualifs;
 use super::ops::{self, NonConstOp};
-use super::qualifs::{NeedsDrop, Qualif};
 use super::qualifs::{NeedsNonConstDrop, Qualif};
 use super::ConstCx;
 
 /// Returns `true` if we should use the more precise live drop checker that runs after drop
@@ -83,8  83,7 @@ impl<'tcx> Visitor<'tcx> for CheckLiveDrops<'_, 'tcx> {
             mir::TerminatorKind::Drop { place: dropped_place, .. } => {
                 let dropped_ty = dropped_place.ty(self.body, self.tcx).ty;
 
-                // FIXME(effects) use `NeedsNonConstDrop`
-                if !NeedsDrop::in_any_value_of_ty(self.ccx, dropped_ty) {
                 if !NeedsNonConstDrop::in_any_value_of_ty(self.ccx, dropped_ty) {
                     // Instead of throwing a bug, we just return here. This is because we have to
                     // run custom `const Drop` impls.
                     return;

diff --git a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
@@ -23,8  23,7 @@ pub fn in_any_value_of_ty<'tcx>(
     ConstQualifs {
         has_mut_interior: HasMutInterior::in_any_value_of_ty(cx, ty),
         needs_drop: NeedsDrop::in_any_value_of_ty(cx, ty),
-        // FIXME(effects)
-        needs_non_const_drop: NeedsDrop::in_any_value_of_ty(cx, ty),
         needs_non_const_drop: NeedsNonConstDrop::in_any_value_of_ty(cx, ty),
         custom_eq: CustomEq::in_any_value_of_ty(cx, ty),
         tainted_by_errors,
     }
@@ -155,12  154,27 @@ impl Qualif for NeedsNonConstDrop {
             return false;
         }
 
-        // FIXME(effects) constness
         // FIXME(effects): If `destruct` is not a `const_trait`,
         // or effects are disabled in this crate, then give up.
         let destruct_def_id = cx.tcx.require_lang_item(LangItem::Destruct, Some(cx.body.span));
         if cx.tcx.generics_of(destruct_def_id).host_effect_index.is_none()
             || !cx.tcx.features().effects
         {
             return NeedsDrop::in_any_value_of_ty(cx, ty);
         }
 
         let obligation = Obligation::new(
             cx.tcx,
             ObligationCause::dummy_with_span(cx.body.span),
             cx.param_env,
-            ty::TraitRef::from_lang_item(cx.tcx, LangItem::Destruct, cx.body.span, [ty]),
             ty::TraitRef::new(
                 cx.tcx,
                 destruct_def_id,
                 [
                     ty::GenericArg::from(ty),
                     ty::GenericArg::from(cx.tcx.expected_const_effect_param_for_body(cx.def_id())),
                 ],
             ),
         );
 
         let infcx = cx.tcx.infer_ctxt().build();

diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
@@ -781,9  781,9 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     pub fn expected_const_effect_param_for_body(self, def_id: LocalDefId) -> ty::Const<'tcx> {
-        // if the callee does have the param, we need to equate the param to some const
-        // value no matter whether the effects feature is enabled in the local crate,
-        // because inference will fail if we don't.
         // FIXME(effects): This is suspicious and should probably not be done,
         // especially now that we enforce host effects and then properly handle
         // effect vars during fallback.
         let mut host_always_on =
             !self.features().effects || self.sess.opts.unstable_opts.unleash_the_miri_inside_of_you;
 

diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -872,9  872,18 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     ) {
         // If the predicate is `~const Destruct` in a non-const environment, we don't actually need
         // to check anything. We'll short-circuit checking any obligations in confirmation, too.
-        // FIXME(effects)
-        if true {
-            candidates.vec.push(ConstDestructCandidate(None));
         let Some(host_effect_index) =
             self.tcx().generics_of(obligation.predicate.def_id()).host_effect_index
         else {
             candidates.vec.push(BuiltinCandidate { has_nested: false });
             return;
         };
         // If the obligation has `host = true`, then the obligation is non-const and it's always
         // trivially implemented.
         if obligation.predicate.skip_binder().trait_ref.args.const_at(host_effect_index)
             == self.tcx().consts.true_
         {
             candidates.vec.push(BuiltinCandidate { has_nested: false });
             return;
         }
 

diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -1172,11  1172,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         obligation: &PolyTraitObligation<'tcx>,
         impl_def_id: Option<DefId>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
-        // `~const Destruct` in a non-const environment is always trivially true, since our type is `Drop`
-        // FIXME(effects)
-        if true {
-            return Ok(vec![]);
-        }
         let Some(host_effect_index) =
             self.tcx().generics_of(obligation.predicate.def_id()).host_effect_index
         else {
             bug!()
         };
         let host_effect_param: ty::GenericArg<'tcx> =
             obligation.predicate.skip_binder().trait_ref.args.const_at(host_effect_index).into();
 
         let drop_trait = self.tcx().require_lang_item(LangItem::Drop, None);
 
@@ -1284,7  1286,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                                 self.tcx(),
                                 LangItem::Destruct,
                                 cause.span,
-                                [nested_ty],
                                 [nested_ty.into(), host_effect_param],
                             ),
                             polarity: ty::ImplPolarity::Positive,
                         }),
@@ -1310,7  1312,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                             self.tcx(),
                             LangItem::Destruct,
                             cause.span,
-                            [nested_ty],
                             [nested_ty.into(), host_effect_param],
                         ),
                         polarity: ty::ImplPolarity::Positive,
                     });

diff --git a/tests/ui/consts/precise-drop-with-promoted.rs b/tests/ui/consts/precise-drop-with-promoted.rs
@@ -1,11  1,6 @@
 // Regression test for issue #89938.
 // check-pass
 // compile-flags: --crate-type=lib
-// known-bug: #103507
-// failure-status: 101
-// normalize-stderr-test "note: .*\n\n" -> ""
-// normalize-stderr-test "thread 'rustc' panicked.*\n.*\n" -> ""
-// normalize-stderr-test "(error: internal compiler error: [^:] ):\d :\d : " -> "$1:LL:CC: "
-// rustc-env:RUST_BACKTRACE=0
 
 #![feature(const_precise_live_drops)]
 

diff --git a/tests/ui/consts/precise-drop-with-promoted.stderr b/tests/ui/consts/precise-drop-with-promoted.stderr
diff --git a/tests/ui/rfcs/rfc-2632-const-trait-impl/effects/minicore.rs b/tests/ui/rfcs/rfc-2632-const-trait-impl/effects/minicore.rs
@@ -1,3  1,5 @@
 // check-pass
 
 #![crate_type = "lib"]
 #![feature(no_core, lang_items, unboxed_closures, auto_traits, intrinsics, rustc_attrs)]
 #![feature(fundamental)]
@@ -6,8  8,6 @@
 #![no_std]
 #![no_core]
 
-// known-bug: #110395
-
 #[lang = "sized"]
 trait Sized {}
 #[lang = "copy"]

diff --git a/tests/ui/rfcs/rfc-2632-const-trait-impl/effects/minicore.stderr b/tests/ui/rfcs/rfc-2632-const-trait-impl/effects/minicore.stderr