Add empty ConstKind::Abstract

Initial pass at expr/abstract const/s

Address comments

Switch to using a list instead of &[ty::Const], rm `AbstractConst`

Remove try_unify_abstract_consts

Update comments

Add edits

Recurse more

More edits

Prevent equating associated consts

Move failing test to ui

Changes this test from incremental to ui, and mark it as failing and a known bug.
Does not cause the compiler to ICE, so should be ok.

Author: JulianKnodt

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -561,6 +561,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             ty::ConstKind::Param(_) | ty::ConstKind::Placeholder(..) => {
                 throw_inval!(TooGeneric)
             }
+            ty::ConstKind::Expr(_) => throw_inval!(TooGeneric),
             ty::ConstKind::Error(reported) => {
                 throw_inval!(AlreadyReported(reported))
             }

compiler/rustc_hir_analysis/src/check/dropck.rs

@@ -193,6 +193,18 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
                     ty::PredicateKind::ConstEvaluatable(a),
                     ty::PredicateKind::ConstEvaluatable(b),
                 ) => relator.relate(predicate.rebind(a), predicate.rebind(b)).is_ok(),
+                /*
+                ) => {
+                    if let (Ok(Some(a)), Ok(Some(b))) = (
+                        tcx.expand_bound_abstract_const(tcx.bound_abstract_const(a.def), a.substs),
+                        tcx.expand_bound_abstract_const(tcx.bound_abstract_const(b.def), b.substs),
+                    ) && a.ty() == b.ty() {
+                        return relator.relate(a, b).is_ok();
+                    } else {
+                        false
+                    }
+                }
+                */
                 (
                     ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty_a, lt_a)),
                     ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty_b, lt_b)),

compiler/rustc_infer/src/infer/freshen.rs

@@ -248,6 +248,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for TypeFreshener<'a, 'tcx> {
             ty::ConstKind::Param(_)
             | ty::ConstKind::Value(_)
             | ty::ConstKind::Unevaluated(..)
+            | ty::ConstKind::Expr(..)
             | ty::ConstKind::Error(_) => ct.super_fold_with(self),
         }
     }

compiler/rustc_infer/src/infer/mod.rs

@@ -23,7 +23,6 @@ use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKin
 use rustc_middle::mir::interpret::{ErrorHandled, EvalToValTreeResult};
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::traits::select;
-use rustc_middle::ty::abstract_const::{AbstractConst, FailureKind};
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::fold::BoundVarReplacerDelegate;
 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
@@ -713,32 +712,6 @@ impl<'tcx> InferCtxt<'tcx> {
         TypeErrCtxt { infcx: self, typeck_results: None, fallback_has_occurred: false }
     }
 
-    /// calls `tcx.try_unify_abstract_consts` after
-    /// canonicalizing the consts.
-    #[instrument(skip(self), level = "debug")]
-    pub fn try_unify_abstract_consts(
-        &self,
-        a: ty::UnevaluatedConst<'tcx>,
-        b: ty::UnevaluatedConst<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
-    ) -> bool {
-        // Reject any attempt to unify two unevaluated constants that contain inference
-        // variables, since inference variables in queries lead to ICEs.
-        if a.substs.has_non_region_infer()
-            || b.substs.has_non_region_infer()
-            || param_env.has_non_region_infer()
-        {
-            debug!("a or b or param_env contain infer vars in its substs -> cannot unify");
-            return false;
-        }
-
-        let param_env_and = param_env.and((a, b));
-        let erased = self.tcx.erase_regions(param_env_and);
-        debug!("after erase_regions: {:?}", erased);
-
-        self.tcx.try_unify_abstract_consts(erased)
-    }
-
     pub fn is_in_snapshot(&self) -> bool {
         self.in_snapshot.get()
     }
@@ -1646,34 +1619,39 @@ impl<'tcx> InferCtxt<'tcx> {
 
         // Postpone the evaluation of constants whose substs depend on inference
         // variables
+        let tcx = self.tcx;
         if substs.has_non_region_infer() {
-            let ac = AbstractConst::new(self.tcx, unevaluated);
+            let substs_erased = tcx.erase_regions(unevaluated.substs);
+            let ac = tcx.expand_bound_abstract_const(
+                tcx.bound_abstract_const(unevaluated.def),
+                substs_erased,
+            );
             match ac {
                 Ok(None) => {
-                    substs = InternalSubsts::identity_for_item(self.tcx, unevaluated.def.did);
+                    substs = InternalSubsts::identity_for_item(tcx, unevaluated.def.did);
                     param_env = self.tcx.param_env(unevaluated.def.did);
                 }
                 Ok(Some(ct)) => {
-                    if ct.unify_failure_kind(self.tcx) == FailureKind::Concrete {
-                        substs = replace_param_and_infer_substs_with_placeholder(self.tcx, substs);
-                    } else {
+                    if ct.has_non_region_infer() || ct.has_non_region_param() {
                         return Err(ErrorHandled::TooGeneric);
+                    } else {
+                        substs = replace_param_and_infer_substs_with_placeholder(tcx, substs);
                     }
                 }
                 Err(guar) => return Err(ErrorHandled::Reported(guar)),
             }
         }
 
-        let param_env_erased = self.tcx.erase_regions(param_env);
-        let substs_erased = self.tcx.erase_regions(substs);
+        let param_env_erased = tcx.erase_regions(param_env);
+        let substs_erased = tcx.erase_regions(substs);
         debug!(?param_env_erased);
         debug!(?substs_erased);
 
         let unevaluated = ty::UnevaluatedConst { def: unevaluated.def, substs: substs_erased };
 
         // The return value is the evaluated value which doesn't contain any reference to inference
         // variables, thus we don't need to substitute back the original values.
-        self.tcx.const_eval_resolve_for_typeck(param_env_erased, unevaluated, span)
+        tcx.const_eval_resolve_for_typeck(param_env_erased, unevaluated, span)
     }
 
     /// `ty_or_const_infer_var_changed` is equivalent to one of these two:

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -644,12 +644,6 @@ impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for Symbol {
     }
 }
 
-impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for &'tcx [ty::abstract_const::Node<'tcx>] {
-    fn decode(d: &mut DecodeContext<'a, 'tcx>) -> Self {
-        ty::codec::RefDecodable::decode(d)
-    }
-}
-
 impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for &'tcx [(ty::Predicate<'tcx>, Span)] {
     fn decode(d: &mut DecodeContext<'a, 'tcx>) -> Self {
         ty::codec::RefDecodable::decode(d)

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -366,7 +366,7 @@ define_tables! {
     mir_for_ctfe: Table<DefIndex, LazyValue<mir::Body<'static>>>,
     promoted_mir: Table<DefIndex, LazyValue<IndexVec<mir::Promoted, mir::Body<'static>>>>,
     // FIXME(compiler-errors): Why isn't this a LazyArray?
-    thir_abstract_const: Table<DefIndex, LazyValue<&'static [ty::abstract_const::Node<'static>]>>,
+    thir_abstract_const: Table<DefIndex, LazyValue<ty::Const<'static>>>,
     impl_parent: Table<DefIndex, RawDefId>,
     impl_polarity: Table<DefIndex, ty::ImplPolarity>,
     constness: Table<DefIndex, hir::Constness>,

compiler/rustc_middle/src/mir/pretty.rs

@@ -476,6 +476,7 @@ impl<'tcx> Visitor<'tcx> for ExtraComments<'tcx> {
                     // These variants shouldn't exist in the MIR.
                     ty::ConstKind::Placeholder(_)
                     | ty::ConstKind::Infer(_)
+                    | ty::ConstKind::Expr(_)
                     | ty::ConstKind::Bound(..) => bug!("unexpected MIR constant: {:?}", literal),
                 },
                 ConstantKind::Unevaluated(uv, _) => {

compiler/rustc_middle/src/mir/syntax.rs

@@ -1185,15 +1185,17 @@ pub enum NullOp {
     AlignOf,
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(HashStable, TyEncodable, TyDecodable, TypeFoldable, TypeVisitable)]
 pub enum UnOp {
     /// The `!` operator for logical inversion
     Not,
     /// The `-` operator for negation
     Neg,
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, PartialOrd, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
+#[derive(Copy, Clone, Debug, PartialEq, PartialOrd, Ord, Eq, Hash)]
+#[derive(TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
 pub enum BinOp {
     /// The `+` operator (addition)
     Add,

compiler/rustc_middle/src/mir/type_foldable.rs

@@ -16,9 +16,7 @@ TrivialTypeTraversalAndLiftImpls! {
     UserTypeAnnotationIndex,
     BorrowKind,
     CastKind,
-    BinOp,
     NullOp,
-    UnOp,
     hir::Movability,
     BasicBlock,
     SwitchTargets,

compiler/rustc_middle/src/query/mod.rs

@@ -400,7 +400,7 @@ rustc_queries! {
     /// Try to build an abstract representation of the given constant.
     query thir_abstract_const(
         key: DefId
-    ) -> Result<Option<&'tcx [ty::abstract_const::Node<'tcx>]>, ErrorGuaranteed> {
+    ) -> Result<Option<ty::Const<'tcx>>, ErrorGuaranteed> {
         desc {
             |tcx| "building an abstract representation for `{}`", tcx.def_path_str(key),
         }
@@ -409,23 +409,14 @@ rustc_queries! {
     /// Try to build an abstract representation of the given constant.
     query thir_abstract_const_of_const_arg(
         key: (LocalDefId, DefId)
-    ) -> Result<Option<&'tcx [ty::abstract_const::Node<'tcx>]>, ErrorGuaranteed> {
+    ) -> Result<Option<ty::Const<'tcx>>, ErrorGuaranteed> {
         desc {
             |tcx|
             "building an abstract representation for the const argument `{}`",
             tcx.def_path_str(key.0.to_def_id()),
         }
     }
 
-    query try_unify_abstract_consts(key:
-        ty::ParamEnvAnd<'tcx, (ty::UnevaluatedConst<'tcx>, ty::UnevaluatedConst<'tcx>
-    )>) -> bool {
-        desc {
-            |tcx| "trying to unify the generic constants `{}` and `{}`",
-            tcx.def_path_str(key.value.0.def.did), tcx.def_path_str(key.value.1.def.did)
-        }
-    }
-
     query mir_drops_elaborated_and_const_checked(
         key: ty::WithOptConstParam<LocalDefId>
     ) -> &'tcx Steal<mir::Body<'tcx>> {