Auto merge of rust-lang#55040 - scalexm:param-env, r=nikomatsakis

Replace `ParamEnv` with a new type in chalk context.

I left a few FIXMEs.

r? @nikomatsakis

Author: bors

src/librustc/dep_graph/dep_node.rs

@@ -70,6 +70,7 @@ use rustc_data_structures::stable_hasher::{StableHasher, HashStable};
 use std::fmt;
 use std::hash::Hash;
 use syntax_pos::symbol::InternedString;
+use traits;
 use traits::query::{
     CanonicalProjectionGoal, CanonicalTyGoal, CanonicalTypeOpEqGoal, CanonicalTypeOpSubtypeGoal,
     CanonicalPredicateGoal, CanonicalTypeOpProvePredicateGoal, CanonicalTypeOpNormalizeGoal,
@@ -550,6 +551,7 @@ define_dep_nodes!( <'tcx>
     [anon] TraitSelect,
 
     [] ParamEnv(DefId),
+    [] Environment(DefId),
     [] DescribeDef(DefId),
 
     // FIXME(mw): DefSpans are not really inputs since they are derived from
@@ -669,7 +671,7 @@ define_dep_nodes!( <'tcx>
     [input] Features,
 
     [] ProgramClausesFor(DefId),
-    [] ProgramClausesForEnv(ParamEnv<'tcx>),
+    [] ProgramClausesForEnv(traits::Environment<'tcx>),
     [] WasmImportModuleMap(CrateNum),
     [] ForeignModules(CrateNum),
 

src/librustc/ich/impls_ty.rs

@@ -1395,10 +1395,16 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for traits::Goal<'tcx> {
 
 impl_stable_hash_for!(
     impl<'tcx> for struct traits::ProgramClause<'tcx> {
-        goal, hypotheses
+        goal, hypotheses, category
     }
 );
 
+impl_stable_hash_for!(enum traits::ProgramClauseCategory {
+    ImpliedBound,
+    WellFormed,
+    Other,
+});
+
 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for traits::Clause<'tcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a>,
@@ -1422,3 +1428,8 @@ impl_stable_hash_for!(struct ty::subst::UserSubsts<'tcx> { substs, user_self_ty
 
 impl_stable_hash_for!(struct ty::subst::UserSelfTy<'tcx> { impl_def_id, self_ty });
 
+impl_stable_hash_for!(
+    impl<'tcx> for struct traits::Environment<'tcx> {
+        clauses,
+    }
+);

src/librustc/traits/mod.rs

@@ -278,6 +278,8 @@ pub type TraitObligations<'tcx> = Vec<TraitObligation<'tcx>>;
 /// * `DomainGoal`
 /// * `Goal`
 /// * `Clause`
+/// * `Environment`
+/// * `InEnvironment`
 /// are used for representing the trait system in the form of
 /// logic programming clauses. They are part of the interface
 /// for the chalk SLG solver.
@@ -335,6 +337,14 @@ impl<'tcx> DomainGoal<'tcx> {
     pub fn into_goal(self) -> GoalKind<'tcx> {
         GoalKind::DomainGoal(self)
     }
+
+    pub fn into_program_clause(self) -> ProgramClause<'tcx> {
+        ProgramClause {
+            goal: self,
+            hypotheses: ty::List::empty(),
+            category: ProgramClauseCategory::Other,
+        }
+    }
 }
 
 impl<'tcx> GoalKind<'tcx> {
@@ -360,6 +370,15 @@ pub enum Clause<'tcx> {
     ForAll(ty::Binder<ProgramClause<'tcx>>),
 }
 
+impl Clause<'tcx> {
+    pub fn category(self) -> ProgramClauseCategory {
+        match self {
+            Clause::Implies(clause) => clause.category,
+            Clause::ForAll(clause) => clause.skip_binder().category,
+        }
+    }
+}
+
 /// Multiple clauses.
 pub type Clauses<'tcx> = &'tcx List<Clause<'tcx>>;
 
@@ -376,6 +395,38 @@ pub struct ProgramClause<'tcx> {
 
     /// ...if we can prove these hypotheses (there may be no hypotheses at all):
     pub hypotheses: Goals<'tcx>,
+
+    /// Useful for filtering clauses.
+    pub category: ProgramClauseCategory,
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub enum ProgramClauseCategory {
+    ImpliedBound,
+    WellFormed,
+    Other,
+}
+
+/// A set of clauses that we assume to be true.
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct Environment<'tcx> {
+    pub clauses: Clauses<'tcx>,
+}
+
+impl Environment<'tcx> {
+    pub fn with<G>(self, goal: G) -> InEnvironment<'tcx, G> {
+        InEnvironment {
+            environment: self,
+            goal,
+        }
+    }
+}
+
+/// Something (usually a goal), along with an environment.
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct InEnvironment<'tcx, G> {
+    pub environment: Environment<'tcx>,
+    pub goal: G,
 }
 
 pub type Selection<'tcx> = Vtable<'tcx, PredicateObligation<'tcx>>;

src/librustc/traits/structural_impls.rs

@@ -496,7 +496,7 @@ impl<'tcx> fmt::Display for traits::Goal<'tcx> {
 
 impl<'tcx> fmt::Display for traits::ProgramClause<'tcx> {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let traits::ProgramClause { goal, hypotheses } = self;
+        let traits::ProgramClause { goal, hypotheses, .. } = self;
         write!(fmt, "{}", goal)?;
         if !hypotheses.is_empty() {
             write!(fmt, " :- ")?;
@@ -647,18 +647,59 @@ impl<'tcx> TypeFoldable<'tcx> for traits::Goal<'tcx> {
 BraceStructTypeFoldableImpl! {
     impl<'tcx> TypeFoldable<'tcx> for traits::ProgramClause<'tcx> {
         goal,
-        hypotheses
+        hypotheses,
+        category,
     }
 }
 
+CloneTypeFoldableAndLiftImpls! {
+    traits::ProgramClauseCategory,
+}
+
 EnumTypeFoldableImpl! {
     impl<'tcx> TypeFoldable<'tcx> for traits::Clause<'tcx> {
         (traits::Clause::Implies)(clause),
         (traits::Clause::ForAll)(clause),
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<traits::Clause<'tcx>> {
+BraceStructTypeFoldableImpl! {
+    impl<'tcx> TypeFoldable<'tcx> for traits::Environment<'tcx> { clauses }
+}
+
+BraceStructTypeFoldableImpl! {
+    impl<'tcx, G> TypeFoldable<'tcx> for traits::InEnvironment<'tcx, G> {
+        environment,
+        goal
+    } where G: TypeFoldable<'tcx>
+}
+
+impl<'a, 'tcx> Lift<'tcx> for traits::Environment<'a> {
+    type Lifted = traits::Environment<'tcx>;
+    fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(&self.clauses).map(|clauses| {
+            traits::Environment {
+                clauses,
+            }
+        })
+    }
+}
+
+impl<'a, 'tcx, G: Lift<'tcx>> Lift<'tcx> for traits::InEnvironment<'a, G> {
+    type Lifted = traits::InEnvironment<'tcx, G::Lifted>;
+    fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(&self.environment).and_then(|environment| {
+            tcx.lift(&self.goal).map(|goal| {
+                traits::InEnvironment {
+                    environment,
+                    goal,
+                }
+            })
+        })
+    }
+}
+
+impl<'tcx> TypeFoldable<'tcx> for traits::Clauses<'tcx> {
     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
         let v = self.iter()
             .map(|t| t.fold_with(folder))

src/librustc/ty/query/config.rs

@@ -12,6 +12,7 @@ use dep_graph::SerializedDepNodeIndex;
 use dep_graph::DepNode;
 use hir::def_id::{CrateNum, DefId, DefIndex};
 use mir::interpret::GlobalId;
+use traits;
 use traits::query::{
     CanonicalPredicateGoal, CanonicalProjectionGoal, CanonicalTyGoal, CanonicalTypeOpEqGoal,
     CanonicalTypeOpNormalizeGoal, CanonicalTypeOpProvePredicateGoal, CanonicalTypeOpSubtypeGoal,
@@ -826,8 +827,14 @@ impl<'tcx> QueryDescription<'tcx> for queries::program_clauses_for<'tcx> {
 }
 
 impl<'tcx> QueryDescription<'tcx> for queries::program_clauses_for_env<'tcx> {
-    fn describe(_tcx: TyCtxt<'_, '_, '_>, _: ty::ParamEnv<'tcx>) -> Cow<'static, str> {
-        "generating chalk-style clauses for param env".into()
+    fn describe(_tcx: TyCtxt<'_, '_, '_>, _: traits::Environment<'tcx>) -> Cow<'static, str> {
+        "generating chalk-style clauses for environment".into()
+    }
+}
+
+impl<'tcx> QueryDescription<'tcx> for queries::environment<'tcx> {
+    fn describe(_tcx: TyCtxt<'_, '_, '_>, _: DefId) -> Cow<'static, str> {
+        "return a chalk-style environment".into()
     }
 }
 

src/librustc/ty/query/keys.rs

@@ -12,6 +12,7 @@
 
 use infer::canonical::Canonical;
 use hir::def_id::{CrateNum, DefId, LOCAL_CRATE, DefIndex};
+use traits;
 use ty::{self, Ty, TyCtxt};
 use ty::subst::Substs;
 use ty::fast_reject::SimplifiedType;
@@ -181,6 +182,15 @@ impl<'tcx, T: Key> Key for ty::ParamEnvAnd<'tcx, T> {
     }
 }
 
+impl<'tcx> Key for traits::Environment<'tcx> {
+    fn query_crate(&self) -> CrateNum {
+        LOCAL_CRATE
+    }
+    fn default_span(&self, _: TyCtxt<'_, '_, '_>) -> Span {
+        DUMMY_SP
+    }
+}
+
 impl Key for InternedString {
     fn query_crate(&self) -> CrateNum {
         LOCAL_CRATE

src/librustc/ty/query/mod.rs

@@ -664,8 +664,11 @@ define_queries! { <'tcx>
         [] fn program_clauses_for: ProgramClausesFor(DefId) -> Clauses<'tcx>,
 
         [] fn program_clauses_for_env: ProgramClausesForEnv(
-            ty::ParamEnv<'tcx>
+            traits::Environment<'tcx>
         ) -> Clauses<'tcx>,
+
+        // Get the chalk-style environment of the given item.
+        [] fn environment: Environment(DefId) -> traits::Environment<'tcx>,
     },
 
     Linking {

src/librustc/ty/query/plumbing.rs

@@ -1156,6 +1156,7 @@ pub fn force_from_dep_node<'a, 'gcx, 'lcx>(tcx: TyCtxt<'a, 'gcx, 'lcx>,
         DepKind::CheckMatch => { force!(check_match, def_id!()); }
 
         DepKind::ParamEnv => { force!(param_env, def_id!()); }
+        DepKind::Environment => { force!(environment, def_id!()); }
         DepKind::DescribeDef => { force!(describe_def, def_id!()); }
         DepKind::DefSpan => { force!(def_span, def_id!()); }
         DepKind::LookupStability => { force!(lookup_stability, def_id!()); }