Merge pull request #213 from detrumi/simplify-coinductive-trait-check

Remove coinductive_traits from ProgramEnvironment

Author: nikomatsakis

src/db.rs

@@ -76,8 +76,9 @@ impl ChalkSolveDatabase for ChalkDatabase {
     }
 
     fn is_coinductive_trait(&self, trait_id: TraitId) -> bool {
-        if let Ok(env) = self.environment() {
-            env.coinductive_traits.contains(&trait_id)
+        if let Ok(program) = self.program_ir() {
+            // Currently, only auto traits are coinductive
+            program.trait_data[&trait_id].binders.value.flags.auto
         } else {
             false
         }

src/program_environment.rs

@@ -1,22 +1,13 @@
 use chalk_ir::ProgramClause;
-use chalk_ir::TraitId;
-use std::collections::BTreeSet;
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct ProgramEnvironment {
-    /// Indicates whether a given trait has coinductive semantics --
-    /// at present, this is true only for auto traits.
-    pub coinductive_traits: BTreeSet<TraitId>,
-
     /// Compiled forms of the above:
     pub program_clauses: Vec<ProgramClause>,
 }
 
 impl ProgramEnvironment {
-    pub fn new(coinductive_traits: BTreeSet<TraitId>, program_clauses: Vec<ProgramClause>) -> Self {
-        Self {
-            coinductive_traits,
-            program_clauses,
-        }
+    pub fn new(program_clauses: Vec<ProgramClause>) -> Self {
+        Self { program_clauses }
     }
 }

src/query.rs

@@ -167,22 +167,7 @@ fn environment(db: &impl LoweringDatabase) -> Result<Arc<ProgramEnvironment>, Ch
         }
     }
 
-    let coinductive_traits = program
-        .trait_data
-        .iter()
-        .filter_map(|(&trait_id, trait_datum)| {
-            if trait_datum.binders.value.flags.auto {
-                Some(trait_id)
-            } else {
-                None
-            }
-        })
-        .collect();
-
-    Ok(Arc::new(ProgramEnvironment::new(
-        coinductive_traits,
-        program_clauses,
-    )))
+    Ok(Arc::new(ProgramEnvironment::new(program_clauses)))
 }
 
 fn solver(db: &impl LoweringDatabase) -> Arc<Mutex<Solver>> {