shaving off a couple more lines

compiler/can/src/def.rs

@@ -1185,18 +1185,11 @@ fn canonicalize_pending_body<'a>(
 
     opt_loc_annotation: Option<Loc<crate::annotation::Annotation>>,
 ) -> DefOutput {
-    // Make types for the body expr, even if we won't end up having a body.
+    // We treat closure definitions `foo = \a, b -> ...` differntly from other body expressions,
-    let expr_var = var_store.fresh();
+    // because they need more bookkeeping (for tail calls, closure captures, etc.)
-    let mut vars_by_symbol = SendMap::default();
-
-    pattern_to_vars_by_symbol(&mut vars_by_symbol, &loc_can_pattern.value, expr_var);
-
-    // First, make sure we are actually assigning an identifier instead of (for example) a tag.
     //
-    // If we're assigning (UserId userId) = ... then this is certainly not a closure declaration,
+    // Only defs of the form `foo = ...` can be closure declarations or self tail calls.
-    // which also implies it's not a self tail call!
+    let (loc_can_expr, def_references) = {
-    //
-    // Only defs of the form (foo = ...) can be closure declarations or self tail calls.
         match (&loc_can_pattern.value, &loc_expr.value) {
             (
                 Pattern::Identifier(defined_symbol)
@@ -1206,9 +1199,8 @@ fn canonicalize_pending_body<'a>(
                 },
                 ast::Expr::Closure(arguments, body),
             ) => {
-            // bookkeeping for tail-call detection. If we're assigning to an
+                // bookkeeping for tail-call detection.
-            // identifier (e.g. `f = \x -> ...`), then this symbol can be tail-called.
+                let outer_tailcallable = env.tailcallable_symbol;
-            let outer_identifier = env.tailcallable_symbol;
                 env.tailcallable_symbol = Some(*defined_symbol);
 
                 let (mut closure_data, can_output) = crate::expr::canonicalize_closure(
@@ -1221,7 +1213,7 @@ fn canonicalize_pending_body<'a>(
                 );
 
                 // reset the tailcallable_symbol
-            env.tailcallable_symbol = outer_identifier;
+                env.tailcallable_symbol = outer_tailcallable;
 
                 // The closure is self tail recursive iff it tail calls itself (by defined name).
                 let is_recursive = match can_output.tail_call {
@@ -1234,28 +1226,29 @@ fn canonicalize_pending_body<'a>(
 
                 let loc_can_expr = Loc::at(loc_expr.region, Expr::Closure(closure_data));
 
-            let def = single_can_def(
+                let def_references = DefReferences::Function(can_output.references.clone());
-                loc_can_pattern,
-                loc_can_expr,
-                expr_var,
-                opt_loc_annotation,
-                vars_by_symbol,
-            );
-
-            let closure_references = can_output.references.clone();
                 output.union(can_output);
 
-            DefOutput {
+                (loc_can_expr, def_references)
-                output,
-                references: DefReferences::Function(closure_references),
-                def,
-            }
             }
 
             _ => {
                 let (loc_can_expr, can_output) =
                     canonicalize_expr(env, var_store, scope, loc_expr.region, &loc_expr.value);
 
+                let def_references = DefReferences::Value(can_output.references.clone());
+                output.union(can_output);
+
+                (loc_can_expr, def_references)
+            }
+        }
+    };
+
+    let expr_var = var_store.fresh();
+    let mut vars_by_symbol = SendMap::default();
+
+    pattern_to_vars_by_symbol(&mut vars_by_symbol, &loc_can_pattern.value, expr_var);
+
     let def = single_can_def(
         loc_can_pattern,
         loc_can_expr,
@@ -1264,16 +1257,11 @@ fn canonicalize_pending_body<'a>(
         vars_by_symbol,
     );
 
-            let refs = can_output.references.clone();
-            output.union(can_output);
-
     DefOutput {
         output,
-                references: DefReferences::Value(refs),
+        references: def_references,
         def,
     }
-        }
-    }
 }
 
 #[inline(always)]