Fix scheduling regression (#53)

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

src/interpreter.rs

@@ -2348,7 +2348,17 @@ impl Interpreter {
                             }
                             v => v,
                         };
+
                         let paths: Vec<&str> = path.iter().map(|s| *s.text()).collect();
+
+                        if let RuleHead::Set { .. } = &rule_head {
+                            // Ensure that sets are created as empty.
+                            let vref = Self::make_or_get_value_mut(&mut self.data, &paths)?;
+                            if *vref == Value::Undefined {
+                                *vref = Value::new_set();
+                            }
+                        }
+
                         self.update_data(span, refr, &paths[..], value)?;
 
                         self.processed.insert(rule.clone());

src/scheduler.rs

@@ -162,6 +162,8 @@ pub fn schedule<Str: Clone + std::cmp::Ord + std::fmt::Debug>(
         (stmt_scheduled, reprocess_var)
     };
 
+    process_var(empty.clone());
+
     let mut done = false;
     while !done {
         done = true;
@@ -840,7 +842,7 @@ impl Analyzer {
                 )?;
                 self.process_comprs(&comprs[..], scope, first_use, &mut used_vars)?;
                 definitions.push(Definition {
-                    var: expr.span().source_str().clone(),
+                    var: expr.span().source_str().clone_empty(),
                     used_vars,
                 });
                 Ok(())

tests/interpreter/cases/scheduler/tests.yaml

@@ -21,3 +21,52 @@ cases:
     query: data.test
     want_result:
       r1: 12
+      
+  - note: input-dependency
+    data: {}
+    modules:
+      - |
+        package test
+
+        default p = null
+        p = input.p
+
+        q {
+          input.p
+          true
+        }
+
+        r1 = s {
+          # Dependency on null input before erroring stmt.
+          input.p
+          s = concat("", ["", p])
+        }
+
+        #r2 = s {
+        #  s = concat("", ["", p])
+        #  # Dependency on null input after erroring stmt.
+        #  # This doesn't reordered before assignment to s
+        #  # since s also has no other local var dependency.
+        #  # The written order of statements is preserved.
+        #  input.p          
+        #}
+
+        r3 = s {
+          # Indirect dependency on null input before erroring stmt.
+          q
+          s = concat("", ["", p])
+        }
+        
+        #r3 = s {
+        #  s := concat("", ["", p])
+        #  # Indirect dependency on null input after erroring stmt.
+        #  # This doesn't reordered before assignment to s
+        #  # since s also has no other local var dependency.
+        #  # The written order of statements is preserved.
+        #  input.p          
+        #  q
+        #}
+        
+    query: data.test
+    want_result:
+      p: null