phase29an(p10): add exitmap feature facts scaffold

src/mir/builder/control_flow/plan/facts/feature_facts.rs

@@ -2,6 +2,7 @@
 
 use crate::ast::ASTNode;
 use crate::mir::builder::control_flow::plan::planner::Freeze;
+use std::collections::BTreeSet;
 
 #[derive(Debug, Clone, Default, PartialEq, Eq)]
 pub(in crate::mir::builder) struct ExitUsageFacts {
@@ -10,9 +11,22 @@ pub(in crate::mir::builder) struct ExitUsageFacts {
     pub has_return: bool,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
+pub(in crate::mir::builder) enum ExitKindFacts {
+    Return,
+    Break,
+    Continue,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub(in crate::mir::builder) struct ExitMapFacts {
+    pub kinds_present: BTreeSet<ExitKindFacts>,
+}
+
 #[derive(Debug, Clone, Default, PartialEq, Eq)]
 pub(in crate::mir::builder) struct LoopFeatureFacts {
     pub exit_usage: ExitUsageFacts,
+    pub exit_map: Option<ExitMapFacts>,
     pub value_join: Option<ValueJoinFacts>,
     pub cleanup: Option<CleanupFacts>,
 }
@@ -32,6 +46,7 @@ pub(in crate::mir::builder) fn try_extract_loop_feature_facts(
     }
     Ok(LoopFeatureFacts {
         exit_usage,
+        exit_map: None,
         value_join: None,
         cleanup: None,
     })
@@ -102,6 +117,7 @@ mod tests {
                 has_return: true,
             }
         );
+        assert!(facts.exit_map.is_none());
     }
 
     #[test]
@@ -115,5 +131,6 @@ mod tests {
         };
         let facts = try_extract_loop_feature_facts(&[nested]).expect("Ok");
         assert_eq!(facts.exit_usage, ExitUsageFacts::default());
+        assert!(facts.exit_map.is_none());
     }
 }