MergeSort to its own file

Allow self-recursive forward refs.
Missing progress.

2 files changed, 12 insertions, 5 deletions

diff --git a/chapter18/src/main/java/com/seaofnodes/simple/Parser.java b/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
index 8f0cf493..4f19dda2 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
@@ -1123,10 +1123,14 @@ public class Parser {
             _scope.define(id, FRefNode.FREF_TYPE, true, XCTRL, loc());
             n = _scope.lookup(id);
         } else {
-            // Lookup worked on an out-of-function value.  No closures, so this
-            // has to be a final constant.
-            if( _scope.outOfFunction(n) && !(n._final && _scope.in(n._idx)._type.isConstant()) )
-                throw error("Variable '"+n._name+"' is out of function scope and must be a final constant");
+            // Lookup worked on an out-of-function value.
+            if( _scope.outOfFunction(n) ) {
+                // No closures, so this has to be a final constant (which
+                // includes forward refs)
+                Node def = _scope.in(n._idx);
+                if( !(def instanceof FRefNode) && !(n._final && def._type.isConstant()) )
+                    throw error("Variable '"+n._name+"' is out of function scope and must be a final constant");
+            }
         }
         return n;
     }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/FunNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/FunNode.java
index 8300d80f..1f0c76eb 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/FunNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/FunNode.java
@@ -71,7 +71,10 @@ public class FunNode extends RegionNode {
         // to collapse
         if( unknownCallers() ) return null;
         Node progress = super.idealize();
-        if( progress!=null ) IterPeeps.add( CodeGen.CODE._stop);
+        if( progress!=null ) {
+            IterPeeps.add( CodeGen.CODE._stop);
+            IterPeeps.add( _ret );
+        }
         return progress;
     }