From e491c528e8d9380bdef823889f0b0a8e08a34f55 Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Sun, 12 Jan 2025 10:54:27 -0800
Subject: Fix deep co-recursive type check

---
 chapter18/src/main/java/com/seaofnodes/simple/Parser.java    |  4 ++--
 chapter18/src/main/java/com/seaofnodes/simple/type/Type.java |  3 +++
 .../src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java | 12 ++++++++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

(limited to 'chapter18/src/main')

diff --git a/chapter18/src/main/java/com/seaofnodes/simple/Parser.java b/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
index a4fd9d52..649145fd 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
@@ -651,7 +651,7 @@ public class Parser {
         // Auto-narrow wide ints to narrow ints
         expr = zsMask(expr,t);
         // Type is sane
-        if( expr._type!=Type.BOTTOM && !expr._type.isa(t) )
+        if( expr._type!=Type.BOTTOM && !expr._type.shallowISA(t) )
             throw error("Type " + expr._type.str() + " is not of declared type " + t.str());
         return expr;
     }
@@ -835,7 +835,7 @@ public class Parser {
         if( !(peek(',') || peek(';')) )
             return posT(old1);
         pos(old2);              // Reset lexer to reparse
-        if( id==null || _scope.lookup(id)!=null )
+        if( id==null )
             return posT(old1);  // Reset lexer to reparse
         // Yes a forward ref, so declare it
         TYPES.put(tname,t1);
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/Type.java b/chapter18/src/main/java/com/seaofnodes/simple/type/Type.java
index 95fdca74..b6757ef2 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/type/Type.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/Type.java
@@ -191,6 +191,9 @@ public class Type {
     // True if this "isa" t; e.g. 17 isa TypeInteger.BOT
     public boolean isa( Type t ) { return meet(t)==t; }
 
+    // True if this "isa" t up to named structures
+    public boolean shallowISA( Type t ) { return isa(t); }
+
     public Type nonZero() { return TypePtr.NPTR; }
 
     // Make a zero version of this type, 0 for integers and null for pointers.
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
index 6dda9c39..c8a5c1f4 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
@@ -64,6 +64,18 @@ public class TypeMemPtr extends TypeNil {
         return _nil==3 ? this : make((byte)3,_obj);
     }
 
+
+    // True if this "isa" t up to named structures
+    @Override public boolean shallowISA( Type t ) {
+        if( !(t instanceof TypeMemPtr that) ) return false;
+        if( this==that ) return true;
+        if( xmeet0(that)!=that._nil ) return false;
+        if( _obj==that._obj ) return true;
+        if( _obj._name.equals(that._obj._name) )
+            return true;        // Shallow, do not follow matching names, just assume ok
+        throw Utils.TODO(); // return _obj.shallowISA(that._obj);
+    }
+
     @Override public TypeMemPtr glb() { return make((byte)3,_obj.glb()); }
     // Is forward-reference
     @Override public boolean isFRef() { return _obj.isFRef(); }
-- 
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