More error cases, error checking

disallow e.g. "struct x { int i; }; x = new x; x.i=3.14;"

6 files changed, 74 insertions, 11 deletions

diff --git a/chapter13/src/main/java/com/seaofnodes/simple/Parser.java b/chapter13/src/main/java/com/seaofnodes/simple/Parser.java
index bde697d6..fee5215e 100644
--- a/chapter13/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter13/src/main/java/com/seaofnodes/simple/Parser.java
@@ -596,7 +596,7 @@ public class Parser {
         Node n = new NewNode(TypeMemPtr.make(obj), ctrl()).peephole().keep();
         int alias = START._aliasStarts.get(obj._name);
         for( Field field : obj._fields ) {
-            memAlias(alias, new StoreNode(field._fname, alias, memAlias(alias), n, new ConstantNode(field._type.makeInit()).peephole()).peephole());
+            memAlias(alias, new StoreNode(field._fname, alias, field._type, memAlias(alias), n, new ConstantNode(field._type.makeInit()).peephole(),true).peephole());
             alias++;
         }
         return n.unkeep();
@@ -637,7 +637,8 @@ public class Parser {
             if( peek('=') ) _lexer._position--;
             else {
                 Node val = parseExpression();
-                memAlias(alias, new StoreNode(name, alias, memAlias(alias), expr, val).peephole());
+                Type glb = base._fields[idx]._type;
+                memAlias(alias, new StoreNode(name, alias,glb, memAlias(alias), expr, val, false).peephole());
                 return expr;        // "obj.a = expr" returns the expression while updating memory
             }
         }
diff --git a/chapter13/src/main/java/com/seaofnodes/simple/node/LoadNode.java b/chapter13/src/main/java/com/seaofnodes/simple/node/LoadNode.java
index 0c5d72e5..4e1421fa 100644
--- a/chapter13/src/main/java/com/seaofnodes/simple/node/LoadNode.java
+++ b/chapter13/src/main/java/com/seaofnodes/simple/node/LoadNode.java
@@ -11,7 +11,6 @@ import java.util.BitSet;
  */
 public class LoadNode extends MemOpNode {
 
-    Type _declaredType;
     /**
      * Load a value from a ptr.field.
      *
@@ -20,8 +19,7 @@ public class LoadNode extends MemOpNode {
      * @param memPtr The ptr to the struct from where we load a field
      */
     public LoadNode(String name, int alias, Type glb, Node memSlice, Node memPtr) {
-        super(name, alias, memSlice, memPtr);
-        _declaredType = glb;
+        super(name, alias, glb, memSlice, memPtr);
     }
 
     @Override public String  label() { return     _name; }
diff --git a/chapter13/src/main/java/com/seaofnodes/simple/node/MemOpNode.java b/chapter13/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
index 7f8d060a..bc8e46d3 100644
--- a/chapter13/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
+++ b/chapter13/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
@@ -11,14 +11,18 @@ public abstract class MemOpNode extends Node {
 
     public final String _name;
     public final int _alias;
+    public final Type _declaredType;
 
-    public MemOpNode(String name, int alias, Node memSlice, Node memPtr) {
+
+    public MemOpNode(String name, int alias, Type glb, Node memSlice, Node memPtr) {
         super(null, memSlice, memPtr);
         _name  = name;
         _alias = alias;
+        _declaredType = glb;
+
     }
-    public MemOpNode(String name, int alias, Node memSlice, Node memPtr, Node value) {
-        this(name, alias, memSlice, memPtr);
+    public MemOpNode(String name, int alias, Type glb, Node memSlice, Node memPtr, Node value) {
+        this(name, alias, glb, memSlice, memPtr);
         addDef(value);
     }
 
diff --git a/chapter13/src/main/java/com/seaofnodes/simple/node/Node.java b/chapter13/src/main/java/com/seaofnodes/simple/node/Node.java
index 52282737..d846fcef 100644
--- a/chapter13/src/main/java/com/seaofnodes/simple/node/Node.java
+++ b/chapter13/src/main/java/com/seaofnodes/simple/node/Node.java
@@ -137,7 +137,7 @@ public abstract class Node implements OutNode {
 
     public boolean isUnused() { return nOuts() == 0; }
 
-    public CFGNode cfg0() { return (CFGNode)in(0); }
+   public CFGNode cfg0() { return (CFGNode)in(0); }
 
     /**
      * Change a <em>def</em> into a Node.  Keeps the edges correct, by removing
diff --git a/chapter13/src/main/java/com/seaofnodes/simple/node/StoreNode.java b/chapter13/src/main/java/com/seaofnodes/simple/node/StoreNode.java
index 89141892..44a14be1 100644
--- a/chapter13/src/main/java/com/seaofnodes/simple/node/StoreNode.java
+++ b/chapter13/src/main/java/com/seaofnodes/simple/node/StoreNode.java
@@ -11,14 +11,17 @@ import java.util.BitSet;
  */
 public class StoreNode extends MemOpNode {
 
+    private final boolean _init; // Initializing writes are allowed to write null
+
     /**
      * @param name The struct field we are assigning to
      * @param memSlice The memory alias node - this is updated after a Store
      * @param memPtr The ptr to the struct where we will store a value
      * @param value Value to be stored
      */
-    public StoreNode(String name, int alias, Node memSlice, Node memPtr, Node value) {
-        super(name, alias, memSlice, memPtr, value);
+    public StoreNode(String name, int alias, Type glb, Node memSlice, Node memPtr, Node value, boolean init) {
+        super(name, alias, glb, memSlice, memPtr, value);
+        _init = init;
     }
 
     @Override public String  label() { return "ST"+_name; }
@@ -65,4 +68,11 @@ public class StoreNode extends MemOpNode {
         return false;
     }
 
+    @Override
+    String err() {
+        String err = super.err();
+        if( err != null ) return err;
+        Type ptr = val()._type;
+        return _init || ptr.isa(_declaredType) ? null : "Cannot store "+ptr+" into field "+_declaredType+" "+_name;
+    }
 }
diff --git a/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index e36c7577..8eceb0fa 100644
--- a/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java
@@ -121,4 +121,54 @@ return f0.i.f.i.i;
         assertEquals("return 17;", stop.toString());
     }
 
+    @Test
+    public void testNullRef0() {
+        Parser parser = new Parser(
+"""
+struct N { N next; int i; }
+N n = new N;
+return n.next;
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return null;", stop.toString());
+    }
+
+    @Test
+    public void testNullRef1() {
+        Parser parser = new Parser(
+"""
+struct N { N next; int i; }
+N n = new N;
+n.next = new N;
+return n.next;
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return new N;", stop.toString());
+    }
+
+    @Test
+    public void testNullRef2() {
+        Parser parser = new Parser(
+"""
+struct N { N next; int i; }
+N n = new N;
+n.next = null;
+return n.next;
+""");
+        try { parser.parse(true).iterate(true); fail(); }
+        catch( Exception e ) { assertEquals("Cannot store null into field *N next",e.getMessage()); }
+    }
+
+    @Test
+    public void testNullRef3() {
+        Parser parser = new Parser(
+"""
+struct N { N next; int i; }
+N n = new N;
+n.i = 3.14;
+return n.i;
+""");
+        try { parser.parse(true).iterate(true); fail(); }
+        catch( Exception e ) { assertEquals("Cannot store 3.14 into field IntBot i",e.getMessage()); }
+    }
 }