Fix a null-check bug

2 files changed, 21 insertions, 3 deletions

diff --git a/chapter15/src/main/java/com/seaofnodes/simple/Parser.java b/chapter15/src/main/java/com/seaofnodes/simple/Parser.java
index 012a010e..728aaca7 100644
--- a/chapter15/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter15/src/main/java/com/seaofnodes/simple/Parser.java
@@ -807,7 +807,7 @@ public class Parser {
                 val = zsMask(val,f._type);
                 Node st = new StoreNode(name, f._alias, f._type, memAlias(f._alias), expr, off, val, false);
                 // Arrays include control, as a proxy for a safety range check.
-                // Structs dont need this; they only need a NPE check which is
+                // Structs don't need this; they only need a NPE check which is
                 // done via the type system.
                 if( base.isAry() )  st.setDef(0,ctrl());
                 memAlias(f._alias, st.peephole());
@@ -815,9 +815,9 @@ public class Parser {
             }
         }
 
-        Node load = new LoadNode(name, f._alias, f._type, memAlias(f._alias), expr, off);
+        Node load = new LoadNode(name, f._alias, f._type.glb(), memAlias(f._alias), expr, off);
         // Arrays include control, as a proxy for a safety range check
-        // Structs dont need this; they only need a NPE check which is
+        // Structs don't need this; they only need a NPE check which is
         // done via the type system.
         if( base.isAry() ) load.setDef(0,ctrl());
         return parsePostfix(load.peephole());
diff --git a/chapter15/src/test/java/com/seaofnodes/simple/Chapter13Test.java b/chapter15/src/test/java/com/seaofnodes/simple/Chapter13Test.java
index e8b71820..416aba31 100644
--- a/chapter15/src/test/java/com/seaofnodes/simple/Chapter13Test.java
+++ b/chapter15/src/test/java/com/seaofnodes/simple/Chapter13Test.java
@@ -163,4 +163,22 @@ return new S1.s=new S2;
         StopNode stop = parser.parse().iterate();
         assertEquals("return S2;", stop.toString());
     }
+
+    @Test
+    public void testcheckNull() {
+        Parser parser = new Parser(
+"""
+struct I {int i;}
+struct P {I pi;}
+P p1 = new P;
+P p2 = new P;
+p2.pi = new I;
+p2.pi.i = 2;
+if (arg) p1 = new P;
+return p1.pi.i + 1;
+""");
+        try { parser.parse(false).iterate();  fail(); }
+        catch( Exception e ) {  assertEquals("Might be null accessing 'i'",e.getMessage());  }
+    }
+
 }