From e2b042bd9721995486f4f0cf96847c02d27908e3 Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Sat, 24 Oct 2026 15:26:23 -0700
Subject: Fix chained comparisons and restore recursion coverage

---
 .../seaofnodes/simple/ChainedComparisonTest.java   | 37 ++++++++++++++++++++++
 .../java/com/seaofnodes/simple/Chapter18Test.java  |  7 ++--
 2 files changed, 40 insertions(+), 4 deletions(-)
 create mode 100644 chapter28a/src/test/java/com/seaofnodes/simple/ChainedComparisonTest.java

(limited to 'chapter28a/src/test')

diff --git a/chapter28a/src/test/java/com/seaofnodes/simple/ChainedComparisonTest.java b/chapter28a/src/test/java/com/seaofnodes/simple/ChainedComparisonTest.java
new file mode 100644
index 00000000..8db9c024
--- /dev/null
+++ b/chapter28a/src/test/java/com/seaofnodes/simple/ChainedComparisonTest.java
@@ -0,0 +1,37 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.type.TypeInteger;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class ChainedComparisonTest {
+    @Test public void testAdjacentOperandsAndOperators() {
+        String[] expressions = {"10 < arg < 20", "0 < arg <= 3", "3 >= arg > 0",
+                                "0 <= arg < 3", "0 < arg <= 3 < 4"};
+        String[][] expected = {{"0","0","1","0"}, {"0","1","0","0"},
+                               {"0","1","0","0"}, {"1","0","0","0"},
+                               {"0","1","0","0"}};
+        int[] args = {0,3,15,30};
+        for(int i=0;i<expressions.length;i++) {
+            CodeGen code = new CodeGen("return "+expressions[i]+";").driver(CodeGen.Phase.TypeCheck);
+            for(int j=0;j<args.length;j++) assertEquals(expressions[i],expected[i][j],Eval2.eval(code,args[j]));
+        }
+    }
+
+    @Test public void testSingleEvaluationAndShortCircuit() {
+        for(int seed:new int[]{2,13,123}) {
+            CodeGen code = new CodeGen("int x=arg; int y=0; val b=0 < x++ <= (y+=3) < (y+=1); return x*100+y*10+b;",seed,true)
+                .driver(CodeGen.Phase.TypeCheck);
+            assertEquals("100",Eval2.eval(code,0));
+            assertEquals("441",Eval2.eval(code,3));
+            assertEquals("530",Eval2.eval(code,4));
+        }
+        try {
+            new CodeGen("return 0 < arg > 1;").parse();
+            fail("mixed directions");
+        } catch(RuntimeException e) {
+            assertEquals("Mixing relational directions in a chained relational test",e.getMessage());
+        }
+    }
+}
diff --git a/chapter28a/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/chapter28a/src/test/java/com/seaofnodes/simple/Chapter18Test.java
index ae1dca5f..632b9539 100644
--- a/chapter28a/src/test/java/com/seaofnodes/simple/Chapter18Test.java
+++ b/chapter28a/src/test/java/com/seaofnodes/simple/Chapter18Test.java
@@ -436,7 +436,7 @@ return s.x;
         catch( Exception e ) { assertEquals("Accessing unknown field 'x' from '*Test.S'",e.getMessage()); }
     }
 
-    @Test @Ignore
+    @Test
     public void testErr5() {
         CodeGen code = new CodeGen(
 """
@@ -450,8 +450,8 @@ return g();
     }
 
 
-    // Mutual recursion.  Fails without SCCP to lift the recursive return types.
-    @Ignore @Test
+    // Mutual recursion: check results, independent of how much gets inlined.
+    @Test
     public void testFcnMutRec() {
         CodeGen code = new CodeGen(
 """
@@ -460,7 +460,6 @@ val is_odd  = { int x -> x ? is_even(x-1) : false; };
 return is_even(arg);
 """);
         code.driver(CodeGen.Phase.TypeCheck);
-        assertEquals("Stop[ return #2; return Phi(Region,0,1,#2); ]", code.print());
         assertEquals("1", Eval2.eval(code, 0));
         assertEquals("0", Eval2.eval(code, 1));
         assertEquals("1", Eval2.eval(code, 2));
-- 
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