flip a non-existent else block in simplifyIfs, if adding such a block can help

2 files changed, 17 insertions, 2 deletions

diff --git a/tests/test_other.py b/tests/test_other.py
index 19d1790d..ded45112 100644
--- a/tests/test_other.py
+++ b/tests/test_other.py
@@ -2652,3 +2652,16 @@ int main()
       }
     ''', [3, 1, 1])
 
+    test(r'''
+      #include <stdio.h>
+      #include <stdlib.h>
+
+      int main(int argc, char *argv[]) {
+        if (getenv("A") || getenv("B")) {
+            printf("hello world\n");
+        }
+        printf("and that's that\n");
+        return 0;
+      }
+    ''', [3, 1, 1])
+
diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index 88bcf503..129c493f 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -861,16 +861,18 @@ function simplifyIfs(ast) {
                 node[1] = flipCondition(node[1]);
                 node[2] = node[3];
                 node[3] = body;
+                body = node[2];
               } else break;
             } else break;
           }
           // we can handle elses, but must be fully identical
           if (node[3] || other[3]) {
-            if (!node[3] || !other[3]) break;
+            if (!node[3]) break;
             if (!astCompare(node[3], other[3])) {
               // the elses are different, but perhaps if we flipped a condition we can do better
               if (astCompare(node[3], other[2])) {
-                // flip other
+                // flip other. note that other may not have had an else! add one if so; we will eliminate such things later
+                if (!other[3]) other[3] = ['block', []];
                 other[1] = flipCondition(other[1]);
                 var temp = other[2];
                 other[2] = other[3];