fix corner case in `evaluate` (#3569)

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/compress.js b/lib/compress.js
index d8ee2bd3..87671d8e 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -2881,6 +2881,7 @@ merge(Compressor.prototype, {
             if (!non_converting_binary[this.operator]) depth++;
             var left = this.left._eval(compressor, cached, depth);
             if (left === this.left) return this;
+            if (this.operator == (left ? "||" : "&&")) return left;
             var right = this.right._eval(compressor, cached, depth);
             if (right === this.right) return this;
             var result;
@@ -3049,7 +3050,10 @@ merge(Compressor.prototype, {
                         cached.push(node);
                     });
                 });
-                return stat.value ? stat.value._eval(compressor, cached, depth) : undefined;
+                if (!stat.value) return undefined;
+                var val = stat.value._eval(compressor, cached, depth);
+                if (val === stat.value) return this;
+                return val;
             } else if (compressor.option("unsafe") && exp instanceof AST_PropAccess) {
                 var key = exp.property;
                 if (key instanceof AST_Node) {