fix corner case in evaluate (#3569)

Author: alexlamsl

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) {

test/compress/evaluate.js

@@ -1876,3 +1876,27 @@ issue_3558: {
     }
     expect_stdout: "1 0"
 }
+
+issue_3568: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+    }
+    input: {
+        var a = 0;
+        function f(b) {
+            return b && b.p;
+        }
+        console.log(f(++a + f()));
+    }
+    expect: {
+        var a = 0;
+        function f(b) {
+            return b && b.p;
+        }
+        console.log(NaN);
+    }
+    expect_stdout: "NaN"
+}