fix corner case in hoist_props (#3869)

fixes #3868

lib/compress.js

@@ -4927,7 +4927,7 @@ merge(Compressor.prototype, {
             if (def.single_use) return;
             if (top_retain(def)) return;
             if (sym.fixed_value() !== right) return;
-            return right instanceof AST_Object;
+            return right instanceof AST_Object && right.properties.length > 0;
         }
     });
 

test/compress/hoist_props.js

@@ -912,3 +912,31 @@ issue_3440: {
     }
     expect_stdout: "PASS"
 }
+
+issue_3868: {
+    options = {
+        hoist_props: true,
+        passes: 2,
+        reduce_vars: true,
+        side_effects: true,
+    }
+    input: {
+        (function(t) {
+            t = {};
+            ({
+                get p() {},
+                q: (console.log("PASS"), +t),
+            }).r;
+        })();
+    }
+    expect: {
+        (function(t) {
+            t = {};
+            ({
+                get p() {},
+                q: (console.log("PASS"), +t),
+            }).r;
+        })();
+    }
+    expect_stdout: "PASS"
+}