enhance unused (#4968)

lib/compress.js

@@ -6890,25 +6890,10 @@ merge(Compressor.prototype, {
             node.value = node.value.transform(tt);
             var name = node.name.transform(trimmer);
             if (!name) {
+                if (node.name instanceof AST_Destructured) return null;
                 var value = node.value.drop_side_effect_free(compressor);
                 if (!value) return null;
-                name = node.name;
-                if (name instanceof AST_Destructured) {
-                    name = name.clone();
-                    name[name instanceof AST_DestructuredArray ? "elements" : "properties"] = [];
-                    if (!(value instanceof AST_Array || value.is_string(compressor)
-                        || name instanceof AST_DestructuredObject
-                            && (value instanceof AST_Object
-                                || value.is_boolean(compressor)
-                                || value.is_number(compressor)))) {
-                        value = make_node(AST_Array, value, {
-                            elements: [ value ],
-                        });
-                    }
-                    node.name = name;
-                } else {
-                    log(name, "Side effects in default value of unused variable {name}");
-                }
+                log(node.name, "Side effects in default value of unused variable {name}");
                 node.value = value;
             }
             return node;

test/compress/default-values.js

@@ -598,6 +598,7 @@ unused_var_1: {
 
 unused_var_2: {
     options = {
+        pure_getters: "strict",
         toplevel: true,
         unused: true,
     }
@@ -609,11 +610,7 @@ unused_var_2: {
         };
     }
     expect: {
-        var {
-            p: [] = [ console.log("FAIL") ],
-        } = {
-            p: [ console.log("PASS") ],
-        };
+        console.log("PASS");
     }
     expect_stdout: "PASS"
     node_version: ">=6"