fix corner case in unused (#4018)

fixes #4017
2020-07-21 01:06:42 +01:00
parent 61b66e83f1
commit bce3919748
2 changed files with 33 additions and 4 deletions
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -4456,8 +4456,13 @@ merge(Compressor.prototype, {
                    var sym = def.name.definition();
                    if (!drop_vars || sym.id in in_use_ids) {
                        if (def.value && indexOf_assign(sym, def) < 0) {
-                            def.value = def.value.drop_side_effect_free(compressor);
-                            if (def.value) def.value.tail_node().write_only = false;
+                            var value = def.value.drop_side_effect_free(compressor);
+                            if (def.value !== value) def.value = value && make_sequence(def.value, [
+                                value,
+                                make_node(AST_Number, def.value, {
+                                    value: 0
+                                }),
+                            ]);
                        }
                        var old_def, var_defs = var_defs_by_id.get(sym.id);
                        if (!def.value) {