enhance `collapse_vars` (#3799)

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 872e2bbf..9504241b 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1264,6 +1264,7 @@ merge(Compressor.prototype, {
                 if (stat_index == 0 && compressor.option("unused")) extract_args();
                 // Find collapsible assignments
                 var hit_stack = [];
+                var declare_only = Object.create(null);
                 extract_candidates(statements[stat_index]);
                 while (candidates.length > 0) {
                     hit_stack = candidates.pop();
@@ -1574,6 +1575,8 @@ merge(Compressor.prototype, {
                             candidates.push(hit_stack.slice());
                         }
                         extract_candidates(expr.value);
+                    } else {
+                        declare_only[expr.name.name] = (declare_only[expr.name.name] || 0) + 1;
                     }
                 }
                 hit_stack.pop();
@@ -1739,6 +1742,7 @@ merge(Compressor.prototype, {
                     if (!member(expr.name, def.orig)) return;
                     var referenced = def.references.length - def.replaced;
                     var declared = def.orig.length - def.eliminated;
+                    declared -= declare_only[def.name] || 0;
                     if (declared > 1 && !(expr.name instanceof AST_SymbolFunarg)) {
                         mangleable_var(expr.value);
                         return make_node(AST_SymbolRef, expr.name, expr.name);