fix corner case in `collapse_vars` (#3591)

1 files changed, 10 insertions, 6 deletions

diff --git a/lib/compress.js b/lib/compress.js
index e85cf5d3..801cbaea 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1691,13 +1691,17 @@ merge(Compressor.prototype, {
                 if (expr instanceof AST_Unary) return false;
                 if (side_effects) return false;
                 if (value_def) return true;
-                if (lhs instanceof AST_SymbolRef) {
-                    var def = lhs.definition();
-                    if (def.references.length - def.replaced == (candidate instanceof AST_VarDef ? 1 : 2)) {
-                        return true;
-                    }
+                if (!(lhs instanceof AST_SymbolRef)) return false;
+                var referenced;
+                if (expr instanceof AST_VarDef) {
+                    referenced = 1;
+                } else if (expr.operator == "=") {
+                    referenced = 2;
+                } else {
+                    return false;
                 }
-                return false;
+                var def = lhs.definition();
+                return def.references.length - def.replaced == referenced;
             }
 
             function symbol_in_lvalues(sym, parent) {