collapse_vars: do not replace a constant in loop condition or init (#1562)

1 files changed, 6 insertions, 3 deletions

diff --git a/lib/compress.js b/lib/compress.js
index d9a67c16..8c3fb155 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -535,10 +535,13 @@ merge(Compressor.prototype, {
                     // Constant single use vars can be replaced in any scope.
                     if (var_decl.value.is_constant()) {
                         var ctt = new TreeTransformer(function(node) {
-                            if (node === ref
-                                && !ctt.find_parent(AST_ForIn)) {
-                                return replace_var(node, ctt.parent(), true);
+                            var parent = ctt.parent();
+                            if (parent instanceof AST_IterationStatement
+                                && (parent.condition === node || parent.init === node)) {
+                                return node;
                             }
+                            if (node === ref)
+                                return replace_var(node, parent, true);
                         });
                         stat.transform(ctt);
                         continue;