workaround quirks on latter specs (#4172)

closes #4171

1 files changed, 9 insertions, 2 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 513528e7..a7e5eaca 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -4851,8 +4851,8 @@ merge(Compressor.prototype, {
                                 && (old_def.name == def.name.name || all(old_def.references, function(ref) {
                                     return ref.scope.find_variable(def.name) === def.name.definition();
                                 })))
-                            && can_rename(def.value, def.name.name)
-                            && (!compressor.has_directive("use strict") || parent instanceof AST_Scope)) {
+                            && can_declare_defun()
+                            && can_rename(def.value, def.name.name)) {
                             AST_Node.warn("Declaring {name} as function [{file}:{line},{col}]", template(def.name));
                             var defun = make_node(AST_Defun, def, def.value);
                             defun.name = make_node(AST_SymbolDefun, def.name, def.name);
@@ -4908,6 +4908,13 @@ merge(Compressor.prototype, {
                         var def = fn.variables.get(name);
                         return !def || fn.name && def === fn.name.definition();
                     }
+
+                    function can_declare_defun() {
+                        if (compressor.has_directive("use strict")) return parent instanceof AST_Scope;
+                        return parent instanceof AST_Block
+                            || parent instanceof AST_For && parent.init === node
+                            || parent instanceof AST_If;
+                    }
                 });
                 switch (head.length) {
                   case 0: