commit 75220674c07abfc90c2cd7862d04cfa2e2354450
author Zackery Spytz <zspytz@gmail.com> Mon Apr 05 13:41:01 2021 -0600
committer GitHub <noreply@github.com> Mon Apr 05 12:41:01 2021 -0700
tree 7da8600bce2e46bd148120f8dc5044946fb6385a
parent 14829b09eb652f457cf837836909169746a810f0

bpo-36470: Allow dataclasses.replace() to handle InitVars with default values (GH-20867)



Co-Authored-By: Claudiu Popa <pcmanticore@gmail.com>

Automerge-Triggered-By: GH:ericvsmith

Lib/dataclasses.py

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 422a95c..3de2ec0 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1300,7 +1300,7 @@ class C:
             continue
 
         if f.name not in changes:
-            if f._field_type is _FIELD_INITVAR:
+            if f._field_type is _FIELD_INITVAR and f.default is MISSING:
                 raise ValueError(f"InitVar {f.name!r} "
                                  'must be specified with replace()')
             changes[f.name] = getattr(obj, f.name)