Closes #12579. Positional fields with str.format_map() now raise a ValueError instead of SystemError.
diff --git a/Misc/ACKS b/Misc/ACKS
index ee9b373..ccbe152 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -78,6 +78,7 @@
Andrew Bennetts
Andy Bensky
Michel Van den Bergh
+Julian Berman
Eric Beser
Steven Bethard
Stephen Bevan
diff --git a/Misc/NEWS b/Misc/NEWS
index bf33745..f444709 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,10 @@
Core and Builtins
-----------------
+- Issue #12579: str.format_map() now raises a ValueError if used on a
+ format string that contains positional fields. Initial patch by
+ Julian Berman.
+
- Issue #11627: Fix segfault when __new__ on a exception returns a non-exception
class.