--- a/mercurial/merge.py	Mon May 11 18:45:45 2020 -0400
+++ b/mercurial/merge.py	Mon Jan 18 10:24:03 2021 +0100
@@ -2324,6 +2324,7 @@
     removefiles=True,
     abortonerror=False,
     noop=False,
+    confirm=False,
 ):
     """Purge the working directory of untracked files.
 
@@ -2344,6 +2345,8 @@
     ``noop`` controls whether to actually remove files. If not defined, actions
     will be taken.
 
+    ``confirm`` ask confirmation before actually removing anything.
+
     Returns an iterable of relative paths in the working directory that were
     or would be removed.
     """
@@ -2371,6 +2374,25 @@
 
         status = repo.status(match=matcher, ignored=ignored, unknown=unknown)
 
+        if confirm:
+            nb_ignored = len(status.ignored)
+            nb_unkown = len(status.unknown)
+            if nb_unkown and nb_ignored:
+                msg = _(b"permanently delete %d unkown and %d ignored files?")
+                msg %= (nb_unkown, nb_ignored)
+            elif nb_unkown:
+                msg = _(b"permanently delete %d unkown files?")
+                msg %= nb_unkown
+            elif nb_ignored:
+                msg = _(b"permanently delete %d ignored files?")
+                msg %= nb_ignored
+            else:
+                # XXX we might be missing directory there
+                return res
+            msg += b" (yN)$$ &Yes $$ &No"
+            if repo.ui.promptchoice(msg, default=1) == 1:
+                raise error.CanceledError(_(b'removal cancelled'))
+
         if removefiles:
             for f in sorted(status.unknown + status.ignored):
                 if not noop: