diff --git a/mercurial/store.py b/mercurial/store.py
--- a/mercurial/store.py
+++ b/mercurial/store.py
@@ -453,7 +453,7 @@ FILETYPE_FILELOG_OTHER = FILEFLAGS_FILEL
 FILETYPE_OTHER = FILEFLAGS_OTHER
 
 
-@attr.s(slots=True)
+@attr.s(slots=True, init=False)
 class BaseStoreEntry:
     """An entry in the store
 
@@ -463,6 +463,16 @@ class BaseStoreEntry:
     is_volatile = attr.ib(default=False)
     file_size = attr.ib(default=None)
 
+    def __init__(
+        self,
+        unencoded_path,
+        is_volatile=False,
+        file_size=None,
+    ):
+        self.unencoded_path = unencoded_path
+        self.is_volatile = is_volatile
+        self.file_size = file_size
+
     def files(self):
         return [
             StoreFile(
@@ -473,14 +483,14 @@ class BaseStoreEntry:
         ]
 
 
-@attr.s(slots=True)
+@attr.s(slots=True, init=False)
 class SimpleStoreEntry(BaseStoreEntry):
     """A generic entry in the store"""
 
     is_revlog = False
 
 
-@attr.s(slots=True)
+@attr.s(slots=True, init=False)
 class RevlogStoreEntry(BaseStoreEntry):
     """A revlog entry in the store"""
 
@@ -488,6 +498,22 @@ class RevlogStoreEntry(BaseStoreEntry):
     revlog_type = attr.ib(default=None)
     is_revlog_main = attr.ib(default=None)
 
+    def __init__(
+        self,
+        unencoded_path,
+        revlog_type,
+        is_revlog_main=False,
+        is_volatile=False,
+        file_size=None,
+    ):
+        super().__init__(
+            unencoded_path=unencoded_path,
+            is_volatile=is_volatile,
+            file_size=file_size,
+        )
+        self.revlog_type = revlog_type
+        self.is_revlog_main = is_revlog_main
+
 
 @attr.s(slots=True)
 class StoreFile: