lint: Stop using mutable objects for default arguments

4 files changed, 10 insertions, 7 deletions

diff --git a/src/buildstream/_gitsourcebase.py b/src/buildstream/_gitsourcebase.py
index 1f74bb972..e3b246677 100644
--- a/src/buildstream/_gitsourcebase.py
+++ b/src/buildstream/_gitsourcebase.py
@@ -70,14 +70,14 @@ def _strip_tag(rev):
 #    tags (list): Tag configuration; see _GitSourceBase._load_tags
 #
 class _GitMirror(SourceFetcher):
-    def __init__(self, source, path, url, ref, *, primary=False, tags=[]):
+    def __init__(self, source, path, url, ref, *, primary=False, tags=None):
 
         super().__init__()
         self.source = source
         self.path = path
         self.url = url
         self.ref = ref
-        self.tags = tags
+        self.tags = tags or []
         self.primary = primary
         self.mirror = os.path.join(source.get_mirror_directory(), utils.url_directory_name(url))
 
diff --git a/src/buildstream/_includes.py b/src/buildstream/_includes.py
index b9a1c0d22..2ecb70a31 100644
--- a/src/buildstream/_includes.py
+++ b/src/buildstream/_includes.py
@@ -42,7 +42,7 @@ class Includes:
     #    current_loader (Loader): Use alternative loader (for junction files)
     #    only_local (bool): Whether to ignore junction files
     #    process_project_options (bool): Whether to process options from current project
-    def _process(self, node, *, included=set(), current_loader=None, only_local=False, process_project_options=True):
+    def _process(self, node, *, included=None, current_loader=None, only_local=False, process_project_options=True):
         if current_loader is None:
             current_loader = self._loader
 
@@ -69,8 +69,11 @@ class Includes:
     #    only_local (bool): Whether to ignore junction files
     #    process_project_options (bool): Whether to process options from current project
     def _process_node(
-        self, node, *, included=set(), current_loader=None, only_local=False, process_project_options=True
+        self, node, *, included=None, current_loader=None, only_local=False, process_project_options=True
     ):
+        if included is None:
+            included = set()
+
         includes_node = node.get_node("(@)", allowed_types=[ScalarNode, SequenceNode], allow_none=True)
 
         if includes_node:
@@ -172,7 +175,7 @@ class Includes:
     #    only_local (bool): Whether to ignore junction files
     #    process_project_options (bool): Whether to process options from current project
     def _process_value(
-        self, value, *, included=set(), current_loader=None, only_local=False, process_project_options=True
+        self, value, *, included=None, current_loader=None, only_local=False, process_project_options=True
     ):
         value_type = type(value)
 
diff --git a/src/buildstream/testing/_utils/junction.py b/src/buildstream/testing/_utils/junction.py
index 6f45ad590..8f80ed6bd 100644
--- a/src/buildstream/testing/_utils/junction.py
+++ b/src/buildstream/testing/_utils/junction.py
@@ -19,7 +19,7 @@ from .site import HAVE_GIT, GIT, GIT_ENV
 # Returns:
 #    (str): The ref
 #
-def generate_junction(tmpdir, subproject_path, junction_path, *, store_ref=True, options={}):
+def generate_junction(tmpdir, subproject_path, junction_path, *, store_ref=True, options=None):
     # Create a repo to hold the subproject and generate
     # a junction element for it
     #
diff --git a/tests/testutils/junction.py b/tests/testutils/junction.py
index 99117b2cf..4889fdb24 100644
--- a/tests/testutils/junction.py
+++ b/tests/testutils/junction.py
@@ -15,7 +15,7 @@ from buildstream.testing import create_repo
 # Returns:
 #    (str): The ref
 #
-def generate_junction(tmpdir, subproject_path, junction_path, *, store_ref=True, options={}):
+def generate_junction(tmpdir, subproject_path, junction_path, *, store_ref=True, options=None):
     # Create a repo to hold the subproject and generate
     # a junction element for it
     #