Clarify list/set/dict/tuple comprehensions and enforce via flake8 (#6957)

Ensure good comprehension hygiene using flake8-comprehensions.

2 files changed, 3 insertions, 3 deletions

diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index 0b45e1f52a..0dba997a23 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -240,7 +240,7 @@ class BucketCollector(object):
         res.append(["+Inf", sum(data.values())])
 
         metric = HistogramMetricFamily(
-            self.name, "", buckets=res, sum_value=sum([x * y for x, y in data.items()])
+            self.name, "", buckets=res, sum_value=sum(x * y for x, y in data.items())
         )
         yield metric
 
diff --git a/synapse/metrics/background_process_metrics.py b/synapse/metrics/background_process_metrics.py
index c53d2a0d40..b65bcd8806 100644
--- a/synapse/metrics/background_process_metrics.py
+++ b/synapse/metrics/background_process_metrics.py
@@ -80,13 +80,13 @@ _background_process_db_sched_duration = Counter(
 # map from description to a counter, so that we can name our logcontexts
 # incrementally. (It actually duplicates _background_process_start_count, but
 # it's much simpler to do so than to try to combine them.)
-_background_process_counts = dict()  # type: dict[str, int]
+_background_process_counts = {}  # type: dict[str, int]
 
 # map from description to the currently running background processes.
 #
 # it's kept as a dict of sets rather than a big set so that we can keep track
 # of process descriptions that no longer have any active processes.
-_background_processes = dict()  # type: dict[str, set[_BackgroundProcess]]
+_background_processes = {}  # type: dict[str, set[_BackgroundProcess]]
 
 # A lock that covers the above dicts
 _bg_metrics_lock = threading.Lock()