Fix psf#1202: remove trailing comma from function arguments list

black.py

@@ -1460,9 +1460,9 @@ def maybe_remove_trailing_comma(self, closing: Leaf) -> bool:
         if not (self.leaves and self.leaves[-1].type == token.COMMA):
             return False
 
-        # We remove trailing commas only in the case of importing a
+        # Remove trailing commas in the case of importing a
         # single name from a module.
-        if not (
+        if (
             self.leaves
             and self.is_import
             and len(self.leaves) > 4
@@ -1487,10 +1487,40 @@ def maybe_remove_trailing_comma(self, closing: Leaf) -> bool:
             )
             and closing.type == token.RPAR
         ):
+            self.remove_trailing_comma()
+            return True
+
+        # Otherwise, if the trailing one is the only one, we might mistakenly
+        # change a tuple into a different type by removing the comma.
+        if hasattr(closing, "bracket_depth"):
+            depth = closing.bracket_depth + 1
+        else:
+            return False
+        if hasattr(closing, "opening_bracket"):
+            opening = closing.opening_bracket
+        else:
             return False
 
-        self.remove_trailing_comma()
-        return True
+        try:
+            _opening_index = self.leaves.index(opening)
+        except ValueError:
+            return False
+
+        for leaf in self.leaves[_opening_index + 1 :]:
+            # stop if we're at the closing bracket
+            if leaf is closing:
+                break
+
+            if (
+                leaf.bracket_depth == depth
+                and leaf.type == token.COMMA
+                and leaf.parent
+                and leaf.parent.type in {syms.arglist, syms.typedargslist}
+            ):
+                self.remove_trailing_comma()
+                return True
+
+        return False
 
     def append_comment(self, comment: Leaf) -> bool:
         """Add an inline or standalone comment to the line."""

blib2to3/pgen2/driver.py

@@ -128,7 +128,7 @@ def parse_stream(self, stream: IO[Text], debug: bool = False) -> NL:
         return self.parse_stream_raw(stream, debug)
 
     def parse_file(
-        self, filename: Path, encoding: Optional[Text] = None, debug: bool = False,
+        self, filename: Path, encoding: Optional[Text] = None, debug: bool = False
     ) -> NL:
         """Parse a file and return the syntax tree."""
         with io.open(filename, "r", encoding=encoding) as stream:

tests/data/collections.py

@@ -154,8 +154,8 @@
         InstanceIds=[instance.id], WaiterConfig={"Delay": 5,}
     )
     ec2client.get_waiter("instance_stopped").wait(
-        InstanceIds=[instance.id], WaiterConfig={"Delay": 5,},
+        InstanceIds=[instance.id], WaiterConfig={"Delay": 5,}
     )
     ec2client.get_waiter("instance_stopped").wait(
-        InstanceIds=[instance.id], WaiterConfig={"Delay": 5,},
+        InstanceIds=[instance.id], WaiterConfig={"Delay": 5,}
     )

tests/data/comments7.py

@@ -93,7 +93,7 @@ def func():
 
 
 def func():
-    c = call(0.0123, 0.0456, 0.0789, 0.0123, 0.0789, a[-1],)  # type: ignore
+    c = call(0.0123, 0.0456, 0.0789, 0.0123, 0.0789, a[-1])  # type: ignore
 
     # The type: ignore exception only applies to line length, not
     # other types of formatting.

tests/data/expression.diff

@@ -212,7 +212,7 @@
 +    .filter(
 +        models.Customer.account_id == account_id, models.Customer.email == email_address
 +    )
-+    .order_by(models.Customer.id.asc(),)
++    .order_by(models.Customer.id.asc())
 +    .all()
 +)
  Ø = set()

tests/data/expression.py

@@ -459,7 +459,7 @@ async def f():
     .filter(
         models.Customer.account_id == account_id, models.Customer.email == email_address
     )
-    .order_by(models.Customer.id.asc(),)
+    .order_by(models.Customer.id.asc())
     .all()
 )
 Ø = set()

tests/data/function.py

@@ -230,7 +230,7 @@ def trailing_comma():
     }
 
 
-def f(a, **kwargs,) -> A:
+def f(a, **kwargs) -> A:
     return (
         yield from A(
             very_long_argument_name1=very_long_value_for_the_argument,

tests/data/function2.py

@@ -25,7 +25,7 @@ def inner():
 
 # output
 
-def f(a, **kwargs,) -> A:
+def f(a, **kwargs) -> A:
     with cache_dir():
         if something:
             result = CliRunner().invoke(

tests/data/function_trailing_comma.py

@@ -9,17 +9,30 @@ def xxxxxxxxxxxxxxxxxxxxxxxxxxxx() -> Set[
 ]:
     pass
 
+def _gopass_process() -> Popen:
+    """Spawn a Gopass process"""
+    return Popen(
+        ['gopass', 'jsonapi', 'listen'],
+        stdout=PIPE,
+        stdin=PIPE,
+    )
+
 # output
 
-def f(a,):
+def f(a):
     ...
 
 
-def f(a: int = 1,):
+def f(a: int = 1):
     ...
 
 
 def xxxxxxxxxxxxxxxxxxxxxxxxxxxx() -> Set[
     "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
 ]:
     pass
+
+
+def _gopass_process() -> Popen:
+    """Spawn a Gopass process"""
+    return Popen(["gopass", "jsonapi", "listen"], stdout=PIPE, stdin=PIPE)