B030: allow splats and calls (#354)

Fixes #352.

I allow calls in addition to splats because a real-world false positive was reported
and buggy code doesn't seem common enough to merit an on-by-default error.

Author: JelleZijlstra

README.rst

@@ -325,6 +325,11 @@ MIT
 Change Log
 ----------
 
+Unreleased
+~~~~~~~~~~
+
+* B030: Allow calls and starred expressions in except handlers.
+
 23.2.13
 ~~~~~~~~~
 

bugbear.py

@@ -333,17 +333,25 @@ def visit_ExceptHandler(self, node):
         handlers = _flatten_excepthandler(node.type)
         good_handlers = []
         bad_handlers = []
+        ignored_handlers = []
         for handler in handlers:
             if isinstance(handler, (ast.Name, ast.Attribute)):
                 good_handlers.append(handler)
+            elif isinstance(handler, (ast.Call, ast.Starred)):
+                ignored_handlers.append(handler)
             else:
                 bad_handlers.append(handler)
         if bad_handlers:
             self.errors.append(B030(node.lineno, node.col_offset))
         names = [_to_name_str(e) for e in good_handlers]
-        if len(names) == 0 and not bad_handlers:
+        if len(names) == 0 and not bad_handlers and not ignored_handlers:
             self.errors.append(B029(node.lineno, node.col_offset))
-        elif len(names) == 1 and not bad_handlers and isinstance(node.type, ast.Tuple):
+        elif (
+            len(names) == 1
+            and not bad_handlers
+            and not ignored_handlers
+            and isinstance(node.type, ast.Tuple)
+        ):
             self.errors.append(B013(node.lineno, node.col_offset, vars=names))
         else:
             maybe_error = _check_redundant_excepthandlers(names, node)

tests/b030.py

@@ -12,3 +12,18 @@
     pass
 except (1, ValueError):  # error
     pass
+
+try:
+    pass
+except (ValueError, *(RuntimeError, TypeError)):  # ok
+    pass
+
+
+def what_to_catch():
+    return (ValueError, TypeError)
+
+
+try:
+    pass
+except what_to_catch():  # ok
+    pass