Fix crash on await (a ** b)

CHANGES.md

@@ -10,6 +10,8 @@
 
 <!-- Changes that affect Black's stable style -->
 
+- Fix crash on formatting code like `await (a ** b)` (#3994)
+
 ### Preview style
 
 - Multiline dictionaries and lists that are the sole argument to a function are now

src/black/linegen.py

@@ -1354,14 +1354,18 @@ def remove_await_parens(node: Node) -> None:
                 if bracket_contents.type != syms.power:
                     ensure_visible(opening_bracket)
                     ensure_visible(closing_bracket)
-                elif (
-                    bracket_contents.type == syms.power
-                    and bracket_contents.children[0].type == token.AWAIT
-                ):
-                    ensure_visible(opening_bracket)
-                    ensure_visible(closing_bracket)
-                    # If we are in a nested await then recurse down.
-                    remove_await_parens(bracket_contents)
+                elif bracket_contents.type == syms.power:
+                    if bracket_contents.children[0].type == token.AWAIT:
+                        ensure_visible(opening_bracket)
+                        ensure_visible(closing_bracket)
+                        # If we are in a nested await then recurse down.
+                        remove_await_parens(bracket_contents)
+                    elif any(
+                        isinstance(child, Leaf) and child.type == token.DOUBLESTAR
+                        for child in bracket_contents.children
+                    ):
+                        ensure_visible(opening_bracket)
+                        ensure_visible(closing_bracket)
 
 
 def _maybe_wrap_cms_in_parens(

tests/data/cases/remove_await_parens.py

@@ -80,6 +80,15 @@ async def main():
 async def main():
     await (yield)
 
+async def main():
+    await (a ** b)
+    await (a[b] ** c)
+    await (a ** b[c])
+    await ((a + b) ** (c + d))
+    await (a + b)
+    await (a[b])
+    await (a[b ** c])
+
 # output
 import asyncio
 
@@ -174,3 +183,13 @@ async def main():
 
 async def main():
     await (yield)
+
+
+async def main():
+    await (a**b)
+    await (a[b] ** c)
+    await (a ** b[c])
+    await ((a + b) ** (c + d))
+    await (a + b)
+    await a[b]
+    await a[b**c]