Fix call patterns that contain as-expression on the kwargs

CHANGES.md

@@ -12,6 +12,8 @@
   (#2686)
 - Fix cases that contain multiple top-level as-expressions, like `case 1 as a, 2 as b`
   (#2716)
+- Fix call patterns that contain as-expressions with keyword arguments, like
+  `case Foo(bar=baz as quux)` (#2749)
 - No longer color diff headers white as it's unreadable in light themed terminals
   (#2691)
 - Tuple unpacking on `return` and `yield` constructs now implies 3.8+ (#2700)

src/blib2to3/Grammar.txt

@@ -187,7 +187,7 @@ arglist: argument (',' argument)* [',']
 argument: ( test [comp_for] |
             test ':=' test |
             test 'as' test |
-            test '=' test |
+            test '=' asexpr_test |
 	    '**' test |
             '*' test )
 

tests/data/pattern_matching_extras.py

@@ -103,3 +103,17 @@ def func(match: case, case: match) -> case:
 
     case 4 as d, (5 as e), (6 | 7 as g), *h:
         pass
+
+
+match bar1:
+    case Foo(aa=Callable() as aa, bb=int()):
+        print(bar1.aa, bar1.bb)
+    case _:
+        print("no match", "\n")
+
+
+match bar1:
+    case Foo(
+        normal=x, perhaps=[list, {an: d, dict: 1.0}] as y, otherwise=something, q=t as u
+    ):
+        pass