Add support for named exprs inside function calls as gen-exps (#3327)

CHANGES.md

@@ -26,6 +26,10 @@
 
 <!-- Changes to the parser or to version autodetection -->
 
+- Parsing support has been added for walruses inside generator expression that are
+  passed as function args (for example,
+  `any(match := my_re.match(text) for text in texts)`) (#3327).
+
 ### Performance
 
 <!-- Changes that improve Black's performance. -->

src/blib2to3/Grammar.txt

@@ -186,7 +186,7 @@ arglist: argument (',' argument)* [',']
 # multiple (test comp_for) arguments are blocked; keyword unpackings
 # that precede iterable unpackings are blocked; etc.
 argument: ( test [comp_for] |
-            test ':=' test |
+            test ':=' test [comp_for] |
             test 'as' test |
             test '=' asexpr_test |
 	    '**' test |

tests/data/py_310/pep_572_py310.py

@@ -2,3 +2,14 @@
 x[a:=0]
 x[a:=0, b:=1]
 x[5, b:=0]
+
+# Walruses are allowed inside generator expressions on function calls since 3.10.
+if any(match := pattern_error.match(s) for s in buffer):
+    if match.group(2) == data_not_available:
+        # Error OK to ignore.
+        pass
+
+f(a := b + c for c in range(10))
+f((a := b + c for c in range(10)), x)
+f(y=(a := b + c for c in range(10)))
+f(x, (a := b + c for c in range(10)), y=z, **q)