method (a, b = '', *c, **d): gets a syntax error?

[Terry Reedy]

>(Gerrit Holl) Python 2.3 does the same.
>
> Python 2.3 (#1, Aug  5 2003, 14:13:25)
> [GCC 3.2.2 20030222 (Red Hat Linux 3.2.2-5)] on linux2
> Type "help", "copyright", "credits" or "license" for more
information.
>   0 >>> zip(**(),)
>   File "<stdin>", line 1
>     zip(**(),)
>             ^
> SyntaxError: invalid syntax
>   1 >>> def foo(**a,): pass
>   File "<stdin>", line 1
>     def foo(**a,): pass
>                ^
> SyntaxError: invalid syntax

Thank you for the verification. I have submitted doc bug report SF
798652

>(Michael Hudson): Because that's what the grammar says

After the grammer in 5.3.4 follows :"A trailing comma may be present
after an argument list but does not affect the semantics. "  I
suggested instead "If an argument list does *not* end with *expr or
**expr, a trailing comma may be added without affecting the
semantics."

I also suggested a change in 7.5 Function definitions to the
production for parameter_list.

>(Piet von Oostrum) [Explanation of why '**dic,)' should be error]

I agree, which is why I filed as doc bug.  Note

>>> def fl(*lis,): pass
  File "<stdin>", line 1
    def fl(*lis,): pass
                ^ # points at ')'
SyntaxError: invalid syntax

The error is detected as ')' instead of ',' because **dic could have
followed, but didn't.

Terry J. Reedy