std.traits.ParameterIdentifierTuple problem

[Carl Sturtivant]

Using the 
[ParameterIdentifierTuple](https://dlang.org/phobos/std_traits.html#ParameterIdentifierTuple) example just there, with one more step stops working. Details:
```D
import std.traits;
int foo(int num, string name, int);
static assert([ParameterIdentifierTuple!foo] == ["num", "name", 
""]);

alias signature = typeof(foo);
pragma(msg, signature.stringof);
enum names = [ParameterIdentifierTuple!signature];
pragma(msg, names.stringof);
static assert(names==["num","name",""], "wrong!");
```
Output on compilation:
```
$ dmd --version
DMD64 D Compiler v2.107.0
Copyright (C) 1999-2024 by The D Language Foundation, All Rights 
Reserved written by Walter Bright

$ dmd -c bug1.d
int(int num, string name, int)
["", "", ""]
bug1.d(9): Error: static assert:  "wrong!"
```
Please explain. How do I get the names of the identifiers out of 
a parameter list at compile time reliably?