CTFE calling a template: Error: expression ... is not a valid template value argument

[Jens Mueller]

Hi,

I do not understand the following error message given the code:

string foo(string f)
{
    if (f == "somestring")
    {
        return "got somestring";
    }
    return bar!(foo("somestring"));
}

template bar(string s)
{
    enum bar = s;
}

I'll with dmd v2.060 get:
test.d(7):        called from here: foo("somestring")
test.d(7):        called from here: foo("somestring")
test.d(7):        called from here: foo("somestring")
test.d(7): Error: expression foo("somestring") is not a valid template value argument
test.d(12):        called from here: foo("somestring")
test.d(12):        called from here: foo("somestring")
test.d(7): Error: template instance test.bar!(foo("somestring")) error instantiating

In line 7 I call the template bar. But I call with the string that is
returned by the CTFE of foo("somestring") which should return "got
somestring" but instead it seems that an expression is passed. How do I
force the evaluation foo("somestring")?
I haven't found a bug on this.

Jens