Instance of a non-templated class using templated constructor interpreted as a function definition?

Question

My issue is best demonstrated by the following code:

#include 
#include 

class Bar
{
    public: template 

        

Answer 1

I think it is related to "C++ most vexing parse" that you will find in Meyer's Effective STL book.

 Bar bar(std::istream_iterator< char >(file), std::istream_iterator < char >()); 

Is being considered as a **function declaration.**

due to which in foo(bar); you are sending a function pointer instead :)

Doing like below will have no error: Bar bar = Bar(//your arguments here); foo(bar);

Answer 2

ArunMu gets partial credit, it is indeed an example of Most Vexing Parse, but that term was coined in Meyer's Effective STL (Chapter 1, Item 6) not Exceptional C++.

It is being interpreted as a function pointer (the (__cdecl *) portion of the error is a dead give away), and apparently the C++ standard requires it to be interpreted that way. Does anyone have a chapter/verse citation for that?

There is also a another solution to provide a disambiguation. Adding an additional set of parenthesis around each parameter works too:

Bar bar( (std::istream_iterator<char>(file)), (std::istream_iterator<char>()) );

It's also worth pointing out that the issue is unrelated to the templates, as I had originally thought.