No call to copy constructor as expected

Question

I have some code like this:

int a = 5;
Foo *foo = new Foo(MoreFoo(a),
    Bar(a));

// Foo CTOR:
Foo(MoreFoo mf, Bar bar): MoreBar(&mf,bar){}

My compiler gives me an error of type:

no matching function for call to ‘Bar::Bar(Bar)’
note: candidates are:
note: Bar::Bar(Bar&)
no known conversion for argument 1 from ‘Bar’ to ‘Bar&’

The error obviously relates to the code Bar(a). Obviously Bar has appropriate CTOR and CCTOR. I understand why the compiler complains about trying to invoke something like Bar::Bar(Bar), I'm creating a nameless variable (Bar(a)) which has to be copied during the call to the Foo constructor, but then shouldn’t it just invoke Bar CCTOR? Why am I getting the error?

Edit:

Why would you ever want to invoke Bar::Bar(Bar) instead of Bar::Bar(Bar&)?

Answer 1

Temporaries cannot be bound to references unless they are references-to-const.

Answer 2

It seems that you declatred the copy constructor of class Bar the following way

Bar( Bar & );

But you need to declare it as

Bar( const Bar & );

if you want to use as an argument a temporary object because temporary objects may not be bound to non-const references.