[Programming] "is of non-class type" and Constructor with no input

class Foo
{
  public:
    Foo() {};
    Foo(int a) {};
    void bar() {};
};
int main()
{
  // this works...
  Foo foo1(1);
  foo1.bar();

  // this does not...
  Foo foo2();
  foo2.bar();

  return 0;
}

ER MSG:

nonclass.cpp: In function ‘int main(int, const char**)’:
nonclass.cpp:17: error: request for member ‘bar’ in ‘foo2’, which is of non-class type ‘Foo ()()’
Correct:

Foo foo2;

Compiler think  the declaration Foo foo2()  is not a constructor. Instead, it is a function "foo2()" which return class FOO.

Therefore, when we are going to access the member function, bar, we "request for member"bar" in foo2但foo2 is of non-class type"

Some similar error msg

error: request for member 'computeLog2Det' in '((ULSA3a*)this)->ULSA3a::matrixComputer', which is of non-class type 'CORRE_MA_OPE*'|

when matrixComputer is declared as CORRE_MA_OPE* matrix computer  

and we use in matrixComputer.computeLog2Det(1.0,cSystem->allSupStru);

[Debugger]Windows/Unix: Memory Initialization

For variable memory initialization:
Windows won't initialize the unassigned variable to zero, while Linux(Fedora) do so.

The bug happened refer to the ULSA2g in M2M Network Simulator when I access the uninitialized reference variable.