invalid use of incomplete type error in pimpl idiom

foo.h

#include"fooImpl.h"

    class foo                                                                                                           
    {                                                                                                                                                 
        private:
            class fooImpl;                                                                                                                
            std::unique_ptr <fooImpl> foo_imple;
        public:
            void bar();                                                                                                                                      

    };

fooImpl.h

#include "foo.h"

    class foo::fooImpl                                                                                                           
    {                                                                                                                                                 
        public:                                                                                                                                       
            void api();                                                                                                                                                                                                                                                                                                          
    };

foo.cpp

#include "foo.h"

foo::bar()
{
    foo_imple->bar();
}

fooImpl.cpp

#include"foo.h"
#include"fooImpl.h"

void                                                                                                                                              
foo::fooImpl::foo()                                                                                                  
{                                                                                                                                                 
    cout << "bar";                                                                                                               
}

Getting the following error:

error: invalid use of incomplete type 'class foo::fooImpl'
      foo_imple->bar();


note: forward declaration of 'class foo::fooImpl'
     class fooImpl;

Not able to find out whats wrong with this pimpl implementation. Error looks like due to some declaration missing.