[Bug c++/67113] New: unintelligent error message "only declarations of constructors can be 'explicit'" in cpp file's constructor define.

["robinh3123 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67113

            Bug ID: 67113
           Summary: unintelligent error message "only declarations of
                    constructors can be 'explicit'" in cpp file's
                    constructor define.
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: robinh3123 at gmail dot com
  Target Milestone: ---

For the following codes (in 3 files):

$ cat a.cpp
#include "a.h"

int A::f()
{
        return n+1;
}

explicit A::A(int _n)   // <=== error at this line
{
        n = _n;
}



$ cat  a.h
class A
{
public:
        int n;
        int f();
        explicit A(int _n);
};



$ cat main.cpp
#include <iostream>
#include "a.h"  // for class A

using namespace std;

int main()
{
        A a(5);
        int i = a.f();
        cout << i << endl;
    return 0;
}


The compiler reports error message:
a.cpp:8:21: error: only declarations of constructors can be 'explicit'
 explicit A::A(int _n)

This is misleading, since A::A is really a constructor.
The error message should be something similar to:
     extra explicit before function A::A