Includes in a separate file

[tobyb121]

When a standard library is included in a separate file from the main sketch ino, the error: " error: '###' was not declared in this scope" occurs when compiling.
This has been tested on Arduino IDE v 1.0.3 on Windows 8 x64
The following code does not compile without line 1 of mainSketch.ino being un-commented.

mainSketch.ino

// #include <Wire.h>
#include "myLibrary.h"

void setup(){
  initWire();
}

void loop(){}

myLibrary.h

#pragma once
#ifndef MY_LIBRARY_H
#define MY_LIBRARY_H

#include <Wire.h>

void initWire();

#endif

myLibrary.cpp

#include "myLibrary.h"

void initWire(){
  Wire.begin();
}

[cmaglie]

Duplicate of #236
Note: the issue started long ago on gc http://code.google.com/p/arduino/issues/detail?id=236