Using Arduino IDE 1.6.7 2015/11/20 05:49 with Windows 7 64 bit The automatically generated prototype for function return type `const __FlashStringHelper*` is missing the space between `const` and `__FlashStringHelper*` ``` arduino void setup() {} void loop() {} const __FlashStringHelper* test() { return F("y"); } ``` error message: `sketch_nov22a:4: error: 'const__FlashStringHelper' does not name a type` This problem doesn't occur in Arduino IDE 1.6.5r5 Originally reported at http://forum.arduino.cc/index.php?topic=361074.0