Generated prototypes are added after global variable declarations

[per1234]

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Using Arduino IDE 1.6.8 2015/12/28 12:34 with Windows 7 64 bit Generated prototypes are added after global variable declarations which causes error when the global variable initialization calls a function.

byte x = one();

byte one() {
  return 1;
}

void setup() {}
void loop() {}

Compiler error: 'one' was not declared in this scope

Generated code:

#include <Arduino.h>
#line 1
#line 1 "C:\\Users\\per\\AppData\\Local\\Temp\\arduino_ada7ab83d38e9f542377ce1f8da0ce54\\sketch_dec29a.ino"
byte x = one();

#line 3 "C:\\Users\\per\\AppData\\Local\\Temp\\arduino_ada7ab83d38e9f542377ce1f8da0ce54\\sketch_dec29a.ino"
byte one();
#line 7 "C:\\Users\\per\\AppData\\Local\\Temp\\arduino_ada7ab83d38e9f542377ce1f8da0ce54\\sketch_dec29a.ino"
void setup();
#line 8 "C:\\Users\\per\\AppData\\Local\\Temp\\arduino_ada7ab83d38e9f542377ce1f8da0ce54\\sketch_dec29a.ino"
void loop();
#line 3
byte one() {
  return 1;
}

void setup() {}
void loop() {}

This compiles fine in Arduino IDE 1.6.5r5 and works in 1.6.6 and up if the function prototype is manually added.

Originally reported at http://forum.arduino.cc/index.php?topic=366573.msg2540168#msg2540168

[matthijskooijman]

The prototypes are generated just before the first function definition. I believe the idea is that this helps to put the prototypes after any type definitions, but in your example it also puts them after the first reference, breaking them. For now, the fix is to add a prototype manually. To really properly fix this, arduino-builder should actually parse the source and construct a dependency tree and use that to figure out where to put each prototype, but the current ctags-based approach doesn't allow that. I believe @cmaglie was looking into using clang instead of ctags, but even then the dependency generation and resolution is still a non-trivial problem...

[per1234]

Understood, thanks. I wasn't sure if this was intentional or unavoidable but thought it was worth at least to document the change from 1.6.5. I have already suggested manually adding the prototype as a workaround to the reporting user

[facchinm]

Will be solved by merging https://github.com/arduino/arduino-builder/pull/191