Platformio-core: Preprocessor bug ignores #ifndef - breaks Blink example

[n0dyjeff]

What kind of issue is this?

• [X] PlatformIO Core. If you’ve found a bug, please provide an information below.

Configuration

Windows 10

PlatformIO Version (platformio --version):
PlatformIO, version 3.4.0a4

Description of problem

Summary: An #ifndef preprocessor conditional is ignored, causing the conditionally included statements to be compiled despite the fact that the symbol is already defined.

Details: I was testing my new installation of PlatformIO IDE, and followed the steps to build the Blink example. I was astonished to find that it didn't work. What I found was the following code ignored the definition of LED_BUILTIN (found in pins_arduino.h, included by Arduino.h and set to 16) and instead redefined it to 13.

#include "Arduino.h"     // #includes "pins_arduino.h", which #defines LED_BUILTIN 16

#ifndef LED_BUILTIN
#define LED_BUILTIN 13   // shouldn't get processed since LED_BUILTIN already defined
#endif

This code caused GPIO 13 to be toggled - which is incorrect, since the LED_BUILTIN value is 16. Changing the code to comment out the #define corrects the issue:

#ifndef LED_BUILTIN
//#define LED_BUILTIN 13
#endif

Steps to Reproduce

1. Build and install the source code below to a NodeMCU V1.0. Note serial output and behavior of built in LED.
2. Comment out the LED_BUILTIN definition and again note serial output and built-in LED behavior.

#ifndef LED_BUILTIN
//#define LED_BUILTIN 13
#endif

Actual Results

Step 1
Serial output:
LED_BUILTIN = 13
Built in LED does not blink (but GPIO 13 toggles)
Step 2
Serial output:
LED_BUILTIN = 16
Built in LED blinks

Note that if LED_BUILTIN was _truly_ undefined (as indicated by the results of Step 1), there should have been a compile failure due to the symbol not being found.

Expected Results

Step 1
Serial output:
LED_BUILTIN = 16
Built in LED blinks
Step 2
Serial output:
LED_BUILTIN = 16
Built in LED blinks

If problems with PlatformIO Build System:

The content of platformio.ini:

[env:nodemcuv2]
platform = espressif8266
board = nodemcuv2
framework = arduino
upload_speed = 460800

Source file to reproduce issue:

#include "Arduino.h"

#ifndef LED_BUILTIN
#define LED_BUILTIN 13
#endif

void setup()
{
  // initialize LED digital pin as an output.
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(115200);
}

void loop()
{
  // turn the LED on (HIGH is the voltage level)
  digitalWrite(LED_BUILTIN, HIGH);
  Serial.print("LED_BUILTIN = ");
  Serial.println(LED_BUILTIN);
  // wait for a second
  delay(1000);

  // turn the LED off by making the voltage LOW
  digitalWrite(LED_BUILTIN, LOW);

   // wait for a second
  delay(1000);
}

Additional info

[ivankravets]

PIO Core doesn't touch your code. Do you use *.cpp extension? I've just even tried to debug and prepared for you real-time picture. As you can see, I overrode LED_BUILTIN with 15 but 13 is the actual value. See watch pointer for ulPin:

[n0dyjeff]

Hi Ivan, thanks for looking in to this.

Yes, my file is named main.cpp

I'm not sure I understand your results. You are getting a value of 13 for LED_BUILTIN. That isn't the value defined in the NodeMCU version of "pins_arduino.h", which is 16. Were you building against "nodemcuv2"? If so, I don't understand where the value of 13 is coming from for you. It should be 16.

Regardless, I see your point that LED_BUILTIN is not being redefined to 15 when you run your code. So in your case, it's behaving as though the symbol is defined and skipping over the #define.

So, we are running similar tests but getting different results. There must be some differences that account for this.

If you would share your source code, I will run it on my system and see what results I get. Perhaps that will help us get to the root of the issue.

[n0dyjeff]

Now that I look more carefully, I see that you are just setting watchpoints to capture the value passed to pinMode. So I guess I don't need your source code :). But I'm a noob to Platform.io, so it may take me a while to figure out how to do watchpoints for a NodeMCU build - if that's even possible. I suspect that I might have to build for the host platform (Windows) to use? I'll find out.

Is it possible you could try to reproduce the problem by downloading to a NodeMCU, as I show in my original note? It would be good to know if someone else gets this same behavior, or if it's unique somehow to my installation.

[ivankravets]

Do you use .cpp or .ino format?

[n0dyjeff]

My file is named main.cpp, exactly as shown in the example application.

[ivankravets]

Thanks, I reproduced this issue!

[n0dyjeff]

Awesome! Thanks for staying with it.

[ivankravets]

The problem that in Arduino for Espressif LED_BUILTIN is set as static variable(not macro). See https://github.com/esp8266/Arduino/blob/master/variants/nodemcu/pins_arduino.h#L37

I'll update tutorial. Please remove that #ifdef block.

[n0dyjeff]

OK, thanks very much. Again, many thanks for digging into it. I was having difficulty committing to move forward with Platformio when such a simple example didn't work. Now I can adopt it with greater confidence.

[ivankravets]

All examples have been updated! Thank you too!