How to make CPP files visible to linker in ESP8266 Eclipse project

Question

There is a "hello world" project in Eclipse IDE that is supposed to compile against ESP8266 RTOS SDK.

File structure is as follows

I added one C++ class to it and put it into its own folder. Here is the class header

#ifndef MAIN_BLINKER_BLINKER_H_
#define MAIN_BLINKER_BLINKER_H_

class Blinker {
public:
  Blinker( int period );
  int Period() const;
private:
  int period_;
};

#endif /* MAIN_BLINKER_BLINKER_H_ */

and the definitions

#include "Blinker.h"

Blinker::Blinker( int period ) :
  period_( period )
{}

int Blinker::Period() const {
  return this->period_;
}

Main.cpp file is like this

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "blinker/Blinker.h"

extern "C" {

void app_main()
{
  auto blnk = Blinker( 3000 );
  int i = 0;
  while ( 1 ) {
    printf( "[%d] Hello beautiful world!\n", i );
    i++;
    vTaskDelay( blnk.Period() / portTICK_PERIOD_MS );
  }
}

}

It compiles but fails at final stage because the linker (or what is supposed to be a linker in xtensa toolchain) does not see definitions of Blinker methods. This is what I get in the build log

If I put class files next to main.cpp file, the build succeeds. However with time there will be hundreds of files, and without any grouping it will quickly turn into an unmanageable mess.

Alternatively I could put this class into top-level components folder and equip it with empty component.mk file. This would also make the build system happy, however it would force me to use ugly header includes like ../components/blinker/Blinker.h, which I would like to avoid.

So the question is how to make build system aware of .c and .cpp files residing in subfolders of main folder?

Answer 1

you can set COMPONENT_SRCDIRS in "main" component.mk file

see: https://docs.espressif.com/projects/esp8266-rtos-sdk/en/latest/api-guides/build-system.html#example-component-makefiles