Weird replacement of LV_CONF_PATH

[polarkernel]

I try to set up a very simple project, that just includes esp32_smartdisplay, without using it yet:

#include <Arduino.h>
#include <esp32_smartdisplay.h>
void setup() {
  #ifdef ARDUINO_USB_CDC_ON_BOOT
      delay(5000);
  #endif
      Serial.begin(115200);
      Serial.println("Hello World!");
}

void loop() {
}

I like to use the board esp32-2432S032R. My platform.ini looks like this:

[env:esp32-2432S032R]
platform = espressif32
board = esp32-2432S032R
framework = arduino

upload_speed = 460800
upload_port = COM12
monitor_speed = 115200
monitor_port = COM12

lib_deps = 
    rzeldent/esp32_smartdisplay

build_flags =
    -Ofast
    -Wall
    -D LV_CONF_PATH="${PROJECT_DIR}/include/lv_conf.h"

But this doesn't compile, I get a bunch of errors, all the same form:

In file included from .pio/libdeps/esp32-2432S032R/lvgl/src/core/lv_obj.h:16,
                 from .pio/libdeps/esp32-2432S032R/lvgl/src/core/lv_event.c:9:
.pio/libdeps/esp32-2432S032R/lvgl/src/core/../lv_conf_internal.h:35:42: fatal error: D:/1/PlatformIO/Display-2432/include/lv_conf.h: No such file or directory
         #include __LV_TO_STR(LV_CONF_PATH)
                                          ^
compilation terminated.

The true project folder D:/ESP32/PlatformIO/Display-2432 is replaced by D:/1/PlatformIO/Display-2432 somehow, which results in a wrong path to the include file lv_conf.h. I tried several forms of definitions for LV_CONF_PATH (only one of them uncommented), all resulting in the same error:

    -D LV_CONF_PATH="${PROJECT_INCLUDE_DIR}/lv_conf.h"
    -D LV_CONF_PATH="D:/ESP32/PlatformIO/Display-2432/include/lv_conf.h"
    -D LV_CONF_PATH="${PROJECT_DIR}/include/lv_conf.h"
    -D LV_CONF_PATH="${platformio.include_dir}/lv_conf.h"

Even if I give the full path, it is replaced. In my desperation, I created a folder D:/1/PlatformIO/Display-2432/include/ and put the lv_conf.h file there. Lo and behold, the program compiles and runs correctly!

Have any of you ever come across something like this, or have any idea where this D:/1/ is constructed? Where is this done? I am at the end of my knowledge and need help.

[polarkernel]

Sometimes it is helps to write about a problem. After some further investigation, I found the reason for this strange behavior. It is really unexpected for me. I found, that the definition created by the build flags is correct, but its expansion (nicely shown by IntelliSense) is wrong:

It seems that "ESP32" is replaced by "1". In a next step, I tried to find out, if "ESP32" also already has a definition, and what I found:

So parts of a folder path can be replaced by such definitions. This can lead to very unexpected results!