Using preprocessor directives defined in platformio.ini

1

I’m trying to use defines placed in platformio.ini in code so that each “env” can have conditional code. However, it’s not working they way it seems it should…

In platformio.ini:

[common_env_data]
build_flags =
    -D VERSION=\"1.2.3\"
    -D BUILD_ENV_NAME=$PIOENV
    -D BUILD_PLATFORM=$PIOPLATFORM
    -D BUILD_TIME=$UNIX_TIME

[env:adafruit_feather_nrf52832]
platform = nordicnrf52
board = adafruit_feather_nrf52832
framework = arduino
build_flags =
    ${common_env_data.build_flags}
lib_deps = 
    ${common_env_data.lib_deps}
monitor_speed = 115200

[env:adafruit_feather_m0]
platform = atmelsam
board = adafruit_feather_m0
framework = arduino
build_flags =
    ${common_env_data.build_flags}
lib_deps = 
    ${common_env_data.lib_deps}
monitor_speed = 115200

[env:featheresp32]
platform = espressif32
board = featheresp32
framework = arduino
build_flags =
    ${common_env_data.build_flags}
    -D ESP32
lib_deps = 
    ${common_env_data.lib_deps}
monitor_speed = 115200

in cpp code:

#if BUILD_ENV_NAME==adafruit_feather_nrf52832
#include <bluefruit.h>
#elif BUILD_ENV_NAME==adafruit_feather_m0
#include "Adafruit_BLE.h"
#include "Adafruit_BluefruitLE_SPI.h"
#include "Adafruit_BluefruitLE_UART.h"
#elif BUILD_ENV_NAME==featheresp32
#include "BluetoothSerial.h"
#endif

What is happening is that the first section is always being included regardless of which env is choses in the IDE, and all others are not. For example if I choose env:featheresp32 in the IDE and then compile I get an error cannot open bluefruit.h. This file should even be attempted loading since this is not the env selected. If I hover the mouse over the BUILD_ENV_NAME the IDE correctly shows that it evaluates to featheresp32. Yet for some reason, the section the wrong part is being included.

I need to be able to use an #if directive with a condition of the specific env being compiled.

1 Like
2

Yeah but probably not in quotes, so it’s not a string. Try quoting the value the same way you did with VERSION. BUILD_PLATFORM needs the same treatment.

3

Oh, actually you can’t use strings in a preprocessor #if(source).

You should use implicitly defined macros like

  • ARDUINO_ARCH_ESP32 (here)
  • ARDUINO_ARCH_NRF52 (here)
  • ARDUINO_ARCH_SAMD (here)

to differentiate the build environment types.

You can still stringify the macros and use them in print statements or whatever.

4

Adafruit is just an example and not specific to the issue, so I can’t rely on adafruit’s *.py lib code for cppdefines when not using adafruit boards. Nor, do I think it should be necessary to track down these cppdefines with whatever board I happen to be using. I’m relying on build_flags in the platformio.ini file as documented in Redirecting..., c.f. “build_flags = -D BUILD_ENV_NAME=$PIOENV”.

So do I understand correctly that this specifically documented use of $PIOENV in platformio.ini has no actual use case with #if directives within cpp code? If so, what could the possible uses of “build_flags = -D BUILD_ENV_NAME=$PIOENV” be?

5

After some experimenting I see that the platformio.ini file build_flags = -D BUILD_ENV_NAME=$PIOENV is when the env is set to “adafruit_feather_nrf52832” is equivalent to cpp #define BUILD_ENV_NAME adafruit_feather_nrf52832 followed by #define adafruit_feather_nrf52832 1. So using that build_flag will cause the value of $PIOENV to be it’s own #define! This is counterintuitive and I wonder if this could cause strange compilation errors if I use an environment name that happens to step on some #define in some library somewhere.

Anyway I can just use #ifdef adafruit_feather_nrf52832 which means that it’s much simpler to change the platformio.ini define to build_flags = -D $PIOENV in this case and not use BUILD_ENV_NAME at all.

However, if I leave build_flags = -D BUILD_ENV_NAME=$PIOENV as is I have to also add in cpp some explicit redefines of the various envs like “#define adafruit_feather_nrf52832 100”, adafruit_feather_m0 101" etc. which will allow me to use #if BUILD_ENV_NAME==adafruit_feather_nrf52832, and follow with an #else and #error "BUILD ENV NOT DEFINED, if I forget to add one. I cannot start the redefines from 1 (as in #define adafruit_feather_nrf52832 1) since the selected environment is already set to 1 and all other environments will compare to 0 which will cause the various #if directives to fail.

So I can get it to work as expected, but it’s not as elegant as I had hoped.

#ifndef BUILD_ENV_NAME
    #error "Add -D BUILD_ENV_NAME=$PIOENV to platformio.ini build_flags"
#else
    #define adafruit_feather_nrf52832 101
    #define adafruit_feather_nrf52840 102
    #define adafruit_feather_32u4 103
    #define adafruit_feather_m0 104
    #define featheresp32 105
#endif

#if BUILD_ENV_NAME==adafruit_feather_nrf52832
#include <bluefruit.h>
#elif BUILD_ENV_NAME==adafruit_feather_nrf52840
#include <bluefruit.h>
#elif BUILD_ENV_NAME==adafruit_feather_m0
#include "Adafruit_BLE.h"
#include "Adafruit_BluefruitLE_SPI.h"
#include "Adafruit_BluefruitLE_UART.h"
#elif BUILD_ENV_NAME==featheresp32
#include "BluetoothSerial.h"
#else
#error "BUILD_ENV_NAME NOT RECOGNIZED"
#endif

I will probably rename all my environments to prepend “env_” to the beginning of them just in case some other library happens to use a #if that happens to be the same name as my envonment.

1 Like