$PIOENV changes include path in build flag

Hello,
trying to do

[env:brain_node]
build_flags = -I src/$PIOENV

in platformio.ini for some reason produces strange path
-I/Users/xxx/.platformio/platforms/ststm32/builder/src/brain_node

Im expecting:
-I src/brain_node

Thanks!
With regards,
Ivan

Ok, again found a solution myself :rofl:

It seems that relative path’s in build_flags with some environment variable always resolves wrong. Solution was to set an absolute path from an extra_script.

Import("env")

PIOENV = env.subst("$PIOENV")
PROJECT_SRC_DIR = env.subst("$PROJECT_SRC_DIR")
 
env.Append(
    CPPPATH=[PROJECT_SRC_DIR + "/" + PIOENV + "/inc"]
)

You should do from os import path and then

    CPPPATH=[path.join(PROJECT_SRC_DIR, PIOENV, "inc")]

there to be safe