How to list defined symbols?

FAQ
2

PlatformIO Build System is based on SCons tool. SCons doesn’t provide this information because it is buid system (not compiler). Nevertheless, you can resolve it with extra_script.

The full process should look like:

  1. Create extra script for PlatformIO Build System
  2. Get a list with build files
  3. Run gcc -fpreprocessed -E -dM on each file
  4. Parse defines

Here is explanation how to list all files that are going to be built https://bitbucket.org/scons/scons/wiki/FindTargetSources
This approach requires Python and SCons skills. I even don’t know how to explain in a few words how to resolve it.

SCons is build tool/framework (Python-based alternative to make/cmake). We created own cross-platform super-fast Build System with automatic Library Dependecy Finder for development platforms . Here is source code and development platforms.