Building the latest versions of Eloquent or Foxy from source produces several warnings on Windows with the following message:

C5105: macro expansion producing 'defined' has undefined behavior

For example (foxy):

Seems to be coming from the following rcutils source files on the foxy branch:

• rcutils\src\filesystem.c
• rcutils\src\logging.c
• rcutils\src\process.c
• rcutils\src\shared_library.c
• rcutils\src\testing\fault_injection.c
• rcutils\src\time_win32.c

I have not observed the warning on Dashing or Rolling.