Should _DEBUG always get defined in configurations with debug symbols?

[rewrking]

Requesting some feedback from anyone who has an opinion on this:

Right now, _DEBUG gets defined in all *-pc-windows-msvc builds when a build configuration has debugging symbols. This is not consistent with GNU-based toolchains where it's not defined automatically for you, and something I've been on the fence about changing.

Should this get defined by other toolchains as well? I have a tendency to add "defines[:debug]": [ "_DEBUG" ] in projects anyway, and use that to define my own project-specific debug macro (or NDEBUG if using assert) in the PCH somewhere.

Additional notes:

• _MT, _DLL and _DEBUG could all get defined by MSVC via /MTd and /MDd. If compiling windows targets via clang, they get set manually right now to mimic the behavior
• __OPTIMIZE__ is the way to query this on GCC/clang

Curious about other's thoughts on this topic.

👍 Yes, automatically define _DEBUG
👎 No, undefine _DEBUG in pc-windows-msvc
👀 No, leave this behaviors as-is

[paulross80]

I've always defined my own macro/const static bool on every project, just to make sure it will work on every platform