C++ API, DEBUG symbol conflict

[adujardin]

Describe the bug
This is technically not a bug but when trying to integrate rerun C++ API into a pretty big C/C++ codebase (with third-party dependencies) the compilation fails because some file already defined "DEBUG" as a macro. While a questionable choice, it's unfortunately pretty common in C code. The compilation fails at

rerun/rerun_cpp/src/rerun/components/text_log_level.hpp

Line 54 in 1f58d96

static const TextLogLevel DEBUG;

with an error like:

text_log_level.hpp:54:26: error: declaration does not declare anything [-fpermissive]
   54 |             static const TextLogLevel DEBUG;
      |                          ^~~~~~~~~~~~

One quick and dirty way to fix or at least to confirm this, is something like this is in the same header:

#ifdef DEBUG
#undef DEBUG
#endif

Another common solution is to not use "DEBUG" and instead DBG, _DBG, etc

Desktop:

• OS: Ubuntu GCC 9.4, although it's not really relevant here

Rerun version
0.10

Additional context

[Wumpf]

Good catch. DEBUG as name is an identifier is very unfortunate indeed, we'll have to put something else in there.
DBG and _DBG are defines I've seen in the past as well, so we'll have to do something else, probably some post/prefix 🤔

[emilk]

Adding #undef DEBUG implies #include <rerun.h> would un-define DEBUG. That means it may break user code that relies on that macro may break.

Other variations of DEBUG such as DEBUG_ DBG etc are also likely to be macros.

An alternative solution is to use PascalCase for constants instead, as those are much less likely to be macros, i.e. change this to static const TextLogLevel Debug; and TextLogLevel::Debug.

Another benefit of the PascalCase convention is that it is closer to Rust.

[Wumpf]

Fixed by #4152