[llvm-dev] [RFC] Change DEBUG() macro to LLVM_DEBUG()

[Nicola Zaghen via llvm-dev]

Hi all,

We recently stumbled upon some issues with the DEBUG() macro being 
redefined in some internal libraries and some external ones, such as 
LLVM. After trying out a few ideas to avoid the problem we thought that 
the simplest solution would be to prefix all generic macro names in 
order to avoid clashes.

A quick search showed that Mesa had a similar issue with DEBUG being 
used by LLVM and had a couple of proposed patches such as 
https://lists.freedesktop.org/archives/mesa-dev/2016-July/124111.html 
and https://lists.freedesktop.org/archives/mesa-dev/2016-June/120738.html

I noticed that others have left comments in the LLVM source about the 
same issue, so I decided to try to replace all DEBUG() uses with 
LLVM_DEBUG() and remove the old macro.
A review for the LLVM side of the patch is here: 
https://reviews.llvm.org/D43624, this was generated mostly by a 
find/replace regex.

This kind of change is quite invasive (~500 files) and might be 
disruptive to multiple parties. One possible way to avoid some of the 
disruption would be to keep arond the old macro during a transition 
period in which it would be "deprecated".

Thoughts?

Thanks,
Nicola