[llvm] [cmake] Enable color diagnostics (PR #79419)

[Timm Baeder via llvm-commits]

tbaederr wrote:

> On my system (linux, ninja), I do get colors in the current and the doc of cmake seems to imply that the default is to let the compiler does what it does by default.

It used to work for me as well IIRC. I have cmake 3.27.7 here and ninja 1.11.1 FWIW.

> But i see tons of ninja-related bugs pertaining to colors, and I am not sure they fixed it recently or not. So i can't tell whether this change is necessary (and how it impacts ci)

Yeah I'm also worried about the impact to CI. I do remember some cmake file adding `-fcolor-diagnostics` to the cflags directly but I can't find it anymore now.




https://github.com/llvm/llvm-project/pull/79419