I avoid C++ and stay in straight C as much as I can. GCC's C error messages have definitely improved in response to clang (especially around deep preprocessor stuff). I had assumed that the C++ messages had likewise improved, and thought that I had heard that as well.

Then I actually had to test that working on Envoy proxy. I was disappointed to get utterly incomprehensible error messages. I'm "GCC-by-default", so a coworker suggested I try switching to clang++... and sure enough, clang++ gave me decent error messages.

Yes and yes. I have seen g++ error messages especially template related ones from being horrendously inscrutable to at par with, and now better than clang. Of course this my subjective judgement. One area where i have found g++ to shine over clang is explaining the vectorization choices it makes -- great for understanding why a loop did not get simd'ed.

Competition has definitely served us well