[clang] [llvm] [ci] New script to generate test reports as Buildkite Annotations (PR #113447)

[David Spickett via cfe-commits]

DavidSpickett wrote:

The version that does not use the lit feature: https://github.com/llvm/llvm-project/pull/113660

It's not complete but it's good enough to compare approaches I think.

Another, probably objectionable choice, is to write a wrapper script that replaces lit, looks for the result filename argument, runs the original lit then moves the file to a new location. Even then we would have to `ninja targets` first so that the lit we replace is the complete one. So it's probably even more change to the build scripts to split building and checking.

I wondered about some sort of virtual file where we could accumulate versions of it but doubted this would work on Windows if there were such a thing. Maybe we could give lit the path to some kind of special Unix pipe and have a listener pull data from that so each EOF makes a new file?

https://github.com/llvm/llvm-project/pull/113447