[clang-tools-extra] [clangd] Let DefineOutline tweak create a definition from scratch (PR #71950)

[Christian Kandeler via cfe-commits]

ckandeler wrote:

> Just fyi, I am ready to merge this, the failures in the builds seem unrelated, but I will first ask about proper procedure for these cases, should not take 3 years tho :)

Given that there was opposition to the general idea by maintainers, it seems appropriate to wait a couple of days before merging, in order to give them time to comment.

https://github.com/llvm/llvm-project/pull/71950