[clang-tools-extra] [clangd] Make EnableFunctionArgSnippets option string-typed (PR #121178)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

> I think we need to add the new `ArgumentLists` config in the clangd config doc https://clangd.llvm.org/config#completion.

Definitely. I'll send out a patch documenting this and other options new in clangd 20 in the near future. (We have an entry about this on the [Release checklist](https://github.com/clangd/clangd/wiki/Release-checklist) now, so we don't forget.)

https://github.com/llvm/llvm-project/pull/121178