[clang] [clang-tools-extra] [flang] [lld] [llvm] [flang][clang] Add Visibility specific help text for options (PR #81869)

[David Spickett via cfe-commits]

DavidSpickett wrote:

I've also tested this with increased array sizes. You can check the .inc files to see that they are intialised properly, `<build dir>/lib/ToolDrivers/llvm-lib/Options.inc` is one.

https://github.com/llvm/llvm-project/pull/81869