[llvm-branch-commits] [clang] [HLSL] Add helpers to simplify HLSL resource type declarations. NFC (PR #73967)

[Justin Bogner via llvm-branch-commits]

https://github.com/bogner created https://github.com/llvm/llvm-project/pull/73967

A few changes to HLSLExternalSemaSource and its BuiltinTypeDeclBuilder
to make defining buffer types less verbose. This will make it a lot
easier to see what the differences between the various buffer types
are once we start introducing more of them.