[clang-tools-extra] [clangd] fix crashes in SemanticHighlighting on NTTP typed `decltype(constexpr-auto-variable)` (PR #207323)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

Thanks for the patch.

I find it a bit surprising that `D->getType()->getContainedAutoType()` is not null but `D->getTypeSourceInfo()->getTypeLoc().getContainedAutoTypeLoc()` is null; I would expect the Type and TypeLoc structures to correspond, so that if there is an AutoType, there is an also an AutoTypeLoc.

I'd like to dig into this a big more before accepting the patch, to make sure there isn't a deeper issue lurking here.

https://github.com/llvm/llvm-project/pull/207323