[clang] [clang-tools-extra] [lldb] [clang] Reland: fix getTemplateInstantiationArgs (PR #208285)

[Nathan Corbyn via cfe-commits]

cofibrant wrote:

I would highlight the stage 2 build failures as a good place to start. LLVM itself makes very extensive use of templates.

https://github.com/llvm/llvm-project/pull/208285