[clang] [clang] Allow delayed function instantiation at TU end if initial instantiation fails (PR #117167)

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StefanPaulet wrote:

Indeed, replacing the lambda with a user declared struct with the same `operator()` works: https://godbolt.org/z/8GWv6d88K

May I try to see if I find a way to delay the instantiations of lambda call operators? 

https://github.com/llvm/llvm-project/pull/117167