[clang] [Sema] Substitute parameter packs when deduced from function arguments (PR #79371)

[Gábor Spaits via cfe-commits]

spaits wrote:

It looks like libc++ test suites are failing. Looking at the logs from the CI I can not really figure out what is the exact reason.
I could only deduce that the failing test case is `libcxx/gdb/gdb_pretty_printer_test.sh.cpp`. This case seems to be related to `libcxx/selftest/convenience_substitutions/build_run.sh.cpp`. I will try to figure out how to set up my environment to run these tests.

https://github.com/llvm/llvm-project/pull/79371