[clang] [Sema] Warning for _Float16 passed to format specifier '%f' (PR #74439)

[Joshua Cranmer via cfe-commits]

jcranmer-intel wrote:

> [N2844](https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2844.pdf), as linked by OP, references the removed language that you are looking for.

Doing some more spelunking, no released version of the TS ever had default argument promotion. The change to the TS was done shortly before integration in C, in response to the C++ proposal for extended floating-point types, but WG14 objected to the change, so it was dropped in actual integration. See https://mailman.oakapple.net/pipermail/cfp-interest/2020-September/001782.html for the summary.

https://github.com/llvm/llvm-project/pull/74439