P1652 Printf corner cases in std::format

[wg21bot]

P1652R0 Printf corner cases in std::format (Zhihao Yuan, Zhihao Yuan, Victor Zverovich)

[tituswinters]

Discussed in Cologne.

Forward to LWG for C++20.
Unanimous consent

Must be included in C++20, we can't change the output formats.

[wg21bot]

P1652R1 Printf corner cases in std::format (Zhihao Yuan, Victor Zverovich)

[wg21bot]

Adopted 2019-07.