[all-commits] [llvm/llvm-project] abfe65: [ADT] Define None as std::nullopt (NFC)

[kazutakahirata via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: abfe65a12b77f9f0292d3ec70bd9fc3b9c13d905
      https://github.com/llvm/llvm-project/commit/abfe65a12b77f9f0292d3ec70bd9fc3b9c13d905
  Author: Kazu Hirata <kazu at google.com>
  Date:   2022-11-22 (Tue, 22 Nov 2022)

  Changed paths:
    M llvm/include/llvm/ADT/None.h

  Log Message:
  -----------
  [ADT] Define None as std::nullopt (NFC)

This patch defines NoneType and None as std::nullopt_t and
std::nullopt, respectively.

This patch effectively makes None and std::nullopt interchangeable, so
we can gradually replace None with std::nullopt all while we continue
to use llvm::Optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

Differential Revision: https://reviews.llvm.org/D138468