[all-commits] [llvm/llvm-project] 7fcc1b: [clangd] Fix the build with clang <3.9.

[Michael Spencer via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 7fcc1bb4b654461c3109b01e1fe7eae191a86f7f
      https://github.com/llvm/llvm-project/commit/7fcc1bb4b654461c3109b01e1fe7eae191a86f7f
  Author: Michael Spencer <bigcheesegs at gmail.com>
  Date:   2020-07-17 (Fri, 17 Jul 2020)

  Changed paths:
    M clang-tools-extra/clangd/ConfigProvider.cpp
    M llvm/utils/TableGen/OptParserEmitter.cpp

  Log Message:
  -----------
  [clangd] Fix the build with clang <3.9.

In clang <3.9 the `unique_ptr` constructor that is supposed to allow
for Derived to Base conversion does not work. Remove this if we drop
support for such configurations.

This is the same fix as in fda901a987ddd, and it updates the comments
to better reflect the actual issue. The same thing reproduces with
libc++ with older clangs.