Clang/MSVC: C++20 final flag, C++23 support

Added in LLVM commit a8f75d497daa2684a03909d7c31d5bce11b427e1, will be released
in 13.0.
28 jobs for !6174 with msvc_cxx20_23 in 6 minutes and 21 seconds (queued for 3 seconds)
latest detached
Status Job ID Name Coverage
  Build
manual #5833027
linux docker build cmake manual
build:centos6-x86_64
passed #5833024
linux docker build cmake
build:debian10-iwyu

00:02:30

manual #5833028
linux-3.17 linux docker build cmake manual
build:fedora33-ninja
passed #5833026
linux-3.17 linux docker build cmake
build:fedora33-sphinx

00:04:16

passed #5833025
linux-3.17 linux docker build cmake
build:fedora33-tidy

00:06:21

manual #5833030
nonconcurrent xcode-12.4 shell macos cmake manual
build:macos-x86_64-makefiles
manual #5833029
xcode-12.4 shell macos cmake nonconcurrent manual
build:macos-x86_64-ninja
manual #5833031
nonconcurrent msvc-19.29-16.10 vs2019 shell windows cmake manual
build:windows-vs2019-x64-ninja
 
  Test
created #5833032
x11 linux-3.17 linux docker cmake
test:fedora33-ninja
created #5833034
nonconcurrent xcode-12.4 shell macos cmake
test:macos-x86_64-makefiles
created #5833033
nonconcurrent xcode-12.4 shell macos cmake
test:macos-x86_64-ninja
created #5833035
nonconcurrent msvc-19.29-16.10 vs2019 shell windows cmake
test:windows-vs2019-x64-ninja
 
  Test Ext
created #5833038
linux docker cuda-rt cmake
test:cuda10.2-nvidia
created #5833036
linux-3.17 linux docker build cmake
test:debian10-ninja
created #5833037
linux-3.17 linux docker build cmake
test:fedora33-makefiles
created #5833039
linux-3.17 linux docker build cmake
test:fedora33-ninja-multi
created #5833040
concurrent xcode-12.4 shell macos cmake
test:macos-x86_64-xcode
created #5833041
concurrent msvc-19.29-16.10 vs2019 shell windows cmake
test:windows-vs2019-x64
 
  External
passed cdash

passed ghostflow-check-master

passed ghostflow-check-release

passed ghostflow-stager

passed cdash

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager