[PATCH] D130689: [LLVM] Update C++ standard to 17

Mon Aug 8 04:49:30 PDT 2022

cor3ntin added a comment.

In D130689#3706135 <https://reviews.llvm.org/D130689#3706135>, @aaron.ballman wrote:

> In D130689#3705131 <https://reviews.llvm.org/D130689#3705131>, @royjacobson wrote:
>
>> This seems to have been more disruptive than expected, since an existing CMakeCache.txt can make LLVM compile in previous C++14 configuration. This seems to make some of the bots fail in a way that makes the patches making use of C++17 features seem at fault.
>>
>> See:
>> https://github.com/llvm/llvm-project/commit/ede96de751224487aea122af8bfb4e82bc54840b#commitcomment-80507826
>> https://reviews.llvm.org/rG32fd0b7fd5ab
>>
>> How would you feel about adding something like
>>
>>   #if defined(__cplusplus) && __cplusplus < 201703L
>>   #error "LLVM requires at least C++17"
>>   #endif
>>
>> to some central header, to make this switch more visible?
>
> FWIW, that revert was not necessarily due to cmake cache issues (though those issues may exist, I haven't checked). I reverted that change because it broke the build for me locally as well as caused some bots to go red. My local build definitely rebuilt the cache and still failed.
>
> https://lab.llvm.org/buildbot/#/builders/127/builds/33955 (build with revert, passing)
> https://lab.llvm.org/buildbot/#/builders/127/builds/33954 (previous build, failing due to compile errors)

Trying to read the logs,, notably `C:\PROGRA~2\MIB055~1\2019\PROFES~1\VC\Tools\MSVC\1429~1.301\bin\Hostx64\x64\cl.exe `, it would seem that this particular bot is running a version much older than the current requirements  (Visual Studio 2019 16.7)
Either I'm reading that wrong or the CMake script does not check the msvc version?

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D130689/new/

https://reviews.llvm.org/D130689