error: thread-local storage is not supported

[Marcus Calhoun-Lopez]

macOS has supported thread-local storage since Mac OS X Lion.
So __thread (GNU extension) and _Thread_local (C11) could be used.
However, the C++11 keyword was not supported until Xcode 8 [1,2].

There is a pull request that attempts to improve the situation [3].

-Marcus

1. https://stackoverflow.com/questions/28094794/why-does-apple-clang-disallow-c11-thread-local-when-official-clang-supports/29929949#29929949
2. https://developer.apple.com/videos/play/wwdc2016-405/?time=354
3. https://github.com/macports/macports-base/pull/161

> On Nov 21, 2019, at 5:10 PM, Ken Cunningham <ken.cunningham.webuse at gmail.com> wrote:
> 
> Well, I’ll be hornswaggled.
> 
> Indeed it appears the compiler.thread_local_storage option in MacPorts is well and truly broken. It basically only works on 10.6 and less (which is where I often am, so I guess it always worked for me).
> 
> Marcus forgot to blacklist command_line clangs < 800. 
> 
> We’ll have to get that fixed.
> 
> <https://github.com/macports/macports-base/blob/2249c806dafa35c0bd2b2bce0bec29c94fa79856/src/port1.0/portconfigure.tcl#L768>
> 
> Ken
> 
> 
> 
>> On Nov 21, 2019, at 11:42 AM, Renee Otten <reneeotten at macports.org> wrote:
>> 
>> [sorry forgot to reply to the list earlier]
>> 
>> Thanks Ken, I am not sure if I can be of much help here - if you’d be willing to take a look that would be great! For now I’ll just blacklist clang below version 8.
>> 
>> Best,
>> Renee
>> 
>> 
>>> On Nov 21, 2019, at 12:52 PM, Ken Cunningham <ken.cunningham.webuse at gmail.com> wrote:
>>> 
>>> yes, clang 800+ supported thread_local.
>>> 
>>> the open-source clangs support thread_local using libc++ way back, but certainly macports-clang-5.0+. 
>>> 
>>> the c++11 gcc versions support it as well, using macports-installed libstdc++.
>>> 
>>> All of that blacklisting logic is incorporated into Marcus' compiler.thread_local command, and the guts are in 'portconfigure.tcl'. The whole idea was to do it once there correctly, and then everyone could use that instead of figuring it out themselves.
>>> 
>>> So -- if  that is not being honoured in the build, something weird must be going on to make this build ignore base.
>>> 
>>> That's what I'll have to help sort out, using a VM or real system running those OS versions.
>>> 
>>> Ken
>>> 
>>> 
>>> 
>>> On 2019-11-21, at 9:35 AM, Renee Otten wrote:
>>> 
>>>> hi Ken, 
>>>> 
>>>> 
>>>> see commits the following commits:
>>>> 
>>>> https://github.com/macports/macports-ports/commit/d6e27064e928b43d412618ac7227cc016e461738
>>>> https://github.com/macports/macports-ports/commit/c9e9e2a6263bbf9d915d9ba61877c80eed1a3089
>>>> 
>>>> in the last commit, doing compiler.blacklist-append {clang < 700} does make it build on OS X 10.8 and 10.9, but not on 10.10 yet, because there it uses Clang “700.1.81”
>>>> 
>>>> I’d appreciate your help with it, perhaps the issue is actually different and I don’t understand it correctly. 
>>>> 
>>>> Thanks again!
>>>> Renee
>> 
>