D equivalent of C++11's function local static initialization?

[via Digitalmars-d-learn]

On Wednesday, 17 May 2017 at 03:08:39 UTC, Timothee Cour wrote:
> NOTE: curious about both cases:
> * thread local
> * shared
>
> On Tue, May 16, 2017 at 8:04 PM, Timothee Cour 
> <thelastmammoth at gmail.com> wrote:
>> what's the best D equivalent of C++11's function local static 
>> initialization?
>> ```
>> void fun(){
>>   static auto a=[](){
>>     //some code
>>    return some_var;
>>   }
>> }
>> ```
>>
>> (C++11 guarantees thread safety)

In D this is a library construct, instead of built into the 
language.
See http://dlang.org/phobos-prerelease/std_concurrency#.initOnce.