?????? [DISCUSS] Update backend c++ standard to gnu20

[BiteTheDDDDt]

Hi All,
  The community recently added ci detection for clang build, which can 
avoid build failures caused by some differences 

between gcc and clang. I think now we can start talking again about whether we 
should upgrade the C++ standard 

from gnu++17 to gnu++20.

  
Over the past few months, some work has been becoming a natural progression. In the past, we needed to patch phmap
 

and introduce the absl library as a dependency. Now the new version of phmap is released to fix its incompatibility with C++20,
 

and the dependence on absl can also help us to upgrade the version of tcmalloc.



------------------ ???????? ------------------
??????:                                                                         
                                               "BiteTheDDDDt"                   
                                                                 
<pxl...@qq.com&gt;;
????????:&nbsp;2022??5??9??(??????) ????5:16
??????:&nbsp;"dev"<dev@doris.apache.org&gt;;

????:&nbsp;?????? [DISCUSS] Update backend c++ standard to gnu20



Maybe we can just use the feature just both gcc and clang supported until we 
decide to use gcc or clang.I think there won't be a lot of code involving new 
features of the C++20 standard, so it's rare to meet compatibility problems.

 



------------------ ???????? ------------------
??????:                                                                         
                                               "dev"                            
                                                        <yangz...@gmail.com&gt;;
????????:&nbsp;2022??5??9??(??????) ????4:56
??????:&nbsp;"dev"<dev@doris.apache.org&gt;;

????:&nbsp;Re: [DISCUSS] Update backend c++ standard to gnu20



I checked the support of gcc[1] and clang[2] for the cxx20 standard, gcc
can partially support it, but the support of clang is poor. If it is
upgraded, how to ensure the compatibility of the code under gcc and clang

[1] https://gcc.gnu.org/projects/cxx-status.html#cxx20
[2] https://clang.llvm.org/cxx_status.html#cxx20
Thanks
Yang Zhengguo


BiteTheDDDDt <pxl...@qq.com.invalid&gt; ??2022??5??9?????? 15:54??????

&gt; Hello&amp;nbsp;everyone:
&gt; I want to update our c++ standard from gnu17 to gnu20, then we can use
&gt; some new feature such as `concept`,`coroutines`,`template lambda function`.
&gt; Currently our code doesn't need much modification to adapt to the c++20
&gt; standard, this is my pull-request
&gt; https://github.com/apache/incubator-doris/pull/9313.
&gt; welcome to discuss this.