[PATCH] D57906: [CTU] Do not allow different CPP dialects in CTU

[Arthur O'Dwyer via Phabricator via cfe-commits]

Quuxplusone added a comment.

> Consider this STL code:
> 
>   template<typename _Alloc>
>     struct __alloc_traits
>   #if __cplusplus >= 201103L
>     : std::allocator_traits<_Alloc>
>   #endif
>     { // ...
>     };
> 
> 
> This class template would create ODR errors during merging the two units,
>  since in one translation unit the class template has a base class, however
>  in the other unit it has none.

How is `#if __cplusplus >= 201103L` qualitatively different from `#ifndef NDEBUG` or `#if MYLIB_ABI_VERSION==2` or `#if __DATE__ == "2018-04-01"`?


Repository:
  rC Clang

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D57906/new/

https://reviews.llvm.org/D57906