[CTU] Do not allow different CPP dialects in CTU
Summary:
If CPP dialects are different then return with error.
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.
Reviewers: xazax.hun, a_sidorin, r.stahl
Subscribers: rnkovacs, dkrupp, Szelethus, gamesh411, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D57906
llvm-svn: 355096