Clang-produced and GCC-produced binaries might be ABI-incompatible on
MinGW. Explanation on GitHub: msys2/MINGW-packages/issues/6855#issuecomment-680859662.
TL;DR: GCC-generated sections are 16-byte-padded, while Clang ones are
not. It causes problems during merge of COMDAT sections.
I observed the problem during compilation of runtime tests, but it is
possible that the problem could affect main compilation pipeline as well.
https://reviews.llvm.org/D86659 (which landed in LLVM 12) fixes
the problem. So we have another motivation for switching to LLD besides
https://youtrack.jetbrains.com/issue/KT-47605.
The only known downside is unsupported defsym which causes slight binary
size increase. I think it is doable.
Sergey Bogolepov
c7c78e0e1a