[cfe-users] build errors with MinGW-W64 GCC-8.1.0 on Windows

[Maarten Verhage via cfe-users]

Dear LLVM/clang people,

I’m new to LLVM. I used TDM-GCC toolchain with gcc version 5.1.0 before but 
I want to move on getting LLVM and Clang to work on my system: Windows 7 
64bit.

I would like to go for a MinGW64 toolchain to build the newest version of 
LLVM and clang.

I downloaded MinGW-W64 GCC-8.1.0 from here:
https://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win32/Personal%20Builds/mingw-builds/8.1.0/threads-posix/

There I selected the x86_64-posix-seh version believing that would be the 
best one. I got llvm and clang plus the llvm libc++ standard library as 
suggested on the getting started webpage.

I put the mingw-w64 bin folder in my PATH.
gcc -dumpversion
shown 8.1.0

In the llvm build folder I did:
cmake -G "MinGW Makefiles" -DCMAKE_BUILD_TYPE=Release ..
that completed succesfully

mingw32-make -f Makefile

It builds to 57%, then a bunch of errors:
1)
C:\dev\llvm\projects\libcxx\src\support\win32\thread_win32.cpp:156:8: error: 
'InitOnceExecuteOnce' was not declared in this scope
2)
C:\dev\llvm\projects\libcxx\src\support\win32\thread_win32.cpp:163:6: error: 
redefinition of 'bool 
std::__1::__libcpp_thread_id_equal(std::__1::__libcpp_thread_id, 
std::__1::__libcpp_thread_id)'
3) And a couple of more errors all in thread_win32.cpp.

So I think it would have been better to select the Mingw-w64 
x86_64-win32-seh or even x86_64-win32-sjlj version instead?

Is a recent Mingw-w64 toolchain version like 8.1.0 a good one to build 
llvm/clang? Or would an older one be more stable?

Thanks anyway for any suggestions.
Best regards,
Maarten Verhage