unresolved external symbol BCrypt*** with ninja and clang-cl

[Abergard]

Hi,

today I have prepared upgarde boost to 1.68 and I can't compile my project. I have prepared test program to reproduce issue:

CMakeLists.txt:

cmake_minimum_required(VERSION 3.10)
project("only4test" CXX)

find_package(Boost 1.6 REQUIRED)

add_executable(only4test
  main.cpp
  )

target_compile_options(only4test
  PRIVATE /W4)

target_link_libraries(only4test
  PRIVATE Boost::boost
  )

main.cpp

#include <iostream>
#include <boost/uuid/uuid_generators.hpp>
#include <boost/uuid/uuid_io.hpp>

using namespace std;

int main()
{
    cout << boost::uuids::to_string(boost::uuids::random_generator()()) << '\n';
}

When it is compile with msvc it works, however when I change compiler to clang-cl the bcrypt library is not automaticly linked.

Msvc compilation:

cmake -G "Visual Studio 15 2017 Win64" .. -DBOOST_ROOT=%SRC%/boost_1_68_0
cmake --build .
Build succeeded.
    0 Warning(s)
    0 Error(s)

Clang compilation:

cmake -G "Ninja" .. -DBOOST_ROOT=%SRC%/boost_1_68_0/ -DCMAKE_CXX_COMPILER=clang-cl -DCMAKE_C_COMPILER=clang-cl
cmake --build .
main.cpp.obj : error LNK2019: unresolved external symbol BCryptOpenAlgorithmProvider referenced in function "public: __cdecl boost::uuids::detail::random_provider_base::random_provider_base(void)" (??0random_provider_base@detail@uuids@boost@@QEAA@XZ)
main.cpp.obj : error LNK2019: unresolved external symbol BCryptGenRandom referenced in function "public: void __cdecl boost::uuids::detail::random_provider_base::get_random_bytes(void *,unsigned __int64)" (?get_random_bytes@random_provider_base@detail@uuids@boost@@QEAAXPEAX_K@Z)
main.cpp.obj : error LNK2019: unresolved external symbol BCryptCloseAlgorithmProvider referenced in function "private: void __cdecl boost::uuids::detail::random_provider_base::destroy(void)" (?destroy@random_provider_base@detail@uuids@boost@@AEAAXXZ)
only4test.exe : fatal error LNK1120: 3 unresolved externals
ninja: build stopped: subcommand failed.

Did I need some additional flag to have auto link worked?

[Lastique]

Yes, see #68 (comment).

I don't know if clang-cl supports auto-linking, but if it does consider creating a pull request for https://github.com/boostorg/config/blob/develop/include/boost/config/auto_link.hpp.

[jeking3]

Some information I found:
http://releases.llvm.org/3.6.2/tools/docs/UsersManual.html

clang supports the Microsoft #pragma comment(lib, "foo.lib") feature for automatically linking against the specified library. Currently this feature only works with the Visual C++ linker.

I would also like to see an additional CI build job added that forces b2 to use clang-cl and link dynamically in order to prove this fix. This is something I could roll into all of the CMT repos eventually, since the appveyor.yml is repository-specific there is no easy way to update them all, but we could start here.

[jeking3]

I was able to reproduce this in a CI build job.

https://ci.appveyor.com/project/jeking3/uuid/builds/24529878/job/sgb58e1rq28pbhmu