在Ubuntu 14.04上编译EOS时缺少C ++ std库方法和其他错误？

Question

I'm trying to compile the EOS blockchain/smart contract project on GitHub on Ubuntu 14.04:

https://github.com/EOSIO/eos

After getting Clang 4.0 to install, installing build_essentials , and upgrading CMake to 3.5, I was able to run the build process without any missing dependencies. However, now I get the errors shown below when I build the EOS source. This seems to me like another general issue with the configuration of the tools on my system since many people are able to compile the EOS code, although usually on Ubuntu 14.04.

Can anyone tell by looking at the errors I'm getting what tool or library I need to install or upgrade?

In file included from /usr/lib/llvm-4.0/include/clang/AST/Decl.h:31:
/usr/lib/llvm-4.0/include/llvm/Support/TrailingObjects.h:259:33: error: 'BaseTy' does not refer to a value
    static_assert(LLVM_IS_FINAL(BaseTy), "BaseTy must be final.");
                            ^
/usr/lib/llvm-4.0/include/llvm/Support/TrailingObjects.h:233:20: note: declared here
template <typename BaseTy, typename... TrailingTys>
               ^
/usr/lib/llvm-4.0/include/llvm/Support/TrailingObjects.h:259:19: error: expected expression
    static_assert(LLVM_IS_FINAL(BaseTy), "BaseTy must be final.");
              ^
/usr/lib/llvm-4.0/include/llvm/Support/type_traits.h:104:45: note: expanded from macro 'LLVM_IS_FINAL'
#define LLVM_IS_FINAL(Ty) std::is_final<Ty>()
                                        ^
Linking CXX executable codegen
/home/robert/Documents/GitHub/eos/programs/launcher/main.cpp:405:18: error: no template named 'underlying_type_t' in namespace 'std'; did you mean
      'underlying_type'?
  using T = std::underlying_type_t <enum_type>;
        ~~~~~^~~~~~~~~~~~~~~~~
             underlying_type
/usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/type_traits:1855:12: note: 'underlying_type' declared here
    struct underlying_type
       ^
/home/robert/Documents/GitHub/eos/programs/launcher/main.cpp:435:17: error: no member named 'put_time' in namespace 'std'
  dstrm << std::put_time(std::localtime(&now_c), "%Y_%m_%d_%H_%M_%S");
       ~~~~~^
[ 64%] Building CXX object libraries/chain/CMakeFiles/eos_chain.dir/chain_controller.cpp.o
/home/robert/Documents/GitHub/eos/programs/launcher/main.cpp:406:39: error: no matching conversion for static_cast from 'allowed_connection' to 'T'
      (aka 'underlying_type<allowed_connection>')
  return lhs = static_cast<enum_type>(static_cast<T>(lhs) | static_cast<T>(rhs));
                                  ^~~~~~~~~~~~~~~~~~~

Answer 1

The Missing _t alias names look like you're having issues with C++14. The header paths in the error messages look like you're using the standard library from GCC 4.8 (the default compiler on Ubuntu 14.04), which is simply too old.

I can see two solutions:

Switch from GCC's libstdc++ to an up-to-date version of LLVM's libc++ . I'm not familiar enough with Ubuntu to tell you how to install it. For the compilation of EOSIO you must pass the -stdlib=libc++ option to Clang to switch to the different stdlib. EOSIO looks like it's using CMake, so you have to include -DCMAKE_CXX_FLAGS=-stdlib=libc++ in your CMake command line.

Use the Toolchain test builds PPA to install a newer GCC and and libstdc++ in addition to your system's default one. For Ubuntu 14.04 GCC 7.2.0 is the latest version available, which is perfectly C++14 capable. Add the PPA to your package sources and then do a:

sudo apt-get install gcc-7 g++-7

This installs both the GCC C compiler and C++ compiler along with the stdlib. Your default compiler is still going to be the old GCC 4.8, so you'll have to tell CMake about the newer versions:

-DCMAKE_CXX_COMPILER=g++-7 -DCMAKE_C_COMPILER=gcc-7

Note that now you compile EOSIO with GCC (and the new stdlib) instead of Clang. Instructing Clang to use a specific version of libstdc++ should be possible, but I don't know how.

Answer 2

Official support is for Ubuntu 16.10. Consider upgrading. (EDITED: I mistakenly said 14.10) Source: https://github.com/EOSIO/eos/wiki/Local-Environment#211-ubuntu-1610