1 背景

1.1 场景

编译器：gcc 9.4
运行系统：Ubuntu 20.04.4 LTS
xmake: v2.6.7
场景：其大致场景是使用c++的future/promise功能，类似如下示意代码：

#include <iostream>
#include <future>using namespace std;int main(int argc, char** argv)
{std::promise<int> p;p.set_value(42);auto f = p.get_future();int res = f.get();std::cout << "future got value: " << res << std::endl;return 0;
}

默认xmake文件如下：

add_rules("mode.debug", "mode.release")target("explicit_stdc++")set_kind("binary")add_files("src/*.cpp")

编译运行以及执行结果如下：

gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake
checking for platform ... linux
checking for architecture ... x86_64
[ 25%]: ccache compiling.release src/main.cpp
[ 50%]: linking.release explicit_stdc++
[100%]: build ok!
gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake run
terminate called after throwing an instance of 'std::system_error'what():  Unknown error -1

编译出来的执行文件的链接库如下所示：

$ ldd build/linux/x86_64/release/explicit_stdc++ linux-vdso.so.1 (0x00007ffe29fbd000)libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f26b8abf000)libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f26b8aa4000)  libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f26b88b2000)libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f26b8763000)/lib64/ld-linux-x86-64.so.2 (0x00007f26b8cb4000)

网上关于这部分的信息几乎是没有，经过一番查找，然后才开始了如下尝试，并最终找到对应的解决方案。

2 问题及现象的原因

根本原因：从c++11开始的future/promise 等于多线程编程相关的标准接口在Linux下的gcc环境下，其底层实现是需要依赖pthread相关接口的，因此需要在xmake脚本中添加相应的库依赖。

3 尝试

3.1 直接添加pthread

既然是因为c++多线程编程相关功能的底层实现在Linux下的gcc环境是依赖的pthread相关接口，而如前面所示，原始的xmake中并未显示地添加pthread库，那么直接在xmake添加pthread 库。其xmake脚本如下所示：

add_rules("mode.debug", "mode.release")target("explicit_stdc++")set_kind("binary")add_syslinks("pthread")add_files("src/*.cpp")

但是从编译以及ldd的结果来看，其并未为在链接库里面新增pthread库，并且运行仍然会出错。

gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ cat xmake.lua
add_rules("mode.debug", "mode.release")target("explicit_stdc++")set_kind("binary")add_syslinks("pthread")add_files("src/*.cpp")gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake
[ 25%]: ccache compiling.release src/main.cpp
[ 50%]: linking.release explicit_stdc++
[100%]: build ok!.../xmake_test/explicit_stdc++$ ldd build/linux/x86_64/release/explicit_stdc++linux-vdso.so.1 (0x00007fff7d3b0000)libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f8d9e680000)libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f8d9e665000)  libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f8d9e473000)libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f8d9e324000)/lib64/ld-linux-x86-64.so.2 (0x00007f8d9e875000)
gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake run
terminate called after throwing an instance of 'std::system_error'what():  Unknown error -1

3.2 更改ld

对于这个问题，一开始笔者也是百思不得其解，折腾了半天，无奈之下，尝试将xmake的构建过程显示出来看看到底是什么情况：

gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake -vvv
[ 25%]: ccache compiling.release src/main.cpp
/usr/bin/gcc -c -m64 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG -o build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o src/main.cpp
[ 50%]: linking.release explicit_stdc++
/usr/bin/g++ -o build/linux/x86_64/release/explicit_stdc++ build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o -m64 -s -lpthread
[100%]: build ok!

如上，所示，其是使用g++作为“ld” 进行链接的，且在链接的参数中已经有显示地添加 -lpthread。

于是想到的另一个尝试就是修改ld，使用gcc作为链接器。xmake的资料相对来说还是太少了，查找了一下，可以如下方式指定ld：

gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake f --ld=gcc
checking for platform ... linux
checking for architecture ... x86_64
gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake -vvvv
checking for gcc ... /usr/bin/gcc
checking for the c++ compiler (cxx) ... gcc
checking for /usr/bin/gcc ... ok
checking for flags (-fPIC) ... ok
checking for flags (-fvisibility-inlines-hidden) ... ok
checking for flags (-O3) ... ok
checking for flags (-DNDEBUG) ... ok
[ 25%]: ccache compiling.release src/main.cpp
/usr/bin/gcc -c -m64 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG -o build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o src/main.cpp
checking for flags (-MMD -MF) ... ok
checking for flags (-fdiagnostics-color=always) ... ok
checking for flags (-fPIC) ... ok
[ 50%]: linking.release explicit_stdc++
gcc -o build/linux/x86_64/release/explicit_stdc++ build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o -m64 -s -lpthread
error: /usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()#2}::_FUN()':
main.cpp:(.text._ZZSt9call_onceIMNSt13__future_base13_State_baseV2EFvPSt8functionIFSt10unique_ptrINS0_12_Result_baseENS4_8_DeleterEEvEEPbEJPS1_S9_SA_EEvRSt9once_flagOT_DpOT0_ENUlvE0_4_FUNEv[_ZZSt9call_onceIMNSt13__future_base13_State_baseV2EFvPSt8functionIFSt10unique_ptrINS0_12_Result_baseENS4_8_DeleterEEvEEPbEJPS1_S9_SA_EEvRSt9once_flagOT_DpOT0_ENUlvE0_4_FUNEv]+0x7): undefined reference to `std::__once_callable'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `std::__future_base::_State_baseV2::~_State_baseV2()':
main.cpp:(.text._ZNSt13__future_base13_State_baseV2D0Ev[_ZNSt13__future_base13_State_baseV2D5Ev]+0x2a): undefined reference to `operator delete(void*, unsigned long)'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `std::_Sp_counted_ptr_inplace<std::__future_base::_State_baseV2, std::allocator<std::__future_base::_State_baseV2>, (__gnu_cxx::_Lock_policy)2>::~_Sp_counted_ptr_inplace()':
main.cpp:(.text._ZNSt23_Sp_counted_ptr_inplaceINSt13__future_base13_State_baseV2ESaIS1_ELN9__gnu_cxx12_Lock_policyE2EED0Ev[_ZNSt23_Sp_counted_ptr_inplaceINSt13__future_base13_State_baseV2ESaIS1_ELN9__gnu_cxx12_Lock_policyE2EED5Ev]+0xa): undefined reference to `operator delete(void*, unsigned long)'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `std::__future_base::_Result<int>::~_Result()':
main.cpp:(.text._ZNSt13__future_base7_ResultIiED2Ev[_ZNSt13__future_base7_ResultIiED5Ev]+0xf): undefined reference to `std::__future_base::_Result_base::~_Result_base()'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `std::__future_base::_Result<int>::~_Result()':
main.cpp:(.text._ZNSt13__future_base7_ResultIiED0Ev[_ZNSt13__future_base7_ResultIiED5Ev]+0x13): undefined reference to `std::__future_base::_Result_base::~_Result_base()'
/usr/bin/ld: main.cpp:(.text._ZNSt13__future_base7_ResultIiED0Ev[_ZNSt13__future_base7_ResultIiED5Ev]+0x21): undefined reference to `operator delete(void*, unsigned long)'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `std::_Sp_counted_ptr_inplace<std::__future_base::_State_baseV2, std::allocator<std::__future_base::_State_baseV2>, (__gnu_cxx::_Lock_policy)2>::_M_destroy()':
main.cpp:(.text._ZNSt23_Sp_counted_ptr_inplaceINSt13__future_base13_State_baseV2ESaIS1_ELN9__gnu_cxx12_Lock_policyE2EE10_M_destroyEv[_ZNSt23_Sp_counted_ptr_inplaceINSt13__future_base13_State_baseV2ESaIS1_ELN9__gnu_cxx12_Lock_policyE2EE10_M_destroyEv]+0x5): undefined reference to `operator delete(void*)'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `std::__future_base::_State_baseV2::_M_do_set(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*)':
main.cpp:(.text._ZNSt13__future_base13_State_baseV29_M_do_setEPSt8functionIFSt10unique_ptrINS_12_Result_baseENS3_8_DeleterEEvEEPb[_ZNSt13__future_base13_State_baseV29_M_do_setEPSt8functionIFSt10unique_ptrINS_12_Result_baseENS3_8_DeleterEEvEEPb]+0x63): undefined reference to `std::__throw_bad_function_call()'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `std::__future_base::_Result<int>::_M_destroy()':
main.cpp:(.text._ZNSt13__future_base7_ResultIiE10_M_destroyEv[_ZNSt13__future_base7_ResultIiE10_M_destroyEv]+0x26): undefined reference to `std::__future_base::_Result_base::~_Result_base()'
/usr/bin/ld: main.cpp:(.text._ZNSt13__future_base7_ResultIiE10_M_destroyEv[_ZNSt13__future_base7_ResultIiE10_M_destroyEv]+0x34): undefined reference to `operator delete(void*, unsigned long)'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `std::promise<int>::~promise()':
main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x5f): undefined reference to `std::future_category()'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x91): undefined reference to `std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_replace(unsigned long, unsigned long, char const*, unsigned long)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0xe3): undefined reference to `std::logic_error::logic_error(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0xf2): undefined reference to `operator delete(void*)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x106): undefined reference to `operator delete(void*)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x10d): undefined reference to `vtable for std::future_error'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x129): undefined reference to `__cxa_allocate_exception'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x137): undefined reference to `typeinfo for std::future_error'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x142): undefined reference to `__cxa_init_primary_exception'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x14d): undefined reference to `std::logic_error::logic_error(std::logic_error const&)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x170): undefined reference to `std::__exception_ptr::exception_ptr::exception_ptr(void*)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x18d): undefined reference to `std::__exception_ptr::exception_ptr::swap(std::__exception_ptr::exception_ptr&)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x195): undefined reference to `std::__exception_ptr::exception_ptr::~exception_ptr()'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x19d): undefined reference to `std::__exception_ptr::exception_ptr::~exception_ptr()'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x1a5): undefined reference to `std::future_error::~future_error()'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x215): undefined reference to `std::__future_base::_Result_base::~_Result_base()'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x222): undefined reference to `operator delete(void*, unsigned long)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x301): undefined reference to `std::__atomic_futex_unsigned_base::_M_futex_notify_all(unsigned int*)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x324): undefined reference to `operator delete(void*)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x338): undefined reference to `operator delete(void*)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiED2Ev[_ZNSt7promiseIiED5Ev]+0x33d): undefined reference to `std::terminate()'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `std::promise<int>::set_value(int&&)':
main.cpp:(.text._ZNSt7promiseIiE9set_valueEOi[_ZNSt7promiseIiE9set_valueEOi]+0xe2): undefined reference to `std::__once_callable'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiE9set_valueEOi[_ZNSt7promiseIiE9set_valueEOi]+0xf6): undefined reference to `std::__once_call'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiE9set_valueEOi[_ZNSt7promiseIiE9set_valueEOi]+0x103): undefined reference to `__once_proxy'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiE9set_valueEOi[_ZNSt7promiseIiE9set_valueEOi]+0x11d): undefined reference to `std::__throw_future_error(int)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiE9set_valueEOi[_ZNSt7promiseIiE9set_valueEOi]+0x171): undefined reference to `std::__atomic_futex_unsigned_base::_M_futex_notify_all(unsigned int*)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiE9set_valueEOi[_ZNSt7promiseIiE9set_valueEOi]+0x17f): undefined reference to `std::__throw_system_error(int)'
/usr/bin/ld: main.cpp:(.text._ZNSt7promiseIiE9set_valueEOi[_ZNSt7promiseIiE9set_valueEOi]+0x189): undefined reference to `std::__throw_future_error(int)'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `main.cold':
main.cpp:(.text.unlikely+0x4): undefined reference to `std::__exception_ptr::exception_ptr::~exception_ptr()'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `main':
main.cpp:(.text.startup+0x31): undefined reference to `operator new(unsigned long)'
/usr/bin/ld: main.cpp:(.text.startup+0x86): undefined reference to `operator new(unsigned long)'
/usr/bin/ld: main.cpp:(.text.startup+0x9b): undefined reference to `std::__future_base::_Result_base::_Result_base()'
/usr/bin/ld: main.cpp:(.text.startup+0x142): undefined reference to `std::__atomic_futex_unsigned_base::_M_futex_wait_until(unsigned int*, unsigned int, bool, std::chrono::duration<long, std::ratio<1l, 1l> >, std::chrono::duration<long, std::ratio<1l, 1000000000l> >)'/usr/bin/ld: main.cpp:(.text.startup+0x16e): undefined reference to `std::__exception_ptr::operator==(std::__exception_ptr::exception_ptr const&, std::__exception_ptr::exception_ptr const&)'
/usr/bin/ld: main.cpp:(.text.startup+0x178): undefined reference to `std::__exception_ptr::exception_ptr::~exception_ptr()'
/usr/bin/ld: main.cpp:(.text.startup+0x1b6): undefined reference to `std::cout'
/usr/bin/ld: main.cpp:(.text.startup+0x1bb): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long)'
/usr/bin/ld: main.cpp:(.text.startup+0x1c5): undefined reference to `std::cout'
/usr/bin/ld: main.cpp:(.text.startup+0x1ca): undefined reference to `std::ostream::operator<<(int)'
/usr/bin/ld: main.cpp:(.text.startup+0x1d2): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
/usr/bin/ld: main.cpp:(.text.startup+0x253): undefined reference to `std::__throw_future_error(int)'
/usr/bin/ld: main.cpp:(.text.startup+0x262): undefined reference to `std::__throw_future_error(int)'
/usr/bin/ld: main.cpp:(.text.startup+0x26d): undefined reference to `std::__exception_ptr::exception_ptr::exception_ptr(std::__exception_ptr::exception_ptr const&)'
/usr/bin/ld: main.cpp:(.text.startup+0x275): undefined reference to `std::rethrow_exception(std::__exception_ptr::exception_ptr)'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o: in function `_GLOBAL__sub_I_main':
main.cpp:(.text.startup+0x2d0): undefined reference to `std::ios_base::Init::Init()'
/usr/bin/ld: main.cpp:(.text.startup+0x2d7): undefined reference to `std::ios_base::Init::~Init()'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o:(.data.rel.ro._ZTISt11_Mutex_baseILN9__gnu_cxx12_Lock_policyE2EE[_ZTISt11_Mutex_baseILN9__gnu_cxx12_Lock_policyE2EE]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o:(.data.rel.ro._ZTISt16_Sp_counted_baseILN9__gnu_cxx12_Lock_policyE2EE[_ZTISt16_Sp_counted_baseILN9__gnu_cxx12_Lock_policyE2EE]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o:(.data.rel.ro._ZTINSt13__future_base13_State_baseV2E[_ZTINSt13__future_base13_State_baseV2E]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o:(.data.rel.ro._ZTINSt13__future_base7_ResultIiEE[_ZTINSt13__future_base7_ResultIiEE]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o:(.data.rel.ro._ZTINSt13__future_base7_ResultIiEE[_ZTINSt13__future_base7_ResultIiEE]+0x10): undefined reference to `typeinfo for std::__future_base::_Result_base'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o:(.data.rel.ro._ZTINSt13__future_base13_State_baseV27_SetterIiOiEE[_ZTINSt13__future_base13_State_baseV27_SetterIiOiEE]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o:(.data.rel.ro._ZTISt23_Sp_counted_ptr_inplaceINSt13__future_base13_State_baseV2ESaIS1_ELN9__gnu_cxx12_Lock_policyE2EE[_ZTISt23_Sp_counted_ptr_inplaceINSt13__future_base13_State_baseV2ESaIS1_ELN9__gnu_cxx12_Lock_policyE2EE]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info'
/usr/bin/ld: build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o:(.data.rel.local.DW.ref.__gxx_personality_v0[DW.ref.__gxx_personality_v0]+0x0): undefined reference to `__gxx_personality_v0'
collect2: error: ld returned 1 exit status

其结果如上，其根本原因是，使用gcc作为链接器，它不会默认链接c++的标准库，因此需要显示在xmake中添加，如下所示：

add_rules("mode.debug", "mode.release")target("explicit_stdc++")set_kind("binary")add_syslinks("stdc++", "pthread")add_files("src/*.cpp")

其编译和运行结果，如下所示：

gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake -vvvv
checking for gcc ... /usr/bin/gcc
checking for dmd ... no
checking for ldc2 ... no
checking for gdc ... no
checking for zig ... no
checking for zig ... no
checking for gcc ... /usr/bin/gcc
checking for the c++ compiler (cxx) ... gcc
checking for /usr/bin/gcc ... ok
checking for flags (-fPIC) ... ok
checking for flags (-fvisibility-inlines-hidden) ... ok
checking for flags (-O3) ... ok
checking for flags (-DNDEBUG) ... ok
[ 25%]: ccache compiling.release src/main.cpp
/usr/bin/gcc -c -m64 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG -o build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o src/main.cpp
checking for flags (-MMD -MF) ... ok
checking for flags (-fdiagnostics-color=always) ... ok
checking for flags (-fPIC) ... ok
[ 50%]: linking.release explicit_stdc++
gcc -o build/linux/x86_64/release/explicit_stdc++ build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o -m64 -s -lstdc++ -lpthread
[100%]: build ok!
gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake run
future got value: 42

如上所示，已经解决了此问题，可以程序可以正常运行了。

Note: 此种解决方案有两个问题：

需要显示地更改ld，构建过程多了xmake f xxx 这样的配置过程

不同操作系统或者运行环境，使用的c++标准库可能会有不同，因此添加的“stdc++”标准可可能需要根据情况进行灵活变更

3.3 只需显示添加sdc++库

虽然根据3.2节可以解决问题，但感觉还是有些复杂。于是乎做了一番尝试，发现其实只需要显示地添加stdc++标准库，即使使用默认的g++作为链接器，也可以正常的编译和运行。如下所示：

gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake -vvvv
checking for platform ... linux
checking for architecture ... x86_64
checking for gcc ... /usr/bin/gcc
checking for dmd ... no
checking for ldc2 ... no
checking for gdc ... no
checking for zig ... no
checking for zig ... no
checking for gcc ... /usr/bin/gcc
checking for the c++ compiler (cxx) ... gcc
checking for /usr/bin/gcc ... ok
checking for flags (-fPIC) ... ok
checking for flags (-fvisibility-inlines-hidden) ... ok
checking for flags (-O3) ... ok
checking for flags (-DNDEBUG) ... ok
[ 25%]: ccache compiling.release src/main.cpp
/usr/bin/gcc -c -m64 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG -o build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o src/main.cpp
checking for flags (-MMD -MF) ... ok
checking for flags (-fdiagnostics-color=always) ... ok
checking for g++ ... /usr/bin/g++
checking for the linker (ld) ... g++
checking for /usr/bin/g++ ... ok
checking for flags (-fPIC) ... ok
[ 50%]: linking.release explicit_stdc++
/usr/bin/g++ -o build/linux/x86_64/release/explicit_stdc++ build/.objs/explicit_stdc++/linux/x86_64/release/src/main.cpp.o -m64 -s -lstdc++ -lpthread
[100%]: build ok!
gw123@DESKTOP-KJUN5HL:~/workspace/temp/xmake_test/explicit_stdc++$ xmake run
future got value: 42

至此，问题解决，笔者最终也是选择的最后这种方案，只需显示地添加stdc++库和pthread库即可。至于这其中的根本原因，笔者目前还不胜了解[捂脸]。有知道其根本原因的大牛也希望能不吝赐教[抱拳]

xmake经验总结1：解决c++ future/promise抛出std::system_error的问题相关推荐

Future.get()抛出ExecutionException或InterruptedException？
ExecutionException和InterruptedException是两个非常不同的事情. ExecutionException封装了正在执行的线程抛出的任何异常,所以如果线程是做某种IO导 ...
future promise java_Future与Promise
https://code.csdn.NET/DOC_Scala/chinese_scala_offical_document/file/Futures-and-Promises-cn.md#ancho ...
rust异步编程--理解并发/多线程/回调/异步/future/promise/async/await/tokio
1. 异步编程简介通常我们将消息通信分成同步和异步两种: 同步就是消息的发送方要等待消息返回才能继续处理其它事情异步就是消息的发送方不需要等待消息返回就可以处理其它事情很显然异步允许我们同时做更 ...
folly教程系列之：future/promise
attension:本文严禁转载. 一.前言 promise/future是一个非常重要的异步编程模型,它可以让我们摆脱传统的回调陷阱,从而使用更加优雅.清晰的方式进行异步编程.c++11中 ...
【转】现代c++开发利器folly教程系列之：future/promise
一.前言 promise/future是一个非常重要的异步编程模型,它可以让我们摆脱传统的回调陷阱,从而使用更加优雅.清晰的方式进行异步编程.c++11中已经开始支持std::future/std:: ...
C++异步调用利器future/promise实现原理
前言在异步编程中,各种回调将让人眼花缭乱,代码分散,维护起来十分困难.boost和C++11 的 future/promise 提供了一个很好的解决方案,使得代码更加漂亮.易维护. 在工作中,我也用 ...
future promise shared_future简单使用
#include #include #include /furture 和promi******************/ int display(const int& value) { re ...
C++11 并发指南四(future 详解一 std::promise 介绍)
前面两讲<C++11 并发指南二(std::thread 详解)>,<C++11 并发指南三(std::mutex 详解)>分别介绍了 std::thread 和 std::m ...
解决Uncaught (in promise) reason的问题
解决Uncaught (in promise) reason的问题报错如下错误代码 new Promise((resolve, reject) => {//resolve(123);reje ...
SpringCloud（10）—— 国寿i动项目经验之（解决前后端跨域请求技术）
国寿i动项目经验之(解决前后端跨域请求技术): 由于网段原因,导致前端js请求后端服务接口出现跨域,没法实现正常的请求,所以需要对请求进行跨域处理引入jar: <!-- 解决前后端接口交互跨域 ...

xmake经验总结1：解决c++ future/promise抛出std::system_error的问题