Link error when building example with Conan

[Pwera]

After successfully install cpr with Conan, i tried to compil an example.
I am using gcc 5.3.

project(Ques)
cmake_minimum_required(VERSION 3.5.2)
SET(CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS} -std=c++14)

include(conanbuildinfo.cmake)
conan_basic_setup()
add_executable(Ques main.cpp)

message(STATUS ${CONAN_LIBS})
target_link_libraries(Ques ${CONAN_LIBS})

main.cpp content:

#include <cpr/cpr.h>
#include <iostream>
#include <string>
int main(int argc, char** argv)
{
    auto r = cpr::Get(cpr::Url{"https://api.github.com/repos/whoshuu/cpr/contributors"},
                      cpr::Authentication{"user", "pass"},
                      cpr::Parameters{{"anon", "true"}, {"key", "value"}});
    r.status_code;                  // 200
    r.header["content-type"];      // application/json; charset=utf-8
    r.text;   
    return 0;
}

TerminalOutput :

[ 50%] Building CXX object CMakeFiles/Ques.dir/main.cpp.o
[100%] Linking CXX executable bin/Ques
CMakeFiles/Ques.dir/main.cpp.o: In function `std::map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, cpr::CaseInsensitiveCompare, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >::operator[](std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&&)':
main.cpp:(.text._ZNSt3mapINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES5_N3cpr22CaseInsensitiveCompareESaISt4pairIKS5_S5_EEEixEOS5_[_ZNSt3mapINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES5_N3cpr22CaseInsensitiveCompareESaISt4pairIKS5_S5_EEEixEOS5_]+0x90): undefined reference to `cpr::CaseInsensitiveCompare::operator()(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
CMakeFiles/Ques.dir/main.cpp.o: In function `void cpr::priv::set_option<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >(cpr::Session&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&&)':
main.cpp:(.text._ZN3cpr4priv10set_optionINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEEEvRNS_7SessionEOT_[_ZN3cpr4priv10set_optionINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEEEvRNS_7SessionEOT_]+0x2a): undefined reference to `cpr::Session::SetOption(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
CMakeFiles/Ques.dir/main.cpp.o: In function `std::_Rb_tree<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::_Select1st<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >, cpr::CaseInsensitiveCompare, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >::_M_get_insert_hint_unique_pos(std::_Rb_tree_const_iterator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
main.cpp:(.text._ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE29_M_get_insert_hint_unique_posESt23_Rb_tree_const_iteratorIS8_ERS7_[_ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE29_M_get_insert_hint_unique_posESt23_Rb_tree_const_iteratorIS8_ERS7_]+0xa1): undefined reference to `cpr::CaseInsensitiveCompare::operator()(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
main.cpp:(.text._ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE29_M_get_insert_hint_unique_posESt23_Rb_tree_const_iteratorIS8_ERS7_[_ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE29_M_get_insert_hint_unique_posESt23_Rb_tree_const_iteratorIS8_ERS7_]+0x147): undefined reference to `cpr::CaseInsensitiveCompare::operator()(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
main.cpp:(.text._ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE29_M_get_insert_hint_unique_posESt23_Rb_tree_const_iteratorIS8_ERS7_[_ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE29_M_get_insert_hint_unique_posESt23_Rb_tree_const_iteratorIS8_ERS7_]+0x202): undefined reference to `cpr::CaseInsensitiveCompare::operator()(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
main.cpp:(.text._ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE29_M_get_insert_hint_unique_posESt23_Rb_tree_const_iteratorIS8_ERS7_[_ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE29_M_get_insert_hint_unique_posESt23_Rb_tree_const_iteratorIS8_ERS7_]+0x2dd): undefined reference to `cpr::CaseInsensitiveCompare::operator()(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
main.cpp:(.text._ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE29_M_get_insert_hint_unique_posESt23_Rb_tree_const_iteratorIS8_ERS7_[_ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE29_M_get_insert_hint_unique_posESt23_Rb_tree_const_iteratorIS8_ERS7_]+0x386): undefined reference to `cpr::CaseInsensitiveCompare::operator()(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
CMakeFiles/Ques.dir/main.cpp.o:main.cpp:(.text._ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE14_M_insert_nodeEPSt18_Rb_tree_node_baseSG_PSt13_Rb_tree_nodeIS8_E[_ZNSt8_Rb_treeINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt4pairIKS5_S5_ESt10_Select1stIS8_EN3cpr22CaseInsensitiveCompareESaIS8_EE14_M_insert_nodeEPSt18_Rb_tree_node_baseSG_PSt13_Rb_tree_nodeIS8_E]+0x5e): more undefined references to `cpr::CaseInsensitiveCompare::operator()(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const' follow
collect2: error: ld returned 1 exit status

Where i did mistake?

[DEGoodmanWilson]

What does your conanfile look like?

[Pwera]

conanfile content

[requires]
cpr/1.2.0@DEGoodmanWilson/testing

[generators]
cmake

conaninfo content:

[settings]
    arch=x86_64
    build_type=Release
    compiler=gcc
    compiler.libcxx=libstdc++
    compiler.version=5.3
    os=Linux

[requires]
    cpr/1.Y.Z

[options]


[full_settings]
    arch=x86_64
    build_type=Release
    compiler=gcc
    compiler.libcxx=libstdc++
    compiler.version=5.3
    os=Linux

[full_requires]
    OpenSSL/1.0.2g@lasote/stable:c9485444fc54028aa59ea9eb50adf168f08452e3
    cpr/1.2.0@DEGoodmanWilson/testing:cf6314884dde623a25b4a301b0753d616b08ceb4
    electric-fence/2.2.0@lasote/stable:52bcde7d26fabb9754f2f3b850001579b1098686
    libcurl/7.49.1@lasote/stable:08913c0fb0493a775104b4be5020b20022e6fc21
    zlib/1.2.8@lasote/stable:52bcde7d26fabb9754f2f3b850001579b1098686

[full_options]
    OpenSSL:386=False
    OpenSSL:no_asm=False
    OpenSSL:no_bf=False
    OpenSSL:no_cast=False
    OpenSSL:no_des=False
    OpenSSL:no_dh=False
    OpenSSL:no_dsa=False
    OpenSSL:no_electric_fence=False
    OpenSSL:no_hmac=False
    OpenSSL:no_md2=False
    OpenSSL:no_md5=False
    OpenSSL:no_mdc2=False
    OpenSSL:no_rc2=False
    OpenSSL:no_rc4=False
    OpenSSL:no_rc5=False
    OpenSSL:no_rsa=False
    OpenSSL:no_sha=False
    OpenSSL:no_sse2=False
    OpenSSL:no_threads=False
    OpenSSL:no_zlib=False
    OpenSSL:shared=False
    OpenSSL:zlib_dynamic=False
    cpr:insecure_curl=False
    cpr:use_ssl=True
    cpr:use_system_curl=False
    electric-fence:shared=False
    libcurl:custom_cacert=False
    libcurl:disable_threads=False
    libcurl:shared=False
    libcurl:with_ldap=False
    libcurl:with_libidn=False
    libcurl:with_libmetalink=False
    libcurl:with_librtmp=False
    libcurl:with_libssh2=False
    libcurl:with_openssl=True
    zlib:shared=False

[scope]
    dev=True

[DEGoodmanWilson]

OK, I've been able to replicate. Digging in now!

[DEGoodmanWilson]

And, compiling without Conan doesn't lead to this error. It looks like Conan is somehow not successfully linking in CPR under gcc 5.3. FWIW, your example works just fine in 4.9. I'm going to page @lasote on this one…

[DEGoodmanWilson]

There are some very interesting differences in the generated conanbuildinfo.cmake files that seem worth mentioning. Here is the output of comparing the file generated with GCC5.3 and GCC4.9 (with the irrelevant difference filtered out).

diff conanbuildinfo.cmake.gcc53 conanbuildinfo.cmake.gcc49

55a56,57
> set(CONAN_PACKAGE_NAME None)
> set(CONAN_PACKAGE_VERSION None)
82a85,88
>     conan_set_find_paths()
> endmacro()
> 
> macro(conan_set_find_paths)
84a91,93
> 
>     # Make find_package() to work
>     set(CMAKE_PREFIX_PATH ${CONAN_CMAKE_MODULE_PATH} ${CMAKE_PREFIX_PATH})
88c97,101
<     include_directories(SYSTEM ${CONAN_INCLUDE_DIRS})
---
>     if(CONAN_SYSTEM_INCLUDES)
>         include_directories(SYSTEM ${CONAN_INCLUDE_DIRS})
>     else()
>         include_directories(${CONAN_INCLUDE_DIRS})
>     endif()

[DEGoodmanWilson]

Although those differences don't appear to actually be relevant. I merged them into the gcc4.9 conanbuildinfo.cmake, and got the same linker errors :(

[DEGoodmanWilson]

@Pwera I have it figured out. The problem is that somewhere along the line, I'm not entirely sure where, something is getting compiled with an ABI-incompatible libstdc++. This should do the trick:

conan install -s compiler=gcc -s compiler.libcxx=libstdc++11 --build=missing

This will ensure that all dependencies, are compiled with the correct libstdc++ ABI

(Alternately, you can update .conan/conan.conf to reflect that setting across the board.)

[lasote]

HI! sorry for the delay. I can see that you have already solve the issue. 👍 If the setting libcxx is not set to libstcd++11 it won't link with C++11 capabilities, so this setting is needed.

[hbobenicio]

This issue is already solved, right?
Think someone can close this, I guess...
@tstack ?

[COM8]

This issue has been solved and the conan package is ready to be used without any problems.
I'm closing this issue.
Feel free to reopen it or open a new issue if you experience any problems with that.