problem with making a c++ project with G++

student_11

3/9/23, 9:11 PM

I am trying to build cascade library using G++ 8.3.0. In the documentation they mention that it was tested on G++ 4.7.2. My question is, is it necessary to downgrade to 4.7.2? if so could you please tell me how? because I tried both 4.8 (oldest version available according to $which gcc command) and 8.3.0 to build cascade and received the following error:

In file included from ../../include/descore/descore.hpp:104,
                 from ../../include/descore/stdafx.h:38,
                 from Wildcard.cpp:44:
../../include/descore/stltree.hpp:74:34: error: redefinition of ‘struct std::less<_Tp*>’
     template <typename T> struct less <T *>
                                  ^~~~~~~~~~
In file included from /usr/include/c++/8/bits/stl_tree.h:65,
                 from /usr/include/c++/8/set:60,
                 from ../../include/descore/descore.hpp:88,
                 from ../../include/descore/stdafx.h:38,
                 from Wildcard.cpp:44:
/usr/include/c++/8/bits/stl_function.h:424:12: note: previous definition of ‘struct std::less<_Tp*>’
     struct less<_Tp*> : public binary_function<_Tp*, _Tp*, bool>
            ^~~~~~~~~~
make: *** [Makefile:17: ../../objs/descore/Wildcard.o] Error 1

Or should I make changes to the .hpp files? (My final aim is to use cascade with G++-11. on ubuntu 19.10)

Thanks in advance.

0 + 0

compiling

gcc

c++

g++

ubfan1

3/9/23, 11:32 PM

You need to use a c++ compiler, which would be g++ on Ubuntu, not gcc.

student_11

3/10/23, 7:46 AM

I have edited my post. thanks. Do you get the same error when using the 'make' command?

steeldriver

3/10/23, 12:48 PM

For me, using `g++-4.8` (on Ubuntu 18.04) overcomes the template redefinition issue (which I think is due to the code rolling its own partial specialization code for pointer types); however there are further errors at the link phase

steeldriver

3/10/23, 1:36 PM

... OK so I did get it to build with g++-4.8 via cmake, by adding `descore` to the `target_link_libraries` and then using `cmake -DCMAKE_CXX_COMPILER=g++-4.8 -DCMAKE_CXX_FLAGS=-pthread`. But I don't know how to make it work with later g++.

student_11

3/10/23, 2:23 PM

Thanks @steeldriver. I've built it using Microsoft VS2015 before. It did not work at first, but after I changed MSC_VERSION macros definitions in defines.hpp (i.e. #if _MSC_VER < 1900 #define va_copy(dst, src) ((void)((dst) = (src)))), it was built successfully. Cant we apply similar changes to g++ or .hpp files in Linux?

steeldriver

3/10/23, 4:04 PM

@student_11 there *may* be a way to do that with g++ however I can't see anything obvious (such as a compiler switch or a `#ifdef` in the `stl_function.h` file that would allow the functionality to be turned off). You may need to remove the conflicting partial specialization code from the project. Good luck.

ubfan1

3/10/23, 4:51 PM

Lines 80-90 of stltree.hpp give you the options for modification.

student_11

3/13/23, 4:03 PM

@ubfun1 thanks. we should comment out the namespace above those lines to get rid of the error.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: problem with making a c++ project with G++

TH: ปัญหาในการสร้างโปรเจ็กต์ c++ ด้วย G++

RO: problemă cu realizarea unui proiect c++ cu G++

RU: проблема с созданием проекта C++ с помощью G++

VI: vấn đề với việc tạo một dự án c ++ với G ++

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