/usr/bin/ld: cannot find -lpythonxx

[Hydaspex]

I have tried to compile an example to no avail on Ubuntu with Python 3.7 (Anaconda) running in a VM on Win10.

Code
g++ modern.cpp -I/usr/include/python3.7 -lpython3.7 --std=c++11 -v

I am not able to get rid of the following error
/usr/bin/ld: cannot find -lpython3.7 collect2: error: ld returned 1 exit status

Any support would be greatly appreciated.

Below I have pasted two excerpts from -verbose log (but I cannot see anything wrong except for the error message).

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/7" ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu" ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/7/../../../../x86_64-linux-gnu/include" #include "..." search starts here: #include <...> search starts here: /usr/include/python3.7 /usr/include/c++/7 /usr/include/x86_64-linux-gnu/c++/7 /usr/include/c++/7/backward /usr/lib/gcc/x86_64-linux-gnu/7/include /usr/local/include /usr/lib/gcc/x86_64-linux-gnu/7/include-fixed /usr/include/x86_64-linux-gnu /usr/include End of search list.
COLLECT_GCC_OPTIONS='-I' '/usr/include/python3.7' '-std=c++11' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64' as -v -I /usr/include/python3.7 --64 -o /tmp/ccfipdIM.o /tmp/cctxAOiD.s GNU assembler version 2.30 (x86_64-linux-gnu) using BFD version (GNU Binutils for Ubuntu) 2.30 COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/7/:/usr/lib/gcc/x86_64-linux-gnu/7/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/7/:/usr/lib/gcc/x86_64-linux-gnu/ LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/7/:/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/7/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/7/../../../:/lib/:/usr/lib/ COLLECT_GCC_OPTIONS='-I' '/usr/include/python3.7' '-std=c++11' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64' /usr/lib/gcc/x86_64-linux-gnu/7/collect2 -plugin /usr/lib/gcc/x86_64-linux-gnu/7/liblto_plugin.so -plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper -plugin-opt=-fresolution=/tmp/cco1QpeW.res -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc --sysroot=/ --build-id --eh-frame-hdr -m elf_x86_64 --hash-style=gnu --as-needed -dynamic-linker /lib64/ld-linux-x86-64.so.2 -pie -z now -z relro /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o -L/usr/lib/gcc/x86_64-linux-gnu/7 -L/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/7/../../../../lib -L/lib/x86_64-linux-gnu -L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/7/../../.. /tmp/ccfipdIM.o -lpython3.7 -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
/usr/bin/ld: cannot find -lpython3.7
collect2: error: ld returned 1 exit status
``

[dist1ll]

Yep, same error. I'm super confused, because I have the binaries in /usr/bin/ld. I don't understand why gcc can't find it.

[lava]

The last time I built against python3, I had to use -lpython3.7m as linker flag. This was on Ubuntu 18.04, maybe your distribution has the same setup.

[FanchenBao]

On my system (MacOS, python3.6 installed via Homebrew), even if I use -lpython3.6m as linker flag, it still gives me error ld: library not found for -lpython3.6m. The final solution is to use the --cflags and --ldflags provided in python3-config, and the cpp file compiles.

g++ minimal.cpp -std=c++11 $(python3-config --cflags) $(python3-config --ldflags)

In addition, if at runtime there is error loading matplotlib.pyplot, follow the instruction in #8

[jpan127]

Thank you @FanchenBao that works great!