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Undefined References when using recommended linking option: Embedding Python in C++ #93358
Description
Documentation
URL: https://docs.python.org/3/extending/embedding.html
System: Ubuntu 22.04 using Python 3.10
Problem:
Using the recommended linking option /opt/bin/python3.10-config --ldflags leads to undefined references when compiling.
command used in terminal:
g++ $(python3.10-config --cflags ) -o 'test.o' 'test.cpp' $(python3.10-config --ldflags)
Output of python3.10-config --ldflags:
-L/usr/lib/python3.10/config-3.10-x86_64-linux-gnu -L/usr/lib/x86_64-linux-gnu -lcrypt -ldl -lm -lm
Solution:
Adding the option --embed solves the issue. By this, -lpython3.10 is also given to the compiler.
command used in terminal:
g++ $(python3.10-config --cflags ) -o 'test.o' 'test.cpp' $(python3.10-config --embed --ldflags)
output of python3.10-config --embed --ldflags:
-L/usr/lib/python3.10/config-3.10-x86_64-linux-gnu -L/usr/lib/x86_64-linux-gnu -lpython3.10 -lcrypt -ldl -lm -lm
test.cpp:
#include < Python.h >
int main()
{
Py_Initialize();
PyRun_SimpleString("print('Hello World from Embedded Python!!!')");
Py_Finalize();
return 0;
}
Activity
[-]Embedding Python in C++: Compiling and Linking under Ubuntu 22.04[/-][+]Undefined References when using recommended linking option: Embedding Python in C++ (Ubuntu 22.04)[/+][-]Undefined References when using recommended linking option: Embedding Python in C++ (Ubuntu 22.04)[/-][+]Undefined References when using recommended linking option: Embedding Python in C++ [/+]TianmingQu commentedon Oct 24, 2022
erlend-aasland commentedon Oct 25, 2022
Yes, the docs are out of date. This was changed in Python 3.8 -- see the 3.8 What's New:
https://docs.python.org/3/whatsnew/3.8.html#debug-build-uses-the-same-abi-as-release-build
Adding
--embedwhen producing the linker flags should help. I'll create a PR for updating the docs.erlend-aasland commentedon Oct 25, 2022
pythongh-93358: Fix python-config docs for how to embed Python
gh-93358: Fix python-config docs for how to embed Python (#98649)
pythongh-93358: Fix python-config docs for how to embed Python (pytho…
pythongh-93358: Fix python-config docs for how to embed Python (pytho…
erlend-aasland commentedon Oct 29, 2022
The docs were updated by the following PRs:
gh-93358: Fix python-config docs for how to embed Python (GH-98649)
gh-93358: Fix python-config docs for how to embed Python (GH-98649)