[BUG]: AttributeError: module has no attribute

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What version (or hash if on master) of pybind11 are you using?

2.10.3

Problem description

OK, I am trying to export the following simple Add function (I took the example from the online tutorial on the pybind11 website) without any success:

#include <cstdint>
#include <pybind11/pybind11.h>

int32_t Add(int32_t a, int32_t b) {
    return a + b;
}

PYBIND11_MODULE(SGPYCPP_MODULE_NAME, m) {
    m.doc() = "A simple Python/C++ example";

    m.def("Add", &Add, "A function that adds two numbers");
}

When I import it, it imports my module, but says it has no attribute named Add:

python3
Python 3.7.3 (default, Jan 22 2021, 20:04:44) 
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import SGPyCpp
>>> SGPyCpp.Add(2,1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'SGPyCpp' has no attribute 'Add'
>>> 

I even tried to name my module example and use the exact sample from the official online tutorial to leave out any other possibility without any luck:

int add(int i, int j) {
    return i + j;
}

PYBIND11_MODULE(example, m) {
    m.doc() = "pybind11 example plugin"; // optional module docstring

    m.def("add", &add, "A function that adds two numbers");
}

I even tried to comment on most of CMakeLists.txt and reduced it to the sample from here without any luck.

I'll attach the full source code as a zip file in order to replicate the issue. After extraction, just issue:

make clean && make

SGPyCpp.zip

I'd appreciate it if you'd let me know what's wrong.

Reproducible example code

A full example is provided in the zip file:


#include <cstdint>
#include <pybind11/pybind11.h>

int32_t Add(int32_t a, int32_t b) {
    return a + b;
}

PYBIND11_MODULE(SGPYCPP_MODULE_NAME, m) {
    m.doc() = "A simple Python/C++ example";

    m.def("Add", &Add, "A function that adds two numbers");
}

### Is this a regression? Put the last known working version here if it is.

Not a regression

Extract the attached SGPyCpp.zip, inspect its CMakeLists.txt and the PYBIND11_MODULE definition, then run make clean && make as requested. Check whether the built module name and imported module match the exported function, and consider the issue done when the cause of the missing Add attribute is reproducible and documented.