ImportError using abi3 wheel on windows

[NicolasHanus]

Hello,
I have a project that generates an extension module through PyO3 with abi3 feature. I am building on Windows. The wheel builds fine, I can install it, but I cannot use it. From git bash:

$ python --version
Python 3.8.0

$ maturin --version
maturin 0.12.19

$ maturin build --release --no-sdist
🔗 Found pyo3 bindings with abi3 support for Python ≥ 3.7
🐍 Using CPython 3.8 at C:\dev\Python38\python.exe to generate to link bindings (With abi3, an interpreter is only required on windows)
Finished release [optimized] target(s) in 0.07s
📦 Built wheel for abi3 Python ≥ 3.7 to C:\Users\nhanus\dev\git\test_maturin\target\wheels\thermal-0.1.0-cp37-abi3-win_amd64.whl

$ pip --version
pip 22.1.2 from c:\users\nhanus\dev\git\test_maturin.venv\lib\site-packages\pip (python 3.8)

$ pip install target/wheels/thermal-0.1.0-cp37-abi3-win_amd64.whl
Processing c:\users\nhanus\dev\git\test_maturin\target\wheels\thermal-0.1.0-cp37-abi3-win_amd64.whl
Installing collected packages: thermal
Successfully installed thermal-0.1.0

$ python
Python 3.8.0 (tags/v3.8.0:fa919fd, Oct 14 2019, 19:37:50) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.

import thermal
Traceback (most recent call last):
File "", line 1, in
File "C:\Users\nhanus\dev\git\test_maturin.venv\lib\site-packages\thermal_init_.py", line 1, in
from .thermal import *
ImportError: DLL load failed while importing thermal: The specified procedure could not be found.

Here are the config files for my project:

Cargo.toml

[package]
name = "thermal"
version = "0.1.0"
authors = ["nico"]
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[lib]
name = "thermal"
# "cdylib" is necessary to produce a shared library for Python to import from.
crate-type = ["cdylib"]

[dependencies.pyo3]
version = "0.16.5"
features = ["extension-module", "abi3-py37"]

pyproject.toml

[build-system]
requires = ["maturin>=0.12,<0.13"]
build-backend = "maturin"

I've been struggling with that for some days now. I'm out of ideas.
Note that it works fine if I remove the 'abi3-py37' flag from the features, but I'd like to support multiple python versions.

Ultimately I'd like to cross compile this from Linux. So far, cross-compiling with the 'abi3-py37' flag, i manage to build the windows wheel but I have the same error at the end when importing it. Without the flag, I am not able to get a wheel (interpreter not found issue).

Can somebody please help ? Any idea what is going on ? What am I doing wrong ?

Many thanks in advance

[messense]

Run python -c 'import sys; print(sys.base_prefix)' then go to the printed directory, verify that it contains a python3.dll file.

Edit: solution is #956 (reply in thread)

[NicolasHanus]

See below

[NicolasHanus]

@davidhewitt @messense I appreciate your help
Any hint of what I could look for in the dumpbin result ? Or any other idea of how I could find out what the dll is looking for at load time ?
Many thanks

[messense]

Perhaps you can refer to this article to debug the dll load issue: https://abitofscotland.wordpress.com/2019/12/20/dll-load-failure/

[NicolasHanus]

I found and solved the issue. I could see in dependency walker that symbol Py_CompileString was not found in dependent DLL python38.dll
I searched and found this issue stating these symbols are indeed missing in Python distribution 3.8.0. That was the one I was using. I installed 3.8.10 instead and it's now working.
Thank you both for your help.

[NicolasHanus]

[NicolasHanus]

Here is the result on my library.
log.txt

And here it is for the python3.dll. Strangely the command shows nothing for this one :/
log.txt

Can you be more specific about what I should be looking for in the first dump ? I see plenty of UNKNOWN or UNDEF but it's not really explicit.

I'm also trying to analyze my library with dependency walker, but so far, the tool is stuck :(

Thx in advance