On 9/2/25 14:51, Rob Cliffe via Python-list wrote:
Hello, can anyone help? All assistance gratefully received. I am
running python 3.13.3 on a Windows 11 machine and trying to do
pip install matplotlib
(No, I don't need to say "python -m ...", I am running the right version
of python.exe.)
This starts by generating the following output (which I can catch by
redirecting it to a file)
Collecting matplotlib
Using cached matplotlib-3.10.6.tar.gz (34.8 MB)
Installing build dependencies: started
Installing build dependencies: finished with status 'done'
Getting requirements to build wheel: started
Getting requirements to build wheel: finished with status 'done'
Installing backend dependencies: started
Installing backend dependencies: finished with status 'done'
Preparing metadata (pyproject.toml): started
Preparing metadata (pyproject.toml): finished with status 'error'
then prints error messages on the screen which are scrolled out too fast
to see, but end as follows:
3: note: in expansion of macro 'PYBIND11_COMPAT_STRDUP'
rec_fget->doc = PYBIND11_COMPAT_STRDUP(rec_fget-
>doc);
^~~~~~~~~~~~~~~~~~~~~~
C:\Users\robcl\AppData\Local\Temp\pip-build-
env-1ud913ho\overlay\Lib\site-packages\pybind11\include/pybind11/
pybind11.h:248:36: note: (if you use '-fpermissive', G++ will accept
your code, but allowing the use of an undeclared name is deprecated)
# define PYBIND11_COMPAT_STRDUP strdup
^~~~~~
C:\Users\robcl\AppData\Local\Temp\pip-build-
env-1ud913ho\overlay\Lib\site-packages\pybind11\include/pybind11/
pybind11.h:2379:33: note: in expansion of macro 'PYBIND11_COMPAT_STRDUP'
rec_fget->doc = PYBIND11_COMPAT_STRDUP(rec_fget-
>doc);
^~~~~~~~~~~~~~~~~~~~~~
C:\Users\robcl\AppData\Local\Temp\pip-build-
env-1ud913ho\overlay\Lib\site-packages\pybind11\include/pybind11/
pybind11.h:248:36: error: there are no arguments to 'strdup' that depend
on a template parameter, so a declaration of 'strdup' must be available
[-fpermissive]
# define PYBIND11_COMPAT_STRDUP strdup
^~~~~~
C:\Users\robcl\AppData\Local\Temp\pip-build-
env-1ud913ho\overlay\Lib\site-packages\pybind11\include/pybind11/
pybind11.h:2387:33: note: in expansion of macro 'PYBIND11_COMPAT_STRDUP'
rec_fset->doc = PYBIND11_COMPAT_STRDUP(rec_fset-
>doc);
^~~~~~~~~~~~~~~~~~~~~~
In file included from ../src/_backend_agg_basic_types.h:17,
from ../src/_backend_agg.h:41,
from ../src/_backend_agg_wrapper.cpp:6:
../src/py_adaptors.h: In member function 'void
mpl::PathIterator::set(pybind11::object, pybind11::object, bool, double)':
../src/py_adaptors.h:96:57: warning: comparison of integer
expressions of different signedness: 'pybind11::ssize_t' {aka 'int'} and
'unsigned int' [-Wsign-compare]
if (m_codes.ndim() != 1 || m_codes.shape(0) !=
m_total_vertices) {
~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
../src/_backend_agg_wrapper.cpp: In lambda function:
../src/_backend_agg_wrapper.cpp:253:37: warning: narrowing
conversion of 'renderer->RendererAgg::get_height()' from 'unsigned int'
to 'int' inside { } [-Wnarrowing]
renderer->get_height(),
~~~~~~~~~~~~~~~~~~~~^~
../src/_backend_agg_wrapper.cpp:253:37: warning: narrowing
conversion of 'renderer->RendererAgg::get_height()' from 'unsigned int'
to 'int' inside { } [-Wnarrowing]
../src/_backend_agg_wrapper.cpp:254:36: warning: narrowing
conversion of 'renderer->RendererAgg::get_width()' from 'unsigned int'
to 'int' inside { } [-Wnarrowing]
renderer->get_width(),
~~~~~~~~~~~~~~~~~~~^~
../src/_backend_agg_wrapper.cpp:254:36: warning: narrowing
conversion of 'renderer->RendererAgg::get_width()' from 'unsigned int'
to 'int' inside { } [-Wnarrowing]
../src/_backend_agg_wrapper.cpp:258:39: warning: narrowing
conversion of '(renderer->RendererAgg::get_width() * 4)' from 'unsigned
int' to 'int' inside { } [-Wnarrowing]
renderer->get_width() * 4,
~~~~~~~~~~~~~~~~~~~~~~^~~
../src/_backend_agg_wrapper.cpp:258:39: warning: narrowing
conversion of '(renderer->RendererAgg::get_width() * 4)' from 'unsigned
int' to 'int' inside { } [-Wnarrowing]
ninja: build stopped: subcommand failed.
There are two roots here:
(1) it's not finding a prebuilt wheel. You can see that because it's
proposing to use the source distribution instead:
> Collecting matplotlib
> Using cached matplotlib-3.10.6.tar.gz (34.8 MB)
and so it, in the initial output.
(2) Although at this point all hope of success is often lost on Windows,
it's still going to try to compile things. It found gcc - there are
messages from g++ in the output. Last I know, Pybind11 only builds with
the Microsoft compiler because it uses msvc-specific types which gcc
does not know about.
Since the matplotlib project definition provides wheels for Python 3.13
on Windows (not just the main Python, but also the free-threaded
versions), you need to figure out why the resolver doesn't think there's
anything applicable available.
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