Pin libgcc for windows installs

[jessegrabowski]

Closes #1398 . Issue was reported and debugged by user DrEntropy here.

Maybe there's a better solution for this issue, but it's probably good to patch it quickly for now. We should also consider running the CI on windows -- testing linux and mac is a bit redundant?

---

📚 Documentation preview 📚: https://pytensor--1399.org.readthedocs.build/en/1399/

[ricardoV94]

The c backend is optional for PyTensor, this is something you want to do at the conda level not here

[maresb]

Ya, libgcc isn't even on PyPI. Would anyone be available for a quick call to explain to me what's going on?

[jessegrabowski]

Yep I quickly discovered this PR is extremely stupid :)

I can close it once we have another one addressing the actual issue.

[ricardoV94]

testing linux and mac is a bit redundant?

We only do a smoke test on mac but why is it redundant. They are very different oses these days, so much mac breaks every other day and I don't remember the last time we had issues on linux

[maresb]

I did a bit more digging and I have a vague hypothesis.

I don't think it's a matter of pinning libgcc, but rather that pytensor is finding the wrong compiler. Perhaps we are picking up the system compiler, or there is a mismatch within the conda environment itself between the gxx version and libgcc version? (ping @lucianopaz)

(Note that we had to change to g++ on Windows, but it has been apparently working well for several months.) conda-forge/pytensor-suite-feedstock#133 (comment)

I reproduced a Windows environment via pixi, and I'm wondering why libgcc is on 15.1.0 while libgcc-devel_win-64 is on 13.3.0:

Environment list

  + C _openmp_mutex                                   4.5 2_gnu                              
  + C anyio                                           4.9.0 pyh29332c3_0                     
  + C argon2-cffi                                     23.1.0 pyhd8ed1ab_1                    
  + C argon2-cffi-bindings                            21.2.0 py312h4389bb4_5                 
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  + C asttokens                                       3.0.0 pyhd8ed1ab_1                     
  + C async-lru                                       2.0.5 pyh29332c3_0                     
  + C attrs                                           25.3.0 pyh71513ae_0                    
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  + C binutils_impl_win-64                            2.43 h095e170_4                        
  + C binutils_win-64                                 2.43 hd1c8def_4                        
  + C blas                                            2.131 openblas                         
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  + C krb5                                            1.21.3 hdf4eb48_0                      
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  + C ld_impl_win-64                                  2.43 hae1bf67_4                        
  + C lerc                                            4.0.0 h6470a55_1                       
  + C libaec                                          1.1.3 h63175ca_0                       
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  + C libbrotlicommon                                 1.1.0 h2466b09_2                       
  + C libbrotlidec                                    1.1.0 h2466b09_2                       
  + C libbrotlienc                                    1.1.0 h2466b09_2                       
  + C libcblas                                        3.9.0 31_h9bd4c3b_openblas             
  + C libcurl                                         8.13.0 h88aaa65_0                      
  + C libdeflate                                      1.23 h76ddb4d_0                        
  + C libexpat                                        2.7.0 he0c23c2_0                       
  + C libffi                                          3.4.6 h537db12_1                       
  + C libfreetype                                     2.13.3 h57928b3_1                      
  + C libfreetype6                                    2.13.3 h0b5ce68_1                      
  + C libgcc                                          15.1.0 h1383e82_2                      
  + C libgcc-devel_win-64                             13.3.0 h5200ebd_102                    
  + C libgd                                           2.3.3 h7208af6_11                      
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  + C libgomp                                         15.1.0 h1383e82_2                      
  + C libhwloc                                        2.11.2 default_ha69328c_1001           
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  + C liblapacke                                      3.9.0 31_h1d0e49f_openblas             
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  + C mingw-w64-ucrt-x86_64-windows-default-manifest  6.4 he206cdd_7                         
  + C mingw-w64-ucrt-x86_64-winpthreads-git           12.0.0.r4.gg4f2fc60ca h7428d3b_9       
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  + C pillow                                          11.2.1 py312h078707f_0                 
  + C pixman                                          0.46.0 had0cd8c_0                      
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  + C pthread-stubs                                   0.4 h0e40799_1002                      
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  + C pytz                                            2025.2 pyhd8ed1ab_0                    
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  + C unicodedata2                                    16.0.0 py312h4389bb4_0                 
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  + C vc                                              14.3 h2b53caa_26                       
  + C vc14_runtime                                    14.42.34438 hfd919c2_26                
  + C vs2015_runtime                                  14.42.34438 h7142326_26                
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  + C win_inet_pton                                   1.1.0 pyh7428d3b_8                     
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  + C xorg-libxau                                     1.0.12 h0e40799_0                      
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  + C xorg-libxext                                    1.3.6 h0e40799_0                       
  + C xorg-libxpm                                     3.5.17 h0e40799_1                      
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  + C zeromq                                          4.3.5 ha9f60a1_7                       
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  + C zstandard                                       0.23.0 py312h4389bb4_2                 
  + C zstd                                            1.5.7 hbeecb71_2             

[maresb]

and I'm wondering why libgcc is on 15.1.0 while libgcc-devel_win-64 is on 13.3.0

I checked on linux-64 and it was the same, but it still works on Linux. 🤷

[jessegrabowski]

Closing this PR since it's entirely wrong, we can move the discussion on how to proceed to #1398