Build failure of SuperLU with the development version of numpy

[WarrenWeckesser]

NumPy has recently changed how it defines complex numbers in its C code. As a result of these changes, the NumPy C header file "npy_common.h" now does #include <complex.h>. This will break the compilation of any extension module that includes the NumPy C header files and that has its own definition of the name complex. See numpy/numpy#24344 and numpy/numpy#24198 and the links therein for details.

We are encountering this problem with the SuperLU code. Specifically, in https://github.com/scipy/scipy/blob/main/scipy/sparse/linalg/_dsolve/SuperLU/SRC/slu_scomplex.h, which has

scipy/scipy/sparse/linalg/_dsolve/SuperLU/SRC/slu_scomplex.h

Line 31 in 7e7d867

typedef struct { float r, i; } complex;

Until SuperLU modernizes its code so that it doesn't rely on its own implementation of complex arithmetic (or at least doesn't use the name complex), AND someone then takes on the challenges of updating our vendored version, I think we'll have to add another patch to our vendored copy, to change the name complex to, say, singlecomplex.

[rgommers]

@lysnikolaou would you have time to patch this up and then upstream the fix to https://github.com/xiaoyeli/superlu?

[lysnikolaou]

@lysnikolaou would you have time to patch this up and then upstream the fix to https://github.com/xiaoyeli/superlu?

Of course! I'll be back home and in front of a computer on Sunday, so I'll probably work on this on Monday. Is that okay?

[rgommers]

Sure no worries! And in case it bothers anyone enough before that time, they can fix it instead.

[lysnikolaou]

Opened #19062.