Nameclash for STATE y.

[1uc]

The following MOD file

NEURON {
    SUFFIX leonhard
}

STATE {
  y
}

INITIAL {
    y = 42.0
}

BREAKPOINT {
    SOLVE dX METHOD cnexp
}

DERIVATIVE dX {
    y' = -y
}

fails to compile with the following error:

$ nrnivmodl
 -> Compiling leonhard.cpp
leonhard.cpp:120:16: error: ‘double y0’ redeclared as different kind of entity
  120 |  static double y0 = 0;
      |                ^~
In file included from /usr/include/features.h:503,
                 from /usr/include/bits/libc-header-start.h:33,
                 from /usr/include/stdio.h:27,
                 from leonhard.cpp:4:
/usr/include/bits/mathcalls.h:223:1: note: previous declaration ‘double y0(double)’
  223 | __MATHCALL (y0,, (_Mdouble_));
      | ^~~~~~~~~~

with nrnivmodl from neuron-nightly.

Is this expected or a recent regression?

[alkino]

So, no idea, only adding informations about this first y0.

mathcalls.h is owned by glibc.

And the comment tells this is for bessel functions:

#if defined __USE_MISC || (defined __USE_XOPEN && __MATH_DECLARING_DOUBLE)
/* Bessel functions.  */
__MATHCALL (j0,, (_Mdouble_));
__MATHCALL (j1,, (_Mdouble_));
__MATHCALL (jn,, (int, _Mdouble_));
__MATHCALL (y0,, (_Mdouble_));
__MATHCALL (y1,, (_Mdouble_));
__MATHCALL (yn,, (int, _Mdouble_));
#endif

Here is the documentation for this function
https://man.archlinux.org/man/y0.3.en

This is a POSIX function.