Fix instantiation of array state variables

[iomaganaris]

For example the following code is printed for:

TITLE passive membrane channel

UNITS {
    (mV) = (millivolt)
    (mA) = (milliamp)
    (S) = (siemens)
}

NEURON {
    SUFFIX pas
    NONSPECIFIC_CURRENT i
    RANGE g, e
}

PARAMETER {
    g = .001    (S/cm2) <0,1e9>
    e = -70 (mV)
}

ASSIGNED {v (mV)  i (mA/cm2)}

BREAKPOINT {
    SOLVE states METHOD cnexp
    i = g*(v - e)
}

STATE {
    ar[3]
    s
}

DERIVATIVE states {
    ar[1] = ar[2] + 1
    s' = 1
}

for (std::size_t arr_index = 0; arr_index < 3; ++arr_index) {
    (inst->ar+id*3)[arr_index] = inst->global->ar0;
}

TODO:

• Add unit test
• Fix instantiation of the corresponding global variable (name + "0") -> default initialized to 0

Related to striatium mod files

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (420fb2d) 88.61% compared to head (37eefdf) 88.63%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1081      +/-   ##
==========================================
+ Coverage   88.61%   88.63%   +0.01%     
==========================================
  Files         169      169              
  Lines       12474    12485      +11     
==========================================
+ Hits        11054    11066      +12     
+ Misses       1420     1419       -1     

Files	Coverage Δ
src/codegen/codegen_cpp_visitor.cpp	85.59% <100.00%> (+0.05%)	⬆️
test/unit/codegen/codegen_cpp_visitor.cpp	100.00% <100.00%> (ø)

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[bbpbuildbot]

Logfiles from GitLab pipeline #162492 (:white_check_mark:) have been uploaded here!

Status and direct links:

• ✅ spack_setup
• ✅ build:intel
• ✅ build:nvhpc
• ✅ test:intel
• ✅ test:nvhpc