release/8.2 problem with aliases in LinearCircuit builder

[nrnhines]

A user sent the attached model which fails to plot or record the V_out alias with NEURON version 8.2.7. It does work with version 9.0

amplifier.zip

If one launches the model with version 9.0, nrngui init.hoc, the correct Graph[2] looks like:

But with 8.2.7, the LinearCircuit[0].V_out line is missing (though it appears in the LincirGraph[0] for LinearCircuit[0] graph.

[nrnhines]

A minimal test that exhibits the error (for 8.2.7) is

$ cat hoctests/tests/test_alias.py
# release/8.2 problem with aliases in LinearCircuit builder #3688

from neuron import h

h(
    r"""
begintemplate A
public a, b
proc init() {
    a = 5
    b = 1
}
endtemplate A
"""
)


def test():
    a = h.A()
    sf = h.StringFunctions()
    sf.alias(a, "V_out", a._ref_a)
    sf.alias(a, "V_out_0", a._ref_b)
    print(f"a.a={a.a} a.V_out={a.V_out}")
    print(f"a.b={a.b} a.V_out_0={a.V_out_0}")
    assert a.V_out == a.a


if __name__ == "__main__":
    test()

yields the result

$ python test_alias.py
a.a=5.0 a.V_out=1.0
a.b=1.0 a.V_out_0=1.0
Traceback (most recent call last):
  File "/home/hines/neuron/aliasbug/test/hoctests/tests/test_alias.py", line 29, in <module>
    test()
    ~~~~^^
  File "/home/hines/neuron/aliasbug/test/hoctests/tests/test_alias.py", line 25, in test
    assert a.V_out == a.a
           ^^^^^^^^^^^^^^
AssertionError