v9.15.0: When multiple @extend, only the last one takes effect

[wang890]

Describe the bug 🐞

MTK v9.15.0:
When multiple @extend in a @mtkmodel
only the last one takes effect

Expected behavior
@extend multiple objects

Minimal Reproducible Example 👇
The example code is a github page here, just one-page jl file,
it can be copied, pasted in your VS code and debugged immediately.
Thanks!
It is a RC circuit system,
but has a conditional HeatPort in order to describe the power loss via Resistor to a thermal network.

Error & Stacktrace ⚠️

Exception has occurred: ArgumentError
ArgumentError: System resistor: variable p does not exist

Environment (please complete the following information):

• Output of using Pkg; Pkg.status()

  [961ee093] ModelingToolkit v9.15.0
  [1dea7af3] OrdinaryDiffEq v6.80.1
  [91a5bcdd] Plots v1.40.4

• Output of versioninfo()

ulia Version 1.10.3
Commit 0b4590a550 (2024-04-30 10:59 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: 6 × AMD Ryzen 5 3500X 6-Core Processor
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-15.0.7 (ORCJIT, znver2)
Threads: 1 default, 0 interactive, 1 GC (on 6 virtual cores)

[wang890]

Still in version v9.46.1, when @extend multiple times, only the last one takes effect,
that is, only the last extended component in the :extend field of ModelingToolkit.Model

ModelingToolkit v9.15.0: When multiple @extend in a @mtkmodel only the last one takes effect

[ven-k]

Sounds like something that can be supported. I'll take a look.

[wang890]

Sounds like something that can be supported. I'll take a look.

Thanks @ven-k when @extend multiple times as following, only the last one (@extend ConditionalHeatPort) takes effect

@mtkmodel Resistor begin   
    @structural_parameters begin        
        use_Heat_Port = false       
    end   

    @extend i,v,p,n = onePort = OnePort()
    @extend T_heatPort, LossPower, heatPort = conditionalHeatPort = ConditionalHeatPort(; useHeatPort=use_Heat_Port)