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14049 :: How to Debug Concept Matching

• sei (orginal) [2026-07-13T21:30:02+02:00] view original

  Hi!

  I have a problem were I use a concept that looks similar to this:

  
  type
      Widgetable* = concept
          proc draw(self: var Self)
  Run

  I use it to feed a converter that converts it to an interface:

  
  type
      WidgetInterface* = object
          proc draw(self: var Self)
  
  converter toWidgetInterface*(w: Widgetable): WidgetInterface =
    let
      w_ptr = w.addr # <- use a pointer to work around compiler error
    
    result.draw = proc() = w_ptr[].draw()
  Run

  This works fine, until I want to use it to compile a program with picosdk4nim, then it fails to match some (but not all!) Widgets to the concept. When compiling normally, without picosdk4nim the concepts match as expected.

  Unfortunately I'm having a hard to time make a reduced example that shows that error, so I'd like to ask how one would go on to debug this kind of problem.

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