Behaviour of Arrays #27

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1. eldering commented on Mar 14, 2026

   

   eldering

   on Mar 14, 2026

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   Is this intended behaviour that a variable is used like a special index in the array? i.e. that those two programs are valid and accept:

   So the way that variables and arrays at the same time are stored internally is as a map (variable name, index) -> value.

   So when you call SET(a=42), then that is stored as ("a", []) -> 42, while if you call SET(a[1]=42), then that's stored as ("a", [1]) -> 42.

   SET(a=1)
   ASSERT(INARRAY(1,a))
   

   So this actually checks if the value 1 exists inside the a variable for any index, including the empty list index associated to the "non-array" variable a. That's why it returns true.

   SET(a=1)
   SET(a[1]=1)
   ASSERT(!UNIQUE(a))
   

   Here, a contains 1 at two different indices: [] and [1], which is why UNIQUE returns false.

   (My assumption would have been that a variable must either be an array or a value but not both at the same time)

   I'm not arguing that this is intuitive or correct behaviour, just what is currently implemented. I think the options are either to clarify that a simple (non-array) variable is basically a special case of an array with empty index, or indeed somehow to disallow a variable to have both a non-array value (i.e. empty index) and any array values (i.e. non-empty indices) at the same time.
2. mzuenni commented on Mar 15, 2026

   

   mzuenni

   on Mar 15, 2026

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   I'm not arguing that this is intuitive or correct behaviour, just what is currently implemented. I think the options are either to clarify that a simple (non-array) variable is basically a special case of an array with empty index, or indeed somehow to disallow a variable to have both a non-array value (i.e. empty index) and any array values (i.e. non-empty indices) at the same time.

   I am fine with both. My python reqrite currently matches main, but if i remmeber correctly the antlr_rewrite differentiates between arrays and values.
3. mzuenni commented on Mar 22, 2026

   

   mzuenni

   on Mar 22, 2026

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   maybe also relevant: if we force that a variable is either an array or a value, would we also force that it must have a fixed dimension?
   In other words would SET(a[1]=1,a[1,1]=2) be an error or ok?
4. eldering commented on Mar 24, 2026

   

   eldering

   on Mar 24, 2026

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   maybe also relevant: if we force that a variable is either an array or a value, would we also force that it must have a fixed dimension? In other words would SET(a[1]=1,a[1,1]=2) be an error or ok?

   In the standard checktestdata specification that's currently allowed.

   One the one hand I don't expect that people typically use/need that, but OTOH it would break backwards compatibility.
5. mzuenni commented on Mar 25, 2026

   

   mzuenni

   on Mar 25, 2026

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   but OTOH it would break backwards compatibility

   For me the questions would be a different: do people use this intentionally VS. do they use it by accident? or in other words if this happens, is it more likely to hint at a bug in the checker? If the answer is yes than we should warn/error?