The for loop wrongly behaves when there are nested arrays in the iteration contexts

[yesamer]

The following FEEL expression:

for x in [ [1,2], [3,4] ], y in x return y

should return [1, 2, 3, 4]

but it currently returns [1, 2, 1, 2]

[yesamer]

Most likely related to #774

[yesamer]

//cc @bncriju

[gitgabrio]

@yesamer
I've found the point where it fails, but it is int the core logic itself, where during the loop evaluation, only the first element is stored (and retrieved ) as x variable (so, the [1, 2] in the given example):

I'm trying also another example
for x in [ 1, 2, 3, 4 ], y in x return y
that, apparently, should return [1, 2, 3, 4]
but it also returns [1, 1, 1, 1] (since 1 is the first x element)

[gitgabrio]

@yesamer @baldimir
Reading spec:

An iteration context may either be an expression that returns a list of elements, or two expressions that return
integers connected by “..”. Examples of valid iteration contexts are:
• [ 1, 2, 3]
• a list
• 1..10
• 50..40
• x..x+10
• @”2021-01-01”..@”2022-01-01”

and

for i in [i1,i2], j in [j1j2] return e = [ r1, r2, r3, r4 ]

it seems that this expression is wrong
for x in [ 1, 2, 3, 4 ], y in x return y (x is always a number)

but this should work

for x in [ [1,2], [3,4] ], y in x return y (x is alway a list)

Unfortunately, it seems that our implementation is expecting only statically defined lists.

I'm digging further...