delete(seq, index) with invalid index deletes an element instead of raising

[timotheecour]

Example

when true:
  var a = @[1,2,3]
  a.delete 6
  echo a

Current Output

@[1, 2]

Expected Output

raise IndexError via raiseIndexError2

Additional Information

devel 1.5.1 505d043
a fix should include a comprehensive test

note that RangeDefect is raised if passing i == 0 with x.len == 0

Error: unhandled exception: value out of range: -1 notin 0 .. 9223372036854775807 [RangeDefect]

note that del correctly raises:
Error: unhandled exception: index 6 not in 0 .. 2 [IndexDefect]

[juancarlospaco]

I hit the bug too, more examples:

var a: seq[int] = @[0]
a.delete(999999999999)

var a: seq[int] = @[0]
discard a.pop()
a.delete(999999999999)

var a: seq[int] = @[0]
discard a.pop()
a.insert(42, 0)
a.delete(999999999999)

del works consistently on all cases:

Error: unhandled exception: index out of bounds, the container is empty [IndexDefect] or similar.

[ringabout]

What do you expect subStr with invalid index?
subStr(s, -4, 10) or ?

See also
#16280 (comment)

[arnetheduck]

well, I argue in #16492 that first and foremost, all these operations would ideally present a logically consistent picture, both native types, library types and at compile time - in fact, the most important thing is that they are consistent with each other - ie when one is defined in a particular way, the others follow.

Generally, I probably have a slight preference for being lenient with ranges / slices (towards python, but also C++ allows some leniency in these kinds of operations), ie simply return the overlapping part, but one could argue for strictness I guess - there's already lots of Defect/panics all over the place which don't really need to be panics, so from that point of view, strictness and lots of panics that users have to guard against is more nim-like.

[hnicke]

Just stumbled across this too.
Coming from kotlin and python, I really didn't expect delete to remove the last element if index is out of bounds.
I consider this to be dangerous.
Instead, I expect it too either raise an Exception or return nil (where else it would return the removed value).

[hnicke]

Is the general consensus that delete should behave exactly like del in this case, e.g. like below?

let xs = @[0,1]
xs.delete(2)
# Error: unhandled exception: index 2 not in 0 .. 1 [IndexDefect]

[Araq]

Can confirm, yes.