JS: no bound checks at top level

[metagn]

This only happens on top level, it works inside proc main or similar. --boundchecks:on doesn't help.

Example

var x = @[1, 2, 3]

echo x[5]
x[5] = 8

Current Output

undefined

Expected Output

Error: unhandled exception: index 5 not in 0 .. 2 [IndexError]

Possible Solution

• jsgen.genArrayAccess checks for optBoundsCheck in p.options which evaluates to false at top level and true anywhere else.
• Workaround:

var x = @[1, 2, 3]

proc main =
  echo x[5]
  x[5] = 8
main()

$ nim -v
Nim Compiler Version 1.3.1 [Windows: amd64]

git hash: 3b5a504692495324afdb7c20159122e66100f767