js: lent doesn't work for seq, ptr

[timotheecour]

js: lent doesn't work for seq, ptr

Example 1

when true:
  proc byLent[T](a: T): lent T = a
  let b = @[21,23]
  doAssert byLent(b).unsafeAddr == b.unsafeAddr # BUG: fails at RT: Error: Error: unhandled exception:

  let r = new(float)
  r[] = 10.0
  doAssert byLent(r)[] == 10.0 # BUG: fails at RT: Error: Error: unhandled exception:

Current Output

assert fails

Expected Output

works, as in c backend

Example 2

more complex, shows what works, what doesn't at once thanks to check:
nim r -b:js -d:nodejs main

when true:
  import std/unittest
  template main2 =
    proc byLent[T](a: T): lent T = a
    # proc byLent[T](a: T): lent T = result=a
    let a = [11,12]
    let ss = {1, 2, 3, 5}
    doAssert byLent(a) == [11,12]
    doAssert byLent(a).unsafeAddr == a.unsafeAddr
    doAssert byLent(ss) == {1, 2, 3, 5}
    doAssert byLent(ss).unsafeAddr == ss.unsafeAddr

    let b = @[21,23]
    doAssert byLent(b) == @[21,23]
    doAssert b.unsafeAddr == b.unsafeAddr
    check byLent(b).unsafeAddr == b.unsafeAddr # BUG: fails at RT: Error: Error: unhandled exception:

    let r = new(float)
    r[] = 10.0
    check byLent(r)[] == 10.0 # BUG: fails at RT: Error: Error: unhandled exception:

    when not defined(js): # bug https://github.com/timotheecour/Nim/issues/372
      let p = create(float)
      p[] = 20.0
      doAssert byLent(p)[] == 20.0

    proc byLent2[T](a: openarray[T]): lent T = a[0]
    doAssert byLent2(a) == 11
    doAssert byLent2(a).unsafeAddr == a[0].unsafeAddr
    doAssert byLent2(b) == 21
    doAssert byLent2(b).unsafeAddr == b[0].unsafeAddr

    proc byLent3[T](a: varargs[T]): lent T = a[1]
    let
      x = 10
      y = 20
      z = 30
    doAssert byLent3(x, y, z) == 20
  main2()

/Users/timothee/git_clone/nim/timn/tests/nim/all/t11336.nim(19, 31): Check failed: byLent(b`gensym0).unsafeAddr == b`gensym0.unsafeAddr
/Users/timothee/git_clone/nim/timn/tests/nim/all/t11336.nim(23, 22): Check failed: byLent(r`gensym0)[] == 10.0
byLent(r`gensym0)[] was undefined

Additional Information

• devel 1.5.1 d9038ed
• related but different from js: lent doesn't work in iterators with tuple destructuring #14574
• when fixing this, un-disable disabled tests added as part of followup #15970 strenghten regression tests #16075