constructor causes SIGBUS if a destroy is defined

[timotheecour]

constructor causes SIGBUS if a destroy is defined

Example 1

when true: # D20200607T202043
  type Foo = object
    x: int
    x2: array[10, int]

  type Vec = object
    vals: seq[Foo]

  proc `=destroy`*(a: var Foo) {.inline.} =
    discard

  proc initFoo(x: int): Foo = Foo(x: x)

  proc add2(v: var Vec, a: Foo) = # ditto with `a: sink Foo`
    v.vals.add a

  proc main()=
    var a: Vec
    var b = Foo(x: 10)
    a.add2 b # ok
    a.vals.add Foo(x: 10) # ok
    a.add2 initFoo(x = 10) # ok
    a.add2 Foo(x: 10) # bug
  main()

Current Output

/Users/timothee/git_clone/nim/timn/tests/nim/all/t10914.nim(95) t10914
/Users/timothee/git_clone/nim/timn/tests/nim/all/t10914.nim(94) main
/Users/timothee/git_clone/nim/timn/tests/nim/all/t10914.nim(86) add2
SIGBUS: Illegal storage access. (Attempt to read from nil?)

Expected Output

works

Example 2

here's another example without seq, directly setting a field in add2:

when true: # gitissue
  type Foo = object
    x: int
    x2: array[10, int]

  type Vec = object
    val: Foo

  proc `=destroy`*(a: var Foo) {.inline.} =
    discard

  proc initFoo(x: int): Foo = Foo(x: x)

  proc add2(v: var Vec, a: Foo) = # ditto with `a: sink Foo`
    v.val = a

  proc main()=
    var a: Vec
    # var a = default(Vec) # ditto
    # var a = Vec() # ditto
    var b = Foo(x: 10)
    a.add2 b # ok
    a.val = Foo(x: 10) # ok
    a.add2 initFoo(x = 10) # ok
    a.add2 Foo(x: 10) # bug
  main()

Additional Information

• devel 1.3.5 52841db
• this reminds strongly of Writing to readonly data gives SIGBUS error; should be CT error instead #8463, SIGBUS (on OSX) likely indicates here that add2 is attempting to write to ROM
  I don't think there's anything invalid with this code however; simply adding a field x2: array[10, int] shouldn't suddendly give rise to SIGBUS errors

[ghost]

@timotheecour both of these work for me on latest devel with both refc/arc, can you confirm?

[timotheecour]

indeed, works, thanks! (and I rechecked that 52841db was still causing the above bug, so not sure what fixed it, but ok!)