fixes#23690
```nim
dest.`:state` = src.`:state`
var :tmp_553651276 = dest.e1.a
`=wasMoved`(dest.e1.a)
dest.e1.a.kind = src.e1.a.kind
case dest.e1.a.kind
of 0:
dest.e1.a.a = src.e1.a.a
of 1:
`=copy`(dest.e1.a.c, src.e1.a.c)
case :tmp_553651276.kind
of 0:
of 1:
`=destroy`(:tmp_553651276.c)
```
`dest.e1.a.kind = src.e1.a.kind` changes the discrimant but it fails to
clear the memory of `dest.e1.a`. Before using hooks for copying, we need
to clear the dest, e.g. `=wasMoved(dest.e1.a.c)`.
```nim
dest.`:state` = src.`:state`
var :tmp_553651276 = dest.e1.a
`=wasMoved`(dest.e1.a)
dest.e1.a.kind = src.e1.a.kind
case dest.e1.a.kind
of 0:
`=wasMoved`(dest.e1.a.a)
dest.e1.a.a = src.e1.a.a
`=wasMoved`(dest.e1.a.b)
of 1:
`=wasMoved`(dest.e1.a.c)
`=copy`(dest.e1.a.c, src.e1.a.c)
case :tmp_553651276.kind
of 0:
of 1:
`=destroy`(:tmp_553651276.c)
```
* fix#18977 disallow change branch of an object variant in ORC
* check errors for goto exception
* fixes conditions
* fixes tests
* add a test case for #18977
* fixes#21023; Segfault when mixing seqs, orc, variants and futures
* fixes none of the branches were explicitly selected
* add one more test
* one more test
* Error -> Defect for defects
The distinction between Error and Defect is subjective,
context-dependent and somewhat arbitrary, so when looking at an
exception, it's hard to guess what it is - this happens often when
looking at a `raises` list _without_ opening the corresponding
definition and digging through layers of inheritance.
With the help of a little consistency in naming, it's at least possible
to start disentangling the two error types and the standard lib can set
a good example here.
* fixes#13102
* closes#13149
* ARC: fixes a move optimizer bug (there are more left regarding array and tuple indexing)
* proper fix; fixes#12957
* fixes yet another case object '=' code generation problem
