Corrupted stack traces

nim --version

Nim Compiler Version 0.17.3 [Windows: amd64]
Copyright (c) 2006-2017 by Andreas Rumpf

git hash: e0e1241a54b8ad03ac45cdd56b845370a7e050f3
active boot switches: -d:release

---

Code (saved as bug2.nim) -

type
    A = ref object of RootObj
    R = ref object of Exception

proc add(): A =
    raise R()

proc p*(): seq[A] =
    result = @[]
    while true:
        try:
            result.add(add())
        except R:
            discard

discard p()

1. nim c --run bug2.nim and then CTRL+C sometimes shows bug2 has stopped working , at other times gives -

SIGINT: Interrupted by Ctrl-C.
Traceback (most recent call last)
bug2.nim(16)             bug2
bug2.nim(12)             p
R:ObjectType(39772872)   �I���H�E�H��`]�UH��H��►H�M►H�U↑H�E►H�E��H��►]�UH��H��0H�M►H�U↑H�E►H�E�H�E�
SIGINT: Interrupted by Ctrl-C.

2. koch temp c bug2.nim and then running bug2.exe from cmd and then CTRL+C sometimes gives -

Traceback (most recent call last)
bug2.nim(16)             bug2
bug2.nim(12)             p
bug2.nim(6)              add
rawAlloc(196608)         gc.nim
HïE°Hâ──`]├UHëσσHâ∞∞PHëM►Hì♣ôm☻(7076416) incRef
gc.nim(4457088)          HïE°Hâ──`]├UHëσσHâ∞∞`Hì♣∟n☻
SIGINT: Interrupted by Ctrl-C.

---

Note:
This is a random corruption. Some times the stack traces are proper.

Oh, this may be compiler/OS dependent, because I can't reproduce it on macOS with clang

Not sure about it being OS specific, but it did take me multiple tries to reproduce the issue myself on Windows.

And this issue occurs only with the default/mark&sweep gc IIRC.
Because for all other gc's there is no stack trace, the application just crashes with application_name has stopped working

[ringabout]

I can't reproduce it in windows with Nim v 1.5

[ringabout]

Feel free to reopen if someone could reproduce this issue.

nim -v           
Nim Compiler Version 1.5.1 [Windows: amd64]
Compiled at 2021-01-10
Copyright (c) 2006-2021 by Andreas Rumpf

active boot switches: -d:release

gcc

Thread model: posix
gcc version 8.1.0 (x86_64-posix-sjlj-rev0, Built by MinGW-W64 project)