Arc, finalizer, out of memory

[StefanSalewski]

$ nim -v
Nim Compiler Version 1.1.1 [Linux: amd64]
Compiled at 2020-01-15
Copyright (c) 2006-2019 by Andreas Rumpf

git hash: d88b52c0bc505db42ba6561518c9ee9b21a99e81
active boot switches: -d:release

type
  Object* = ref object of RootRef
    impl*: pointer

type
  InitiallyUnowned* = ref object of Object

type
  Widget* = ref object of InitiallyUnowned

proc finalizeGObject*[T](o: ref T) =
  echo "finalizeGObject"

proc main =
  var w: Widget
  new(w, finalizeGObject)
  echo "OK"

main()

3 $ nim c -r t0.nim 
Hint: used config file '/home/stefan/Nim/config/nim.cfg' [Conf]
Hint: used config file '/home/stefan/Nim/config/config.nims' [Conf]
Hint: system [Processing]
Hint: widestrs [Processing]
Hint: io [Processing]
Hint: t0 [Processing]
CC: stdlib_io.nim
CC: stdlib_system.nim
CC: t0.nim
Hint: gcc   -o /tmp/gtk3/t0  /tmp/stefan/.cache/nim/t0_d/stdlib_io.nim.c.o /tmp/stefan/.cache/nim/t0_d/stdlib_system.nim.c.o /tmp/stefan/.cache/nim/t0_d/@mt0.nim.c.o    -ldl [Link]
Hint: 22185 LOC; 0.410 sec; 24.613MiB peakmem; Debug build; proj: /tmp/gtk3/t0.nim; out: /tmp/gtk3/t0 [SuccessX]
Hint: /tmp/gtk3/t0  [Exec]
OK
stefan@nuc /tmp/gtk3 $ nim c --gc:arc t0.nim 
Hint: used config file '/home/stefan/Nim/config/nim.cfg' [Conf]
Hint: used config file '/home/stefan/Nim/config/config.nims' [Conf]
Hint: system [Processing]
Hint: widestrs [Processing]
Hint: io [Processing]
Hint: t0 [Processing]
CC: stdlib_io.nim
CC: stdlib_system.nim
CC: t0.nim
Hint: gcc   -o /tmp/gtk3/t0  /tmp/stefan/.cache/nim/t0_d/stdlib_allocators.nim.c.o /tmp/stefan/.cache/nim/t0_d/stdlib_io.nim.c.o /tmp/stefan/.cache/nim/t0_d/stdlib_system.nim.c.o /tmp/stefan/.cache/nim/t0_d/@mt0.nim.c.o    -ldl [Link]
Hint: 20027 LOC; 0.298 sec; 19.695MiB peakmem; Debug build; proj: /tmp/gtk3/t0.nim; out: /tmp/gtk3/t0 [SuccessX]
stefan@nuc /tmp/gtk3 $ ./t0
out of memory

But with valgrind it seems to work:

$ valgrind ./t0
==9971== Memcheck, a memory error detector
==9971== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==9971== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info
==9971== Command: ./t0
==9971== 
OK
finalizeGObject
==9971== 
==9971== HEAP SUMMARY:
==9971==     in use at exit: 0 bytes in 0 blocks
==9971==   total heap usage: 1 allocs, 1 frees, 1,024 bytes allocated
==9971== 
==9971== All heap blocks were freed -- no leaks are possible
==9971== 
==9971== For lists of detected and suppressed errors, rerun with: -s
==9971== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

[StefanSalewski]

$ nim c -f --gc:arc -d:useMalloc t0.nim
Hint: used config file '/home/stefan/Nim/config/nim.cfg' [Conf]
Hint: used config file '/home/stefan/Nim/config/config.nims' [Conf]
Hint: system [Processing]
Hint: widestrs [Processing]
Hint: io [Processing]
Hint: t0 [Processing]
CC: stdlib_allocators.nim
CC: stdlib_io.nim
CC: stdlib_system.nim
CC: t0.nim
Hint: gcc -o /tmp/gtk3/t0 /tmp/stefan/.cache/nim/t0_d/stdlib_allocators.nim.c.o /tmp/stefan/.cache/nim/t0_d/stdlib_io.nim.c.o /tmp/stefan/.cache/nim/t0_d/stdlib_system.nim.c.o /tmp/stefan/.cache/nim/t0_d/@mt0.nim.c.o -ldl [Link]
Hint: 18535 LOC; 0.201 sec; 15.934MiB peakmem; Debug build; proj: /tmp/gtk3/t0.nim; out: /tmp/gtk3/t0 [SuccessX]
stefan@nuc /tmp/gtk3 $ ./t0
Traceback (most recent call last)
/tmp/gtk3/t0.nim(19) t0
/tmp/gtk3/t0.nim(16) main
/home/stefan/Nim/lib/system/refs_v2.nim(68) nimNewObj
SIGSEGV: Illegal storage access. (Attempt to read from nil?)
Segmentation fault (core dumped)

[Araq]

Can't reproduce. Linux specific?

[StefanSalewski]

Can test only on Linux currently, sorry. But good that it works at least at Windows.

[StefanSalewski]

With clang it works:

$ nim c --cc:clang  -f --gc:arc -d:useMalloc t0.nim 
Hint: used config file '/home/stefan/Nim/config/nim.cfg' [Conf]
Hint: used config file '/home/stefan/Nim/config/config.nims' [Conf]
Hint: system [Processing]
Hint: widestrs [Processing]
Hint: io [Processing]
Hint: t0 [Processing]
CC: stdlib_allocators.nim
CC: stdlib_io.nim
CC: stdlib_system.nim
CC: t0.nim
Hint: clang   -o /tmp/gtk3/t0  /tmp/stefan/.cache/nim/t0_d/stdlib_allocators.nim.c.o /tmp/stefan/.cache/nim/t0_d/stdlib_io.nim.c.o /tmp/stefan/.cache/nim/t0_d/stdlib_system.nim.c.o /tmp/stefan/.cache/nim/t0_d/@mt0.nim.c.o    -ldl [Link]
Hint: 18535 LOC; 0.257 sec; 15.867MiB peakmem; Debug build; proj: /tmp/gtk3/t0.nim; out: /tmp/gtk3/t0 [SuccessX]
stefan@nuc /tmp/gtk3 $ ./t0
OK
finalizeGObject

my gcc is

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/9.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /tmp/portage/sys-devel/gcc-9.2.0-r3/work/gcc-9.2.0/configure --host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/9.2.0 --includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/include --datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/9.2.0 --mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/9.2.0/man --infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/9.2.0/info --with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/include/g++-v9 --with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/9.2.0/python --enable-languages=c,c++,fortran --enable-obsolete --enable-secureplt --disable-werror --with-system-zlib --enable-nls --without-included-gettext --enable-checking=release --with-bugurl=https://bugs.gentoo.org/ --with-pkgversion='Gentoo 9.2.0-r3 p4' --disable-esp --enable-libstdcxx-time --with-build-config=bootstrap-lto --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --disable-multilib --with-multilib-list=m64 --disable-altivec --disable-fixed-point --enable-targets=all --enable-libgomp --disable-libmudflap --disable-libssp --disable-systemtap --enable-vtable-verify --enable-lto --with-isl --disable-isl-version-check --enable-default-pie --enable-default-ssp
Thread model: posix
gcc version 9.2.0 (Gentoo 9.2.0-r3 p4) 

[alaviss]

Related C code:

	w = (tyObject_WidgetcolonObjectType___ieGGPagr26qBKNEbfjKDtQ*) nimNewObj(finalizeGObject__ULFuyHiD4DwOUoH61TX19cw);

For some reason the finalizer proc is being passed to nimNewObject, while that proc expects a size instead.