[3.x] Using Dictionary as own key crashes Godot

[johnfn]

Godot version:
3.2.3

OS/device including version:
MacOS Catalina 10.15.5

Issue description:
Write this code:

func _ready():
  var test = {}
  test[test] = test

The game crashes immediately when it hits this code.

[Calinou]

I can confirm this on 3.2 Git 185520c.

Minimal reproduction project: test_cyclic_reference_crash.zip

Backtrace:

[1] /lib64/libc.so.6(+0x3da60) [0x7f2aba7bfa60] (??:0)
[2] Variant::hash() const (/home/hugo/Documents/Git/godotengine/godot-3.2/core/variant.cpp:2747)
[3] Dictionary::hash() const (/home/hugo/Documents/Git/godotengine/godot-3.2/core/dictionary.cpp:196)
[4] Variant::hash() const (/home/hugo/Documents/Git/godotengine/godot-3.2/core/variant.cpp:2884)
[5] VariantHasher::hash(Variant const&) (/home/hugo/Documents/Git/godotengine/godot-3.2/./core/variant.h:460)
[6] HashMap<Variant, List<Pair<Variant const*, Variant>, DefaultAllocator>::Element*, VariantHasher, VariantComparator, (unsigned char)3, (unsigned char)8>::create_element(Variant const&) (/home/hugo/Documents/Git/godotengine/godot-3.2/./core/hash_map.h:208)
[7] HashMap<Variant, List<Pair<Variant const*, Variant>, DefaultAllocator>::Element*, VariantHasher, VariantComparator, (unsigned char)3, (unsigned char)8>::set(HashMap<Variant, List<Pair<Variant const*, Variant>, DefaultAllocator>::Element*, VariantHasher, VariantComparator, (unsigned char)3, (unsigned char)8>::Pair const&) (/home/hugo/Documents/Git/godotengine/godot-3.2/./core/hash_map.h:273)
[8] HashMap<Variant, List<Pair<Variant const*, Variant>, DefaultAllocator>::Element*, VariantHasher, VariantComparator, (unsigned char)3, (unsigned char)8>::set(Variant const&, List<Pair<Variant const*, Variant>, DefaultAllocator>::Element* const&) (/home/hugo/Documents/Git/godotengine/godot-3.2/./core/hash_map.h:258)
[9] OrderedHashMap<Variant, Variant, VariantHasher, VariantComparator, (unsigned char)3, (unsigned char)8>::insert(Variant const&, Variant const&) (/home/hugo/Documents/Git/godotengine/godot-3.2/./core/ordered_hash_map.h:217)
[10] OrderedHashMap<Variant, Variant, VariantHasher, VariantComparator, (unsigned char)3, (unsigned char)8>::operator[](Variant const&) (/home/hugo/Documents/Git/godotengine/godot-3.2/./core/ordered_hash_map.h:253)
[11] Dictionary::operator[](Variant const&) (/home/hugo/Documents/Git/godotengine/godot-3.2/core/dictionary.cpp:81)
[12] Variant::set(Variant const&, Variant const&, bool*) (/home/hugo/Documents/Git/godotengine/godot-3.2/core/variant_op.cpp:2190)
[13] GDScriptFunction::call(GDScriptInstance*, Variant const**, int, Variant::CallError&, GDScriptFunction::CallState*) (/home/hugo/Documents/Git/godotengine/godot-3.2/modules/gdscript/gdscript_function.cpp:579)
[14] GDScriptInstance::_ml_call_reversed(GDScript*, StringName const&, Variant const**, int) (/home/hugo/Documents/Git/godotengine/godot-3.2/modules/gdscript/gdscript.cpp:1269)
[15] GDScriptInstance::call_multilevel_reversed(StringName const&, Variant const**, int) (/home/hugo/Documents/Git/godotengine/godot-3.2/modules/gdscript/gdscript.cpp:1278)
[16] Node::_notification(int) (/home/hugo/Documents/Git/godotengine/godot-3.2/scene/main/node.cpp:152)
[17] Node::_notificationv(int, bool) (/home/hugo/Documents/Git/godotengine/godot-3.2/./scene/main/node.h:46)
[18] CanvasItem::_notificationv(int, bool) (/home/hugo/Documents/Git/godotengine/godot-3.2/./scene/2d/canvas_item.h:?)
[19] Node2D::_notificationv(int, bool) (/home/hugo/Documents/Git/godotengine/godot-3.2/./scene/2d/node_2d.h:?)
[20] Object::notification(int, bool) (/home/hugo/Documents/Git/godotengine/godot-3.2/core/object.cpp:929)
[21] Node::_propagate_ready() (/home/hugo/Documents/Git/godotengine/godot-3.2/scene/main/node.cpp:196)
[22] Node::_propagate_ready() (/home/hugo/Documents/Git/godotengine/godot-3.2/scene/main/node.cpp:186)
[23] Node::_set_tree(SceneTree*) (/home/hugo/Documents/Git/godotengine/godot-3.2/scene/main/node.cpp:?)
[24] SceneTree::init() (/home/hugo/Documents/Git/godotengine/godot-3.2/scene/main/scene_tree.cpp:463)
[25] OS_X11::run() (/home/hugo/Documents/Git/godotengine/godot-3.2/platform/x11/os_x11.cpp:?)
[26] bin/godot.x11.tools.64.llvm(main+0x181) [0x261dc11] (/home/hugo/Documents/Git/godotengine/godot-3.2/platform/x11/godot_x11.cpp:56)
[27] /lib64/libc.so.6(__libc_start_main+0xf2) [0x7f2aba7aa1e2] (??:0)
[28] bin/godot.x11.tools.64.llvm(_start+0x2e) [0x261d9ce] (??:?)
-- END OF BACKTRACE --
[1]    69713 IOT instruction (core dumped)  bin/godot.x11.tools.64.llvm --path 

[akien-mga]

Fixed by #80888.