Stateful functors sometimes crash on prebuilt souffle, work correctly when built locally

[sifislag]

Hi, We've noticed crashes on code using stateful functors that occur only when using the prebuilt souffle packages.

Setup a github action on our souffle-addon repository (used by Gigahorse), demonstrating this:

• job build-and-test runs on a container which includes souffle 2.4.1 built inside it. All commands are executed successfully.
• job build-and-test-with-package gets the prebuilt package, crashes when running lists_test.dl

The crash throws the following stack trace:

souffle lists_test.dl 
souffle: /souffle/src/include/souffle/datastructure/ConcurrentFlyweight.h:290: const Key& souffle::ConcurrentFlyweight<LanesPolicy, Key, Hash, KeyEqual, KeyFactory>::fetch(souffle::ConcurrentFlyweight<LanesPolicy, Key, Hash, KeyEqual, KeyFactory>::lane_id, souffle::ConcurrentFlyweight<LanesPolicy, Key, Hash, KeyEqual, KeyFactory>::index_type) const [with LanesPolicy = souffle::ConcurrentLanes; Key = std::__cxx11::basic_string<char>; Hash = std::hash<std::__cxx11::basic_string<char> >; KeyEqual = std::equal_to<std::__cxx11::basic_string<char> >; KeyFactory = souffle::details::Factory<std::__cxx11::basic_string<char> >; souffle::ConcurrentFlyweight<LanesPolicy, Key, Hash, KeyEqual, KeyFactory>::lane_id = long unsigned int; souffle::ConcurrentFlyweight<LanesPolicy, Key, Hash, KeyEqual, KeyFactory>::index_type = long unsigned int]: Assertion `Idx < SlotCount.load(std::memory_order_relaxed)' failed.
Aborted (core dumped

The crash is caused by the following snippet in the lists_test.dl:

.decl BreakSouffle(x:StringList)
BreakSouffle(["ddd", nil]).
BreakSouffle(@list_append(["ddd", nil], "ddd")) :- BreakSouffle(["ddd", nil]).

.output BreakSouffle