[erlang-bugs] Internal error in sys_core_fold when matching on map is guaranteed to fail

[Ulf Norell]

-module(bug).
f() ->
  case maybe_map of
    #{}     -> ok;
    not_map -> error
  end.

$ erl
Erlang/OTP 17 [RELEASE CANDIDATE 2] [erts-6.0] [source-a74e66a] [64-bit]
[smp:8:8] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V6.0  (abort with ^G)
1> c(bug).
Function: f/0
bug.erl: internal error in core_fold_module;
crash reason: {case_clause,{none}}

  in function  sys_core_fold:will_match/2 (sys_core_fold.erl, line 1748)
  in call from sys_core_fold:clauses/5 (sys_core_fold.erl, line 1701)
  in call from sys_core_fold:clauses/5 (sys_core_fold.erl, line 1718)
  in call from sys_core_fold:expr/3 (sys_core_fold.erl, line 352)
  in call from sys_core_fold:clause/4 (sys_core_fold.erl, line 1481)
  in call from sys_core_fold:clauses/5 (sys_core_fold.erl, line 1699)
  in call from sys_core_fold:expr/3 (sys_core_fold.erl, line 352)
  in call from sys_core_fold:expr/3 (sys_core_fold.erl, line 279)
bug.erl:2: Warning: function f/0 is unused
error

/ Ulf
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