% mmc --debug --allow-stubs -C some_bug.m
% Uncaught Mercury exception:
% Software Error: map.lookup: key not found
%         Key Type: term.var(parse_tree.prog_data.prog_var_type)
%         Key Value: var(10)
%         Value Type: ll_backend.var_locn.var_state
% Stack dump follows:
%    0       pred exception.throw/1-0 (erroneous) (exception.m:411)
%    1       pred require.error/1-0 (erroneous) (require.m:122)
%    2       pred require.report_lookup_error/3-0 (erroneous) (require.m:98)
%    3       pred map.lookup/3-0 (det) (map.m:721)
%    4       pred ll_backend.var_locn.actually_place_var/7-0 (det) (var_locn.m:1380)
%    5       pred ll_backend.var_locn.var_locn_place_var/6-0 (det) (var_locn.m:1366)
%    6    4* pred ll_backend.var_locn.actually_place_vars/5-0 (det) (var_locn.m:1361 and others)
%   10       pred ll_backend.var_locn.var_locn_place_vars/5-0 (det) (var_locn.m:1353)
%   11       pred ll_backend.code_info.setup_call/6-0 (det) (code_info.m:3981)
%   12       pred ll_backend.call_gen.generate_call/8-0 (det) (call_gen.m:96)
%   13       pred ll_backend.code_gen.generate_goal_2/7-0 (det) (code_gen.m:281)
%   14       pred ll_backend.code_gen.generate_goal/5-0 (det) (code_gen.m:126)
%   15    2* pred ll_backend.code_gen.generate_goals/5-0 (det) (code_gen.m:325 and others)
%   17       pred ll_backend.code_gen.generate_goal_2/7-0 (det) (code_gen.m:244)
%   18       pred ll_backend.code_gen.generate_goal/5-0 (det) (code_gen.m:126)
%   19    2* pred ll_backend.switch_gen.generate_if_then_else_chain_cases/14-0 (det) (switch_gen.m:591 and others)
%   21       pred ll_backend.switch_gen.order_and_generate_cases/13-0 (det) (switch_gen.m:283)
%   22       pred ll_backend.switch_gen.generate_switch/8-0 (det) (switch_gen.m:184)
%   23       pred ll_backend.code_gen.generate_goal_2/7-0 (det) (code_gen.m:262)
%   24       pred ll_backend.code_gen.generate_goal/5-0 (det) (code_gen.m:126)
%   25    2* pred ll_backend.code_gen.generate_goals/5-0 (det) (code_gen.m:325 and others)
%   27       pred ll_backend.code_gen.generate_goal_2/7-0 (det) (code_gen.m:244)
%   28       pred ll_backend.code_gen.generate_goal/5-0 (det) (code_gen.m:126)
%   29       pred ll_backend.proc_gen.generate_category_code/10-0 (det) (proc_gen.m:657)
%   30       pred ll_backend.proc_gen.generate_proc_code/8-0 (det) (proc_gen.m:350)
%   31       pred top_level.mercury_compile_llds_back_end.llds_backend_pass_by_preds_4/12-0 (det) (mercury_compile_llds_back_end.m:383)
%   32       pred top_level.mercury_compile_llds_back_end.llds_backend_pass_by_preds_3/10-0 (det) (mercury_compile_llds_back_end.m:287)
%   33       pred top_level.mercury_compile_llds_back_end.llds_backend_pass_by_preds_2/10-0 (det) (mercury_compile_llds_back_end.m:258)
%   34       pred top_level.mercury_compile_llds_back_end.llds_backend_pass_by_preds/7-0 (det) (mercury_compile_llds_back_end.m:207)
%   35       pred top_level.mercury_compile_llds_back_end.llds_backend_pass/8-0 (det) (mercury_compile_llds_back_end.m:133)
%   36       pred top_level.mercury_compile.mercury_compile_after_front_end/11-0 (det) (mercury_compile.m:1769)

:- module some_bug.
:- interface.

:- import_module maybe.
:- import_module univ.

:- pred univ_named_arg_2(T::in, maybe(univ)::out) is det.

:- implementation.

univ_named_arg_2(Term, MaybeArgument) :-
    SecTagLocn = sectag_locn,
    (
        (
            SecTagLocn = stag_none,
            SecTag = 0
        ;
            SecTagLocn = stag_remote,
            SecTag = get_remote_secondary_tag
        ),
        Arg = get_arg(Term, SecTag),
        type_to_univ(Arg, Univ),
        MaybeArgument = yes(Univ)
    ;
        SecTagLocn = stag_variable,
        MaybeArgument = no
    ).

:- type sectag_locn
    --->    stag_none
    ;       stag_remote
    ;       stag_variable.

:- func sectag_locn = sectag_locn.

:- func get_remote_secondary_tag = int.

:- some [T] func get_arg(U, int) = T.