%---------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%---------------------------------------------------------------------------%
% Copyright (C) 1996-2001, 2003-2012 The University of Melbourne.
% Copyright (C) 2015, 2024-2026 The Mercury team.
% This file may only be copied under the terms of the GNU General
% Public License - see the file COPYING in the Mercury distribution.
%---------------------------------------------------------------------------%
%
% File: modecheck_call.m.
% Main author: fjh.
%
% This file contains the code to modecheck a call.
%
% Check that there is a mode declaration for the predicate which matches
% the current instantiation of the arguments. (Also handle calls to implied
% modes.) If the called predicate is one for which we must infer the modes,
% then a new mode for the called predicate whose initial insts are the result
% of normalising the current inst of the arguments.
%
%---------------------------------------------------------------------------%

:- module check_hlds.modecheck_call.
:- interface.

:- import_module check_hlds.mode_info.
:- import_module check_hlds.modecheck_util.
:- import_module hlds.
:- import_module hlds.hlds_goal.
:- import_module hlds.hlds_pred.
:- import_module parse_tree.
:- import_module parse_tree.prog_data.

:- import_module list.
:- import_module maybe.

%---------------------------------------------------------------------------%

:- pred modecheck_plain_or_foreign_call(pred_id::in, maybe(determinism)::in,
    proc_id::in, proc_id::out, list(prog_var)::in, list(prog_var)::out,
    hlds_goal_info::in, extra_goals::out, mode_info::in, mode_info::out)
    is det.

:- inst generic_call_higher_order for generic_call/0
    --->    higher_order(ground, ground, ground, ground, ground).

:- pred modecheck_higher_order_call(
    generic_call::in(generic_call_higher_order),
    list(prog_var)::in, list(prog_var)::out, list(mer_mode)::out,
    determinism::out, extra_goals::out, mode_info::in, mode_info::out) is det.

:- pred modecheck_event_call(list(mer_mode)::in,
    list(prog_var)::in, list(prog_var)::out,
    mode_info::in, mode_info::out) is det.

:- pred modecheck_builtin_cast(list(mer_mode)::in,
    list(prog_var)::in, list(prog_var)::out, determinism::out,
    extra_goals::out, mode_info::in, mode_info::out) is det.

%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%

:- implementation.

:- import_module check_hlds.mode_comparison.
:- import_module check_hlds.mode_errors.
:- import_module check_hlds.proc_requests.
:- import_module hlds.hlds_markers.
:- import_module hlds.hlds_module.
:- import_module hlds.hlds_proc_util.
:- import_module hlds.inst_lookup.
:- import_module hlds.inst_test.
:- import_module hlds.inst_util.
:- import_module hlds.instmap.
:- import_module hlds.mode_util.
:- import_module mdbcomp.
:- import_module mdbcomp.prim_data.
:- import_module parse_tree.prog_mode.
:- import_module parse_tree.prog_type_test.
:- import_module parse_tree.prog_util.
:- import_module parse_tree.set_of_var.
:- import_module parse_tree.var_table.

:- import_module bool.
:- import_module map.
:- import_module require.
:- import_module term.

%---------------------------------------------------------------------------%

modecheck_plain_or_foreign_call(PredId, MaybeDetism, ProcId0, SelectedProcId,
        ArgVars0, ArgVars, _GoalInfo, ExtraGoals, !ModeInfo) :-
    mode_info_get_may_change_called_proc(!.ModeInfo, MayChangeCalledProc),
    mode_info_get_module_info(!.ModeInfo, ModuleInfo),
    module_info_pred_info(ModuleInfo, PredId, PredInfo),
    pred_info_get_proc_table(PredInfo, ProcTable),
    (
        MayChangeCalledProc = may_not_change_called_proc,
        ( if ProcId0 = invalid_proc_id then
            unexpected($pred, "invalid proc_id")
        else
            ProcIds = [ProcId0]
        )
    ;
        MayChangeCalledProc = may_change_called_proc,
        % Get the list of different possible modes for the called predicate.
        ProcIds = pred_info_all_proc_ids(PredInfo)
    ),

    ArgOffset = compute_pred_modecheck_arg_offset(PredInfo),
    pred_info_get_markers(PredInfo, Markers),
    mode_info_get_instmap(!.ModeInfo, InstMap),
    % In order to give better diagnostics, we handle the cases where there
    % are zero or one modes for the called predicate specially.
    % XXX Then we should have a switch on ProcIds.
    ( if
        ProcIds = [],
        not marker_is_present(Markers, marker_infer_modes)
    then
        set_of_var.init(WaitingVars),
        PredOrFunc = pred_info_is_pred_or_func(PredInfo),
        expect(unify(PredOrFunc, pf_predicate), $pred,
            "function with no mode, not even the default"),
        ModeError = mode_error_callee_pred_has_no_mode_decl(PredId),
        mode_info_error(WaitingVars, ModeError, !ModeInfo),
        SelectedProcId = invalid_proc_id,
        ArgVars = ArgVars0,
        ExtraGoals = no_extra_goals
    else if
        ProcIds = [ProcId],
        ( not marker_is_present(Markers, marker_infer_modes)
        ; MayChangeCalledProc = may_not_change_called_proc
        )
    then
        SelectedProcId = ProcId,
        map.lookup(ProcTable, ProcId, ProcInfo),

        % Check that `ArgsVars0' have livenesses which match the
        % expected livenesses.
        proc_info_arglives(ModuleInfo, ProcInfo, ProcArgLives0),
        modecheck_vars_are_live_no_exact_match(ArgOffset,
            ArgVars0, ProcArgLives0, !ModeInfo),

        % Check that `ArgsVars0' have insts which match the expected
        % initial insts, and set their new final insts (introducing
        % extra unifications for implied modes, if necessary).
        proc_info_get_argmodes(ProcInfo, ProcArgModes0),
        proc_info_get_inst_varset(ProcInfo, ProcInstVarSet),
        mode_info_get_instvarset(!.ModeInfo, InstVarSet0),
        rename_apart_inst_vars(InstVarSet0, ProcInstVarSet, InstVarSet,
            ProcArgModes0, ProcArgModes),
        mode_info_set_instvarset(InstVarSet, !ModeInfo),
        mode_list_get_initial_insts(ModuleInfo, ProcArgModes, InitialInsts),
        MatchWhat = match_plain_call(PredId),
        modecheck_vars_have_insts_no_exact_match(MatchWhat, ArgOffset,
            ArgVars0, InitialInsts, InstVarSub, _BoundInstVars, !ModeInfo),

        modecheck_end_of_call(ProcInfo, ArgOffset, ProcArgModes, ArgVars0,
            InstVarSub, ArgVars, ExtraGoals, !ModeInfo)
    else
        % We save and restore the error list in order to allow
        % modecheck_find_matching_modes to use that field of !ModeInfo
        % for its own purposes.
        mode_info_get_errors(!.ModeInfo, OldErrors),
        set_of_var.init(WaitingVars0),
        modecheck_find_matching_modes(PredId, ProcTable, ArgOffset,
            ArgVars0, ProcIds, [], RevMatchingProcModes, [], RevMismatches,
            WaitingVars0, WaitingVars1, !ModeInfo),
        mode_info_set_errors(OldErrors, !ModeInfo),
        (
            RevMatchingProcModes = [],
            list.reverse(RevMismatches, Mismatches),
            no_matching_modes(PredId, ArgVars0, Mismatches,
                MaybeDetism, WaitingVars1, SelectedProcId, !ModeInfo),
            ArgVars = ArgVars0,
            ExtraGoals = no_extra_goals
        ;
            RevMatchingProcModes = [_ | _],
            list.reverse(RevMatchingProcModes, MatchingProcModes),
            choose_best_match(!.ModeInfo, MatchingProcModes, PredId, ProcTable,
                ArgVars0, SelectedProcId, InstVarSub, ProcArgModes),
            map.lookup(ProcTable, SelectedProcId, ProcInfo),
            look_up_proc_mode_errors(!.ModeInfo, PredId, SelectedProcId,
                CalleeModeErrors),
            (
                CalleeModeErrors = [],
                modecheck_end_of_call(ProcInfo, ArgOffset,
                    ProcArgModes, ArgVars0, InstVarSub, ArgVars,
                    ExtraGoals, !ModeInfo)
            ;
                CalleeModeErrors = [_ | _],
                % Mode error in callee for this mode.
                ArgVars = ArgVars0,
                WaitingVars = set_of_var.list_to_set(ArgVars),
                ExtraGoals = no_extra_goals,
                instmap_lookup_vars(InstMap, ArgVars, ArgInsts),
                mode_info_set_call_arg_context(0, !ModeInfo),
                ModeError = mode_error_in_callee(ArgVars, ArgInsts,
                    PredId, SelectedProcId, CalleeModeErrors),
                mode_info_error(WaitingVars, ModeError, !ModeInfo)
            )
        )
    ).

%---------------------%

:- pred modecheck_find_matching_modes(pred_id::in, proc_table::in,
    modecheck_arg_offset::in, list(prog_var)::in, list(proc_id)::in,
    list(proc_mode)::in, list(proc_mode)::out,
    list(mode_mismatch)::in, list(mode_mismatch)::out,
    set_of_progvar::in, set_of_progvar::out,
    mode_info::in, mode_info::out) is det.

modecheck_find_matching_modes(_PredId, _ProcTable, _ArgOffset, _ArgVars,
        [], !RevMatchingProcModes, !RevMismatches, !WaitingVars, !ModeInfo).
modecheck_find_matching_modes(PredId, ProcTable, ArgOffset, ArgVars0,
        [ProcId | ProcIds], !RevMatchingProcModes, !RevMismatches,
        !WaitingVars, !ModeInfo) :-
    % Clear the errors field of !ModeInfo so that we can check below
    % whether this procedure is a match. Our caller has already saved
    % the old contents of this field.
    mode_info_set_errors([], !ModeInfo),

    % Find the initial insts and the final livenesses of the arguments
    % for this mode of the called pred.
    map.lookup(ProcTable, ProcId, ProcInfo),
    proc_info_get_argmodes(ProcInfo, ProcArgModes0),
    proc_info_get_inst_varset(ProcInfo, ProcInstVarSet),
    mode_info_get_instvarset(!.ModeInfo, InstVarSet0),
    rename_apart_inst_vars(InstVarSet0, ProcInstVarSet, InstVarSet,
        ProcArgModes0, ProcArgModes),
    % This adds the renamed-apart inst variables from the ProcInstVarSet of
    % the callee *permanently* to the inst_varset of the current procedure,
    % the caller.
    mode_info_set_instvarset(InstVarSet, !ModeInfo),
    mode_info_get_module_info(!.ModeInfo, ModuleInfo),
    proc_info_arglives(ModuleInfo, ProcInfo, ProcArgLives0),

    % Check whether the livenesses of the args matches their expected liveness.
    modecheck_vars_are_live_no_exact_match(ArgOffset, ArgVars0, ProcArgLives0,
        !ModeInfo),

    MatchWhat = match_plain_call(PredId),
    mode_list_get_initial_insts(ModuleInfo, ProcArgModes, InitialInsts),
    % Check whether the insts of the args matches their expected initial insts.
    %
    % If we are doing mode inference for the called procedure, and the
    % called procedure has been inferred as an invalid mode, then don't use
    % it unless it is an exact match.
    %
    % XXX Do we really want mode inference to use implied modes?
    % Would it be better to always require an exact match when doing mode
    % inference, to ensure that we add new inferred modes rather than using
    % implied modes?
    look_up_proc_mode_errors(!.ModeInfo, PredId, ProcId, ProcModeErrors),
    (
        ProcModeErrors = [],
        ExactOrNot = eon_not_exact,
        modecheck_vars_have_insts_no_exact_match(MatchWhat, ArgOffset,
            ArgVars0, InitialInsts, InstVarSub, BoundInstVars, !ModeInfo)
    ;
        ProcModeErrors = [_ | _],
        ExactOrNot = eon_exact,
        modecheck_vars_have_insts_exact_match(MatchWhat, ArgOffset,
            ArgVars0, InitialInsts, InstVarSub, BoundInstVars, !ModeInfo)
    ),

    % If we got an error, reset the error list and save the list of vars
    % to wait on. Otherwise, insert the proc_id in the list of matching
    % proc_ids.
    % XXX Should we include Errors in mo Mismatch?
    mode_info_get_errors(!.ModeInfo, Errors),
    (
        Errors = [FirstError | _],
        % NOTE The waiting vars and mismatches we collect here are used ONLY
        % if we find no matching modes.
        FirstError = mode_error_info(ErrorWaitingVars, _, _, _),
        set_of_var.union(ErrorWaitingVars, !WaitingVars),
        Mismatch = mode_mismatch(ExactOrNot, InitialInsts, BoundInstVars),
        !:RevMismatches = [Mismatch | !.RevMismatches]
    ;
        Errors = [],
        NewMatchingProcMode = proc_mode(ProcId, InstVarSub, ProcArgModes),
        !:RevMatchingProcModes = [NewMatchingProcMode | !.RevMatchingProcModes]
    ),

    % Keep trying with the other modes for the called pred.
    modecheck_find_matching_modes(PredId, ProcTable, ArgOffset,
        ArgVars0, ProcIds, !RevMatchingProcModes, !RevMismatches,
        !WaitingVars, !ModeInfo).

%---------------------%

:- pred no_matching_modes(pred_id::in, list(prog_var)::in,
    list(mode_mismatch)::in, maybe(determinism)::in, set_of_progvar::in,
    proc_id::out, mode_info::in, mode_info::out) is det.

no_matching_modes(PredId, ArgVars, Mismatches, MaybeDetism, WaitingVars,
        NewProcId, !ModeInfo) :-
    % There were no matching modes.
    % If we are inferring modes for this called predicate, then
    % just insert a new mode declaration which will match.
    % Otherwise, report an error.

    mode_info_get_pred_id_table(!.ModeInfo, PredIdTable),
    map.lookup(PredIdTable, PredId, PredInfo),
    pred_info_get_markers(PredInfo, Markers),
    ( if marker_is_present(Markers, marker_infer_modes) then
        insert_new_mode(PredId, ArgVars, MaybeDetism, NewProcId, !ModeInfo),
        % We don't yet know the final insts for the newly created mode
        % of the called predicate, so we set the instmap to unreachable,
        % indicating that we have no information about the modes at this
        % point in the computation.
        instmap.init_unreachable(Instmap),
        mode_info_set_instmap(Instmap, !ModeInfo)
    else
        NewProcId = invalid_proc_id,    % dummy value
        mode_info_get_instmap(!.ModeInfo, InstMap),
        mode_info_set_call_arg_context(0, !ModeInfo),
        list.det_head_tail(Mismatches, HeadMismatch, TailMismatches),
        MatchWhat = match_plain_call(PredId),
        ModeError = mode_error_no_matching_mode(MatchWhat, InstMap, ArgVars,
            HeadMismatch, TailMismatches),
        mode_info_error(WaitingVars, ModeError, !ModeInfo)
    ).

    % Insert a new inferred mode for a predicate.
    % The initial insts are determined by using a normalised
    % version of the call pattern (i.e. the insts of the arg vars).
    % The final insts are initially just assumed to be all `not_reached'.
    % The determinism for this mode will be inferred.
    %
:- pred insert_new_mode(pred_id::in, list(prog_var)::in,
    maybe(determinism)::in, proc_id::out,
    mode_info::in, mode_info::out) is det.

insert_new_mode(PredId, ArgVars, MaybeDet, ProcId, !ModeInfo) :-
    % Figure out the values of all the variables we need
    % to create a new mode for this predicate.
    get_var_insts_and_lives(!.ModeInfo, ArgVars, InitialInsts, ArgLives),
    mode_info_get_module_info(!.ModeInfo, ModuleInfo0),
    module_info_pred_info(ModuleInfo0, PredId, PredInfo0),
    pred_info_get_context(PredInfo0, Context),
    list.length(ArgVars, Arity),
    list.duplicate(Arity, not_reached, FinalInsts),
    inst_lists_to_mode_list(InitialInsts, FinalInsts, Modes),
    mode_info_get_instvarset(!.ModeInfo, InstVarSet),

    % Call request_proc, which will create the new procedure,
    % set its "can-process" flag to `no', and insert it into the queue
    % of requested procedures.
    request_proc(PredId, Modes, InstVarSet, yes(ArgLives), MaybeDet, Context,
        ProcId, ModuleInfo0, ModuleInfo),
    mode_info_set_module_info(ModuleInfo, !ModeInfo),

    % Since we have created a new inferred mode for this predicate,
    % things have changed, so we will need to do at least one more pass
    % of the fixpoint analysis.
    mode_info_set_changed_flag(yes, !ModeInfo).

:- pred get_var_insts_and_lives(mode_info::in, list(prog_var)::in,
    list(mer_inst)::out, list(is_live)::out) is det.

get_var_insts_and_lives(_, [], [], []).
get_var_insts_and_lives(ModeInfo, [Var | Vars],
        [Inst | Insts], [IsLive | IsLives]) :-
    get_var_inst(ModeInfo, Var, Inst),
    mode_info_var_is_live(ModeInfo, Var, IsLive0),
    mode_info_get_module_info(ModeInfo, ModuleInfo),
    (
        IsLive0 = is_live,
        IsLive = is_live
    ;
        IsLive0 = is_dead,
        % To reduce the potentially exponential explosion in the number of
        % modes, we only set IsLive to `dead' (meaning that the procedure
        % requires its argument to be dead, so that it can do destructive
        % update) if there really is a good chance of being able to do
        % destructive update.
        mode_info_get_var_table(ModeInfo, VarTable),
        lookup_var_type(VarTable, Var, Type),
        ( if
            inst_is_ground(ModuleInfo, Type, Inst),
            inst_is_mostly_unique(ModuleInfo, Inst)
        then
            IsLive = is_dead
        else
            IsLive = is_live
        )
    ),
    get_var_insts_and_lives(ModeInfo, Vars, Insts, IsLives).

%---------------------%

:- pred modecheck_end_of_call(proc_info::in, modecheck_arg_offset::in,
    list(mer_mode)::in, list(prog_var)::in, inst_var_sub::in,
    list(prog_var)::out, extra_goals::out,
    mode_info::in, mode_info::out) is det.

modecheck_end_of_call(ProcInfo, ArgOffset, ProcArgModes, ArgVars0,
        InstVarSub, ArgVars, ExtraGoals, !ModeInfo) :-
    mode_info_get_module_info(!.ModeInfo, ModuleInfo),
    mode_list_get_initial_final_insts(ModuleInfo, ProcArgModes,
        InitialInsts0, FinalInsts0),
    inst_list_apply_substitution(InstVarSub, InitialInsts0, InitialInsts),
    inst_list_apply_substitution(InstVarSub, FinalInsts0, FinalInsts),
    modecheck_set_var_insts(ArgOffset, ArgVars0, InitialInsts, FinalInsts,
        ArgVars, ExtraGoals, !ModeInfo),
    can_proc_info_ever_succeed(ProcInfo, CanSucceed),
    (
        CanSucceed = proc_cannot_succeed,
        instmap.init_unreachable(Instmap),
        mode_info_set_instmap(Instmap, !ModeInfo)
    ;
        CanSucceed = proc_can_maybe_succeed
    ).

%---------------------------------------------------------------------------%

modecheck_higher_order_call(GenericCall, ArgVars0, ArgVars, Modes,
        Detism, ExtraGoals, !ModeInfo) :-
    GenericCall = higher_order(PredVar, _, PredOrFunc, _, _),
    % First, check that `PredVar' has a higher-order inst,
    % with the right pred_or_func and the appropriate arity.
    mode_info_get_instmap(!.ModeInfo, InstMap0),
    instmap_lookup_var(InstMap0, PredVar, PredVarInst0),
    mode_info_get_module_info(!.ModeInfo, ModuleInfo0),
    inst_expand(ModuleInfo0, PredVarInst0, PredVarInst),
    ActualPredFormArity = arg_list_arity(ArgVars0),
    user_arity_pred_form_arity(PredOrFunc,
        ActualUserArity, ActualPredFormArity),
    get_higher_order_inst_match(!.ModeInfo, PredOrFunc, PredVar, PredVarInst,
        ActualUserArity, Match),
    (
        Match = higher_order_match(PredInstInfo),
        PredInstInfo = pred_inst_info(_, Modes0, _, Detism0),
        ( if
            % If PredVar is inst `any' then it gets bound. If it is locked,
            % this is a mode error.
            PredVarInst = any(A, B),
            mode_info_var_is_locked(!.ModeInfo, PredVar, Reason)
        then
            BetterPredVarInst = ground(A, B),
            WaitingVars = set_of_var.make_singleton(PredVar),
            ModeError = mode_error_bind_locked_var(Reason, PredVar,
                PredVarInst, BetterPredVarInst),
            mode_info_error(WaitingVars, ModeError, !ModeInfo),
            Modes = [],
            Detism = detism_erroneous,
            ArgVars = ArgVars0,
            ExtraGoals = no_extra_goals
        else
            Modes = Modes0,
            Detism = Detism0,
            ArgOffset = higher_order_modecheck_arg_offset,
            modecheck_arg_list(match_higher_order_call(GenericCall),
                ArgOffset, Modes, ExtraGoals, ArgVars0, ArgVars, !ModeInfo),
            ( if determinism_components(Detism, _, at_most_zero) then
                instmap.init_unreachable(Instmap),
                mode_info_set_instmap(Instmap, !ModeInfo)
            else
                true
            )
        )
    ;
        Match = higher_order_mismatch(Mismatch),
        % The error occurred in argument 1, i.e. the pred term.
        mode_info_set_call_arg_context(1, !ModeInfo),
        WaitingVars = set_of_var.make_singleton(PredVar),
        ModeError = mode_error_bad_higher_order_inst(PredVar, PredVarInst,
            PredOrFunc, ActualUserArity, Mismatch),
        mode_info_error(WaitingVars, ModeError, !ModeInfo),
        Modes = [],
        Detism = detism_erroneous,
        ArgVars = ArgVars0,
        ExtraGoals = no_extra_goals
    ).

:- type maybe_higher_order_match
    --->    higher_order_match(pred_inst_info)
    ;       higher_order_mismatch(higher_order_mismatch_info).

:- pred get_higher_order_inst_match(mode_info::in, pred_or_func::in,
    prog_var::in, mer_inst::in, user_arity::in,
    maybe_higher_order_match::out) is det.

get_higher_order_inst_match(ModeInfo, ExpectedPredOrFunc, PredVar, PredVarInst,
        ExpectedUserArity, MaybeMatch) :-
    ( if
        ( PredVarInst = ground(_Uniq, HOInstInfo)
        ; PredVarInst = any(_Uniq, HOInstInfo)
        )
    then
        (
            HOInstInfo = higher_order(PredInstInfo),
            check_for_pf_arity_mismatch(ExpectedPredOrFunc, ExpectedUserArity,
                PredInstInfo, MaybeMatch)
        ;
            % If PredVarInst has no higher-order inst information,
            % then look for higher-order inst information in the type.
            % Otherwise, if PredVar has a function type, assume the default
            % function mode.
            HOInstInfo = none_or_default_func,
            mode_info_get_var_table(ModeInfo, VarTable),
            lookup_var_type(VarTable, PredVar, Type0),
            Type = strip_kind_annotation(Type0),
            ( if
                Type = higher_order_type(TypePredOrFunc, ArgTypes,
                    TypeHOInstInfo, _Purity)
            then
                (
                    TypeHOInstInfo = higher_order(PredInstInfo),
                    PredInstInfo = pred_inst_info(TypeHOPredOrFunc, _, _, _),
                    expect(unify(TypePredOrFunc, TypeHOPredOrFunc), $pred,
                        "TypePredOrFunc != TypeHOPredOrFunc"),
                    check_for_pf_arity_mismatch(ExpectedPredOrFunc,
                        ExpectedUserArity, PredInstInfo, MaybeMatch)
                ;
                    TypeHOInstInfo = none_or_default_func,
                    (
                        TypePredOrFunc = pf_function,
                        list.length(ArgTypes, NumArgs),
                        PredInstInfo =
                            pred_inst_info_default_func_mode(NumArgs),
                        check_for_pf_arity_mismatch(ExpectedPredOrFunc,
                            ExpectedUserArity, PredInstInfo, MaybeMatch)
                    ;
                        TypePredOrFunc = pf_predicate,
                        HOMismatch0 = ho_mismatch_no_higher_order_inst_info,
                        MaybeMatch = higher_order_mismatch(HOMismatch0)
                    )
                )
            else
                HOMismatch0 = ho_mismatch_not_higher_order_type,
                MaybeMatch = higher_order_mismatch(HOMismatch0)
            )
        )
    else
        MaybeMatch =
            higher_order_mismatch(ho_mismatch_no_higher_order_inst_info)
    ).

:- pred check_for_pf_arity_mismatch(pred_or_func::in, user_arity::in,
    pred_inst_info::in, maybe_higher_order_match::out) is det.

check_for_pf_arity_mismatch(ExpectedPredOrFunc, ExpectedUserArity,
        PredInstInfo, MaybeMatch) :-
    PredInstInfo = pred_inst_info(ActualPredOrFunc, Modes, _, _),
    ( if ExpectedPredOrFunc = ActualPredOrFunc then
        ActualPredFormArity = arg_list_arity(Modes),
        user_arity_pred_form_arity(ActualPredOrFunc,
            ActualUserArity, ActualPredFormArity),
        ( if ExpectedUserArity = ActualUserArity then
            MaybeMatch = higher_order_match(PredInstInfo)
        else
            HOMismatch = ho_mismatch_on_arity(ActualUserArity),
            MaybeMatch = higher_order_mismatch(HOMismatch)
        )
    else
        HOMismatch = ho_mismatch_pred_vs_func(ActualPredOrFunc),
        MaybeMatch = higher_order_mismatch(HOMismatch)
    ).

%---------------------------------------------------------------------------%

modecheck_event_call(Modes, Args0, Args, !ModeInfo) :-
    ArgOffset = unify_method_event_cast_modecheck_arg_offset,
    modecheck_arg_list(match_event, ArgOffset, Modes, ExtraGoals,
        Args0, Args, !ModeInfo),
    expect(unify(ExtraGoals, no_extra_goals), $pred, "ExtraGoals").

%---------------------------------------------------------------------------%

modecheck_builtin_cast(Modes, Args0, Args, Det, ExtraGoals, !ModeInfo) :-
    Det = detism_det,
    % These should always be mode correct.
    ArgOffset = unify_method_event_cast_modecheck_arg_offset,
    modecheck_arg_list(match_cast, ArgOffset, Modes, ExtraGoals,
        Args0, Args, !ModeInfo).

%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%

    % Modecheck the arguments of
    %
    % - higher order calls,
    % - events, and
    % - casts.
    %
:- pred modecheck_arg_list(match_what::in, modecheck_arg_offset::in,
    list(mer_mode)::in, extra_goals::out, list(prog_var)::in,
    list(prog_var)::out, mode_info::in, mode_info::out) is det.

modecheck_arg_list(MatchWhat, ArgOffset, Modes, ExtraGoals, Args0, Args,
        !ModeInfo) :-
    % Check that `Args0' have livenesses which match the expected livenesses.
    mode_info_get_module_info(!.ModeInfo, ModuleInfo0),
    get_arg_lives(ModuleInfo0, Modes, ExpectedArgLives),
    modecheck_vars_are_live_no_exact_match(ArgOffset, Args0, ExpectedArgLives,
        !ModeInfo),

    % Check that `Args0' have insts which match the expected initial insts,
    % and set their new final insts (introducing extra unifications for
    % implied modes, if necessary).
    mode_list_get_initial_insts(ModuleInfo0, Modes, InitialInsts),
    modecheck_vars_have_insts_no_exact_match(MatchWhat, ArgOffset,
        Args0, InitialInsts, InstVarSub, _BoundInstVars, !ModeInfo),
    mode_list_get_final_insts(ModuleInfo0, Modes, FinalInsts0),
    inst_list_apply_substitution(InstVarSub, FinalInsts0, FinalInsts),
    modecheck_set_var_insts(ArgOffset, Args0, InitialInsts, FinalInsts,
        Args, ExtraGoals, !ModeInfo).

%---------------------------------------------------------------------------%
:- end_module check_hlds.modecheck_call.
%---------------------------------------------------------------------------%
