1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  1997-2025, University of Amsterdam
    7                              VU University Amsterdam
    8                              CWI, Amsterdam
    9                              SWI-Prolog Solutions b.v.
   10    All rights reserved.
   11
   12    Redistribution and use in source and binary forms, with or without
   13    modification, are permitted provided that the following conditions
   14    are met:
   15
   16    1. Redistributions of source code must retain the above copyright
   17       notice, this list of conditions and the following disclaimer.
   18
   19    2. Redistributions in binary form must reproduce the above copyright
   20       notice, this list of conditions and the following disclaimer in
   21       the documentation and/or other materials provided with the
   22       distribution.
   23
   24    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   25    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   26    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   27    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   28    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   29    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   30    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   31    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   32    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   34    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   35    POSSIBILITY OF SUCH DAMAGE.
   36*/
   37
   38:- module('$messages',
   39          [ print_message/2,            % +Kind, +Term
   40            print_message_lines/3,      % +Stream, +Prefix, +Lines
   41            message_to_string/2         % +Term, -String
   42          ]).   43
   44:- multifile
   45    prolog:message//1,              % entire message
   46    prolog:error_message//1,        % 1-st argument of error term
   47    prolog:message_context//1,      % Context of error messages
   48    prolog:deprecated//1,	    % Deprecated features
   49    prolog:message_location//1,     % (File) location of error messages
   50    prolog:message_line_element/2.  % Extend printing
   51:- '$hide'((
   52    prolog:message//1,
   53    prolog:error_message//1,
   54    prolog:message_context//1,
   55    prolog:deprecated//1,
   56    prolog:message_location//1,
   57    prolog:message_line_element/2)).   58% Lang, Term versions
   59:- multifile
   60    prolog:message//2,              % entire message
   61    prolog:error_message//2,        % 1-st argument of error term
   62    prolog:message_context//2,      % Context of error messages
   63    prolog:message_location//2,	    % (File) location of error messages
   64    prolog:deprecated//2.	    % Deprecated features
   65:- '$hide'((
   66    prolog:message//2,
   67    prolog:error_message//2,
   68    prolog:message_context//2,
   69    prolog:deprecated//2,
   70    prolog:message_location//2)).   71
   72:- discontiguous
   73    prolog_message/3.   74
   75:- public
   76    translate_message//1,           % +Message (deprecated)
   77    prolog:translate_message//1.    % +Message
   78
   79:- create_prolog_flag(message_context, [thread], []).

 translate_message(+Term)// is det

Translate a message Term into message lines. The produced lines is a list of

nl

Emit a newline

Fmt - Args

Emit the result of format(Fmt, Args)

Fmt

Emit the result of format(Fmt)

ansi(Code, Fmt, Args)

Use ansi_format/3 for color output.

flush

Used only as last element of the list. Simply flush the output instead of producing a final newline.

at_same_line

Start the messages at the same line (instead of using ~N)

deprecated

- Use code for message translation should call translate_message//1.

  103prolog:translate_message(Term) -->
  104    translate_message(Term).

 translate_message(+Term)// is det

Translate a message term into message lines. This version may be called from user and library definitions for message translation.

  111translate_message(Term) -->
  112    { nonvar(Term) },
  113    (   { message_lang(Lang) },
  114        prolog:message(Lang, Term)
  115    ;   prolog:message(Term)
  116    ),
  117    !.
  118translate_message(Term) -->
  119    { nonvar(Term) },
  120    translate_message2(Term),
  121    !.
  122translate_message(Term) -->
  123    { nonvar(Term),
  124      Term = error(_, _)
  125    },
  126    [ 'Unknown exception: ~p'-[Term] ].
  127translate_message(Term) -->
  128    [ 'Unknown message: ~p'-[Term] ].
  129
  130translate_message2(Term) -->
  131    prolog_message(Term).
  132translate_message2(error(resource_error(stack), Context)) -->
  133    !,
  134    out_of_stack(Context).
  135translate_message2(error(resource_error(tripwire(Wire, Context)), _)) -->
  136    !,
  137    tripwire_message(Wire, Context).
  138translate_message2(error(existence_error(reset, Ball), SWI)) -->
  139    swi_location(SWI),
  140    tabling_existence_error(Ball, SWI).
  141translate_message2(error(ISO, SWI)) -->
  142    swi_location(SWI),
  143    term_message(ISO),
  144    swi_extra(SWI).
  145translate_message2(unwind(Term)) -->
  146    unwind_message(Term).
  147translate_message2(message_lines(Lines), L, T) :- % deal with old C-warning()
  148    make_message_lines(Lines, L, T).
  149translate_message2(format(Fmt, Args)) -->
  150    [ Fmt-Args ].
  151
  152make_message_lines([], T, T) :- !.
  153make_message_lines([Last],  ['~w'-[Last]|T], T) :- !.
  154make_message_lines([L0|LT], ['~w'-[L0],nl|T0], T) :-
  155    make_message_lines(LT, T0, T).

 term_message(+Term)//

Deal with the formal argument of error(Format, ImplDefined) exception terms. The ImplDefined argument is handled by swi_location//2.

  163:- public term_message//1.  164term_message(Term) -->
  165    {var(Term)},
  166    !,
  167    [ 'Unknown error term: ~p'-[Term] ].
  168term_message(Term) -->
  169    { message_lang(Lang) },
  170    prolog:error_message(Lang, Term),
  171    !.
  172term_message(Term) -->
  173    prolog:error_message(Term),
  174    !.
  175term_message(Term) -->
  176    iso_message(Term).
  177term_message(Term) -->
  178    swi_message(Term).
  179term_message(Term) -->
  180    [ 'Unknown error term: ~p'-[Term] ].
  181
  182iso_message(resource_error(c_stack)) -->
  183    out_of_c_stack.
  184iso_message(resource_error(Missing)) -->
  185    [ 'Not enough resources: ~w'-[Missing] ].
  186iso_message(type_error(evaluable, Actual)) -->
  187    { callable(Actual) },
  188    [ 'Arithmetic: `~p'' is not a function'-[Actual] ].
  189iso_message(type_error(free_of_attvar, Actual)) -->
  190    [ 'Type error: `~W'' contains attributed variables'-
  191      [Actual,[portray(true), attributes(portray)]] ].
  192iso_message(type_error(Expected, Actual)) -->
  193    [ 'Type error: `~w'' expected, found `~p'''-[Expected, Actual] ],
  194    type_error_comment(Expected, Actual).
  195iso_message(domain_error(Domain, Actual)) -->
  196    [ 'Domain error: '-[] ], domain(Domain),
  197    [ ' expected, found `~p'''-[Actual] ].
  198iso_message(instantiation_error) -->
  199    [ 'Arguments are not sufficiently instantiated' ].
  200iso_message(uninstantiation_error(Var)) -->
  201    [ 'Uninstantiated argument expected, found ~p'-[Var] ].
  202iso_message(representation_error(What)) -->
  203    [ 'Cannot represent due to `~w'''-[What] ].
  204iso_message(permission_error(Action, Type, Object)) -->
  205    permission_error(Action, Type, Object).
  206iso_message(evaluation_error(Which)) -->
  207    [ 'Arithmetic: evaluation error: `~p'''-[Which] ].
  208iso_message(existence_error(procedure, Proc)) -->
  209    [ 'Unknown procedure: ~q'-[Proc] ],
  210    unknown_proc_msg(Proc).
  211iso_message(existence_error(answer_variable, Var)) -->
  212    [ '$~w was not bound by a previous query'-[Var] ].
  213iso_message(existence_error(matching_rule, Goal)) -->
  214    [ 'No rule matches ~p'-[Goal] ].
  215iso_message(existence_error(Type, Object)) -->
  216    [ '~w `~p'' does not exist'-[Type, Object] ].
  217iso_message(existence_error(export, PI, module(M))) --> % not ISO
  218    [ 'Module ', ansi(code, '~q', [M]), ' does not export ',
  219      ansi(code, '~q', [PI]) ].
  220iso_message(existence_error(Type, Object, In)) --> % not ISO
  221    [ '~w `~p'' does not exist in ~p'-[Type, Object, In] ].
  222iso_message(busy(Type, Object)) -->
  223    [ '~w `~p'' is busy'-[Type, Object] ].
  224iso_message(syntax_error(swi_backslash_newline)) -->
  225    [ 'Deprecated ... \\<newline><white>*.  Use \\c' ].
  226iso_message(syntax_error(Id)) -->
  227    [ 'Syntax error: ' ],
  228    syntax_error(Id).
  229iso_message(occurs_check(Var, In)) -->
  230    [ 'Cannot unify ~p with ~p: would create an infinite tree'-[Var, In] ].

 permission_error(Action, Type, Object)//

Translate permission errors. Most follow te pattern "No permission to Action Type Object", but some are a bit different.

  237permission_error(Action, built_in_procedure, Pred) -->
  238    { user_predicate_indicator(Pred, PI)
  239    },
  240    [ 'No permission to ~w built-in predicate `~p'''-[Action, PI] ],
  241    (   {Action \== export}
  242    ->  [ nl,
  243          'Use :- redefine_system_predicate(+Head) if redefinition is intended'
  244        ]
  245    ;   []
  246    ).
  247permission_error(import_into(Dest), procedure, Pred) -->
  248    [ 'No permission to import ~p into ~w'-[Pred, Dest] ].
  249permission_error(Action, static_procedure, Proc) -->
  250    [ 'No permission to ~w static procedure `~p'''-[Action, Proc] ],
  251    defined_definition('Defined', Proc).
  252permission_error(input, stream, Stream) -->
  253    [ 'No permission to read from output stream `~p'''-[Stream] ].
  254permission_error(output, stream, Stream) -->
  255    [ 'No permission to write to input stream `~p'''-[Stream] ].
  256permission_error(input, text_stream, Stream) -->
  257    [ 'No permission to read bytes from TEXT stream `~p'''-[Stream] ].
  258permission_error(output, text_stream, Stream) -->
  259    [ 'No permission to write bytes to TEXT stream `~p'''-[Stream] ].
  260permission_error(input, binary_stream, Stream) -->
  261    [ 'No permission to read characters from binary stream `~p'''-[Stream] ].
  262permission_error(output, binary_stream, Stream) -->
  263    [ 'No permission to write characters to binary stream `~p'''-[Stream] ].
  264permission_error(open, source_sink, alias(Alias)) -->
  265    [ 'No permission to reuse alias "~p": already taken'-[Alias] ].
  266permission_error(tnot, non_tabled_procedure, Pred) -->
  267    [ 'The argument of tnot/1 is not tabled: ~p'-[Pred] ].
  268permission_error(assert, procedure, Pred) -->
  269    { '$pi_head'(Pred, Head),
  270      predicate_property(Head, ssu)
  271    },
  272    [ '~p: an SSU (Head => Body) predicate cannot have normal Prolog clauses'-
  273      [Pred] ].
  274permission_error(Action, Type, Object) -->
  275    [ 'No permission to ~w ~w `~p'''-[Action, Type, Object] ].
  276
  277
  278unknown_proc_msg(_:(^)/2) -->
  279    !,
  280    unknown_proc_msg((^)/2).
  281unknown_proc_msg((^)/2) -->
  282    !,
  283    [nl, '  ^/2 can only appear as the 2nd argument of setof/3 and bagof/3'].
  284unknown_proc_msg((:-)/2) -->
  285    !,
  286    [nl, '  Rules must be loaded from a file'],
  287    faq('ToplevelMode').
  288unknown_proc_msg((=>)/2) -->
  289    !,
  290    [nl, '  Rules must be loaded from a file'],
  291    faq('ToplevelMode').
  292unknown_proc_msg((:-)/1) -->
  293    !,
  294    [nl, '  Directives must be loaded from a file'],
  295    faq('ToplevelMode').
  296unknown_proc_msg((?-)/1) -->
  297    !,
  298    [nl, '  ?- is the Prolog prompt'],
  299    faq('ToplevelMode').
  300unknown_proc_msg(Proc) -->
  301    { dwim_predicates(Proc, Dwims) },
  302    (   {Dwims \== []}
  303    ->  [nl, '  However, there are definitions for:', nl],
  304        dwim_message(Dwims)
  305    ;   []
  306    ).
  307
  308dependency_error(shared(Shared), private(Private)) -->
  309    [ 'Shared table for ~p may not depend on private ~p'-[Shared, Private] ].
  310dependency_error(Dep, monotonic(On)) -->
  311    { '$pi_head'(PI, Dep),
  312      '$pi_head'(MPI, On)
  313    },
  314    [ 'Dependent ~p on monotonic predicate ~p is not monotonic or incremental'-
  315      [PI, MPI]
  316    ].
  317
  318faq(Page) -->
  319    [nl, '  See FAQ at https://www.swi-prolog.org/FAQ/', Page, '.html' ].
  320
  321type_error_comment(_Expected, Actual) -->
  322    { type_of(Actual, Type),
  323      (   sub_atom(Type, 0, 1, _, First),
  324          memberchk(First, [a,e,i,o,u])
  325      ->  Article = an
  326      ;   Article = a
  327      )
  328    },
  329    [ ' (~w ~w)'-[Article, Type] ].
  330
  331type_of(Term, Type) :-
  332    (   attvar(Term)      -> Type = attvar
  333    ;   var(Term)         -> Type = var
  334    ;   atom(Term)        -> Type = atom
  335    ;   integer(Term)     -> Type = integer
  336    ;   string(Term)      -> Type = string
  337    ;   Term == []        -> Type = empty_list
  338    ;   blob(Term, BlobT) -> blob_type(BlobT, Type)
  339    ;   rational(Term)    -> Type = rational
  340    ;   float(Term)       -> Type = float
  341    ;   is_stream(Term)   -> Type = stream
  342    ;   is_dict(Term)     -> Type = dict
  343    ;   is_list(Term)     -> Type = list
  344    ;   cyclic_term(Term) -> Type = cyclic
  345    ;   compound(Term)    -> Type = compound
  346    ;                        Type = unknown
  347    ).
  348
  349blob_type(BlobT, Type) :-
  350    atom_concat(BlobT, '_reference', Type).
  351
  352syntax_error(end_of_clause) -->
  353    [ 'Unexpected end of clause' ].
  354syntax_error(end_of_clause_expected) -->
  355    [ 'End of clause expected' ].
  356syntax_error(end_of_file) -->
  357    [ 'Unexpected end of file' ].
  358syntax_error(end_of_file_in_block_comment) -->
  359    [ 'End of file in /* ... */ comment' ].
  360syntax_error(end_of_file_in_quoted(Quote)) -->
  361    [ 'End of file in quoted ' ],
  362    quoted_type(Quote).
  363syntax_error(illegal_number) -->
  364    [ 'Illegal number' ].
  365syntax_error(long_atom) -->
  366    [ 'Atom too long (see style_check/1)' ].
  367syntax_error(long_string) -->
  368    [ 'String too long (see style_check/1)' ].
  369syntax_error(operator_clash) -->
  370    [ 'Operator priority clash' ].
  371syntax_error(operator_expected) -->
  372    [ 'Operator expected' ].
  373syntax_error(operator_balance) -->
  374    [ 'Unbalanced operator' ].
  375syntax_error(quoted_punctuation) -->
  376    [ 'Operand expected, unquoted comma or bar found' ].
  377syntax_error(list_rest) -->
  378    [ 'Unexpected comma or bar in rest of list' ].
  379syntax_error(cannot_start_term) -->
  380    [ 'Illegal start of term' ].
  381syntax_error(punct(Punct, End)) -->
  382    [ 'Unexpected `~w\' before `~w\''-[Punct, End] ].
  383syntax_error(undefined_char_escape(C)) -->
  384    [ 'Unknown character escape in quoted atom or string: `\\~w\''-[C] ].
  385syntax_error(void_not_allowed) -->
  386    [ 'Empty argument list "()"' ].
  387syntax_error(Term) -->
  388    { compound(Term),
  389      compound_name_arguments(Term, Syntax, [Text])
  390    }, !,
  391    [ '~w expected, found '-[Syntax], ansi(code, '"~w"', [Text]) ].
  392syntax_error(Message) -->
  393    [ '~w'-[Message] ].
  394
  395quoted_type('\'') --> [atom].
  396quoted_type('\"') --> { current_prolog_flag(double_quotes, Type) }, [Type-[]].
  397quoted_type('\`') --> { current_prolog_flag(back_quotes, Type) }, [Type-[]].
  398
  399domain(range(Low,High)) -->
  400    !,
  401    ['[~q..~q]'-[Low,High] ].
  402domain(Domain) -->
  403    ['`~w\''-[Domain] ].

 tabling_existence_error(+Ball, +Context)//

Called on invalid shift/1 calls. Track those that result from tabling errors.

  410tabling_existence_error(Ball, Context) -->
  411    { table_shift_ball(Ball) },
  412    [ 'Tabling dependency error' ],
  413    swi_extra(Context).
  414
  415table_shift_ball(dependency(_Head)).
  416table_shift_ball(dependency(_Skeleton, _Trie, _Mono)).
  417table_shift_ball(call_info(_Skeleton, _Status)).
  418table_shift_ball(call_info(_GenSkeleton, _Skeleton, _Status)).

 dwim_predicates(+PI, -Dwims)

Find related predicate indicators.

  424dwim_predicates(Module:Name/_Arity, Dwims) :-
  425    !,
  426    findall(Dwim, dwim_predicate(Module:Name, Dwim), Dwims).
  427dwim_predicates(Name/_Arity, Dwims) :-
  428    findall(Dwim, dwim_predicate(user:Name, Dwim), Dwims).
  429
  430dwim_message([]) --> [].
  431dwim_message([M:Head|T]) -->
  432    { hidden_module(M),
  433      !,
  434      functor(Head, Name, Arity)
  435    },
  436    [ '        ~q'-[Name/Arity], nl ],
  437    dwim_message(T).
  438dwim_message([Module:Head|T]) -->
  439    !,
  440    { functor(Head, Name, Arity)
  441    },
  442    [ '        ~q'-[Module:Name/Arity], nl],
  443    dwim_message(T).
  444dwim_message([Head|T]) -->
  445    {functor(Head, Name, Arity)},
  446    [ '        ~q'-[Name/Arity], nl],
  447    dwim_message(T).
  448
  449
  450swi_message(io_error(Op, Stream)) -->
  451    [ 'I/O error in ~w on stream ~p'-[Op, Stream] ].
  452swi_message(thread_error(TID, false)) -->
  453    [ 'Thread ~p died due to failure:'-[TID] ].
  454swi_message(thread_error(TID, exception(Error))) -->
  455    [ 'Thread ~p died abnormally:'-[TID], nl ],
  456    translate_message(Error).
  457swi_message(dependency_error(Tabled, DependsOn)) -->
  458    dependency_error(Tabled, DependsOn).
  459swi_message(shell(execute, Cmd)) -->
  460    [ 'Could not execute `~w'''-[Cmd] ].
  461swi_message(shell(signal(Sig), Cmd)) -->
  462    [ 'Caught signal ~d on `~w'''-[Sig, Cmd] ].
  463swi_message(format(Fmt, Args)) -->
  464    [ Fmt-Args ].
  465swi_message(signal(Name, Num)) -->
  466    [ 'Caught signal ~d (~w)'-[Num, Name] ].
  467swi_message(limit_exceeded(Limit, MaxVal)) -->
  468    [ 'Exceeded ~w limit (~w)'-[Limit, MaxVal] ].
  469swi_message(goal_failed(Goal)) -->
  470    [ 'goal unexpectedly failed: ~p'-[Goal] ].
  471swi_message(shared_object(_Action, Message)) --> % Message = dlerror()
  472    [ '~w'-[Message] ].
  473swi_message(system_error(Error)) -->
  474    [ 'error in system call: ~w'-[Error]
  475    ].
  476swi_message(system_error) -->
  477    [ 'error in system call'
  478    ].
  479swi_message(failure_error(Goal)) -->
  480    [ 'Goal failed: ~p'-[Goal] ].
  481swi_message(timeout_error(Op, Stream)) -->
  482    [ 'Timeout in ~w from ~p'-[Op, Stream] ].
  483swi_message(not_implemented(Type, What)) -->
  484    [ '~w `~p\' is not implemented in this version'-[Type, What] ].
  485swi_message(context_error(nodirective, Goal)) -->
  486    { goal_to_predicate_indicator(Goal, PI) },
  487    [ 'Wrong context: ~p can only be used in a directive'-[PI] ].
  488swi_message(context_error(edit, no_default_file)) -->
  489    (   { current_prolog_flag(windows, true) }
  490    ->  [ 'Edit/0 can only be used after opening a \c
  491               Prolog file by double-clicking it' ]
  492    ;   [ 'Edit/0 can only be used with the "-s file" commandline option'
  493        ]
  494    ),
  495    [ nl, 'Use "?- edit(Topic)." or "?- emacs."' ].
  496swi_message(context_error(function, meta_arg(S))) -->
  497    [ 'Functions are not (yet) supported for meta-arguments of type ~q'-[S] ].
  498swi_message(format_argument_type(Fmt, Arg)) -->
  499    [ 'Illegal argument to format sequence ~~~w: ~p'-[Fmt, Arg] ].
  500swi_message(format(Msg)) -->
  501    [ 'Format error: ~w'-[Msg] ].
  502swi_message(conditional_compilation_error(unterminated, File:Line)) -->
  503    [ 'Unterminated conditional compilation from '-[], url(File:Line) ].
  504swi_message(conditional_compilation_error(no_if, What)) -->
  505    [ ':- ~w without :- if'-[What] ].
  506swi_message(duplicate_key(Key)) -->
  507    [ 'Duplicate key: ~p'-[Key] ].
  508swi_message(initialization_error(failed, Goal, File:Line)) -->
  509    !,
  510    [ url(File:Line), ': ~p: false'-[Goal] ].
  511swi_message(initialization_error(Error, Goal, File:Line)) -->
  512    [ url(File:Line), ': ~p '-[Goal] ],
  513    translate_message(Error).
  514swi_message(determinism_error(PI, det, Found, property)) -->
  515    (   { '$pi_head'(user:PI, Head),
  516          predicate_property(Head, det)
  517        }
  518    ->  [ 'Deterministic procedure ~p'-[PI] ]
  519    ;   [ 'Procedure ~p called from a deterministic procedure'-[PI] ]
  520    ),
  521    det_error(Found).
  522swi_message(determinism_error(PI, det, fail, guard)) -->
  523    [ 'Procedure ~p failed after $-guard'-[PI] ].
  524swi_message(determinism_error(PI, det, fail, guard_in_caller)) -->
  525    [ 'Procedure ~p failed after $-guard in caller'-[PI] ].
  526swi_message(determinism_error(Goal, det, fail, goal)) -->
  527    [ 'Goal ~p failed'-[Goal] ].
  528swi_message(determinism_error(Goal, det, nondet, goal)) -->
  529    [ 'Goal ~p succeeded with a choice point'-[Goal] ].
  530swi_message(qlf_format_error(File, Message)) -->
  531    [ '~w: Invalid QLF file: ~w'-[File, Message] ].
  532swi_message(goal_expansion_error(bound, Term)) -->
  533    [ 'Goal expansion bound a variable to ~p'-[Term] ].
  534
  535det_error(nondet) -->
  536    [ ' succeeded with a choicepoint'- [] ].
  537det_error(fail) -->
  538    [ ' failed'- [] ].

 swi_location(+Term)// is det

Print location information for error(Formal, ImplDefined) from the ImplDefined term.

  546:- public swi_location//1.  547swi_location(X) -->
  548    { var(X) },
  549    !.
  550swi_location(Context) -->
  551    { message_lang(Lang) },
  552    prolog:message_location(Lang, Context),
  553    !.
  554swi_location(Context) -->
  555    prolog:message_location(Context),
  556    !.
  557swi_location(context(Caller, _Msg)) -->
  558    { ground(Caller) },
  559    !,
  560    caller(Caller).
  561swi_location(file(Path, Line, -1, _CharNo)) -->
  562    !,
  563    [ url(Path:Line), ': ' ].
  564swi_location(file(Path, Line, LinePos, _CharNo)) -->
  565    [ url(Path:Line:LinePos), ': ' ].
  566swi_location(stream(Stream, Line, LinePos, CharNo)) -->
  567    (   { is_stream(Stream),
  568          stream_property(Stream, file_name(File))
  569        }
  570    ->  swi_location(file(File, Line, LinePos, CharNo))
  571    ;   [ 'Stream ~w:~d:~d '-[Stream, Line, LinePos] ]
  572    ).
  573swi_location(autoload(File:Line)) -->
  574    [ url(File:Line), ': ' ].
  575swi_location(_) -->
  576    [].
  577
  578caller(system:'$record_clause'/3) -->
  579    !,
  580    [].
  581caller(Module:Name/Arity) -->
  582    !,
  583    (   { \+ hidden_module(Module) }
  584    ->  [ '~q:~q/~w: '-[Module, Name, Arity] ]
  585    ;   [ '~q/~w: '-[Name, Arity] ]
  586    ).
  587caller(Name/Arity) -->
  588    [ '~q/~w: '-[Name, Arity] ].
  589caller(Caller) -->
  590    [ '~p: '-[Caller] ].

 swi_extra(+Term)// is det

Extract information from the second argument of an error(Formal, ImplDefined) that is printed after the core of the message.

See also

- swi_location//1 uses the same term to insert context before the core of the message.

  601swi_extra(X) -->
  602    { var(X) },
  603    !,
  604    [].
  605swi_extra(Context) -->
  606    { message_lang(Lang) },
  607    prolog:message_context(Lang, Context),
  608    !.
  609swi_extra(Context) -->
  610    prolog:message_context(Context).
  611swi_extra(context(_, Msg)) -->
  612    { nonvar(Msg),
  613      Msg \== ''
  614    },
  615    !,
  616    swi_comment(Msg).
  617swi_extra(string(String, CharPos)) -->
  618    { sub_string(String, 0, CharPos, _, Before),
  619      sub_string(String, CharPos, _, 0, After)
  620    },
  621    [ nl, '~w'-[Before], nl, '** here **', nl, '~w'-[After] ].
  622swi_extra(_) -->
  623    [].
  624
  625swi_comment(already_from(Module)) -->
  626    !,
  627    [ ' (already imported from ~q)'-[Module] ].
  628swi_comment(directory(_Dir)) -->
  629    !,
  630    [ ' (is a directory)' ].
  631swi_comment(not_a_directory(_Dir)) -->
  632    !,
  633    [ ' (is not a directory)' ].
  634swi_comment(Msg) -->
  635    [ ' (~w)'-[Msg] ].
  636
  637
  638thread_context -->
  639    { thread_self(Me), Me \== main, thread_property(Me, id(Id)) },
  640    !,
  641    ['[Thread ~w] '-[Id]].
  642thread_context -->
  643    [].
  644
  645		 /*******************************
  646		 *        UNWIND MESSAGES	*
  647		 *******************************/
  648
  649unwind_message(Var) -->
  650    { var(Var) }, !,
  651    [ 'Unknown unwind message: ~p'-[Var] ].
  652unwind_message(abort) -->
  653    [ 'Execution Aborted' ].
  654unwind_message(halt(_)) -->
  655    [].
  656unwind_message(thread_exit(Term)) -->
  657    [ 'Invalid thread_exit/1.  Payload: ~p'-[Term] ].
  658unwind_message(Term) -->
  659    [ 'Unknown "unwind" exception: ~p'-[Term] ].
  660
  661
  662                 /*******************************
  663                 *        NORMAL MESSAGES       *
  664                 *******************************/
  665
  666prolog_message(welcome) -->
  667    [ 'Welcome to SWI-Prolog (' ],
  668    prolog_message(threads),
  669    prolog_message(address_bits),
  670    ['version ' ],
  671    prolog_message(version),
  672    [ ')', nl ],
  673    prolog_message(copyright),
  674    [ nl ],
  675    translate_message(user_versions),
  676    [ nl ],
  677    prolog_message(documentaton),
  678    [ nl, nl ].
  679prolog_message(user_versions) -->
  680    (   { findall(Msg, prolog:version_msg(Msg), Msgs),
  681          Msgs \== []
  682        }
  683    ->  [nl],
  684        user_version_messages(Msgs)
  685    ;   []
  686    ).
  687prolog_message(deprecated(Term)) -->
  688    { nonvar(Term) },
  689    (   { message_lang(Lang) },
  690        prolog:deprecated(Lang, Term)
  691    ->  []
  692    ;   prolog:deprecated(Term)
  693    ->  []
  694    ;   deprecated(Term)
  695    ).
  696prolog_message(unhandled_exception(E)) -->
  697    { nonvar(E) },
  698    [ 'Unhandled exception: ' ],
  699    (   translate_message(E)
  700    ->  []
  701    ;   [ '~p'-[E] ]
  702    ).

 prolog_message(+Term)//

  706prolog_message(initialization_error(_, E, File:Line)) -->
  707    !,
  708    [ url(File:Line),
  709      ': Initialization goal raised exception:', nl
  710    ],
  711    translate_message(E).
  712prolog_message(initialization_error(Goal, E, _)) -->
  713    [ 'Initialization goal ~p raised exception:'-[Goal], nl ],
  714    translate_message(E).
  715prolog_message(initialization_failure(_Goal, File:Line)) -->
  716    !,
  717    [ url(File:Line),
  718      ': Initialization goal failed'-[]
  719    ].
  720prolog_message(initialization_failure(Goal, _)) -->
  721    [ 'Initialization goal failed: ~p'-[Goal]
  722    ].
  723prolog_message(initialization_exception(E)) -->
  724    [ 'Prolog initialisation failed:', nl ],
  725    translate_message(E).
  726prolog_message(init_goal_syntax(Error, Text)) -->
  727    !,
  728    [ '-g ~w: '-[Text] ],
  729    translate_message(Error).
  730prolog_message(init_goal_failed(failed, @(Goal,File:Line))) -->
  731    !,
  732    [ url(File:Line), ': ~p: false'-[Goal] ].
  733prolog_message(init_goal_failed(Error, @(Goal,File:Line))) -->
  734    !,
  735    [ url(File:Line), ': ~p '-[Goal] ],
  736    translate_message(Error).
  737prolog_message(init_goal_failed(failed, Text)) -->
  738    !,
  739    [ '-g ~w: false'-[Text] ].
  740prolog_message(init_goal_failed(Error, Text)) -->
  741    !,
  742    [ '-g ~w: '-[Text] ],
  743    translate_message(Error).
  744prolog_message(goal_failed(Context, Goal)) -->
  745    [ 'Goal (~w) failed: ~p'-[Context, Goal] ].
  746prolog_message(no_current_module(Module)) -->
  747    [ '~w is not a current module (created)'-[Module] ].
  748prolog_message(commandline_arg_type(Flag, Arg)) -->
  749    [ 'Bad argument to commandline option -~w: ~w'-[Flag, Arg] ].
  750prolog_message(missing_feature(Name)) -->
  751    [ 'This version of SWI-Prolog does not support ~w'-[Name] ].
  752prolog_message(singletons(_Term, List)) -->
  753    [ 'Singleton variables: ~w'-[List] ].
  754prolog_message(multitons(_Term, List)) -->
  755    [ 'Singleton-marked variables appearing more than once: ~w'-[List] ].
  756prolog_message(profile_no_cpu_time) -->
  757    [ 'No CPU-time info.  Check the SWI-Prolog manual for details' ].
  758prolog_message(non_ascii(Text, Type)) -->
  759    [ 'Unquoted ~w with non-portable characters: ~w'-[Type, Text] ].
  760prolog_message(io_warning(Stream, Message)) -->
  761    { stream_property(Stream, position(Position)),
  762      !,
  763      stream_position_data(line_count, Position, LineNo),
  764      stream_position_data(line_position, Position, LinePos),
  765      (   stream_property(Stream, file_name(File))
  766      ->  Obj = File
  767      ;   Obj = Stream
  768      )
  769    },
  770    [ '~p:~d:~d: ~w'-[Obj, LineNo, LinePos, Message] ].
  771prolog_message(io_warning(Stream, Message)) -->
  772    [ 'stream ~p: ~w'-[Stream, Message] ].
  773prolog_message(option_usage(pldoc)) -->
  774    [ 'Usage: --pldoc[=port]' ].
  775prolog_message(interrupt(begin)) -->
  776    [ 'Action (h for help) ? ', flush ].
  777prolog_message(interrupt(end)) -->
  778    [ 'continue' ].
  779prolog_message(interrupt(trace)) -->
  780    [ 'continue (trace mode)' ].
  781prolog_message(unknown_in_module_user) -->
  782    [ 'Using a non-error value for unknown in the global module', nl,
  783      'causes most of the development environment to stop working.', nl,
  784      'Please use :- dynamic or limit usage of unknown to a module.', nl,
  785      'See https://www.swi-prolog.org/howto/database.html'
  786    ].
  787prolog_message(untable(PI)) -->
  788    [ 'Reconsult: removed tabling for ~p'-[PI] ].
  789prolog_message(unknown_option(Set, Opt)) -->
  790    [ 'Unknown ~w option: ~p'-[Set, Opt] ].
  791
  792
  793                 /*******************************
  794                 *         LOADING FILES        *
  795                 *******************************/
  796
  797prolog_message(modify_active_procedure(Who, What)) -->
  798    [ '~p: modified active procedure ~p'-[Who, What] ].
  799prolog_message(load_file(failed(user:File))) -->
  800    [ 'Failed to load ~p'-[File] ].
  801prolog_message(load_file(failed(Module:File))) -->
  802    [ 'Failed to load ~p into module ~p'-[File, Module] ].
  803prolog_message(load_file(failed(File))) -->
  804    [ 'Failed to load ~p'-[File] ].
  805prolog_message(mixed_directive(Goal)) -->
  806    [ 'Cannot pre-compile mixed load/call directive: ~p'-[Goal] ].
  807prolog_message(cannot_redefine_comma) -->
  808    [ 'Full stop in clause-body?  Cannot redefine ,/2' ].
  809prolog_message(illegal_autoload_index(Dir, Term)) -->
  810    [ 'Illegal term in INDEX file of directory ~w: ~w'-[Dir, Term] ].
  811prolog_message(redefined_procedure(Type, Proc)) -->
  812    [ 'Redefined ~w procedure ~p'-[Type, Proc] ],
  813    defined_definition('Previously defined', Proc).
  814prolog_message(declare_module(Module, abolish(Predicates))) -->
  815    [ 'Loading module ~w abolished: ~p'-[Module, Predicates] ].
  816prolog_message(import_private(Module, Private)) -->
  817    [ 'import/1: ~p is not exported (still imported into ~q)'-
  818      [Private, Module]
  819    ].
  820prolog_message(ignored_weak_import(Into, From:PI)) -->
  821    [ 'Local definition of ~p overrides weak import from ~q'-
  822      [Into:PI, From]
  823    ].
  824prolog_message(undefined_export(Module, PI)) -->
  825    [ 'Exported procedure ~q:~q is not defined'-[Module, PI] ].
  826prolog_message(no_exported_op(Module, Op)) -->
  827    [ 'Operator ~q:~q is not exported (still defined)'-[Module, Op] ].
  828prolog_message(discontiguous((-)/2,_)) -->
  829    prolog_message(minus_in_identifier).
  830prolog_message(discontiguous(Proc,Current)) -->
  831    [ 'Clauses of ', ansi(code, '~p', [Proc]),
  832      ' are not together in the source-file', nl ],
  833    current_definition(Proc, 'Earlier definition at '),
  834    [ 'Current predicate: ', ansi(code, '~p', [Current]), nl,
  835      'Use ', ansi(code, ':- discontiguous ~p.', [Proc]),
  836      ' to suppress this message'
  837    ].
  838prolog_message(decl_no_effect(Goal)) -->
  839    [ 'Deprecated declaration has no effect: ~p'-[Goal] ].
  840prolog_message(load_file(start(Level, File))) -->
  841    [ '~|~t~*+Loading '-[Level] ],
  842    load_file(File),
  843    [ ' ...' ].
  844prolog_message(include_file(start(Level, File))) -->
  845    [ '~|~t~*+include '-[Level] ],
  846    load_file(File),
  847    [ ' ...' ].
  848prolog_message(include_file(done(Level, File))) -->
  849    [ '~|~t~*+included '-[Level] ],
  850    load_file(File).
  851prolog_message(load_file(done(Level, File, Action, Module, Time, Clauses))) -->
  852    [ '~|~t~*+'-[Level] ],
  853    load_file(File),
  854    [ ' ~w'-[Action] ],
  855    load_module(Module),
  856    [ ' ~2f sec, ~D clauses'-[Time, Clauses] ].
  857prolog_message(dwim_undefined(Goal, Alternatives)) -->
  858    { goal_to_predicate_indicator(Goal, Pred)
  859    },
  860    [ 'Unknown procedure: ~q'-[Pred], nl,
  861      '    However, there are definitions for:', nl
  862    ],
  863    dwim_message(Alternatives).
  864prolog_message(dwim_correct(Into)) -->
  865    [ 'Correct to: ~q? '-[Into], flush ].
  866prolog_message(error(loop_error(Spec), file_search(Used))) -->
  867    [ 'File search: too many levels of indirections on: ~p'-[Spec], nl,
  868      '    Used alias expansions:', nl
  869    ],
  870    used_search(Used).
  871prolog_message(minus_in_identifier) -->
  872    [ 'The "-" character should not be used to separate words in an', nl,
  873      'identifier.  Check the SWI-Prolog FAQ for details.'
  874    ].
  875prolog_message(qlf(removed_after_error(File))) -->
  876    [ 'Removed incomplete QLF file ~w'-[File] ].
  877prolog_message(qlf(recompile(Spec,_Pl,_Qlf,Reason))) -->
  878    [ '~p: recompiling QLF file'-[Spec] ],
  879    qlf_recompile_reason(Reason).
  880prolog_message(qlf(can_not_recompile(Spec,QlfFile,_Reason))) -->
  881    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  882      '\tLoading from source'-[]
  883    ].
  884prolog_message(qlf(system_lib_out_of_date(Spec,QlfFile))) -->
  885    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  886      '\tLoading QlfFile'-[]
  887    ].
  888prolog_message(redefine_module(Module, OldFile, File)) -->
  889    [ 'Module "~q" already loaded from ~w.'-[Module, OldFile], nl,
  890      'Wipe and reload from ~w? '-[File], flush
  891    ].
  892prolog_message(redefine_module_reply) -->
  893    [ 'Please answer y(es), n(o) or a(bort)' ].
  894prolog_message(reloaded_in_module(Absolute, OldContext, LM)) -->
  895    [ '~w was previously loaded in module ~w'-[Absolute, OldContext], nl,
  896      '\tnow it is reloaded into module ~w'-[LM] ].
  897prolog_message(expected_layout(Expected, Pos)) -->
  898    [ 'Layout data: expected ~w, found: ~p'-[Expected, Pos] ].
  899
  900defined_definition(Message, Spec) -->
  901    { strip_module(user:Spec, M, Name/Arity),
  902      functor(Head, Name, Arity),
  903      predicate_property(M:Head, file(File)),
  904      predicate_property(M:Head, line_count(Line))
  905    },
  906    !,
  907    [ nl, '~w at '-[Message], url(File:Line) ].
  908defined_definition(_, _) --> [].
  909
  910used_search([]) -->
  911    [].
  912used_search([Alias=Expanded|T]) -->
  913    [ '        file_search_path(~p, ~p)'-[Alias, Expanded], nl ],
  914    used_search(T).
  915
  916load_file(file(Spec, _Path)) -->
  917    (   {atomic(Spec)}
  918    ->  [ '~w'-[Spec] ]
  919    ;   [ '~p'-[Spec] ]
  920    ).
  921%load_file(file(_, Path)) -->
  922%       [ '~w'-[Path] ].
  923
  924load_module(user) --> !.
  925load_module(system) --> !.
  926load_module(Module) -->
  927    [ ' into ~w'-[Module] ].
  928
  929goal_to_predicate_indicator(Goal, PI) :-
  930    strip_module(Goal, Module, Head),
  931    callable_name_arity(Head, Name, Arity),
  932    user_predicate_indicator(Module:Name/Arity, PI).
  933
  934callable_name_arity(Goal, Name, Arity) :-
  935    compound(Goal),
  936    !,
  937    compound_name_arity(Goal, Name, Arity).
  938callable_name_arity(Goal, Goal, 0) :-
  939    atom(Goal).
  940
  941user_predicate_indicator(Module:PI, PI) :-
  942    hidden_module(Module),
  943    !.
  944user_predicate_indicator(PI, PI).
  945
  946hidden_module(user) :- !.
  947hidden_module(system) :- !.
  948hidden_module(M) :-
  949    sub_atom(M, 0, _, _, $).
  950
  951current_definition(Proc, Prefix) -->
  952    { pi_uhead(Proc, Head),
  953      predicate_property(Head, file(File)),
  954      predicate_property(Head, line_count(Line))
  955    },
  956    [ '~w'-[Prefix], url(File:Line), nl ].
  957current_definition(_, _) --> [].
  958
  959pi_uhead(Module:Name/Arity, Module:Head) :-
  960    !,
  961    atom(Module), atom(Name), integer(Arity),
  962    functor(Head, Name, Arity).
  963pi_uhead(Name/Arity, user:Head) :-
  964    atom(Name), integer(Arity),
  965    functor(Head, Name, Arity).
  966
  967qlf_recompile_reason(old) -->
  968    !,
  969    [ ' (out of date)'-[] ].
  970qlf_recompile_reason(_) -->
  971    [ ' (incompatible with current Prolog version)'-[] ].
  972
  973prolog_message(file_search(cache(Spec, _Cond), Path)) -->
  974    [ 'File search: ~p --> ~p (cache)'-[Spec, Path] ].
  975prolog_message(file_search(found(Spec, Cond), Path)) -->
  976    [ 'File search: ~p --> ~p OK ~p'-[Spec, Path, Cond] ].
  977prolog_message(file_search(tried(Spec, Cond), Path)) -->
  978    [ 'File search: ~p --> ~p NO ~p'-[Spec, Path, Cond] ].
  979
  980                 /*******************************
  981                 *              GC              *
  982                 *******************************/
  983
  984prolog_message(agc(start)) -->
  985    thread_context,
  986    [ 'AGC: ', flush ].
  987prolog_message(agc(done(Collected, Remaining, Time))) -->
  988    [ at_same_line,
  989      'reclaimed ~D atoms in ~3f sec. (remaining: ~D)'-
  990      [Collected, Time, Remaining]
  991    ].
  992prolog_message(cgc(start)) -->
  993    thread_context,
  994    [ 'CGC: ', flush ].
  995prolog_message(cgc(done(CollectedClauses, _CollectedBytes,
  996                        RemainingBytes, Time))) -->
  997    [ at_same_line,
  998      'reclaimed ~D clauses in ~3f sec. (pending: ~D bytes)'-
  999      [CollectedClauses, Time, RemainingBytes]
 1000    ].
 1001
 1002		 /*******************************
 1003		 *        STACK OVERFLOW	*
 1004		 *******************************/
 1005
 1006out_of_stack(Context) -->
 1007    { human_stack_size(Context.localused,   Local),
 1008      human_stack_size(Context.globalused,  Global),
 1009      human_stack_size(Context.trailused,   Trail),
 1010      human_stack_size(Context.stack_limit, Limit),
 1011      LCO is (100*(Context.depth - Context.environments))/Context.depth
 1012    },
 1013    [ 'Stack limit (~s) exceeded'-[Limit], nl,
 1014      '  Stack sizes: local: ~s, global: ~s, trail: ~s'-[Local,Global,Trail], nl,
 1015      '  Stack depth: ~D, last-call: ~0f%, Choice points: ~D'-
 1016         [Context.depth, LCO, Context.choicepoints], nl
 1017    ],
 1018    overflow_reason(Context, Resolve),
 1019    resolve_overflow(Resolve).
 1020
 1021human_stack_size(Size, String) :-
 1022    Size < 100,
 1023    format(string(String), '~dKb', [Size]).
 1024human_stack_size(Size, String) :-
 1025    Size < 100 000,
 1026    Value is Size / 1024,
 1027    format(string(String), '~1fMb', [Value]).
 1028human_stack_size(Size, String) :-
 1029    Value is Size / (1024*1024),
 1030    format(string(String), '~1fGb', [Value]).
 1031
 1032overflow_reason(Context, fix) -->
 1033    show_non_termination(Context),
 1034    !.
 1035overflow_reason(Context, enlarge) -->
 1036    { Stack = Context.get(stack) },
 1037    !,
 1038    [ '  In:'-[], nl ],
 1039    stack(Stack).
 1040overflow_reason(_Context, enlarge) -->
 1041    [ '  Insufficient global stack'-[] ].
 1042
 1043show_non_termination(Context) -->
 1044    (   { Stack = Context.get(cycle) }
 1045    ->  [ '  Probable infinite recursion (cycle):'-[], nl ]
 1046    ;   { Stack = Context.get(non_terminating) }
 1047    ->  [ '  Possible non-terminating recursion:'-[], nl ]
 1048    ),
 1049    stack(Stack).
 1050
 1051stack([]) --> [].
 1052stack([frame(Depth, M:Goal, _)|T]) -->
 1053    [ '    [~D] ~q:'-[Depth, M] ],
 1054    stack_goal(Goal),
 1055    [ nl ],
 1056    stack(T).
 1057
 1058stack_goal(Goal) -->
 1059    { compound(Goal),
 1060      !,
 1061      compound_name_arity(Goal, Name, Arity)
 1062    },
 1063    [ '~q('-[Name] ],
 1064    stack_goal_args(1, Arity, Goal),
 1065    [ ')'-[] ].
 1066stack_goal(Goal) -->
 1067    [ '~q'-[Goal] ].
 1068
 1069stack_goal_args(I, Arity, Goal) -->
 1070    { I =< Arity,
 1071      !,
 1072      arg(I, Goal, A),
 1073      I2 is I + 1
 1074    },
 1075    stack_goal_arg(A),
 1076    (   { I2 =< Arity }
 1077    ->  [ ', '-[] ],
 1078        stack_goal_args(I2, Arity, Goal)
 1079    ;   []
 1080    ).
 1081stack_goal_args(_, _, _) -->
 1082    [].
 1083
 1084stack_goal_arg(A) -->
 1085    { nonvar(A),
 1086      A = [Len|T],
 1087      !
 1088    },
 1089    (   {Len == cyclic_term}
 1090    ->  [ '[cyclic list]'-[] ]
 1091    ;   {T == []}
 1092    ->  [ '[length:~D]'-[Len] ]
 1093    ;   [ '[length:~D|~p]'-[Len, T] ]
 1094    ).
 1095stack_goal_arg(A) -->
 1096    { nonvar(A),
 1097      A = _/_,
 1098      !
 1099    },
 1100    [ '<compound ~p>'-[A] ].
 1101stack_goal_arg(A) -->
 1102    [ '~p'-[A] ].
 1103
 1104resolve_overflow(fix) -->
 1105    [].
 1106resolve_overflow(enlarge) -->
 1107    { current_prolog_flag(stack_limit, LimitBytes),
 1108      NewLimit is LimitBytes * 2
 1109    },
 1110    [ nl,
 1111      'Use the --stack_limit=size[KMG] command line option or'-[], nl,
 1112      '?- set_prolog_flag(stack_limit, ~I). to double the limit.'-[NewLimit]
 1113    ].

 out_of_c_stack

The thread's C-stack limit was exceeded. Give some advice on how to resolve this.

 1120out_of_c_stack -->
 1121    { statistics(c_stack, Limit), Limit > 0 },
 1122    !,
 1123    [ 'C-stack limit (~D bytes) exceeded.'-[Limit], nl ],
 1124    resolve_c_stack_overflow(Limit).
 1125out_of_c_stack -->
 1126    { statistics(c_stack, Limit), Limit > 0 },
 1127    [ 'C-stack limit exceeded.'-[Limit], nl ],
 1128    resolve_c_stack_overflow(Limit).
 1129
 1130resolve_c_stack_overflow(_Limit) -->
 1131    { thread_self(main) },
 1132    [ 'Use the shell command ' ], code('~w', 'ulimit -s size'),
 1133    [ ' to enlarge the limit.' ].
 1134resolve_c_stack_overflow(_Limit) -->
 1135    [ 'Use the ' ], code('~w', 'c_stack(KBytes)'),
 1136    [ ' option of '], code(thread_create/3), [' to enlarge the limit.' ].
 1137
 1138
 1139                 /*******************************
 1140                 *        MAKE/AUTOLOAD         *
 1141                 *******************************/
 1142
 1143prolog_message(make(reload(Files))) -->
 1144    { length(Files, N)
 1145    },
 1146    [ 'Make: reloading ~D files'-[N] ].
 1147prolog_message(make(done(_Files))) -->
 1148    [ 'Make: finished' ].
 1149prolog_message(make(library_index(Dir))) -->
 1150    [ 'Updating index for library ~w'-[Dir] ].
 1151prolog_message(autoload(Pred, File)) -->
 1152    thread_context,
 1153    [ 'autoloading ~p from ~w'-[Pred, File] ].
 1154prolog_message(autoload(read_index(Dir))) -->
 1155    [ 'Loading autoload index for ~w'-[Dir] ].
 1156prolog_message(autoload(disabled(Loaded))) -->
 1157    [ 'Disabled autoloading (loaded ~D files)'-[Loaded] ].
 1158prolog_message(autoload(already_defined(PI, From))) -->
 1159    code(PI),
 1160    (   { '$pi_head'(PI, Head),
 1161          predicate_property(Head, built_in)
 1162        }
 1163    ->  [' is a built-in predicate']
 1164    ;   [ ' is already imported from module ' ],
 1165        code(From)
 1166    ).
 1167
 1168swi_message(autoload(Msg)) -->
 1169    [ nl, '  ' ],
 1170    autoload_message(Msg).
 1171
 1172autoload_message(not_exported(PI, Spec, _FullFile, _Exports)) -->
 1173    [ ansi(code, '~w', [Spec]),
 1174      ' does not export ',
 1175      ansi(code, '~p', [PI])
 1176    ].
 1177autoload_message(no_file(Spec)) -->
 1178    [ ansi(code, '~p', [Spec]), ': No such file' ].
 1179
 1180
 1181                 /*******************************
 1182                 *       COMPILER WARNINGS      *
 1183                 *******************************/
 1184
 1185% print warnings about dubious code raised by the compiler.
 1186% TBD: pass in PC to produce exact error locations.
 1187
 1188prolog_message(compiler_warnings(Clause, Warnings0)) -->
 1189    {   print_goal_options(DefOptions),
 1190        (   prolog_load_context(variable_names, VarNames)
 1191        ->  warnings_with_named_vars(Warnings0, VarNames, Warnings),
 1192            Options = [variable_names(VarNames)|DefOptions]
 1193        ;   Options = DefOptions,
 1194            Warnings = Warnings0
 1195        )
 1196    },
 1197    compiler_warnings(Warnings, Clause, Options).
 1198
 1199warnings_with_named_vars([], _, []).
 1200warnings_with_named_vars([H|T0], VarNames, [H|T]) :-
 1201    term_variables(H, Vars),
 1202    '$member'(V1, Vars),
 1203    '$member'(_=V2, VarNames),
 1204    V1 == V2,
 1205    !,
 1206    warnings_with_named_vars(T0, VarNames, T).
 1207warnings_with_named_vars([_|T0], VarNames, T) :-
 1208    warnings_with_named_vars(T0, VarNames, T).
 1209
 1210
 1211compiler_warnings([], _, _) --> [].
 1212compiler_warnings([H|T], Clause, Options) -->
 1213    (   compiler_warning(H, Clause, Options)
 1214    ->  []
 1215    ;   [ 'Unknown compiler warning: ~W'-[H,Options] ]
 1216    ),
 1217    (   {T==[]}
 1218    ->  []
 1219    ;   [nl]
 1220    ),
 1221    compiler_warnings(T, Clause, Options).
 1222
 1223compiler_warning(eq_vv(A,B), _Clause, Options) -->
 1224    (   { A == B }
 1225    ->  [ 'Test is always true: ~W'-[A==B, Options] ]
 1226    ;   [ 'Test is always false: ~W'-[A==B, Options] ]
 1227    ).
 1228compiler_warning(eq_singleton(A,B), _Clause, Options) -->
 1229    [ 'Test is always false: ~W'-[A==B, Options] ].
 1230compiler_warning(neq_vv(A,B), _Clause, Options) -->
 1231    (   { A \== B }
 1232    ->  [ 'Test is always true: ~W'-[A\==B, Options] ]
 1233    ;   [ 'Test is always false: ~W'-[A\==B, Options] ]
 1234    ).
 1235compiler_warning(neq_singleton(A,B), _Clause, Options) -->
 1236    [ 'Test is always true: ~W'-[A\==B, Options] ].
 1237compiler_warning(unify_singleton(A,B), _Clause, Options) -->
 1238    [ 'Unified variable is not used: ~W'-[A=B, Options] ].
 1239compiler_warning(always(Bool, Pred, Arg), _Clause, Options) -->
 1240    { Goal =.. [Pred,Arg] },
 1241    [ 'Test is always ~w: ~W'-[Bool, Goal, Options] ].
 1242compiler_warning(unbalanced_var(V), _Clause, Options) -->
 1243    [ 'Variable not introduced in all branches: ~W'-[V, Options] ].
 1244compiler_warning(branch_singleton(V), _Clause, Options) -->
 1245    [ 'Singleton variable in branch: ~W'-[V, Options] ].
 1246compiler_warning(negation_singleton(V), _Clause, Options) -->
 1247    [ 'Singleton variable in \\+: ~W'-[V, Options] ].
 1248compiler_warning(multiton(V), _Clause, Options) -->
 1249    [ 'Singleton-marked variable appears more than once: ~W'-[V, Options] ].
 1250
 1251print_goal_options(
 1252    [ quoted(true),
 1253      portray(true)
 1254    ]).
 1255
 1256
 1257                 /*******************************
 1258                 *      TOPLEVEL MESSAGES       *
 1259                 *******************************/
 1260
 1261prolog_message(version) -->
 1262    { current_prolog_flag(version_git, Version) },
 1263    !,
 1264    [ '~w'-[Version] ].
 1265prolog_message(version) -->
 1266    { current_prolog_flag(version_data, swi(Major,Minor,Patch,Options))
 1267    },
 1268    (   { memberchk(tag(Tag), Options) }
 1269    ->  [ '~w.~w.~w-~w'-[Major, Minor, Patch, Tag] ]
 1270    ;   [ '~w.~w.~w'-[Major, Minor, Patch] ]
 1271    ).
 1272prolog_message(address_bits) -->
 1273    { current_prolog_flag(address_bits, Bits)
 1274    },
 1275    !,
 1276    [ '~d bits, '-[Bits] ].
 1277prolog_message(threads) -->
 1278    { current_prolog_flag(threads, true)
 1279    },
 1280    !,
 1281    [ 'threaded, ' ].
 1282prolog_message(threads) -->
 1283    [].
 1284prolog_message(copyright) -->
 1285    [ 'SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.', nl,
 1286      'Please run ', ansi(code, '?- license.', []), ' for legal details.'
 1287    ].
 1288prolog_message(documentaton) -->
 1289    [ 'For online help and background, visit ', url('https://www.swi-prolog.org') ],
 1290    (   { exists_source(library(help)) }
 1291    ->  [ nl,
 1292          'For built-in help, use ', ansi(code, '?- help(Topic).', []),
 1293          ' or ', ansi(code, '?- apropos(Word).', [])
 1294        ]
 1295    ;   []
 1296    ).
 1297prolog_message(about) -->
 1298    [ 'SWI-Prolog version (' ],
 1299    prolog_message(threads),
 1300    prolog_message(address_bits),
 1301    ['version ' ],
 1302    prolog_message(version),
 1303    [ ')', nl ],
 1304    prolog_message(copyright).
 1305prolog_message(halt) -->
 1306    [ 'halt' ].
 1307prolog_message(break(begin, Level)) -->
 1308    [ 'Break level ~d'-[Level] ].
 1309prolog_message(break(end, Level)) -->
 1310    [ 'Exit break level ~d'-[Level] ].
 1311prolog_message(var_query(_)) -->
 1312    [ '... 1,000,000 ............ 10,000,000 years later', nl, nl,
 1313      '~t~8|>> 42 << (last release gives the question)'
 1314    ].
 1315prolog_message(close_on_abort(Stream)) -->
 1316    [ 'Abort: closed stream ~p'-[Stream] ].
 1317prolog_message(cancel_halt(Reason)) -->
 1318    [ 'Halt cancelled: ~p'-[Reason] ].
 1319prolog_message(on_error(halt(Status))) -->
 1320    { statistics(errors, Errors),
 1321      statistics(warnings, Warnings)
 1322    },
 1323    [ 'Halting with status ~w due to ~D errors and ~D warnings'-
 1324      [Status, Errors, Warnings] ].
 1325
 1326prolog_message(query(QueryResult)) -->
 1327    query_result(QueryResult).
 1328
 1329query_result(no) -->            % failure
 1330    [ ansi(truth(false), 'false.', []) ],
 1331    extra_line.
 1332query_result(yes(true, [])) -->      % prompt_alternatives_on: groundness
 1333    !,
 1334    [ ansi(truth(true), 'true.', []) ],
 1335    extra_line.
 1336query_result(yes(Delays, Residuals)) -->
 1337    result([], Delays, Residuals),
 1338    extra_line.
 1339query_result(done) -->          % user typed <CR>
 1340    extra_line.
 1341query_result(yes(Bindings, Delays, Residuals)) -->
 1342    result(Bindings, Delays, Residuals),
 1343    prompt(yes, Bindings, Delays, Residuals).
 1344query_result(more(Bindings, Delays, Residuals)) -->
 1345    result(Bindings, Delays, Residuals),
 1346    prompt(more, Bindings, Delays, Residuals).
 1347query_result(help) -->
 1348    [ ansi(bold, '  Possible actions:', []), nl,
 1349      '  ; (n,r,space,TAB): redo              | t:         trace&redo'-[], nl,
 1350      '  *:                 show choicepoint  | c (a,RET): stop'-[], nl,
 1351      '  w:                 write             | p:         print'-[], nl,
 1352      '  +:                 max_depth*10      | -:         max_depth//10'-[], nl,
 1353      '  b:                 break             | h (?):     help'-[],
 1354      nl, nl
 1355    ].
 1356query_result(action) -->
 1357    [ 'Action? '-[], flush ].
 1358query_result(confirm) -->
 1359    [ 'Please answer \'y\' or \'n\'? '-[], flush ].
 1360query_result(eof) -->
 1361    [ nl ].
 1362query_result(toplevel_open_line) -->
 1363    [].
 1364
 1365prompt(Answer, [], true, []-[]) -->
 1366    !,
 1367    prompt(Answer, empty).
 1368prompt(Answer, _, _, _) -->
 1369    !,
 1370    prompt(Answer, non_empty).
 1371
 1372prompt(yes, empty) -->
 1373    !,
 1374    [ ansi(truth(true), 'true.', []) ],
 1375    extra_line.
 1376prompt(yes, _) -->
 1377    !,
 1378    [ full_stop ],
 1379    extra_line.
 1380prompt(more, empty) -->
 1381    !,
 1382    [ ansi(truth(true), 'true ', []), flush ].
 1383prompt(more, _) -->
 1384    !,
 1385    [ ' '-[], flush ].
 1386
 1387result(Bindings, Delays, Residuals) -->
 1388    { current_prolog_flag(answer_write_options, Options0),
 1389      Options = [partial(true)|Options0],
 1390      GOptions = [priority(999)|Options0]
 1391    },
 1392    wfs_residual_program(Delays, GOptions),
 1393    bindings(Bindings, [priority(699)|Options]),
 1394    (   {Residuals == []-[]}
 1395    ->  bind_delays_sep(Bindings, Delays),
 1396        delays(Delays, GOptions)
 1397    ;   bind_res_sep(Bindings, Residuals),
 1398        residuals(Residuals, GOptions),
 1399        (   {Delays == true}
 1400        ->  []
 1401        ;   [','-[], nl],
 1402            delays(Delays, GOptions)
 1403        )
 1404    ).
 1405
 1406bindings([], _) -->
 1407    [].
 1408bindings([binding(Names,Skel,Subst)|T], Options) -->
 1409    { '$last'(Names, Name) },
 1410    var_names(Names), value(Name, Skel, Subst, Options),
 1411    (   { T \== [] }
 1412    ->  [ ','-[], nl ],
 1413        bindings(T, Options)
 1414    ;   []
 1415    ).
 1416
 1417var_names([Name]) -->
 1418    !,
 1419    [ '~w = '-[Name] ].
 1420var_names([Name1,Name2|T]) -->
 1421    !,
 1422    [ '~w = ~w, '-[Name1, Name2] ],
 1423    var_names([Name2|T]).
 1424
 1425
 1426value(Name, Skel, Subst, Options) -->
 1427    (   { var(Skel), Subst = [Skel=S] }
 1428    ->  { Skel = '$VAR'(Name) },
 1429        [ '~W'-[S, Options] ]
 1430    ;   [ '~W'-[Skel, Options] ],
 1431        substitution(Subst, Options)
 1432    ).
 1433
 1434substitution([], _) --> !.
 1435substitution([N=V|T], Options) -->
 1436    [ ', ', ansi(comment, '% where', []), nl,
 1437      '    ~w = ~W'-[N,V,Options] ],
 1438    substitutions(T, Options).
 1439
 1440substitutions([], _) --> [].
 1441substitutions([N=V|T], Options) -->
 1442    [ ','-[], nl, '    ~w = ~W'-[N,V,Options] ],
 1443    substitutions(T, Options).
 1444
 1445
 1446residuals(Normal-Hidden, Options) -->
 1447    residuals1(Normal, Options),
 1448    bind_res_sep(Normal, Hidden),
 1449    (   {Hidden == []}
 1450    ->  []
 1451    ;   [ansi(comment, '% with pending residual goals', []), nl]
 1452    ),
 1453    residuals1(Hidden, Options).
 1454
 1455residuals1([], _) -->
 1456    [].
 1457residuals1([G|Gs], Options) -->
 1458    (   { Gs \== [] }
 1459    ->  [ '~W,'-[G, Options], nl ],
 1460        residuals1(Gs, Options)
 1461    ;   [ '~W'-[G, Options] ]
 1462    ).
 1463
 1464wfs_residual_program(true, _Options) -->
 1465    !.
 1466wfs_residual_program(Goal, _Options) -->
 1467    { current_prolog_flag(toplevel_list_wfs_residual_program, true),
 1468      '$current_typein_module'(TypeIn),
 1469      (   current_predicate(delays_residual_program/2)
 1470      ->  true
 1471      ;   use_module(library(wfs), [delays_residual_program/2])
 1472      ),
 1473      delays_residual_program(TypeIn:Goal, TypeIn:Program),
 1474      Program \== []
 1475    },
 1476    !,
 1477    [ ansi(comment, '% WFS residual program', []), nl ],
 1478    [ ansi(wfs(residual_program), '~@', ['$messages':list_clauses(Program)]) ].
 1479wfs_residual_program(_, _) --> [].
 1480
 1481delays(true, _Options) -->
 1482    !.
 1483delays(Goal, Options) -->
 1484    { current_prolog_flag(toplevel_list_wfs_residual_program, true)
 1485    },
 1486    !,
 1487    [ ansi(truth(undefined), '~W', [Goal, Options]) ].
 1488delays(_, _Options) -->
 1489    [ ansi(truth(undefined), undefined, []) ].
 1490
 1491:- public list_clauses/1. 1492
 1493list_clauses([]).
 1494list_clauses([H|T]) :-
 1495    (   system_undefined(H)
 1496    ->  true
 1497    ;   portray_clause(user_output, H, [indent(4)])
 1498    ),
 1499    list_clauses(T).
 1500
 1501system_undefined((undefined :- tnot(undefined))).
 1502system_undefined((answer_count_restraint :- tnot(answer_count_restraint))).
 1503system_undefined((radial_restraint :- tnot(radial_restraint))).
 1504
 1505bind_res_sep(_, []) --> !.
 1506bind_res_sep(_, []-[]) --> !.
 1507bind_res_sep([], _) --> !.
 1508bind_res_sep(_, _) --> [','-[], nl].
 1509
 1510bind_delays_sep([], _) --> !.
 1511bind_delays_sep(_, true) --> !.
 1512bind_delays_sep(_, _) --> [','-[], nl].
 1513
 1514extra_line -->
 1515    { current_prolog_flag(toplevel_extra_white_line, true) },
 1516    !,
 1517    ['~N'-[]].
 1518extra_line -->
 1519    [].
 1520
 1521prolog_message(if_tty(Message)) -->
 1522    (   {current_prolog_flag(tty_control, true)}
 1523    ->  [ at_same_line | Message ]
 1524    ;   []
 1525    ).
 1526prolog_message(halt(Reason)) -->
 1527    [ '~w: halt'-[Reason] ].
 1528prolog_message(no_action(Char)) -->
 1529    [ 'Unknown action: ~c (h for help)'-[Char], nl ].
 1530
 1531prolog_message(history(help(Show, Help))) -->
 1532    [ 'History Commands:', nl,
 1533      '    !!.              Repeat last query', nl,
 1534      '    !nr.             Repeat query numbered <nr>', nl,
 1535      '    !str.            Repeat last query starting with <str>', nl,
 1536      '    !?str.           Repeat last query holding <str>', nl,
 1537      '    ^old^new.        Substitute <old> into <new> of last query', nl,
 1538      '    !nr^old^new.     Substitute in query numbered <nr>', nl,
 1539      '    !str^old^new.    Substitute in query starting with <str>', nl,
 1540      '    !?str^old^new.   Substitute in query holding <str>', nl,
 1541      '    ~w.~21|Show history list'-[Show], nl,
 1542      '    ~w.~21|Show this list'-[Help], nl, nl
 1543    ].
 1544prolog_message(history(no_event)) -->
 1545    [ '! No such event' ].
 1546prolog_message(history(bad_substitution)) -->
 1547    [ '! Bad substitution' ].
 1548prolog_message(history(expanded(Event))) -->
 1549    [ '~w.'-[Event] ].
 1550prolog_message(history(history(Events))) -->
 1551    history_events(Events).
 1552
 1553history_events([]) -->
 1554    [].
 1555history_events([Nr/Event|T]) -->
 1556    [ '~t~w   ~8|~W~W'-[ Nr,
 1557                         Event, [partial(true)],
 1558                         '.', [partial(true)]
 1559                       ],
 1560      nl
 1561    ],
 1562    history_events(T).