Files
mercury/compiler/term_errors.m
Fergus Henderson a318013779 Fix one bug and work around another.
Estimated hours taken: 0.5

compiler/term_errors.m:
	Fix one bug and work around another.
	- The error messages said "... in the recursive call _at_ p/3 at
	  line 42 ...", instead of "... in the recursive call _to_ p/3 at
	  line 42 ...".
	- When compiling library/relation.m with --trans-opt-int enabled,
	  one of the sanity checks in the error message printing failed.
	  I've just commented it out, since getting the error message is
	  more useful than a call to error/1.
1998-01-24 17:02:57 +00:00

585 lines
20 KiB
Mathematica

%-----------------------------------------------------------------------------%
% Copyright (C) 1997-1998 The University of Melbourne.
% This file may only be copied under the terms of the GNU General
% Public License - see the file COPYING in the Mercury distribution.
%-----------------------------------------------------------------------------%
%
% term_errors.m
% Main author: crs.
%
% This module prints out the various error messages that are produced by
% the various modules of termination analysis.
%
%-----------------------------------------------------------------------------%
:- module term_errors.
:- interface.
:- import_module hlds_module.
:- import_module io, bag, std_util, list, assoc_list, term.
:- type termination_error
---> pragma_c_code
% The analysis result depends on the change constant
% of a piece of pragma C code, (which cannot be
% obtained without analyzing the C code, which is
% something we cannot do).
% Valid in both passes.
; imported_pred
% The SCC contains some imported procedures,
% whose code is not accessible.
; can_loop_proc_called(pred_proc_id, pred_proc_id)
% can_loop_proc_called(Caller, Callee, Context)
% The call from Caller to Callee at the associated
% context is to a procedure (Callee) whose termination
% info is set to can_loop.
% Although this error does not prevent us from
% producing argument size information, it would
% prevent us from proving termination.
% We look for this error in pass 1; if we find it,
% we do not perform pass 2.
; horder_args(pred_proc_id, pred_proc_id)
% horder_args(Caller, Callee, Context)
% The call from Caller to Callee at the associated
% context has some arguments of a higher order type.
% Valid in both passes.
; horder_call
% horder_call
% There is a higher order call at the associated
% context.
% Valid in both passes.
; inf_termination_const(pred_proc_id, pred_proc_id)
% inf_termination_const(Caller, Callee, Context)
% The call from Caller to Callee at the associated
% context is to a procedure (Callee) whose arg size
% info is set to infinite.
% Valid in both passes.
; not_subset(pred_proc_id, bag(var), bag(var))
% not_subset(Proc, SupplierVariables, InHeadVariables)
% This error occurs when the bag of active variables
% is not a subset of the input head variables.
% Valid error only in pass 1.
; inf_call(pred_proc_id, pred_proc_id)
% inf_call(Caller, Callee)
% The call from Caller to Callee at the associated
% context has infinite weight.
% Valid error only in pass 2.
; cycle(pred_proc_id, assoc_list(pred_proc_id, term__context))
% cycle(StartPPId, CallSites)
% In the cycle of calls starting at StartPPId and
% going through the named call sites may be an
% infinite loop.
% Valid error only in pass 2.
; no_eqns
% There are no equations in this SCC.
% This has 2 possible causes. (1) If the predicate has
% no output arguments, no equations will be created
% for them. The change constant of the predicate is
% undefined, but it will also never be used.
% (2) If the procedure is a builtin predicate, with
% an empty body, traversal cannot create any equations.
% Valid error only in pass 1.
; too_many_paths
% There were too many distinct paths to be analyzed.
% Valid in both passes (which analyze different sets
% of paths).
; solver_failed
% The solver could not find finite termination
% constants for the procedures in the SCC.
% Valid only in pass 1.
; is_builtin(pred_id)
% The termination constant of the given builtin is
% set to infinity; this happens when the type of at
% least one output argument permits a norm greater
% than zero.
; does_not_term_pragma(pred_id).
% The given procedure has a does_not_terminate pragma.
:- type term_errors__error == pair(term__context, termination_error).
:- pred term_errors__report_term_errors(list(pred_proc_id)::in,
list(term_errors__error)::in, module_info::in,
io__state::di, io__state::uo) is det.
% An error is considered an indirect error if it is due either to a
% language feature we cannot analyze or due to an error in another part
% of the code. By default, we do not issue warnings about indirect errors,
% since in the first case, the programmer cannot do anything about it,
% and in the second case, the piece of code that the programmer *can* do
% something about is not this piece.
:- pred indirect_error(term_errors__termination_error).
:- mode indirect_error(in) is semidet.
:- implementation.
:- import_module hlds_out, prog_out, hlds_pred, passes_aux, error_util.
:- import_module mercury_to_mercury, term_util, options, globals.
:- import_module bool, int, string, map, bag, require, varset.
indirect_error(horder_call).
indirect_error(pragma_c_code).
indirect_error(imported_pred).
indirect_error(can_loop_proc_called(_, _)).
indirect_error(horder_args(_, _)).
indirect_error(does_not_term_pragma(_)).
term_errors__report_term_errors(SCC, Errors, Module) -->
{ get_context_from_scc(SCC, Module, Context) },
( { SCC = [PPId] } ->
{ Pieces0 = ["Termination", "of"] },
{ term_errors__describe_one_proc_name(PPId, Module, PredName) },
{ list__append(Pieces0, [PredName], Pieces1) },
{ Single = yes(PPId) }
;
{ Pieces0 = ["Termination", "of", "the",
"mutually", "recursive", "procedures"] },
{ term_errors__describe_several_proc_names(SCC, Module, Context,
PredNames) },
{ list__append(Pieces0, PredNames, Pieces1) },
{ Single = no }
),
(
{ Errors = [] },
% XXX this should never happen
% XXX but for some reason, it often does
% { error("empty list of errors") }
{ Pieces2 = ["not", "proven,", "for", "unknown",
"reason(s)."] },
{ list__append(Pieces1, Pieces2, Pieces) },
write_error_pieces(Context, 0, Pieces)
;
{ Errors = [Error] },
{ Pieces2 = ["not", "proven", "for", "the",
"following", "reason:"] },
{ list__append(Pieces1, Pieces2, Pieces) },
write_error_pieces(Context, 0, Pieces),
term_errors__output_error(Error, Single, no, 0, Module)
;
{ Errors = [_, _ | _] },
{ Pieces2 = ["not", "proven", "for", "the",
"following", "reasons:"] },
{ list__append(Pieces1, Pieces2, Pieces) },
write_error_pieces(Context, 0, Pieces),
term_errors__output_errors(Errors, Single, 1, 0, Module)
).
:- pred term_errors__report_arg_size_errors(list(pred_proc_id)::in,
list(term_errors__error)::in, module_info::in,
io__state::di, io__state::uo) is det.
term_errors__report_arg_size_errors(SCC, Errors, Module) -->
{ get_context_from_scc(SCC, Module, Context) },
( { SCC = [PPId] } ->
{ Pieces0 = ["Termination", "constant", "of"] },
{ term_errors__describe_one_proc_name(PPId, Module, PredName) },
{ list__append(Pieces0, [PredName], Pieces1) },
{ Single = yes(PPId) }
;
{ Pieces0 = ["Termination", "constants", "of", "the",
"mutually", "recursive", "procedures"] },
{ term_errors__describe_several_proc_names(SCC, Module, Context,
PredNames) },
{ list__append(Pieces0, PredNames, Pieces1) },
{ Single = no }
),
(
{ Errors = [] },
{ error("empty list of errors") }
;
{ Errors = [Error] },
{ Pieces2 = ["set", "to", "infinity", "for", "the",
"following", "reason:"] },
{ list__append(Pieces1, Pieces2, Pieces) },
write_error_pieces(Context, 0, Pieces),
term_errors__output_error(Error, Single, no, 0, Module)
;
{ Errors = [_, _ | _] },
{ Pieces2 = ["set", "to", "infinity", "for", "the",
"following", "reasons:"] },
{ list__append(Pieces1, Pieces2, Pieces) },
write_error_pieces(Context, 0, Pieces),
term_errors__output_errors(Errors, Single, 1, 0, Module)
).
:- pred term_errors__output_errors(list(term_errors__error)::in,
maybe(pred_proc_id)::in, int::in, int::in, module_info::in,
io__state::di, io__state::uo) is det.
term_errors__output_errors([], _, _, _, _) --> [].
term_errors__output_errors([Error | Errors], Single, ErrNum0, Indent, Module)
-->
term_errors__output_error(Error, Single, yes(ErrNum0), Indent, Module),
{ ErrNum1 is ErrNum0 + 1 },
term_errors__output_errors(Errors, Single, ErrNum1, Indent, Module).
:- pred term_errors__output_error(term_errors__error::in,
maybe(pred_proc_id)::in, maybe(int)::in, int::in, module_info::in,
io__state::di, io__state::uo) is det.
term_errors__output_error(Context - Error, Single, ErrorNum, Indent, Module) -->
{ term_errors__description(Error, Single, Module, Pieces0, Reason) },
{ ErrorNum = yes(N) ->
string__int_to_string(N, Nstr),
string__append_list(["Reason ", Nstr, ":"], Preamble),
Pieces = [Preamble | Pieces0]
;
Pieces = Pieces0
},
write_error_pieces(Context, Indent, Pieces),
( { Reason = yes(InfArgSizePPId) } ->
{ lookup_proc_arg_size_info(Module, InfArgSizePPId, ArgSize) },
( { ArgSize = yes(infinite(ArgSizeErrors)) } ->
% XXX the next line is cheating
{ ArgSizePPIdSCC = [InfArgSizePPId] },
term_errors__report_arg_size_errors(ArgSizePPIdSCC,
ArgSizeErrors, Module)
;
{ error("inf arg size procedure does not have inf arg size") }
)
;
[]
).
:- pred term_errors__description(termination_error::in,
maybe(pred_proc_id)::in, module_info::in, list(string)::out,
maybe(pred_proc_id)::out) is det.
term_errors__description(horder_call, _, _, Pieces, no) :-
Pieces = ["It", "contains", "a", "higher", "order", "call."].
term_errors__description(pragma_c_code, _, _, Pieces, no) :-
Pieces = ["It", "depends", "on", "the", "properties", "of",
"foreign", "language", "code", "included", "via", "a",
"`pragma c_code'", "declaration."].
term_errors__description(inf_call(CallerPPId, CalleePPId),
Single, Module, Pieces, no) :-
(
Single = yes(PPId),
require(unify(PPId, CallerPPId), "caller outside this SCC"),
Piece1 = "It"
;
Single = no,
term_errors__describe_one_proc_name(CallerPPId, Module, Piece1)
),
Piece2 = "calls",
term_errors__describe_one_proc_name(CalleePPId, Module, CalleePiece),
Pieces3 = ["with", "an", "unbounded", "increase", "in", "the",
"size", "of", "the", "input", "arguments."],
Pieces = [Piece1, Piece2, CalleePiece | Pieces3].
term_errors__description(can_loop_proc_called(CallerPPId, CalleePPId),
Single, Module, Pieces, no) :-
(
Single = yes(PPId),
require(unify(PPId, CallerPPId), "caller outside this SCC"),
Piece1 = "It"
;
Single = no,
term_errors__describe_one_proc_name(CallerPPId, Module, Piece1)
),
Piece2 = "calls",
term_errors__describe_one_proc_name(CalleePPId, Module, CalleePiece),
Pieces3 = ["which", "could", "not", "be", "proven", "to", "terminate."],
Pieces = [Piece1, Piece2, CalleePiece | Pieces3].
term_errors__description(imported_pred, _, _, Pieces, no) :-
Pieces = ["It", "contains", "one", "or", "more",
"predicates", "and/or", "functions",
"imported", "from", "another", "module."].
term_errors__description(horder_args(CallerPPId, CalleePPId), Single, Module,
Pieces, no) :-
(
Single = yes(PPId),
require(unify(PPId, CallerPPId), "caller outside this SCC"),
Piece1 = "It"
;
Single = no,
term_errors__describe_one_proc_name(CallerPPId, Module, Piece1)
),
Piece2 = "calls",
term_errors__describe_one_proc_name(CalleePPId, Module, CalleePiece),
Pieces3 = ["with", "one", "or", "more",
"higher", "order", "arguments."],
Pieces = [Piece1, Piece2, CalleePiece | Pieces3].
term_errors__description(inf_termination_const(CallerPPId, CalleePPId),
Single, Module, Pieces, yes(CalleePPId)) :-
(
Single = yes(PPId),
require(unify(PPId, CallerPPId), "caller outside this SCC"),
Piece1 = "It"
;
Single = no,
term_errors__describe_one_proc_name(CallerPPId, Module, Piece1)
),
Piece2 = "calls",
term_errors__describe_one_proc_name(CalleePPId, Module, CalleePiece),
Pieces3 = ["which", "has", "a", "termination", "constant", "of",
"infinity."],
Pieces = [Piece1, Piece2, CalleePiece | Pieces3].
term_errors__description(not_subset(ProcPPId, OutputSuppliers, HeadVars),
Single, Module, Pieces, no) :-
(
Single = yes(PPId),
( PPId = ProcPPId ->
Pieces1 = ["The", "set", "of", "its", "output",
"supplier", "variables"]
;
% XXX this should never happen (but it does)
% error("not_subset outside this SCC"),
term_errors__describe_one_proc_name(ProcPPId, Module,
PPIdPiece),
Pieces1 = ["The", "set", "of", "output", "supplier",
"variables", "of", PPIdPiece]
)
;
Single = no,
term_errors__describe_one_proc_name(ProcPPId, Module,
PPIdPiece),
Pieces1 = ["The", "set", "of", "output", "supplier",
"variables", "of", PPIdPiece]
),
ProcPPId = proc(PredId, ProcId),
module_info_pred_proc_info(Module, PredId, ProcId, _, ProcInfo),
proc_info_varset(ProcInfo, Varset),
term_errors_var_bag_description(OutputSuppliers, Varset,
OutputSuppliersPieces),
Pieces3 = ["was", "not", "a", "subset", "of", "the", "head",
"variables"],
term_errors_var_bag_description(HeadVars, Varset, HeadVarsPieces),
list__condense([Pieces1, OutputSuppliersPieces, Pieces3,
HeadVarsPieces], Pieces).
term_errors__description(cycle(_StartPPId, CallSites), _, Module, Pieces, no) :-
( CallSites = [DirectCall] ->
term_errors__describe_one_call_site(DirectCall, Module, Site),
Pieces = ["At", "the", "recursive", "call", "to", Site,
"the", "arguments", "are", "not", "guaranteed",
"to", "decrease", "in", "size."]
;
Pieces1 = ["In", "the", "recursive", "cycle",
"through", "the", "calls", "to"],
term_errors__describe_several_call_sites(CallSites, Module,
Sites),
Pieces2 = ["the", "arguments", "are", "not", "guaranteed",
"to", "decrease", "in", "size."],
list__condense([Pieces1, Sites, Pieces2], Pieces)
).
% Pieces = ["there", "was", "a", "cycle", "in", "the", "call", "graph",
% "of", "this", "SCC", "where", "the", "variables", "did", "not",
% "decrease", "in", "size."].
% term_errors__description(positive_value(CallerPPId, CalleePPId),
% Single, Module, Pieces, no) :-
% (
% Single = yes(PPId),
% PPId = CallerPPId,
% Piece1 = "it"
% ;
% Single = no,
% term_errors__describe_one_proc_name(CallerPPId, Module, Piece1)
% ),
% ( CallerPPId = CalleePPId ->
% Pieces2 = ["contains", "a", "directly", "recursive", "call"]
% ;
% term_errors__describe_one_proc_name(CalleePPId, Module,
% CalleePiece),
% Pieces2 = ["recursive", "call", "to", CalleePiece]
% ),
% Pieces3 = ["with", "the", "size", "of", "the", "inputs", "increased."],
% list__append([Piece1 | Pieces2], Pieces3, Pieces).
term_errors__description(too_many_paths, _, _, Pieces, no) :-
Pieces = ["There", "were", "too", "many", "execution", "paths",
"for", "the", "analysis", "to", "process."].
term_errors__description(no_eqns, _, _, Pieces, no) :-
Pieces = ["The", "analysis", "was", "unable", "to", "form", "any",
"constraints", "between", "the", "arguments", "of", "this",
"group", "of", "procedures."].
term_errors__description(solver_failed, _, _, Pieces, no) :-
Pieces = ["The", "solver", "found", "the", "constraints", "produced",
"by", "the", "analysis", "to", "be", "infeasible."].
term_errors__description(is_builtin(_PredId), _Single, _, Pieces, no) :-
% XXX require(unify(Single, yes(_)), "builtin not alone in SCC"),
Pieces = ["It", "is", "a", "builtin", "predicate."].
term_errors__description(does_not_term_pragma(PredId), Single, Module,
Pieces, no) :-
Pieces1 = ["There", "was", "a", "`does_not_terminate'", "pragma",
"defined", "on"],
(
Single = yes(PPId),
PPId = proc(SCCPredId, _),
require(unify(PredId, SCCPredId), "does not terminate pragma outside this SCC"),
Piece2 = "it."
;
Single = no,
term_errors__describe_one_pred_name(PredId, Module,
Piece2Nodot),
string__append(Piece2Nodot, ".", Piece2)
),
list__append(Pieces1, [Piece2], Pieces).
%----------------------------------------------------------------------------%
:- pred term_errors_var_bag_description(bag(var)::in, varset::in,
list(string)::out) is det.
term_errors_var_bag_description(HeadVars, Varset, Pieces) :-
bag__to_assoc_list(HeadVars, HeadVarCountList),
term_errors_var_bag_description_2(HeadVarCountList, Varset, yes,
Pieces).
:- pred term_errors_var_bag_description_2(assoc_list(var, int)::in, varset::in,
bool::in, list(string)::out) is det.
term_errors_var_bag_description_2([], _, _, ["{}"]).
term_errors_var_bag_description_2([Var - Count | VarCounts], Varset, First,
[Piece | Pieces]) :-
varset__lookup_name(Varset, Var, VarName),
( Count > 1 ->
string__append(VarName, "*", VarCountPiece0),
string__int_to_string(Count, CountStr),
string__append(VarCountPiece0, CountStr, VarCountPiece)
;
VarCountPiece = VarName
),
( First = yes ->
string__append("{", VarCountPiece, Piece0)
;
Piece0 = VarCountPiece
),
( VarCounts = [] ->
string__append(Piece0, "}.", Piece),
Pieces = []
;
Piece = Piece0,
term_errors_var_bag_description_2(VarCounts, Varset, First,
Pieces)
).
%----------------------------------------------------------------------------%
:- pred term_errors__describe_one_pred_name(pred_id::in, module_info::in,
string::out) is det.
% The code of this predicate duplicates the functionality of
% hlds_out__write_pred_id. Changes here should be made there as well.
term_errors__describe_one_pred_name(PredId, Module, Piece) :-
module_info_pred_info(Module, PredId, PredInfo),
pred_info_module(PredInfo, ModuleName),
pred_info_name(PredInfo, PredName),
pred_info_arity(PredInfo, Arity),
pred_info_get_is_pred_or_func(PredInfo, PredOrFunc),
(
PredOrFunc = predicate,
PredOrFuncPart = "predicate ",
OrigArity = Arity
;
PredOrFunc = function,
PredOrFuncPart = "function ",
OrigArity is Arity - 1
),
string__int_to_string(OrigArity, ArityPart),
string__append_list([
PredOrFuncPart,
ModuleName,
":",
PredName,
"/",
ArityPart
], Piece).
:- pred term_errors__describe_one_proc_name(pred_proc_id::in, module_info::in,
string::out) is det.
term_errors__describe_one_proc_name(proc(PredId, ProcId), Module, Piece) :-
term_errors__describe_one_pred_name(PredId, Module, PredPiece),
proc_id_to_int(ProcId, ProcIdInt),
string__int_to_string(ProcIdInt, ProcIdPart),
string__append_list([
PredPiece,
" mode ",
ProcIdPart
], Piece).
:- pred term_errors__describe_several_proc_names(list(pred_proc_id)::in,
module_info::in, term__context::in, list(string)::out) is det.
term_errors__describe_several_proc_names([], _, _, []).
term_errors__describe_several_proc_names([PPId | PPIds], Module,
Context, Pieces) :-
term_errors__describe_one_proc_name(PPId, Module, Piece0),
( PPIds = [] ->
Pieces = [Piece0]
; PPIds = [LastPPId] ->
term_errors__describe_one_proc_name(LastPPId, Module,
LastPiece),
Pieces = [Piece0, "and", LastPiece]
;
string__append(Piece0, ",", Piece),
term_errors__describe_several_proc_names(PPIds, Module,
Context, Pieces1),
Pieces = [Piece | Pieces1]
).
:- pred term_errors__describe_one_call_site(pair(pred_proc_id,
term__context)::in, module_info::in, string::out) is det.
term_errors__describe_one_call_site(PPId - Context, Module, Piece) :-
term_errors__describe_one_proc_name(PPId, Module, ProcName),
Context = term__context(FileName, LineNumber),
string__int_to_string(LineNumber, LineNumberPart),
string__append_list([
ProcName,
" at ",
FileName,
":",
LineNumberPart
], Piece).
:- pred term_errors__describe_several_call_sites(assoc_list(pred_proc_id,
term__context)::in, module_info::in, list(string)::out) is det.
term_errors__describe_several_call_sites([], _, []).
term_errors__describe_several_call_sites([Site | Sites], Module, Pieces) :-
term_errors__describe_one_call_site(Site, Module, Piece0),
( Sites = [] ->
Pieces = [Piece0]
; Sites = [LastSite] ->
term_errors__describe_one_call_site(LastSite, Module,
LastPiece),
Pieces = [Piece0, "and", LastPiece]
;
string__append(Piece0, ",", Piece),
term_errors__describe_several_call_sites(Sites, Module,
Pieces1),
Pieces = [Piece | Pieces1]
).
%----------------------------------------------------------------------------%