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c08ca7fbc8
Estimated hours taken: 3 Branches: main compiler/*.m: Import only one module per line in the modules of the compiler where my previous diff did not already do so. Misc other cleanups. Where relevant, use the new mechanism in tree.m. compiler/tree.m: Fix a performance problem I noticed while update :- import_module items. Instead of supplying a function to convert lists of trees to a tree, make the tree data structure able to hold a list of subtrees directly. This reduces the number of times where we have to convert list of trees to trees that are sticks just to stay within the old definition of what a tree is.
508 lines
17 KiB
Mathematica
508 lines
17 KiB
Mathematica
%-----------------------------------------------------------------------------%
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% Copyright (C) 1997-2000, 2003-2005 The University of Melbourne.
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% This file may only be copied under the terms of the GNU General
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% Public License - see the file COPYING in the Mercury distribution.
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%-----------------------------------------------------------------------------%
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%
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% term_errors.m
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% Main author: crs.
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%
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% This module prints out the various error messages that are produced by
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% the various modules of termination analysis.
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%
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%-----------------------------------------------------------------------------%
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:- module transform_hlds__term_errors.
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:- interface.
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:- import_module hlds__hlds_module.
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:- import_module hlds__hlds_pred.
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:- import_module parse_tree__prog_data.
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:- import_module assoc_list.
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:- import_module bag.
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:- import_module io.
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:- import_module list.
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:- import_module std_util.
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:- type termination_error
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---> pragma_foreign_code
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% The analysis result depends on the change constant
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% of a piece of pragma foreign code, (which cannot be
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% obtained without analyzing the foreign code, which is
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% something we cannot do).
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% Valid in both passes.
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; imported_pred
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% The SCC contains some imported procedures,
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% whose code is not accessible.
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; can_loop_proc_called(pred_proc_id, pred_proc_id)
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% can_loop_proc_called(Caller, Callee, Context)
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% The call from Caller to Callee at the associated
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% context is to a procedure (Callee) whose termination
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% info is set to can_loop.
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% Although this error does not prevent us from
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% producing argument size information, it would
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% prevent us from proving termination.
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% We look for this error in pass 1; if we find it,
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% we do not perform pass 2.
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; horder_args(pred_proc_id, pred_proc_id)
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% horder_args(Caller, Callee, Context)
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% The call from Caller to Callee at the associated
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% context has some arguments of a higher order type.
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% Valid in both passes.
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; horder_call
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% horder_call
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% There is a higher order call at the associated
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% context.
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% Valid in both passes.
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; inf_termination_const(pred_proc_id, pred_proc_id)
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% inf_termination_const(Caller, Callee, Context)
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% The call from Caller to Callee at the associated
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% context is to a procedure (Callee) whose arg size
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% info is set to infinite.
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% Valid in both passes.
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; not_subset(pred_proc_id, bag(prog_var), bag(prog_var))
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% not_subset(Proc, SupplierVariables, InHeadVariables)
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% This error occurs when the bag of active variables
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% is not a subset of the input head variables.
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% Valid error only in pass 1.
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; inf_call(pred_proc_id, pred_proc_id)
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% inf_call(Caller, Callee)
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% The call from Caller to Callee at the associated
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% context has infinite weight.
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% Valid error only in pass 2.
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; cycle(pred_proc_id, assoc_list(pred_proc_id, prog_context))
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% cycle(StartPPId, CallSites)
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% In the cycle of calls starting at StartPPId and
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% going through the named call sites may be an
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% infinite loop.
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% Valid error only in pass 2.
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; no_eqns
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% There are no equations in this SCC.
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% This has 2 possible causes. (1) If the predicate has
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% no output arguments, no equations will be created
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% for them. The change constant of the predicate is
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% undefined, but it will also never be used.
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% (2) If the procedure is a builtin predicate, with
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% an empty body, traversal cannot create any equations.
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% Valid error only in pass 1.
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; too_many_paths
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% There are too many distinct paths to be analyzed.
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% Valid in both passes (which analyze different sets
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% of paths).
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; solver_failed
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% The solver could not find finite termination
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% constants for the procedures in the SCC.
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% Valid only in pass 1.
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; is_builtin(pred_id)
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% The termination constant of the given builtin is
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% set to infinity; this happens when the type of at
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% least one output argument permits a norm greater
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% than zero.
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; does_not_term_pragma(pred_id)
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% The given procedure has a does_not_terminate pragma.
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; inconsistent_annotations
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% The pragma terminates/does_not_terminate declarations
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% for the procedures in this SCC are inconsistent.
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; does_not_term_foreign(pred_proc_id).
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% The procedure contains foreign code that may
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% make calls back to Mercury. By default such
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% code is assumed to be non-terminating.
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:- type term_errors__error == pair(prog_context, termination_error).
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:- pred term_errors__report_term_errors(list(pred_proc_id)::in,
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list(term_errors__error)::in, module_info::in, io::di, io::uo) is det.
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% An error is considered an indirect error if it is due either to a
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% language feature we cannot analyze or due to an error in another part
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% of the code. By default, we do not issue warnings about indirect errors,
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% since in the first case, the programmer cannot do anything about it,
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% and in the second case, the piece of code that the programmer *can* do
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% something about is not this piece.
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:- pred indirect_error(term_errors__termination_error::in) is semidet.
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:- implementation.
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:- import_module hlds__hlds_error_util.
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:- import_module hlds__hlds_out.
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:- import_module hlds__passes_aux.
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:- import_module libs__globals.
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:- import_module libs__options.
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:- import_module parse_tree__error_util.
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:- import_module parse_tree__mercury_to_mercury.
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:- import_module parse_tree__prog_out.
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:- import_module transform_hlds__term_util.
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:- import_module bag.
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:- import_module bool.
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:- import_module int.
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:- import_module map.
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:- import_module require.
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:- import_module string.
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:- import_module term.
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:- import_module varset.
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indirect_error(horder_call).
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indirect_error(pragma_foreign_code).
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indirect_error(imported_pred).
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indirect_error(can_loop_proc_called(_, _)).
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indirect_error(horder_args(_, _)).
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indirect_error(does_not_term_pragma(_)).
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term_errors__report_term_errors(SCC, Errors, Module, !IO) :-
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get_context_from_scc(SCC, Module, Context),
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( SCC = [PPId] ->
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Pieces1 = [words("Termination of")] ++
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describe_one_proc_name(Module, should_module_qualify,
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PPId),
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Single = yes(PPId)
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;
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Pieces1 = [words("Termination of the "),
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words("mutually recursive procedures")] ++
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describe_several_proc_names(Module,
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should_module_qualify, SCC),
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Single = no
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),
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(
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Errors = [],
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% XXX this should never happen
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% XXX but for some reason, it often does
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% error("empty list of errors")
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Pieces2 = [words("not proven, for unknown reason(s).")],
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list__append(Pieces1, Pieces2, Pieces),
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write_error_pieces(Context, 0, Pieces, !IO)
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;
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Errors = [Error],
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Pieces2 = [words("not proven for the following reason:")],
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list__append(Pieces1, Pieces2, Pieces),
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write_error_pieces(Context, 0, Pieces, !IO),
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term_errors__output_error(Error, Single, no, 0, Module, !IO)
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;
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Errors = [_, _ | _],
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Pieces2 = [words("not proven for the following reasons:")],
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list__append(Pieces1, Pieces2, Pieces),
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write_error_pieces(Context, 0, Pieces, !IO),
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term_errors__output_errors(Errors, Single, 1, 0, Module, !IO)
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).
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:- pred term_errors__report_arg_size_errors(list(pred_proc_id)::in,
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list(term_errors__error)::in, module_info::in,
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io::di, io::uo) is det.
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term_errors__report_arg_size_errors(SCC, Errors, Module, !IO) :-
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get_context_from_scc(SCC, Module, Context),
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( SCC = [PPId] ->
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Pieces1 = [words("Termination constant of")] ++
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describe_one_proc_name(Module, should_module_qualify,
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PPId),
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Single = yes(PPId)
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;
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Pieces1 = [words("Termination constants"),
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words("of the mutually recursive procedures")] ++
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describe_several_proc_names(Module,
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should_module_qualify, SCC),
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Single = no
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),
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Piece2 = words("set to infinity for the following"),
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(
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Errors = [],
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error("empty list of errors")
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;
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Errors = [Error],
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Piece3 = words("reason:"),
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list__append(Pieces1, [Piece2, Piece3], Pieces),
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write_error_pieces(Context, 0, Pieces, !IO),
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term_errors__output_error(Error, Single, no, 0, Module, !IO)
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;
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Errors = [_, _ | _],
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Piece3 = words("reasons:"),
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list__append(Pieces1, [Piece2, Piece3], Pieces),
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write_error_pieces(Context, 0, Pieces, !IO),
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term_errors__output_errors(Errors, Single, 1, 0, Module, !IO)
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).
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:- pred term_errors__output_errors(list(term_errors__error)::in,
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maybe(pred_proc_id)::in, int::in, int::in, module_info::in,
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io::di, io::uo) is det.
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term_errors__output_errors([], _, _, _, _, !IO).
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term_errors__output_errors([Error | Errors], Single, ErrNum0, Indent, Module,
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!IO) :-
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term_errors__output_error(Error, Single, yes(ErrNum0), Indent, Module,
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!IO),
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term_errors__output_errors(Errors, Single, ErrNum0 + 1, Indent, Module,
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!IO).
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:- pred term_errors__output_error(term_errors__error::in,
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maybe(pred_proc_id)::in, maybe(int)::in, int::in, module_info::in,
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io::di, io::uo) is det.
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term_errors__output_error(Context - Error, Single, ErrorNum, Indent, Module,
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!IO) :-
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term_errors__description(Error, Single, Module, Pieces0, Reason),
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( ErrorNum = yes(N) ->
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string__int_to_string(N, Nstr),
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string__append_list(["Reason ", Nstr, ":"], Preamble),
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Pieces = [fixed(Preamble) | Pieces0]
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;
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Pieces = Pieces0
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),
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write_error_pieces(Context, Indent, Pieces, !IO),
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( Reason = yes(InfArgSizePPId) ->
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lookup_proc_arg_size_info(Module, InfArgSizePPId, ArgSize),
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( ArgSize = yes(infinite(ArgSizeErrors)) ->
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% XXX the next line is cheating
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ArgSizePPIdSCC = [InfArgSizePPId],
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term_errors__report_arg_size_errors(ArgSizePPIdSCC,
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ArgSizeErrors, Module, !IO)
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;
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error("inf arg size procedure " ++
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"does not have inf arg size")
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)
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;
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true
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).
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:- pred term_errors__description(termination_error::in,
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maybe(pred_proc_id)::in, module_info::in, list(format_component)::out,
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maybe(pred_proc_id)::out) is det.
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term_errors__description(horder_call, _, _, Pieces, no) :-
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Pieces = [words("It contains a higher order call.")].
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term_errors__description(pragma_foreign_code, _, _, Pieces, no) :-
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Pieces = [words("It depends on the properties of"),
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words("foreign language code included via a"),
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fixed("`:- pragma c_code'"),
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words("or"),
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fixed("`:- pragma foreign'"),
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words("declaration.")].
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term_errors__description(inf_call(CallerPPId, CalleePPId),
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Single, Module, Pieces, no) :-
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(
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Single = yes(PPId),
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require(unify(PPId, CallerPPId), "caller outside this SCC"),
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Pieces1 = [words("It")]
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;
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Single = no,
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Pieces1 = describe_one_proc_name(Module, should_module_qualify,
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CallerPPId)
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),
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Piece2 = words("calls"),
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CalleePieces = describe_one_proc_name(Module, should_module_qualify,
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CalleePPId),
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Pieces3 = [words("with an unbounded increase"),
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words("in the size of the input arguments.")],
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Pieces = Pieces1 ++ [Piece2] ++ CalleePieces ++ Pieces3.
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term_errors__description(can_loop_proc_called(CallerPPId, CalleePPId),
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Single, Module, Pieces, no) :-
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(
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Single = yes(PPId),
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require(unify(PPId, CallerPPId), "caller outside this SCC"),
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Pieces1 = [words("It")]
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;
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Single = no,
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Pieces1 = describe_one_proc_name(Module, should_module_qualify,
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CallerPPId)
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),
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Piece2 = words("calls"),
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CalleePieces = describe_one_proc_name(Module, should_module_qualify,
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CalleePPId),
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Piece3 = words("which could not be proven to terminate."),
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Pieces = Pieces1 ++ [Piece2] ++ CalleePieces ++ [Piece3].
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term_errors__description(imported_pred, _, _, Pieces, no) :-
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Pieces = [words("It contains one or more"),
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words("predicates and/or functions"),
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words("imported from another module.")].
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term_errors__description(horder_args(CallerPPId, CalleePPId), Single, Module,
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Pieces, no) :-
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(
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Single = yes(PPId),
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require(unify(PPId, CallerPPId), "caller outside this SCC"),
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Pieces1 = [words("It")]
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;
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Single = no,
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Pieces1 = describe_one_proc_name(Module, should_module_qualify,
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CallerPPId)
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),
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Piece2 = words("calls"),
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CalleePieces = describe_one_proc_name(Module, should_module_qualify,
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CalleePPId),
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Piece3 = words("with one or more higher order arguments."),
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Pieces = Pieces1 ++ [Piece2] ++ CalleePieces ++ [Piece3].
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term_errors__description(inf_termination_const(CallerPPId, CalleePPId),
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Single, Module, Pieces, yes(CalleePPId)) :-
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(
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Single = yes(PPId),
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require(unify(PPId, CallerPPId), "caller outside this SCC"),
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Pieces1 = [words("It")]
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;
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Single = no,
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Pieces1 = describe_one_proc_name(Module, should_module_qualify,
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CallerPPId)
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),
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Piece2 = words("calls"),
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CalleePieces = describe_one_proc_name(Module, should_module_qualify,
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CalleePPId),
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Piece3 = words("which has a termination constant of infinity."),
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Pieces = Pieces1 ++ [Piece2] ++ CalleePieces ++ [Piece3].
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term_errors__description(not_subset(ProcPPId, OutputSuppliers, HeadVars),
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Single, Module, Pieces, no) :-
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(
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Single = yes(PPId),
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( PPId = ProcPPId ->
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Pieces1 = [words("The set of"),
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words("its output supplier variables")]
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;
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% XXX this should never happen (but it does)
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% error("not_subset outside this SCC"),
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PPIdPieces = describe_one_proc_name(Module,
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should_module_qualify, ProcPPId),
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Pieces1 = [words("The set of"),
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words("output supplier variables of") |
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PPIdPieces]
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)
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;
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Single = no,
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PPIdPieces = describe_one_proc_name(Module,
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should_module_qualify, ProcPPId),
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Pieces1 = [words("The set of output supplier variables of") |
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PPIdPieces]
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),
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ProcPPId = proc(PredId, ProcId),
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module_info_pred_proc_info(Module, PredId, ProcId, _, ProcInfo),
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proc_info_varset(ProcInfo, Varset),
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term_errors_var_bag_description(OutputSuppliers, Varset,
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OutputSuppliersNames),
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list__map((pred(OS::in, FOS::out) is det :- FOS = fixed(OS)),
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OutputSuppliersNames, OutputSuppliersPieces),
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Pieces3 = [words("is not a subset of the head variables")],
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term_errors_var_bag_description(HeadVars, Varset, HeadVarsNames),
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list__map((pred(HV::in, FHV::out) is det :- FHV = fixed(HV)),
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HeadVarsNames, HeadVarsPieces),
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list__condense([Pieces1, OutputSuppliersPieces, Pieces3,
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HeadVarsPieces], Pieces).
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term_errors__description(cycle(_StartPPId, CallSites), _, Module, Pieces, no) :-
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( CallSites = [DirectCall] ->
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SitePieces = describe_one_call_site(Module,
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should_module_qualify, DirectCall),
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Pieces = [words("At the recursive call to") | SitePieces] ++
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[words("the arguments are"),
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words("not guaranteed to decrease in size.")]
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;
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Pieces1 = [words("In the recursive cycle"),
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words("through the calls to")],
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SitePieces = describe_several_call_sites(Module,
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should_module_qualify, CallSites),
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Pieces2 = [words("the arguments are"),
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words("not guaranteed to decrease in size.")],
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list__condense([Pieces1, SitePieces, Pieces2], Pieces)
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).
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term_errors__description(too_many_paths, _, _, Pieces, no) :-
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Pieces = [words("There are too many execution paths"),
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words("for the analysis to process.")].
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term_errors__description(no_eqns, _, _, Pieces, no) :-
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Pieces = [words("The analysis was unable to form any constraints"),
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words("between the arguments of this group of procedures.")].
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term_errors__description(solver_failed, _, _, Pieces, no) :-
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Pieces = [words("The solver found the constraints produced"),
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words("by the analysis to be infeasible.")].
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term_errors__description(is_builtin(_PredId), _Single, _, Pieces, no) :-
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% XXX require(unify(Single, yes(_)), "builtin not alone in SCC"),
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Pieces = [words("It is a builtin predicate.")].
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term_errors__description(does_not_term_pragma(PredId), Single, Module,
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Pieces, no) :-
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Pieces1 = [words(
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"There is a `:- pragma does_not_terminate' declaration for")],
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(
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Single = yes(PPId),
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PPId = proc(SCCPredId, _),
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require(unify(PredId, SCCPredId),
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"does not terminate pragma outside this SCC"),
|
|
Pieces2 = [words("it.")]
|
|
;
|
|
Single = no,
|
|
Pieces2 = describe_one_pred_name(Module, should_module_qualify,
|
|
PredId) ++ [suffix(".")]
|
|
),
|
|
list__append(Pieces1, Pieces2, Pieces).
|
|
|
|
term_errors__description(inconsistent_annotations, _, _, Pieces, no) :-
|
|
Pieces = [words("The termination pragmas are inconsistent.")].
|
|
|
|
term_errors__description(does_not_term_foreign(_), _, _, Pieces, no) :-
|
|
Piece1 = words("It contains foreign code that"),
|
|
Piece2 = words("may make one or more calls back to Mercury."),
|
|
Pieces = [Piece1, Piece2].
|
|
|
|
%----------------------------------------------------------------------------%
|
|
|
|
:- pred term_errors_var_bag_description(bag(prog_var)::in, prog_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(prog_var, int)::in,
|
|
prog_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)
|
|
).
|
|
|
|
%----------------------------------------------------------------------------%
|
|
%----------------------------------------------------------------------------%
|