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Improve the compiler's ability to deal with determinism errors, in three ways.
1. Add a new pragma, no_determinism_warning, that suppresses the compiler's
warning about a determinism declaration that is not as tight as possible.
2. When printing determinism errors about disjunctions in supposed-to-be-det
code, print the list of switch arms that the disjunction is in. Without
this, it can be hard to find duplicated cases in a long list of switch
cases. (If the report tells you there is a disjunction in the arm for
f/1 in the switch on X, it tells you that you have duplicated the arm
for X = f(_).)
3. When the compiler prints a message about a switch on a variable not covering
some cases, sometimes the variable is an anonymous variable:
The switch on V_16 does not cover ...
These anonymous variables are created by common-structure elimination,
which groups disjuncts containing unifications such as A = f(a), A = f(b),
A = f(c) into a single arm of the switch on A, A = f(V_16), with a switch
inside that on V_16.
The third part of this diff gives the context of the error in the error
switch as not being the arm for f/1 in the switch on A, but as the arm for
f(V_16) in the switch on A, thus letting users know where the anonymous
variable comes from.
doc/reference_manual.texi:
Document the new pragma.
compiler/prog_item.m:
Add the new pragma to the list of pragmas we recognize.
compiler/hlds_pred.m:
Add the new kind of predicate marker whose presence indicates
that this pragma was given for this predicate.
compiler/prog_io_pragma.m:
Parse the new pragma.
compiler/add_pragma.m:
Process the new pragma: when found, set the marker on the named
predicate.
compiler/det_report.m:
Make all three changes listed above.
In addition, fix a problem that used to happen only rarely:
when printing switch contexts, we used to print them from the inside
out, not the outside in.
Capitalize only the first clause in a multi-clause error message.
compiler/hlds_out_util.m:
Add a function for printing a cons_id either with or without its
arguments, for use by det_report.m Let this function string module
qualifiers from cons_ids, since these are virtually always obvious,
and whose printing is therefore unnecessary clutter.
compiler/equiv_type.m:
compiler/hlds_out_pred.m:
compiler/make_hlds_passes.m:
compiler/mercury_to_mercury.m:
compiler/module_qual.m:
compiler/modules.m:
compiler/recompilation.version.m:
compiler/table_gen.m:
Conform to the changes above.
tests/invalid/det_errors.{m,err_exp}:
Add some predicates to this module to test the new functionality,
and update the expected output.
143 lines
2.0 KiB
Mathematica
143 lines
2.0 KiB
Mathematica
% vim: ts=4 sw=4 et ft=mercury
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:- module det_errors.
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:- interface.
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:- pred p1(int::in) is det.
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:- pred p2(int::in) is det.
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:- pred p3(int::in) is det.
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:- pred p4(int::in) is det.
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:- pred p5(int::in) is det.
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:- type t
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---> a
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; b
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; c
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; d
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; e
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; f
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; g
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; h(int)
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; i(int).
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:- pred q(t::in, int::out) is det.
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:- type u
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---> u1
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; u2
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; u3(t)
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; u4(t).
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:- pred r(u::in, int::out) is det.
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:- pred s(u::in, int::out) is det.
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:- pred t(int::out) is det.
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:- implementation.
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:- import_module int.
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:- import_module require.
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p1(42).
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p2(X) :- X = 42.
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p3(X) :- X = 42.
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p4(X) :- X = 21 + 21.
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p5(_) :- true.
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q(a, 1).
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q(b, 2).
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q(c, 3).
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r(U, X) :-
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(
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U = u1,
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X = 11
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;
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U = u3(a),
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X = 31
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;
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U = u3(b),
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X = 32
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;
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U = u3(c),
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X = 33
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;
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U = u4(a),
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X = 41
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;
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U = u4(b),
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X = 42
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;
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U = u4(c),
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X = 43
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;
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U = u4(d),
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X = 441
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;
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U = u4(d),
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X = 442
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;
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U = u4(e),
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X = 45
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;
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U = u4(f),
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X = 46
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;
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U = u4(g),
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X = 47
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).
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s(U, X) :-
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(
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U = u1,
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X = 11
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;
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U = u3(a),
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X = 31
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;
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U = u3(b),
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X = 32
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;
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U = u3(c),
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X = 33
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;
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U = u4(V),
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(
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V = a,
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X = 41
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;
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V = b,
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X = 42
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;
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V = c,
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X = 43
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;
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V = d,
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X = 441
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;
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V = d,
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X = 442
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;
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( V = e
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; V = f
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),
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( X = 461
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; X = 462
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)
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;
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V = g,
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X = 47
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;
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( V = h(_)
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; V = i(_)
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),
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( X = 481
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; X = 482
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)
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)
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).
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:- pragma no_determinism_warning(t/1).
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t(_) :-
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error("t called").
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