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9ed0d90e10
compiler/deforest.m:
Don't push goals that may have output variables into semidet conjunctions,
since that turns them into nondet conjunctions, leading to determinism
errors.
tests/hard_coded/bug392.{m,exp}:
A tougher version of the mantis test case.
tests/hard_coded/Mmakefile:
tests/hard_coded/Mercury.options:
Enable the new test case, and run it with the options that used to
tickle the bug.
70 lines
1.2 KiB
Mathematica
70 lines
1.2 KiB
Mathematica
% vim: ts=4 sw=4 et ft=mercury
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%
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% This is a regression test. When we invoked the compiler on this file
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% with the command line
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%
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% mmc -O0 --deforestation -C bug392.m
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%
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% we used to get this error:
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%
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% Uncaught Mercury exception:
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% Software Error: ll_backend.code_gen:
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% predicate `ll_backend.code_gen.generate_goal'/5:
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% Unexpected: nondet model in det/semidet context
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%
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% The problem was in quux. Pushing the switch on R into the initial disjunction
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% gave it an output variable (Q), turning it from a semidet disjunction into
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% a nondet disjunction.
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:- module bug392.
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:- interface.
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:- import_module io.
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:- pred main(io::di, io::uo) is det.
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:- implementation.
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:- import_module bool.
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:- import_module maybe.
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main(!IO) :-
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foo(yes, Xyes),
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io.write_int(Xyes, !IO),
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io.nl(!IO),
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foo(no, Xno),
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io.write_int(Xno, !IO),
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io.nl(!IO).
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:- pred foo(bool, int).
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:- mode foo(in, out) is det.
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foo(B, X) :-
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bar(X0),
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( if quux(B, no, X1) then
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X = X1
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else
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X = X0
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).
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:- pred bar(int).
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:- mode bar(out) is det.
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bar(42).
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:- pred quux(bool, maybe(int), int).
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:- mode quux(in, in, out) is semidet.
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quux(B, R, Q) :-
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(
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B = yes
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;
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R = yes(_)
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),
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(
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R = yes(Q)
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;
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R = no,
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Q = 55
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).
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