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sbacc: fix a serious bug

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Reported by Thibaud Michaud

* spot/twaalgos/sbacc.cc: Do not label rejecting SCCs with the empty
mark, as it might be accepting.
* tests/core/sbacc.test: Add test cases.
* NEWS: Mention the bug.
This commit is contained in:
Alexandre Duret-Lutz 2017-04-19 18:46:35 +02:00
parent cb920242a7
commit 9377db2e5e
3 changed files with 86 additions and 1 deletions
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17
spot/twaalgos/sbacc.cc
View file

@ -22,6 +22,7 @@
#include <utility>
#include <spot/twaalgos/sbacc.hh>
#include <spot/twaalgos/sccinfo.hh>
#include <spot/twaalgos/stripacc.hh>
namespace spot
{
@ -33,6 +34,18 @@ namespace spot
throw std::runtime_error
("sbacc() does not support alternation");
// We will need a mark that is rejecting to mark rejecting states.
// If no such mark exist, our work is actually quite simple: we
// just have to copy the automaton and give it "t" as acceptance
// condition.
auto unsat_mark = old->acc().unsat_mark();
if (!unsat_mark.first)
{
auto res = make_twa_graph(old, twa::prop_set::all());
strip_acceptance_here(res);
return res;
}
scc_info si(old);
unsigned ns = old->num_states();
@ -97,7 +110,7 @@ namespace spot
{
unsigned scc_dst = si.scc_of(t.dst);
acc_cond::mark_t acc = 0U;
bool dst_acc = si.is_accepting_scc(scc_dst);
bool dst_acc = !si.is_rejecting_scc(scc_dst);
if (maybe_accepting && scc_src == scc_dst)
acc = t.acc - common_out[t.src];
else if (dst_acc)
@ -106,6 +119,8 @@ namespace spot
acc = one_in[t.dst];
if (dst_acc)
acc |= common_out[t.dst];
else
acc = unsat_mark.second;
res->new_edge(one.second, new_state(t.dst, acc),
t.cond, one.first.second);
}