scc_filter: do not remove Fin sets from rejecting SCCs

* src/twaalgos/sccfilter.cc (acc_filter_some, acc_filter_all): Merge
into...
(acc_filter_mask): ... this single parametrized class, and only
remove sets that are only used as Inf.
* src/twa/acc.hh: Add missing operator~.
* src/tests/sccsimpl.test: Add test case.
* src/tests/sccdot.test: Adjust.
* NEWS: Mention the bug.

NEWS

@@ -2,6 +2,8 @@ New in spot 1.99.1a (not yet released)
 
   * Bugs fixed:
     - p[+][:*2] was not detected as belonging to siPSL
+    - scc_filter() would incorrectly remove Fin marks from
+      rejecting SCCs.
 
 New in spot 1.99.1 (2015-06-23)
 

src/tests/sccdot.test

@@ -168,7 +168,7 @@ State: 2
 [0&1] 0 {0 1}
 State: 3
 [1] 1
-[!1] 3
+[!1] 3 {2}
 State: 4
 [!0&1] 4 {0 1}
 [0&1] 4 {0 2}

src/tests/sccsimpl.test

@@ -240,3 +240,105 @@ grep 'Acceptance: 2 ' out8.txt
 run 0 ../ikwiad -R3 -s -RDS -ks \
   '(G(!((b) R (a)))) R (((c) R (!(d))) U (G((a) | (!(G(e))))))' > out9.txt
 grep 'states: 6$' out9.txt
+
+
+# Spot 1.99.1 used to incorrectly remove Fin sets from rejecting SCCs
+# in scc_filter().
+cat >input <<EOF
+HOA: v1
+States: 2
+Start: 1
+Acceptance: 1 Fin(0)
+AP: 1 "p0"
+--BODY--
+State: 0
+[t] 0
+State: 1
+[!0] 1 {0}
+[0] 0
+--END--
+HOA: v1
+States: 2
+Start: 1
+Acceptance: 2 Fin(0)&Inf(1)
+AP: 1 "p0"
+--BODY--
+State: 0 {1}
+[t] 0
+State: 1
+[!0] 1 {0 1}
+[0] 0
+--END--
+EOF
+
+# run 0 ../../bin/autfilt -C -H --any --high input >output
+# cat >expected <<EOF
+# HOA: v1
+# States: 2
+# Start: 1
+# AP: 1 "p0"
+# acc-name: Buchi
+# Acceptance: 1 Inf(0)
+# properties: trans-labels explicit-labels state-acc complete
+# properties: deterministic inherently-weak
+# --BODY--
+# State: 0 {0}
+# [t] 0
+# State: 1
+# [0] 0
+# [!0] 1
+# --END--
+# HOA: v1
+# States: 2
+# Start: 1
+# AP: 1 "p0"
+# acc-name: Buchi
+# Acceptance: 1 Inf(0)
+# properties: trans-labels explicit-labels state-acc complete
+# properties: deterministic inherently-weak
+# --BODY--
+# State: 0 {0}
+# [t] 0
+# State: 1
+# [0] 0
+# [!0] 1
+# --END--
+# EOF
+# cat output
+# diff output expected
+
+run 0 ../../bin/autfilt -C -H --det --high input >output
+cat >expected <<EOF
+HOA: v1
+States: 2
+Start: 1
+AP: 1 "p0"
+acc-name: Buchi
+Acceptance: 1 Inf(0)
+properties: trans-labels explicit-labels state-acc complete
+properties: deterministic inherently-weak
+--BODY--
+State: 0 {0}
+[t] 0
+State: 1
+[0] 0
+[!0] 1
+--END--
+HOA: v1
+States: 2
+Start: 1
+AP: 1 "p0"
+acc-name: Buchi
+Acceptance: 1 Inf(0)
+properties: trans-labels explicit-labels state-acc complete
+properties: deterministic inherently-weak
+--BODY--
+State: 0 {0}
+[t] 0
+State: 1
+[0] 0
+[!0] 1
+--END--
+EOF
+cat output
+diff output expected

src/twa/acc.hh

@@ -157,6 +157,11 @@ namespace spot
 	return id & ~r.id;
       }
 
+      mark_t operator~() const
+      {
+	return ~id;
+      }
+
       mark_t operator^(mark_t r) const
       {
 	return id ^ r.id;

src/twaalgos/sccfilter.cc

@@ -125,14 +125,24 @@ namespace spot
     };
 
     // Remove acceptance conditions from all edges outside of
-    // non-accepting SCCs.
+    // non-accepting SCCs.  If "RemoveAll" is false, keep those on
-    template <class next_filter = id_filter>
+    // transitions entering accepting SCCs.
-    struct acc_filter_all: next_filter
+    template <bool RemoveAll, class next_filter = id_filter>
+    struct acc_filter_mask: next_filter
     {
+      acc_cond::mark_t accmask;
+
       template<typename... Args>
-      acc_filter_all(scc_info* si, Args&&... args)
+      acc_filter_mask(scc_info* si, Args&&... args)
 	: next_filter(si, std::forward<Args>(args)...)
       {
+	acc_cond::mark_t fin;
+	acc_cond::mark_t inf;
+	std::tie(inf, fin) =
+	  si->get_aut()->acc().get_acceptance().used_inf_fin_sets();
+	// If an SCC is rejecting, we can mask all the sets that are
+	// used only as Inf in the acceptance.
+	accmask = ~(inf - fin);
       }
 
       filtered_trans trans(unsigned src, unsigned dst,
@@ -144,41 +154,18 @@ namespace spot
 
 	if (keep)
 	  {
-	    unsigned u = this->si->scc_of(src);
+	    unsigned u = this->si->scc_of(dst);
 	    // If the edge is between two SCCs, or in a
 	    // non-accepting SCC.  Remove the acceptance sets.
-	    if (this->si->is_rejecting_scc(u) || u != this->si->scc_of(dst))
+	    if ((this->si->is_rejecting_scc(u))
-	      acc = 0U;
+		|| (RemoveAll && u != this->si->scc_of(src)))
+	      acc &= accmask;
 	  }
 
 	return filtered_trans(keep, cond, acc);
       }
     };
 
-    // Remove acceptance conditions from all edges whose
-    // destination is not an accepting SCCs.
-    template <class next_filter = id_filter>
-    struct acc_filter_some: next_filter
-    {
-      template<typename... Args>
-      acc_filter_some(scc_info* si, Args&&... args)
-	: next_filter(si, std::forward<Args>(args)...)
-      {
-      }
-
-      filtered_trans trans(unsigned src, unsigned dst,
-			   bdd cond, acc_cond::mark_t acc)
-      {
-	bool keep;
-	std::tie(keep, cond, acc) =
-	  this->next_filter::trans(src, dst, cond, acc);
-
-	if (this->si->is_rejecting_scc(this->si->scc_of(dst)))
-	  acc = 0U;
-	return filtered_trans(keep, cond, acc);
-      }
-    };
-
     // Simplify redundant acceptance sets used in each SCCs.
     template <class next_filter = id_filter>
     struct acc_filter_simplify: next_filter
@@ -329,22 +316,24 @@ namespace spot
     if (aut->acc().is_generalized_buchi())
       {
 	if (remove_all_useless)
-	  res = scc_filter_apply<state_filter
+	  res =
-				 <acc_filter_all
+	    scc_filter_apply<state_filter
-				  <acc_filter_simplify<>>>>(aut, given_si);
+			     <acc_filter_mask
+			      <true, acc_filter_simplify<>>>>(aut, given_si);
 	else
-	  res = scc_filter_apply<state_filter
+	  res =
-				 <acc_filter_some
+	    scc_filter_apply<state_filter
-				  <acc_filter_simplify<>>>>(aut, given_si);
+			     <acc_filter_mask
+			      <false, acc_filter_simplify<>>>>(aut, given_si);
       }
     else
       {
 	if (remove_all_useless)
 	  res = scc_filter_apply<state_filter
-				 <acc_filter_all<>>>(aut, given_si);
+				 <acc_filter_mask<true>>>(aut, given_si);
 	else
 	  res = scc_filter_apply<state_filter
-				 <acc_filter_some<>>>(aut, given_si);
+				 <acc_filter_mask<false>>>(aut, given_si);
       }
     res->merge_edges();
     res->prop_copy(aut,
@@ -365,19 +354,19 @@ namespace spot
     if (remove_all_useless)
       res = scc_filter_apply<susp_filter
 			     <state_filter
-			      <acc_filter_all
+			      <acc_filter_mask
-			       <acc_filter_simplify<>>>>>(aut, given_si,
+			       <true, acc_filter_simplify<>>>>>(aut, given_si,
-							  suspvars,
+								suspvars,
-							  ignoredvars,
+								ignoredvars,
-							  early_susp);
+								early_susp);
     else
       res = scc_filter_apply<susp_filter
 			     <state_filter
-			      <acc_filter_some
+			      <acc_filter_mask
-			       <acc_filter_simplify<>>>>>(aut, given_si,
+			       <false, acc_filter_simplify<>>>>>(aut, given_si,
-							  suspvars,
+								 suspvars,
-							  ignoredvars,
+								 ignoredvars,
-							  early_susp);
+								 early_susp);
     res->merge_edges();
     res->prop_copy(aut,
 		   { false,  // state-based acceptance is not preserved