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fix #4589

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2020-07-24 15:46:54 -07:00
parent 780346c7ca
commit e63992c8bd
3 changed files with 14 additions and 3 deletions
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4
src/ast/datatype_decl_plugin.cpp
View file

@ -679,6 +679,7 @@ namespace datatype {
bool util::is_recursive_core(sort* s) const {
obj_map<sort, status> already_found;
ptr_vector<sort> todo, subsorts;
sort* s0 = s;
todo.push_back(s);
status st;
while (!todo.empty()) {
@ -700,7 +701,8 @@ namespace datatype {
if (is_datatype(s2)) {
if (already_found.find(s2, st)) {
// type is recursive
if (st == GRAY) return true;
if (st == GRAY && s0 == s2)
return true;
}
else {
todo.push_back(s2);

7
src/ast/seq_decl_plugin.cpp
View file

@ -1285,13 +1285,18 @@ unsigned seq_util::str::min_length(expr* s) const {
unsigned seq_util::str::max_length(expr* s) const {
SASSERT(u.is_seq(s));
unsigned result = 0;
expr* s1 = nullptr, *s2 = nullptr;
expr* s1 = nullptr, *s2 = nullptr, *s3 = nullptr;
unsigned n = 0;
zstring st;
auto get_length = [&](expr* s1) {
if (is_empty(s1))
return 0u;
else if (is_unit(s1))
return 1u;
else if (is_at(s1))
return 1u;
else if (is_extract(s1, s1, s2, s3))
return (arith_util(m).is_unsigned(s3, n)) ? n : UINT_MAX;
else if (is_string(s1, st))
return st.length();
else

6
src/smt/seq_axioms.cpp
View file

@ -252,10 +252,14 @@ void seq_axioms::add_extract_suffix_axiom(expr* e, expr* s, expr* i) {
s = "" or !contains(x*s1, s)
*/
void seq_axioms::tightest_prefix(expr* s, expr* x) {
literal s_eq_emp = mk_eq_empty(s);
if (seq.str.max_length(s) <= 1) {
add_axiom(s_eq_emp, ~mk_literal(seq.str.mk_contains(x, s)));
return;
}
expr_ref s1 = m_sk.mk_first(s);
expr_ref c = m_sk.mk_last(s);
expr_ref s1c = mk_concat(s1, seq.str.mk_unit(c));
literal s_eq_emp = mk_eq_empty(s);
add_axiom(s_eq_emp, mk_seq_eq(s, s1c));
add_axiom(s_eq_emp, ~mk_literal(seq.str.mk_contains(mk_concat(x, s1), s)));
}