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update well_sorted to check patterns, fix variable shift in pattern inference

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This commit is contained in:
Nikolaj Bjorner 2026-07-06 16:57:52 -07:00
parent 470e966791
commit 5534dba680
2 changed files with 22 additions and 11 deletions
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29
src/ast/pattern/pattern_inference.cpp
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@ -42,9 +42,7 @@ bool smaller_pattern::process(expr * p1, expr * p2) {
m_cache.reset();
save(p1, p2);
while (!m_todo.empty()) {
expr_pair & curr = m_todo.back();
p1 = curr.first;
p2 = curr.second;
auto [p1, p2] = m_todo.back();
m_todo.pop_back();
ast_kind k1 = p1->get_kind();
if (k1 != AST_VAR && k1 != p2->get_kind())
@ -126,9 +124,7 @@ void pattern_inference_cfg::collect::operator()(expr * n, unsigned num_bindings)
m_num_bindings = num_bindings;
m_todo.push_back(entry(n, 0));
while (!m_todo.empty()) {
entry & e = m_todo.back();
n = e.m_node;
unsigned delta = e.m_delta;
entry [n, delta] = m_todo.back();
TRACE(collect, tout << "processing: " << n->get_id() << " " << delta << " kind: " << n->get_kind() << "\n";);
TRACE(collect_info, tout << mk_pp(n, m) << "\n";);
if (visit_children(n, delta)) {
@ -264,11 +260,24 @@ void pattern_inference_cfg::collect::save_candidate(expr * n, unsigned delta) {
return;
}
// The lambda/quantifier itself is a valid sub-term in a pattern.
// Propagate the free variables from the body (they already refer
// to the outer quantifier's bindings) and keep the node as-is.
expr * new_body = body_info->m_node.get();
// body_info->m_node was normalized into the *outer* quantifier's de
// Bruijn space (the enclosing binders, including this lambda's own
// num_decls binders, were stripped). Re-wrapping it under the lambda
// therefore requires shifting the (outer) free variables back up by
// num_decls so they do not collide with the lambda's bound variables.
// The lambda's own bound variables never occur in body_info (any
// sub-term referring to them was rejected as a candidate), so the
// shift is always sound.
expr * body = body_info->m_node.get();
expr_ref new_body(m);
if (num_decls > 0) {
var_shifter shift(m);
shift(body, num_decls, new_body);
}
else
new_body = body;
quantifier_ref new_q(m);
if (new_body != q->get_expr())
if (new_body.get() != q->get_expr())
new_q = m.update_quantifier(q, new_body);
else
new_q = q;