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Derived by the wrong "leading character"

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CEisenhofer 2026-06-09 16:56:05 +02:00
parent 7a909aedb7
commit 89a2ac133f
1 changed files with 5 additions and 2 deletions
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7
src/smt/theory_nseq.cpp
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@ -463,8 +463,11 @@ namespace smt {
euf::snode* re_node = mem.m_regex;
euf::snode* str_node = mem.m_str;
do {
// eliminate leading character by derivatives
re_node = m_sgraph.brzozowski_deriv(re_node, mem.m_str->first());
// eliminate leading character by derivatives; derive by the
// CURRENT leading char (str_node->first()), not the original
// mem.m_str->first() — otherwise a multi-char prefix is derived
// by its first char repeatedly (unsound).
re_node = m_sgraph.brzozowski_deriv(re_node, str_node->first());
str_node = m_sgraph.drop_first(str_node);
} while (!str_node->is_empty() && str_node->first()->is_char());