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Fix off-by-one CHARCLASS validation and collapse full-domain to re.full_char

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Two bugs were biting any CHARCLASS that started at character 0:

1. The validation loop in mk_func_decl seeded prev_hi at -1, so the
   non-adjacency check 'lo <= prev_hi + 1' rejected the very first range
   whenever its low bound was 0. Now the check is guarded by have_prev
   so it never fires on the initial range.

2. mk_charclass would produce a CHARCLASS node spanning the full char
   domain instead of collapsing to re.full_char, leaving subsequent
   intersections and complements with a non-canonical full-domain shape.

The validation error now also dumps the offending ranges so
mis-construction is much easier to localise in the future.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This commit is contained in:
Margus Veanes 2026-06-14 21:57:12 -07:00
parent 292a925826
commit 23edf638b7
1 changed files with 14 additions and 3 deletions
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17
src/ast/seq_decl_plugin.cpp
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@ -505,7 +505,8 @@ func_decl* seq_decl_plugin::mk_func_decl(decl_kind k, unsigned num_parameters, p
if ((num_parameters % 2) != 0)
m.raise_exception("re.charclass expects an even number of int parameters (lo, hi pairs)");
unsigned mx = get_char_plugin().max_char();
int prev_hi = -1;
bool have_prev = false;
int prev_hi = 0;
for (unsigned i = 0; i + 1 < num_parameters; i += 2) {
if (!parameters[i].is_int() || !parameters[i + 1].is_int())
m.raise_exception("re.charclass parameters must be integers");
@ -513,9 +514,16 @@ func_decl* seq_decl_plugin::mk_func_decl(decl_kind k, unsigned num_parameters, p
int hi = parameters[i + 1].get_int();
if (lo < 0 || hi < 0 || lo > hi || static_cast<unsigned>(hi) > mx)
m.raise_exception("re.charclass range out of character domain");
if (lo <= prev_hi + 1)
m.raise_exception("re.charclass ranges must be sorted, disjoint, and non-adjacent");
if (have_prev && lo <= prev_hi + 1) {
std::stringstream ss;
ss << "re.charclass ranges must be sorted, disjoint, and non-adjacent (got";
for (unsigned k = 0; k + 1 < num_parameters; k += 2)
ss << " [" << parameters[k].get_int() << "," << parameters[k + 1].get_int() << "]";
ss << ")";
m.raise_exception(ss.str().c_str());
}
prev_hi = hi;
have_prev = true;
}
if (!range) range = mk_reglan();
return m.mk_func_decl(m_sigs[k]->m_name, arity, domain, range,
@ -1169,6 +1177,9 @@ app* seq_util::rex::mk_charclass(seq::range_predicate const& p, sort* seq_sort)
if (p.is_empty())
return mk_empty(re_sort);
unsigned n = p.num_ranges();
unsigned mx = u.max_char();
if (n == 1 && p[0].first == 0 && p[0].second == mx)
return mk_full_char(re_sort);
vector<parameter> params;
for (unsigned i = 0; i < n; ++i) {
auto r = p[i];