[ARROW-13154] [C++] Unions can not have 126 and 127 as type_codes

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 5.0.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/28854
• Assignee: Ian Alexander Joiner
• Reporter: Ian Alexander Joiner
• Created: 23/Jun/21 22:57
• Updated: 11/Jan/23 08:31
• Resolved: 28/Jun/21 08:43

Description

Due to the following in builder_union.cc (Line 67-70)
 

type_id_to_children_.resize(union_type.max_type_code() + 1, nullptr);
 DCHECK_LT(
 type_id_to_children_.size(),
 static_cast<decltype(type_id_to_children_)::size_type>(UnionType::kMaxTypeCode));

and type.cc (Line 640-644)

uint8_t UnionType::max_type_code() const {
 return type_codes_.size() == 0
 ? 0
 : *std::max_element(type_codes_.begin(), type_codes_.end());
 }

 
In practice type codes of the union type must always be below or equal to 125 which is not intended behavior.

Issue Links

• links to: GitHub Pull Request #10599