`ResultSet::getString()` throws `std::bad_alloc` with IBM Db2 CLI unless `getStringLength()` is called first.

[nemesysolano]

Summary

ResultSet::getString() throws std::bad_alloc when retrieving a string column through the IBM Db2 CLI/ODBC driver from C++ programs compiled with clang or g++ with -std=c++23 flag.

Calling ResultSet::getStringLength() for the same column immediately before getString() makes the retrieval succeed.

The query itself works correctly through isql, so the Db2 datasource, authentication, SQL statement, and IBM CLI/ODBC driver are functional.

Environment

• OS: Ubuntu 22.04
• Compiler: clang++ 18
• C++ standard: C++23
• Driver manager: unixODBC
• Database: IBM Db2 LUW
• Db2 driver: IBM Data Server Driver for ODBC and CLI
• Driver library: libdb2.so
• Wrapper: odbc-cpp-wrapper