DBI shim leaves non-JDBC statements inactive and recurses on fallback dispatch

Start in the non-JDBC branch of DBI::execute in src/main/perl/lib/DBI.pm, then read DBI::fetchall_arrayref, DBI::disconnect and _dispatch_implementor_method. Reproduce by running t/dbi.t from SQL-Interp-1.28 with its t/lib/DBD/Mock.pm on PERL5LIB. Done means successful SELECTs are fetchable, Active and ActiveKids counts stay correct, a missing implementor method does not recurse, and a new regression test using a small non-JDBC driver passes on system Perl and both PerlOnJava backends.

Summary

The SQL-Interp 1.28 test suite fails under PerlOnJava when DBIx::Interp wraps a DBI handle backed by the pure-Perl DBD::Mock test driver. The test failures expose two problems in the bundled DBI shim's non-JDBC implementor path: successful execute calls do not mark result statements active, and fallback method resolution can redispatch to DBI's own wrapper instead of reaching a driver implementation.

Reproduction

Run SQL-Interp-1.28's t/dbi.t with the distribution's t/lib/DBD/Mock.pm on PERL5LIB. The test connects to DBI:Mock:, creates a DBIx::Interp wrapper, executes SELECT statements, then reads fetched rows and the mock driver's statement history.

On PerlOnJava, the initial failure is:

Failed test 'selectall_arrayref'
  $got = undef
  $expected = ARRAY(...)

Related fetchall_arrayref assertions and checks of generated SQL / bound parameters also fail. During teardown, the test emits:

Deep recursion on subroutine "DBI::_dispatch_implementor_method"

Evidence

• CPAN run 20261013-145839-84917; target DBIx::Interp, distribution SQL-Interp-1.28.
• System Perl 5.42.2: all five test programs pass, 184/184 tests.
• PerlOnJava 5.44.1, Java 24.0.2, macOS arm64: the archived JVM run fails 16 assertions in t/dbi.t; the other four test programs pass. Re-running t/dbi.t with the archived executable reproduces the same 16 failures on the interpreter backend.
• The test driver is in the distribution's own t/lib; SQL-Interp itself is pure Perl and has no native dependency involved in this failure.
• The tested distribution's .perlonjava-cpan-perl5lib overlay file is empty, so no dependency blib shadows the bundled DBI module.
• Duplicate searches for DBD::Mock active-state handling and _dispatch_implementor_method found no matching issue.

Root cause

The failing result-set reads trace to the non-JDBC branch of DBI::execute in the bundled src/main/perl/lib/DBI.pm. That branch dispatches execute to the implementor and populates statement metadata, but it does not update sth->{Active} or the parent's ActiveKids. The bundled DBI::fetchall_arrayref checks sth->{Active} and returns undef when it remains false, so successful DBD::Mock SELECT executions appear to have no rows.

The later recursion is another failure in non-JDBC dispatch. DBI::disconnect sends non-JDBC handles to _dispatch_implementor_method; when the implementor has no concrete disconnect method, can() can resolve an inherited DBI dispatch wrapper, which calls _dispatch_implementor_method again. This test reaches that path during cleanup.

Proposed fix

Bring non-JDBC handle bookkeeping in DBI::execute in line with the existing JDBC path: after a successful implementor call, mark result-returning statements active and update ActiveKids, while keeping DML statements inactive and avoiding double-counting. Adjust implementor method resolution so it does not select a DBI dispatch wrapper as the driver's implementation when the method is absent from the concrete implementor; either dispatch to the actual driver method or report the missing method without recursing.

Add project-owned DBI regression coverage using a small non-JDBC implementor/test driver. Cover successful SELECT execution followed by fetchall_arrayref, repeated execute/finish state transitions, and cleanup where the driver inherits but does not implement disconnect. Validate the regression on system Perl first, then both PerlOnJava backends, and rerun SQL-Interp-1.28's focused test.

Acceptance criteria

• Successful non-JDBC SELECT execution makes its statement fetchable through fetchall_arrayref on both PerlOnJava backends.
• Active statement counts remain correct across finish, repeated execution, and non-result statements.
• Missing implementor methods do not recurse through DBI's own dispatch wrappers.
• The focused DBI regression and SQL-Interp-1.28 test suite pass on both PerlOnJava backends; system Perl remains green.