Support local *$globref dynamic typeglob localization

[fglock]

Summary

PerlOnJava cannot compile the valid Perl construct local *$globref, where a typeglob is selected through a scalar glob reference. This blocks Test::Spec v0.54 because Test::Trap::Builder::TempFile uses this construct to temporarily replace an output glob.

CPAN evidence

Archived CPAN random tester run: 20260908-125510-82561

Distribution: Test-Spec v0.54

The upstream suite passes under system Perl:

• 19 test programs
• 171 tests passed
• 2 author-only test programs skipped

PerlOnJava fails 23/23 executed subtests across 17/19 test programs. The failures occur while loading the dependency Test::Trap::Builder::TempFile, before most Test::Spec tests can run.

Representative diagnostic:

Unsupported local operand: OperatorNode

The CPAN run reports the source location as the local *$globref statement in Test::Trap::Builder::TempFile.pm.

Minimal reproduction

With Test::Trap available in PERL5LIB, this succeeds under system Perl:

perl -MTest::Trap::Builder::TempFile -e 1

Both PerlOnJava backends fail deterministically:

./jperl -MTest::Trap::Builder::TempFile -e 1
./jperl --interpreter -MTest::Trap::Builder::TempFile -e 1

Both produce the same Unsupported local operand: OperatorNode diagnostic. The failure is pure Perl and does not require XS, a service, a display, or network access.

Triggering code

Test::Trap::Builder::TempFile contains the following pattern:

my ($name, $fileno, $globref) = @_;
local *$globref;
{
    no warnings 'io';
    local ($!, $^E);
    open *$globref, '>>', $file;
}

The glob reference is then used for PerlIO::get_layers, binmode, and autoflush operations.

Root cause

PerlOnJava has partial typeglob localization support, but the supported AST shapes do not include a glob dereference whose operand is a scalar variable:

• Named local *FH is handled by the JVM emitter and bytecode compiler.
• Dynamic local *{expr} is handled by the bytecode compiler when the * operand contains a BlockNode.
• local *$globref parses as local applied to a * OperatorNode whose operand is the $globref OperatorNode.

The bytecode compiler's local handling accepts the named-identifier and block-expression forms, then falls through to its generic error path and raises Unsupported local operand for this shape. The JVM emitter similarly recognizes only a * operand containing an IdentifierNode; the glob-reference form is not emitted as a dynamic glob localization operation.

The implementation needs to resolve the runtime RuntimeGlob represented by the glob reference and pass it through the existing local-glob save/restore machinery. The behavior must preserve the complete glob, including its IO slot, and restore it when the dynamic scope exits. The subsequent open *$globref, binmode *$globref, and method calls must operate on the localized glob.

Expected behavior

local *$globref should compile and run on both JVM and interpreter backends with Perl-compatible dynamic scoping. After the scope exits, the original glob and its IO state should be restored.

Regression coverage

Add a project-owned focused unit test covering at least:

1. A scalar containing a glob reference.
2. local *$globref inside a dynamic scope.
3. Opening or assigning through *$globref inside that scope.
4. Restoration of the original glob after scope exit.
5. JVM and interpreter backend success.

Test-Spec v0.54 should then be rerun as integration coverage.