[perl #56184] [BUG] more lexical failures

[Patrick R. Michaud]

I'm attaching this bug report to an existing ticket (RT#56184) because 
I believe they are in fact the same problem.  But I think this
description may make the problem more clear.

Summary:  Lexical access from immediate blocks in closures don't work.

Consider the following Perl 6 code:

    sub foo() {
        my $a = 'hello';
        my sub bar($b) { say $a, $b; { say $a, $b; } }
        return &bar;
    }

    my $x = foo();
    $x('world');

The C<foo> sub returns a C<bar> closure that is then invoked
from main.  Within C<bar> there is an immediate block, and this
is where lexicals don't work.

Here's a PIR translation of the above Perl 6:

    .sub 'main' :main
        .local pmc x
        x = 'foo'()
        x('world')
    .end
    
    .sub 'foo' :outer('main')
        .local pmc a, bar
        a = new 'String'
        a = 'hello '
        .lex '$a', a
        $P0 = get_global 'bar'
        bar = newclosure $P0
        .return (bar)
    .end
    
    .sub 'bar' :outer('foo')
        .param pmc b
        .lex '$b', b
        .local pmc a
        a = find_lex '$a'
        print a
        say b
        'bar_inner'()
    .end
    
    .sub 'bar_inner' :outer('bar')
        .local pmc a, b
        a = find_lex '$a'
        b = find_lex '$b'
        print a
        say b
    .end

When run, Parrot r28767 produces the following:

    $ ./parrot lex3.pir
    hello world
    hello Null PMC access in get_string()
    current instr.: 'bar_inner' pc -86686 ((unknown file):-1)
    called from Sub 'bar_inner' pc 85 (lex3.pir:43)
    called from Sub 'bar' pc 63 (lex3.pir:34)
    called from Sub 'main' pc 15 (lex3.pir:14)
    $

As you can see, the first "say $a, $b" in the closure works fine, 
but the lexical accesses in the nested immediate block do not.

Comments and suggestions welcomed.

Pm