Wrong file:line reported by caller during global destruction

[KES777]

Context

PERLDB_OPTS="white_box" PERL5DB="use DB::Hooks qw'::Terminal ::TraceVariable NonStop'" perl -d $(which morbo) -w /home/kes/work/projects/modal_window/app/public/invoice/api-v1.yaml \
-w lib/ -w templates/ -w etc/ -w ext/ /home/kes/work/projects/modal_window/app/script/invoice
Use of uninitialized value $_[1] in string ne at /home/kes/work/projects/modal_window/app/local/lib/perl5/DB/Hooks.pm line 196.
Use of uninitialized value $_[1] in string ne at /home/kes/work/projects/modal_window/app/local/lib/perl5/DB/Hooks.pm line 196.
Web application available at http://127.0.0.1:3000
^C

Dumping new frames SUB:Syntax::SourceHighlight::DESTROY 
main - /home/kes/work/projects/modal_window/app/local/bin/morbo - 0 - DB::__ANON__[/home/kes/work/projects/modal_window/app/local/lib/perl5/DB/Hooks.pm:615]
main - /home/kes/work/projects/modal_window/app/local/bin/morbo - 0 - (eval)
	(in cleanup) Modification of non-creatable array value attempted, subscript -1 at /home/kes/work/projects/modal_window/app/local/lib/perl5/DB/Hooks.pm line 196 during global destruction.


Dumping new frames SUB:Syntax::SourceHighlight::LangMap::DESTROY 
main - /home/kes/work/projects/modal_window/app/local/bin/morbo - 0 - DB::__ANON__[/home/kes/work/projects/modal_window/app/local/lib/perl5/DB/Hooks.pm:615]
main - /home/kes/work/projects/modal_window/app/local/bin/morbo - 0 - (eval)
	(in cleanup) Modification of non-creatable array value attempted, subscript -1 at /home/kes/work/projects/modal_window/app/local/lib/perl5/DB/Hooks.pm line 196 during global destruction.


Dumping new frames SUB:Syntax::SourceHighlight::DESTROY 
main - /home/kes/work/projects/modal_window/app/local/bin/morbo - 0 - DB::__ANON__[/home/kes/work/projects/modal_window/app/local/lib/perl5/DB/Hooks.pm:615]
main - /home/kes/work/projects/modal_window/app/local/bin/morbo - 0 - (eval)
	(in cleanup) Modification of non-creatable array value attempted, subscript -1 at /home/kes/work/projects/modal_window/app/local/lib/perl5/DB/Hooks.pm line 196 during global destruction.


Dumping new frames SUB:Syntax::SourceHighlight::LangMap::DESTROY 
main - /home/kes/work/projects/modal_window/app/local/bin/morbo - 0 - DB::__ANON__[/home/kes/work/projects/modal_window/app/local/lib/perl5/DB/Hooks.pm:615]
main - /home/kes/work/projects/modal_window/app/local/bin/morbo - 0 - (eval)
	(in cleanup) Modification of non-creatable array value attempted, subscript -1 at /home/kes/work/projects/modal_window/app/local/lib/perl5/DB/Hooks.pm line 196 during global destruction.

DB/Hooks.pm
...
sub sub {
DB::state( 'ddd' ); <<< here is line 615
...
sub dbstate {
my( $name, $value ) = @;
return @>1 ? $DB::state[-1]{ ddd } = $value : $DB::state[-1]{ ddd } // 0
if $name eq 'ddd';

Description
I am using Syntax::SourceHighlight to highlight code at my debugger. This module is loaded from my debugger like this:

package DB::Commands;
...
my $hl;  << I expect to see these package lines when `caller` dumps frames when `DESTROY` sub is called
my $lm;  <<
sub highlighting {
    require Syntax::SourceHighlight;

    $hl = Syntax::SourceHighlight->new('esc.outlang');
    $lm = Syntax::SourceHighlight::LangMap->new();
    $hl->setStyleFile('esc256.style');

    return 1;
}

my $highlight     =  $is_exists && !$ENV{ DEBUGGER_NO_COLOR } ? highlighting() : 0;

I do not see DESTROY subs at Syntax::SourceHighlight or Syntax::SourceHighlight::LangMap files.

Because these modules are loaded before debugger they are destroyed later, after debugger. Stack looks like this:

Syntax::* are loaded
debugger is loaded
... body of a debugged script
debugger is destroyed   << error happened somewhere here, I assume.
Syntax::* are destroyed

During destruction at DB::state sub when I perl tries to run $DB::state[-1] code, the @DB::state array does not exists already (or empty?). And error is occurred.

I dumped from DB::state frames to check from which part of code this call was done

my $lvl;
my $count //=  -1; # infinite

my @frames;
local $" =  ' - ';
while( $count--  &&  (my @frame =  caller( ++$lvl )) ) {
	push @frames, [ @frame[0..3] ];
}

print $DB::OUT "\n\nDumping new frames SUB:$_[2] \n";
print $DB::OUT "@$_\n"   for @frames;

I found this line:

main - /home/kes/work/projects/modal_window/app/local/bin/morbo - 0 - (eval)

We see this, because perl adds debuger loading into the source of the debugged script as use DB::Hooks.... as line 0.

It looks like it makes sense, because everything should be destroyed when program is finished, but
$hm and $lm are not located at the main script, but these variables actually are located at DB::Commands module. So I expect to see path to DB::Commands package and line where $hm, $lm were defined.

Steps to Reproduce
None. You do not have sources for this debugger. By I tried to describe in details what is going on here.

Expected behavior
When DESTROY is called caller should dump package:line from where these objects were destroyed, or, as another solution, where they were created: $hl = ->new() and $lm = ->new()` lines.

Perl configuration

Summary of my perl5 (revision 5 version 41 subversion 2) configuration:
   
  Platform:
    osname=linux
    osvers=6.5.0-1027-oem
    archname=x86_64-linux
    uname='linux work 6.5.0-1027-oem #28-ubuntu smp preempt_dynamic thu jul 25 13:32:46 utc 2024 x86_64 x86_64 x86_64 gnulinux '
    config_args='-de -Dprefix=/home/kes/perl5/perlbrew/perls/perl-5.41.2 -Dusedevel -Aeval:scriptdir=/home/kes/perl5/perlbrew/perls/perl-5.41.2/bin'
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=undef
    usemultiplicity=undef
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
  Compiler:
    cc='cc'
    ccflags ='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
    optimize='-O2'
    cppflags='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion=''
    gccversion='13.1.0'
    gccosandvers=''
    intsize=4
    longsize=8
    ptrsize=8
    doublesize=8
    byteorder=12345678
    doublekind=3
    d_longlong=define
    longlongsize=8
    d_longdbl=define
    longdblsize=16
    longdblkind=3
    ivtype='long'
    ivsize=8
    nvtype='double'
    nvsize=8
    Off_t='off_t'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='cc'
    ldflags =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/x86_64-linux-gnu /usr/lib /usr/lib64
    libs=-lpthread -ldl -lm -lcrypt -lutil -lc
    perllibs=-lpthread -ldl -lm -lcrypt -lutil -lc
    libc=/lib/x86_64-linux-gnu/libc.so.6
    so=so
    useshrplib=false
    libperl=libperl.a
    gnulibc_version='2.35'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=so
    d_dlsymun=undef
    ccdlflags='-Wl,-E'
    cccdlflags='-fPIC'
    lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'


Characteristics of this binary (from libperl): 
  Compile-time options:
    HAS_LONG_DOUBLE
    HAS_STRTOLD
    HAS_TIMES
    PERLIO_LAYERS
    PERL_COPY_ON_WRITE
    PERL_DONT_CREATE_GVSV
    PERL_HASH_FUNC_SIPHASH13
    PERL_HASH_USE_SBOX32
    PERL_MALLOC_WRAP
    PERL_OP_PARENT
    PERL_PRESERVE_IVUV
    PERL_USE_DEVEL
    PERL_USE_SAFE_PUTENV
    USE_64_BIT_ALL
    USE_64_BIT_INT
    USE_LARGE_FILES
    USE_LOCALE
    USE_LOCALE_COLLATE
    USE_LOCALE_CTYPE
    USE_LOCALE_NUMERIC
    USE_LOCALE_TIME
    USE_PERLIO
    USE_PERL_ATOF
  Built under linux
  Compiled at Aug 17 2024 19:35:18
  %ENV:
    PERLBREW="command perlbrew"
    PERLBREW_HOME="/home/kes/.perlbrew"
    PERLBREW_MANPATH="/home/kes/perl5/perlbrew/perls/perl-5.41.2/man"
    PERLBREW_PATH="/home/kes/perl5/perlbrew/bin:/home/kes/perl5/perlbrew/perls/perl-5.41.2/bin"
    PERLBREW_PERL="perl-5.41.2"
    PERLBREW_ROOT="/home/kes/perl5/perlbrew"
    PERLBREW_SHELLRC_VERSION="0.98"
    PERLBREW_VERSION="0.98"
  @INC:
    /home/kes/perl5/perlbrew/perls/perl-5.41.2/lib/site_perl/5.41.2/x86_64-linux
    /home/kes/perl5/perlbrew/perls/perl-5.41.2/lib/site_perl/5.41.2
    /home/kes/perl5/perlbrew/perls/perl-5.41.2/lib/5.41.2/x86_64-linux
    /home/kes/perl5/perlbrew/perls/perl-5.41.2/lib/5.41.2

[jkeenan]

If, as you acknowledge, no one will be able to reproduce this bug, can you provide us with a reduced example which we will be able to reproduce?

[KES777]

@jkeenan
Yes, I could try.

But before that, what are thinking what file:line should be reported when DESTROY is called for the object?

[tonycoz]

From what I can see global destruction is done with PL_curcop pointing at PL_compiling, which due to the way the values get saved as we recurse during compilation I expect will be set to the script name and line 0.

So the caller you're seeing here seems reasonable.

Note that there's no code in your DB::Commands package doing the destruction, that's being done by perl in perl_destruct.

If you do want DB::Commands in the backtrace you could add END { undef $hl; } to DB/Commands.pm.