Bug 40106: Improve error message in case of deep recursion in variable definition

    ref $_[0] eq 'ARRAY' ? join '/', @{$_[0]} : $_[0];

}

sub error_many_lookups {

    my ($project, $name_str, $lookups_count) = @_;

    my $errmsg = "High number of config lookups for option $name_str" .

                 " in project $project.\n" .

                 "This may indicate a loop in the definition of $name_str.\n\n" .

                 "Most requested options, possibly part of the loop, are:\n";

    my @opts = sort {

        $lookups_count->{$b} cmp $lookups_count->{$a}

    } keys %$lookups_count;

    foreach my $opt (@opts[0 .. 9]) {

        last unless $lookups_count->{$opt};

        $errmsg .= " - $opt ($lookups_count->{$opt})\n";

    }

    exit_error($errmsg);

}

sub project_config {

    my ($project, $name, $options) = @_;

    $used_projects{$project} = 1 if $store_used_projects;

    CORE::state %config_cache;

    CORE::state %lookups_count;

    my $res;

    my $error_if_undef = $options->{error_if_undef};

    $options = {%$options, error_if_undef => 0} if $options;

    my $cache_id = pp($config->{run})

                        . pp({ %{$config->{opt}}, $options ? %$options : () });

    my $name_str = ref $name eq 'ARRAY' ? join '/', @$name : $name;

    error_many_lookups($project, $name_str, $lookups_count{$project})

        if (++$lookups_count{$project}{$name_str} > 500);

    my $step = $config->{step};

    if (exists $config_cache{$project}{$step}{$name_str}{$cache_id}) {

        $res = $config_cache{$project}{$step}{$name_str}{$cache_id};

    $config_cache{$project}{$step}{$name_str}{$cache_id} = $res;

    $config->{opt} = $opt_save;

    FINISH:

    --$lookups_count{$project}{$name_str};

    if (!defined($res) && $error_if_undef) {

        my $msg = $error_if_undef eq '1' ?

                "Option " . confkey_str($name) . " is undefined"