use strict;

my $ParseErrorFh;

BEGIN {
    open(my $olderr, '>&STDERR') or die "Cannot dup STDERR: $!";
    close STDERR or die "Cannot close STDERR: $!";
    open(STDERR, '+>', undef) or die "Cannot open anonymous file: $!";
    select STDERR; $| = 1;

    open($ParseErrorFh, '>&STDERR') or die "Cannot dup anonymous file:
+ $!";

    require Parse::RecDescent;

    close STDERR or die "Cannot close STDERR: $!";
    open(STDERR, '>&', $olderr) or die "Cannot restore STDERR: $!";
}

sub parse {
    my ($grammar, $str) = @_;

    local $::RD_ERROR = 1;
    local $::RD_WARN = 2;

    seek($ParseErrorFh, 0, 0);

    my $p = Parse::RecDescent->new($grammar)
        or die "Grammar is invalid";

    my $x = $p->start($str);

    if (not defined $x) {
        seek($ParseErrorFh, 0, 0);
        die join '', grep { $_ !~ m/^\s*$/ } <$ParseErrorFh>;
    }

    return $x;
}

print parse('start: /foo/ | <error>', 'fo'), "\n";
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Running this you will get the output

$ perl rectest.pl
        ERROR (line 1): Invalid start: Was expecting /foo/
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Now, if you change require at line 13 to use,

$ perl rectest2.pl

       ERROR (line 1): Invalid start: Was expecting /foo/
Died at recdescent.pl line 34.
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Here, the first two lines are printed to STDERR, while the last one indicates that nothing is captured in the dup'd filehandle. Regardless of what the documentation says about use being equivalent to require Module; import Module;, this example shows that it is not the case this time.