PP: Better declared but undef scalar detection

lib/Package/Stash/PP.pm

@@ -250,6 +250,14 @@ sub has_symbol {
     if (reftype($entry_ref) eq 'GLOB') {
         if ($type eq 'SCALAR') {
             if (BROKEN_SCALAR_INITIALIZATION) {
+                {
+                    my $package = $self->name;
+
+                    # Turning off warnings does not silence this, so intercept it instead.
+                    local $SIG{__WARN__} = sub {1};
+                    return 1 if eval "package $package; my \$y = ${sigil}${name}; 1";
+                }
+
                 return defined ${ *{$entry_ref}{$type} };
             }
             else {

t/pp_imported_scalars.t

@@ -0,0 +1,22 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use Test::More;
+
+BEGIN { $Package::Stash::IMPLEMENTATION = 'PP' }
+
+use Package::Stash;
+
+{
+    package Foo::Test::Scalar;
+    use vars qw/$xyz/;
+
+    sub xyz { 1 };
+    sub abc { 1 };
+}
+
+my $ps = Package::Stash->new('Foo::Test::Scalar');
+Test::More::ok($ps->has_symbol('$xyz'), "Found imported scalar, even though it is undef.");
+Test::More::ok(!$ps->has_symbol('$abc'), "did not find undeclared scalar");
+
+done_testing;