Fix (and test) module listing in the debugger

This was also broken when 'use strict' was added.

3 files changed, 29 insertions, 3 deletions

diff --git a/lib/perl5db.pl b/lib/perl5db.pl
index b692f6f216..6e08d59883 100644
--- a/lib/perl5db.pl
+++ b/lib/perl5db.pl
@@ -7202,8 +7202,9 @@ sub list_modules {    # versions
 
         # If the package has a $VERSION package global (as all good packages
         # should!) decode it and save as partial message.
-        if ( defined ${ $_ . '::VERSION' } ) {
-            $version{$file} = "${ $_ . '::VERSION' } from ";
+        my $pkg_version = do { no strict 'refs'; ${ $_ . '::VERSION' } };
+        if ( defined $pkg_version ) {
+            $version{$file} = "$pkg_version from ";
         }
 
         # Finish up the message with the file the package came from.
diff --git a/lib/perl5db.t b/lib/perl5db.t
index 634288cac6..7cca75c59f 100644
--- a/lib/perl5db.t
+++ b/lib/perl5db.t
@@ -28,7 +28,7 @@ BEGIN {
     }
 }
 
-plan(31);
+plan(32);
 
 my $rc_filename = '.perldb';
 
@@ -831,6 +831,25 @@ package main;
     );
 }
 
+# Test for 'M' (module list).
+{
+    my $wrapper = DebugWrap->new(
+        {
+            cmds =>
+            [
+                'M',
+                'q',
+            ],
+            prog => '../lib/perl5db/t/load-modules'
+        }
+    );
+
+    $wrapper->contents_like(
+        qr[Scalar/Util\.pm],
+        'M (module list) works fine',
+    );
+}
+
 END {
     1 while unlink ($rc_filename, $out_fn);
 }
diff --git a/lib/perl5db/t/load-modules b/lib/perl5db/t/load-modules
new file mode 100644
index 0000000000..202326357c
--- /dev/null
+++ b/lib/perl5db/t/load-modules
@@ -0,0 +1,6 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Scalar::Util;