The following works for me:

foreach (@{ $DBI::EXPORT_TAGS{sql_types} }) {
  my $ref = \&{"DBI::$_"};
  printf "%s=%d\n", $_, &$ref;
}
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It is documented in strict:

There is one exception to this rule:

                 $bar = \&{’foo’};
                 &$bar;

             is allowed so that "goto &$AUTOLOAD" would not break unde
+r stricture.
[download]

Hth,