On Perl 5.40 and above, use the various builtin:: functions to provid…

…e those in Scalar::Util, avoiding the need for our own custom xsubs in that case

ListUtil.xs

@@ -1717,6 +1717,7 @@ CODE:
     ST(0) = boolSV((SvPOK(sv) || SvPOKp(sv)) && (SvNIOK(sv) || SvNIOKp(sv)));
     XSRETURN(1);
 
+#if !PERL_VERSION_GE(5, 40, 0)
 SV *
 blessed(sv)
     SV *sv
@@ -1820,6 +1821,8 @@ CODE:
     ST(0) = boolSV(SvROK(sv) && SvWEAKREF(sv));
     XSRETURN(1);
 
+#endif /* !PERL_VERSION_GE(5, 40, 0) */
+
 int
 readonly(sv)
     SV *sv

lib/Scalar/Util.pm

@@ -23,6 +23,19 @@ $VERSION =~ tr/_//d;
 require List::Util; # List::Util loads the XS
 List::Util->VERSION( $VERSION ); # Ensure we got the right XS version (RT#100863)
 
+if( $] >= 5.040 ) {
+  # On Perl 5.40 and above, these builtins are stable, so we can use them
+  # instead of our own XS implementation
+
+  # Using this instead of a globref means we don't create an empty
+  # "builtins::" glob on older perls
+  no strict 'refs';
+  my $builtins = \%{"builtin::"};
+
+  *$_ = \&{ $builtins->{$_} } for (qw( blessed refaddr reftype weaken unweaken ));
+  *isweak = \&{ $builtins->{is_weak} };  # renamed
+}
+
 # populating @EXPORT_FAIL is done in the XS code
 sub export_fail {
   if (grep { /^isvstring$/ } @_ ) {