Add GV_NOUNIVERSAL flag to skip UNIVERSAL lookup

For the `isa` infix operator, we can fall back to `sv_derived_from_sv`
instead of looking up UNIVERSAL::isa. Passing GV_NOUNIVERSAL will tell
gv_fetchmeth_internal not to look at UNIVERSAL for the method, and instead
return NULL. Then `Perl_sv_isa_sv` will skip the if block and check
`sv_derived_from_sv` which does the same thing UNIVERSAL::isa would have done.

1 files changed, 1 insertions, 4 deletions

diff --git a/universal.c b/universal.c
index b839e5151d..5932767bdf 100644
--- a/universal.c
+++ b/universal.c
@@ -216,10 +216,7 @@ Perl_sv_isa_sv(pTHX_ SV *sv, SV *namesv)
     if(!SvROK(sv) || !SvOBJECT(SvRV(sv)))
         return FALSE;
 
-    /* TODO: Consider if we want a NOUNIVERSAL flag to skip the
-     * UNIVERSAL lookup
-     */
-    isagv = gv_fetchmeth_pvn(SvSTASH(SvRV(sv)), "isa", 3, -1, 0);
+    isagv = gv_fetchmeth_pvn(SvSTASH(SvRV(sv)), "isa", 3, -1, GV_NOUNIVERSAL);
     if(isagv) {
         dSP;
         CV *isacv = isGV(isagv) ? GvCV(isagv) : (CV *)isagv;