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, 1 deletions

diff --git a/gv.c b/gv.c
index 861f65c237..4660003a53 100644
--- a/gv.c
+++ b/gv.c
@@ -890,7 +890,7 @@ S_gv_fetchmeth_internal(pTHX_ HV* stash, SV* meth, const char* name, STRLEN len,
     }
 
     /* Check UNIVERSAL without caching */
-    if(level == 0 || level == -1) {
+    if((level == 0 || level == -1) && !(flags & GV_NOUNIVERSAL)) {
         candidate = gv_fetchmeth_internal(NULL, meth, name, len, 1,
                                           flags &~GV_SUPER);
         if(candidate) {