Only call mro_package_moved on new substashes

Commit 298d65111 added this mro_package_moved call.

It does not need to happen if the substash already exists, as it will
already have had effective names assigned to it.

It also may not be a good idea to set it in such cases, as it may make
a recursive call to mro_get_linear_isa. I know this is utter paranoia,
but someone may write a mro plugin that is not reëntrant. (The speed
gain is worth it, though.)

1 files changed, 10 insertions, 8 deletions

diff --git a/gv.c b/gv.c
index 9a72996f93..b2cb5a4146 100644
--- a/gv.c
+++ b/gv.c
@@ -1072,16 +1072,18 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 		    return NULL;
 
 		if (!(stash = GvHV(gv)))
-		    stash = GvHV(gv) = newHV();
-
-		if (!HvNAME_get(stash))
 		{
-		    hv_name_set(stash, nambeg, name_cursor - nambeg, 0);
-		    /* If the containing stash has multiple effective
-		       names, see that this one gets them, too. */
-		    if (HvAUX(GvSTASH(gv))->xhv_name_count)
-			mro_package_moved(stash, NULL, gv, 1);
+		    stash = GvHV(gv) = newHV();
+		    if (!HvNAME_get(stash)) {
+			hv_name_set(stash, nambeg, name_cursor-nambeg, 0);
+			/* If the containing stash has multiple effective
+			   names, see that this one gets them, too. */
+			if (HvAUX(GvSTASH(gv))->xhv_name_count)
+			    mro_package_moved(stash, NULL, gv, 1);
+		    }
 		}
+		else if (!HvNAME_get(stash))
+		    hv_name_set(stash, nambeg, name_cursor - nambeg, 0);
 	    }
 
 	    if (*name_cursor == ':')