Copy PADTMPS passed to XSUBs

This resolves the last remaining issue in ticket #78194, that
newRV is supposedly buggy because it doesn’t copy its referent.
The full implications of the PADTMP are not explained anywhere in
the API docs, and even XSUBs shouldn’t have to worry about special
handling.  (E.g., what if they do SvREFCNT_dec(SvRV(sv)); SvRV(sv)=...?)

So the real solution here is not to let XSUBs see them.

1 files changed, 9 insertions, 0 deletions

diff --git a/pp_hot.c b/pp_hot.c
index 3adeb1e8f7..b08643fcc1 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -2727,6 +2727,15 @@ try_autoload:
 		PUTBACK ;		
 	    }
 	}
+	else {
+	    SV **mark = PL_stack_base + markix;
+	    I32 items = SP - mark;
+	    while (items--) {
+		mark++;
+		if (*mark && SvPADTMP(*mark) && !IS_PADGV(*mark))
+		    *mark = sv_mortalcopy(*mark);
+	    }
+	}
 	/* We assume first XSUB in &DB::sub is the called one. */
 	if (PL_curcopdb) {
 	    SAVEVPTR(PL_curcop);