Perl_newSV_type_mortal - new inline function introduced and used

There's no efficient way to create a mortal SV of any type other than
SVt_NULL (via sv_newmortal). The options are either to do:

* SV* sv = sv_newmortal; sv_upgrade(sv, SVt_SOMETYPE);
  but sv_upgrade is needlessly inefficient on new SVs.

* SV* sv = sv_2mortal(newSV_type(SVt_SOMETYPE)
  but this will perform runtime checks to see if (sv) and if (SvIMMORTAL(sv),
  and for a new SV we know that those answers will always be yes and no.

This commit adds a new inline function which is basically a mortalizing
wrapper around the now-inlined newSV_type.

1 files changed, 1 insertions, 1 deletions

diff --git a/mg.c b/mg.c
index 5f3eeae4fe..c470beaec1 100644
--- a/mg.c
+++ b/mg.c
@@ -877,7 +877,7 @@ Perl_sv_string_from_errnum(pTHX_ int errnum, SV *tgtsv)
 {
     char const *errstr;
     if(!tgtsv)
-        tgtsv = sv_newmortal();
+        tgtsv = newSV_type_mortal(SVt_PV);
     errstr = my_strerror(errnum);
     if(errstr) {
         sv_setpv(tgtsv, errstr);