_fresh functions: allow on PVIV & PVNVs too

sv.c

@@ -1629,9 +1629,9 @@ Perl_sv_grow(pTHX_ SV *const sv, STRLEN newlen)
 =for apidoc sv_grow_fresh
 
 A cut-down version of sv_grow intended only for when sv is a freshly-minted
-SVt_PV. i.e. sv has the default flags, has never been any other type, and
-does not have an existing string. Basically, just assigns a char* buffer.
-Returns a pointer to the character buffer.
+SVt_PV, SVt_PVIV, or SVt_PVNV. i.e. sv has the default flags, has never been
+any other type, and does not have an existing string. Basically, just assigns
+a char buffer and returns a pointer to it.
 
 =cut
 */
@@ -1644,7 +1644,8 @@ Perl_sv_grow_fresh(pTHX_ SV *const sv, STRLEN newlen)
 
     PERL_ARGS_ASSERT_SV_GROW_FRESH;
 
-    assert(SvTYPE(sv) == SVt_PV);
+    assert(SvTYPE(sv) == SVt_PV || SvTYPE(sv) == SVt_PVIV
+           || SvTYPE(sv) == SVt_PVNV);
     assert(!SvROK(sv));
     assert(!SvOOK(sv));
     assert(!SvIsCOW(sv));
@@ -4976,7 +4977,8 @@ They differ only in that:
 C<sv_setpvn> does not handle 'set' magic; C<sv_setpvn_mg> does.
 
 C<sv_setpvn_fresh> is a cut-down alternative to C<sv_setpvn>, intended ONLY
-to be used with a fresh sv that has been upgraded to a SVt_PV.
+to be used with a fresh sv that has been upgraded to a SVt_PV, SVt_PVIV, or
+SVt_PVNV.
 
 =cut
 */
@@ -5028,16 +5030,17 @@ Perl_sv_setpvn_fresh(pTHX_ SV *const sv, const char *const ptr, const STRLEN len
     char *dptr;
 
     PERL_ARGS_ASSERT_SV_SETPVN_FRESH;
-    assert(SvTYPE(sv) == SVt_PV);
+    assert(SvTYPE(sv) == SVt_PV || SvTYPE(sv) == SVt_PVIV
+           || SvTYPE(sv) == SVt_PVNV);
     assert(!SvTHINKFIRST(sv));
     assert(!isGV_with_GP(sv));
 
     if (ptr) {
         const IV iv = len;
         /* len is STRLEN which is unsigned, need to copy to signed */
-	if (iv < 0)
-	    Perl_croak(aTHX_ "panic: sv_setpvn_fresh called with negative strlen %"
-		       IVdf, iv);
+        if (iv < 0)
+            Perl_croak(aTHX_ "panic: sv_setpvn_fresh called with negative strlen %"
+                       IVdf, iv);
 
         dptr = sv_grow_fresh(sv, len + 1);
         Move(ptr,dptr,len,char);