Patching magic from Inaba-san's keyboard: fix for [perl #8769]:

"scalar upgraded to UTF-8 as a side effect of quote-interpolation
when 'use encoding' is engaged"-- wasn't actually encoding's fault.

p4raw-id: //depot/perl@18764

1 files changed, 9 insertions, 2 deletions

diff --git a/sv.c b/sv.c
index 73fef98fed..b132a1e6f3 100644
--- a/sv.c
+++ b/sv.c
@@ -8288,7 +8288,11 @@ Perl_sv_vcatpvfn(pTHX_ SV *sv, const char *pat, STRLEN patlen, va_list *args, SV
     I32 svix = 0;
     static char nullstr[] = "(null)";
     SV *argsv = Nullsv;
-    bool has_utf8 = FALSE; /* has the result utf8? */
+    bool has_utf8; /* has the result utf8? */
+    bool pat_utf8; /* the pattern is in utf8? */
+    SV *nsv = Nullsv;
+
+    has_utf8 = pat_utf8 = DO_UTF8(sv);
 
     /* no matter what, this is a string now */
     (void)SvPV_force(sv, origlen);
@@ -8389,7 +8393,10 @@ Perl_sv_vcatpvfn(pTHX_ SV *sv, const char *pat, STRLEN patlen, va_list *args, SV
 	/* echo everything up to the next format specification */
 	for (q = p; q < patend && *q != '%'; ++q) ;
 	if (q > p) {
-	    sv_catpvn(sv, p, q - p);
+	    if (has_utf8 && !pat_utf8)
+		sv_catpvn_utf8_upgrade(sv, p, q - p, nsv);
+	    else
+		sv_catpvn(sv, p, q - p);
 	    p = q;
 	}
 	if (q++ >= patend)