compile.c: fix performance of strconcat

* compile.c (compile_dstr_fragments): fix performance by omitting
  the first empty string only for keeping literal encoding if
  other literals are too.  [ruby-core:70930] [Bug #11556]
* string.c (rb_str_append_literal): append but keep encoding non
  US-ASCII.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51970 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 0 deletions

diff --git a/vm.c b/vm.c
index 92b33f3ffe..ee9f4076c1 100644
--- a/vm.c
+++ b/vm.c
@@ -21,6 +21,8 @@
 #include "probes.h"
 #include "probes_helper.h"
 
+VALUE rb_str_append_literal(VALUE str, VALUE str2);
+
 static inline VALUE *
 VM_EP_LEP(VALUE *ep)
 {