lib/standard: format use `plain_to_s` for fast concat

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/lib/standard/text/abstract_text.nit b/lib/standard/text/abstract_text.nit
index 5f17f39..df1c15f 100644 (file)
--- a/lib/standard/text/abstract_text.nit
+++ b/lib/standard/text/abstract_text.nit
@@ -875,7 +875,7 @@ abstract class Text
                        i += 1
                end
                s.push substring(curr_st, length - curr_st)
-               return s.to_s
+               return s.plain_to_s
        end
 
        # Copies `n` bytes from `self` at `src_offset` into `dest` starting at `dest_offset`