bugfix: replace_str uses string_extend incorrectly.

One test case for this is that (append "ABC" "DEF")
returns an "ABCDEF" string whose length reports as 9
instead of the correct 6. This will wreak various havoc.

The bug was introduced in the very first version of
replace_str, in commit d011fda9b6b078f09027eb65d500c8beffc99414
on January 26, 2012.

In the same commit, the string_extend behavior is
introduced of supporting an integer value specifying the
number of characters by which to extend the string.
This feature of string_extend is used in replace_str,
but wrongly.

* lib.c (replace_str): Pass just the size delta
to string_extend; do not add the old length to the
delta such that the total size is wrongly passed.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib.c b/lib.c
index 64387e17..657b39f3 100644
--- a/lib.c
+++ b/lib.c
@@ -3936,7 +3936,7 @@ val replace_str(val str_in, val items, val from, val to)
       cnum t = c_num(to);
       cnum l = c_num(len);
 
-      string_extend(str_in, plus(len, len_diff));
+      string_extend(str_in, len_diff);
       wmemmove(str_in->st.str + t + c_num(len_diff),
                str_in->st.str + t, (l - t) + 1);
       to = plus(from, len_it);