vim-patch:8.2.3663: using %S in printf() does not work correctly

Problem:    Using %S in printf() does not work correctly.
Solution:   Fix the problem and add more tests. (closes vim/vim#9208)
https://github.com/vim/vim/commit/1f2453fec6f8f0f315f00ca7b562a02090cb1e37

1 files changed, 11 insertions, 16 deletions

diff --git a/src/nvim/strings.c b/src/nvim/strings.c
index efcd40bb75..291138ef23 100644
--- a/src/nvim/strings.c
+++ b/src/nvim/strings.c
@@ -1001,25 +1001,20 @@ int vim_vsnprintf_typval(char *str, size_t str_m, const char *fmt, va_list ap, t
                                  - str_arg);
           }
           if (fmt_spec == 'S') {
-            size_t base_width = min_field_width;
-            size_t pad_cell = 0;
-
-            if (precision) {
-              char_u *p1;
-              size_t i = 0;
-
-              for (p1 = (char_u *)str_arg; *p1;
-                   p1 += utfc_ptr2len(p1)) {
-                i += (size_t)utf_ptr2cells(p1);
-                if (i > precision) {
-                  break;
-                }
+            char_u *p1;
+            size_t i;
+
+            for (i = 0, p1 = (char_u *)str_arg; *p1; p1 += utfc_ptr2len(p1)) {
+              size_t cell = (size_t)utf_ptr2cells(p1);
+              if (precision_specified && i + cell > precision) {
+                break;
               }
-              pad_cell = min_field_width - precision;
-              base_width = str_arg_l = (size_t)(p1 - (char_u *)str_arg);
+              i += cell;
             }
+
+            str_arg_l = (size_t)(p1 - (char_u *)str_arg);
             if (min_field_width != 0) {
-              min_field_width = base_width + pad_cell;
+              min_field_width += str_arg_l - i;
             }
           }
           break;