vim-patch:8.1.0120: buffer 'modified' set even when :sort has no changes

Problem:    Buffer 'modified' set even when :sort has no changes.
Solution:   Only set 'modified' when lines are moved. (Jason Franklin)
https://github.com/vim/vim/commit/dc9e955fb07f410d5d3e981ce18d895dd2847c85

1 files changed, 13 insertions, 2 deletions

diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index aaa4dbdfb7..892458dab7 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -424,6 +424,7 @@ void ex_sort(exarg_T *eap)
 
   sort_abort = sort_ic = sort_rx = sort_nr = sort_flt = 0;
   size_t format_found = 0;
+  bool change_occurred = false;   // Buffer contents changed.
 
   for (p = eap->arg; *p != NUL; ++p) {
     if (ascii_iswhite(*p)) {
@@ -585,7 +586,15 @@ void ex_sort(exarg_T *eap)
   // Insert the lines in the sorted order below the last one.
   lnum = eap->line2;
   for (i = 0; i < count; ++i) {
-    s = ml_get(nrs[eap->forceit ? count - i - 1 : i].lnum);
+    const linenr_T get_lnum = nrs[eap->forceit ? count - i - 1 : i].lnum;
+
+    // If the original line number of the line being placed is not the same
+    // as "lnum" (accounting for offset), we know that the buffer changed.
+    if (get_lnum + ((linenr_T)count - 1) != lnum) {
+      change_occurred = true;
+    }
+
+    s = ml_get(get_lnum);
     if (!unique || i == 0
         || (sort_ic ? STRICMP(s, sortbuf1) : STRCMP(s, sortbuf1)) != 0) {
       // Copy the line into a buffer, it may become invalid in
@@ -617,7 +626,9 @@ void ex_sort(exarg_T *eap)
   } else if (deleted < 0) {
     mark_adjust(eap->line2, MAXLNUM, -deleted, 0L, false);
   }
-  changed_lines(eap->line1, 0, eap->line2 + 1, -deleted, true);
+  if (change_occurred || deleted != 0) {
+    changed_lines(eap->line1, 0, eap->line2 + 1, -deleted, true);
+  }
 
   curwin->w_cursor.lnum = eap->line1;
   beginline(BL_WHITE | BL_FIX);