vim-patch:8.1.0291: 'incsearch' highlighting not used for :sort

Problem:    'incsearch' highlighting not used for :sort.
Solution:   Handle pattern in :sort command.
81f56536b1

src/nvim/ex_getln.c

@@ -314,6 +314,7 @@ static bool do_incsearch_highlighting(int firstc, incsearch_state_T *s,
             && (STRNCMP(cmd, "substitute", p - cmd) == 0
                 || STRNCMP(cmd, "smagic", p - cmd) == 0
                 || STRNCMP(cmd, "snomagic", MAX(p - cmd, 3)) == 0
+                || STRNCMP(cmd, "sort", p - cmd) == 0
                 || STRNCMP(cmd, "global", p - cmd) == 0
                 || STRNCMP(cmd, "vglobal", p - cmd) == 0)) {
           if (*cmd == 's' && cmd[1] == 'm') {
@@ -330,6 +331,17 @@ static bool do_incsearch_highlighting(int firstc, incsearch_state_T *s,
               return false;
             }
           }
+
+          // For ":sort" skip over flags.
+          if (cmd[0] == 's' && cmd[1] == 'o') {
+            while (ASCII_ISALPHA(*(p = skipwhite(p)))) {
+              ++p;
+            }
+            if (*p == NUL) {
+              return false;
+            }
+          }
+
           p = skipwhite(p);
           delim = *p++;
           end = skip_regexp(p, delim, p_magic, NULL);
@@ -352,7 +364,7 @@ static bool do_incsearch_highlighting(int firstc, incsearch_state_T *s,
                 search_first_line = ea.line1;
                 search_last_line = ea.line2;
               }
-            } else if (*cmd == 's') {
+            } else if (cmd[0] == 's' && cmd[1] != 'o') {
               // :s defaults to the current line
               search_first_line = curwin->w_cursor.lnum;
               search_last_line = curwin->w_cursor.lnum;

src/nvim/testdir/test_search.vim

@@ -692,6 +692,33 @@ func Test_incsearch_substitute_dump()
   call delete('Xis_subst_script')
 endfunc
 
+" Similar to Test_incsearch_substitute_dump() for :sort
+func Test_incsearch_ssort_dump()
+  if !exists('+incsearch')
+    return
+  endif
+  if !CanRunVimInTerminal()
+    throw 'Skipped: cannot make screendumps'
+  endif
+  call writefile([
+	\ 'set incsearch hlsearch scrolloff=0',
+	\ 'call setline(1, ["another one 2", "that one 3", "the one 1"])',
+	\ ], 'Xis_sort_script')
+  let buf = RunVimInTerminal('-S Xis_sort_script', {'rows': 9, 'cols': 70})
+  " Give Vim a chance to redraw to get rid of the spaces in line 2 caused by
+  " the 'ambiwidth' check.
+  sleep 100m
+
+  " Need to send one key at a time to force a redraw.
+  call term_sendkeys(buf, ':sort ni u /on')
+  sleep 100m
+  call VerifyScreenDump(buf, 'Test_incsearch_sort_01', {})
+  call term_sendkeys(buf, "\<Esc>")
+
+  call StopVimInTerminal(buf)
+  call delete('Xis_sort_script')
+endfunc
+
 func Test_incsearch_with_change()
   if !has('timers') || !exists('+incsearch') || !CanRunVimInTerminal()
     throw 'Skipped: cannot make screendumps and/or timers feature and/or incsearch option missing'

test/functional/legacy/search_spec.lua

@@ -21,6 +21,7 @@ describe('search cmdline', function()
       err = { foreground = Screen.colors.Grey100, background = Screen.colors.Red },
       more = { bold = true, foreground = Screen.colors.SeaGreen4 },
       tilde = { bold = true, foreground = Screen.colors.Blue1 },
+      hl = { background = Screen.colors.Yellow },
     })
   end)
 
@@ -570,4 +571,20 @@ describe('search cmdline', function()
       ?the                                    |
     ]])
   end)
+
+  it('incsearch works with :sort', function()
+    -- oldtest: Test_incsearch_sort_dump().
+    screen:try_resize(20, 4)
+    command('set incsearch hlsearch scrolloff=0')
+    funcs.setline(1, {'another one 2', 'that one 3', 'the one 1'})
+
+    feed(':sort ni u /on')
+    screen:expect([[
+      another {inc:on}e 2       |
+      that {hl:on}e 3          |
+      the {hl:on}e 1           |
+      :sort ni u /on^      |
+    ]])
+    feed('<esc>')
+  end)
 end)