vim-patch:8.0.0692: CTRL-G with 'incsearch' and ? goes in the wrong direction

Problem:    Using CTRL-G with 'incsearch' and ? goes in the wrong direction.
            (Ramel Eshed)
Solution:   Adjust search_start. (Christian Brabandt)

da5116da45

src/nvim/ex_getln.c

@@ -1063,6 +1063,13 @@ static void command_line_next_incsearch(CommandLineState *s, bool next_match)
       s->search_start = t;
       (void)decl(&s->search_start);
     }
+    else if (next_match && s->firstc == '?') {
+      // move just after the current match, so that
+      // when nv_search finishes the cursor will be
+      // put back on the match
+      s->search_start = t;
+      (void)incl(&s->search_start);
+    }
     if (lt(t, s->search_start) && next_match) {
       // wrap around
       s->search_start = t;

src/nvim/testdir/test_search.vim

@@ -327,3 +327,39 @@ func Test_search_cmdline3()
   call test_override("char_avail", 0)
   bw!
 endfunc
+
+func Test_search_cmdline4()
+  " See test/functional/legacy/search_spec.lua
+  throw 'skipped: Nvim does not support test_override()'
+  if !exists('+incsearch')
+    return
+  endif
+  " need to disable char_avail,
+  " so that expansion of commandline works
+  call test_override("char_avail", 1)
+  new
+  call setline(1, ['  1 the first', '  2 the second', '  3 the third'])
+  set incsearch
+  $
+  call feedkeys("?the\<c-g>\<cr>", 'tx')
+  call assert_equal('  3 the third', getline('.'))
+  $
+  call feedkeys("?the\<c-g>\<c-g>\<cr>", 'tx')
+  call assert_equal('  1 the first', getline('.'))
+  $
+  call feedkeys("?the\<c-g>\<c-g>\<c-g>\<cr>", 'tx')
+  call assert_equal('  2 the second', getline('.'))
+  $
+  call feedkeys("?the\<c-t>\<cr>", 'tx')
+  call assert_equal('  1 the first', getline('.'))
+  $
+  call feedkeys("?the\<c-t>\<c-t>\<cr>", 'tx')
+  call assert_equal('  3 the third', getline('.'))
+  $
+  call feedkeys("?the\<c-t>\<c-t>\<c-t>\<cr>", 'tx')
+  call assert_equal('  2 the second', getline('.'))
+  " clean up
+  set noincsearch
+  call test_override("char_avail", 0)
+  bw!
+endfunc

test/functional/legacy/search_spec.lua

@@ -6,6 +6,7 @@ local eq = helpers.eq
 local eval = helpers.eval
 local feed = helpers.feed
 local funcs = helpers.funcs
+local wait = helpers.wait
 
 describe('search cmdline', function()
   local screen
@@ -471,4 +472,113 @@ describe('search cmdline', function()
         coladd = 0, skipcol = 0, curswant = 0},
        funcs.winsaveview())
   end)
+
+  it("CTRL-G with 'incsearch' and ? goes in the right direction", function()
+    -- oldtest: Test_search_cmdline4().
+    screen:detach()
+    screen = Screen.new(40, 4)
+    screen:attach()
+    screen:set_default_attr_ids({
+      inc = {reverse = true},
+      err = { foreground = Screen.colors.Grey100, background = Screen.colors.Red },
+      more = { bold = true, foreground = Screen.colors.SeaGreen4 },
+      tilde = { bold = true, foreground = Screen.colors.Blue1 },
+    })
+    command('enew!')
+    funcs.setline(1, {'  1 the first', '  2 the second', '  3 the third'})
+    command('set laststatus=0 shortmess+=s')
+    command('set incsearch')
+    command('$')
+    -- Send the input in chunks, so the cmdline logic regards it as
+    -- "interactive".  This mimics Vim's test_override("char_avail").
+    -- (See legacy test: test_search.vim)
+    feed('?the')
+    wait()
+    feed('<c-g>')
+    wait()
+    feed('<cr>')
+    screen:expect([[
+        1 the first                           |
+        2 the second                          |
+        3 ^the third                           |
+      ?the                                    |
+    ]])
+
+    command('$')
+    feed('?the')
+    wait()
+    feed('<c-g>')
+    wait()
+    feed('<c-g>')
+    wait()
+    feed('<cr>')
+    screen:expect([[
+        1 ^the first                           |
+        2 the second                          |
+        3 the third                           |
+      ?the                                    |
+    ]])
+
+    command('$')
+    feed('?the')
+    wait()
+    feed('<c-g>')
+    wait()
+    feed('<c-g>')
+    wait()
+    feed('<c-g>')
+    wait()
+    feed('<cr>')
+    screen:expect([[
+        1 the first                           |
+        2 ^the second                          |
+        3 the third                           |
+      ?the                                    |
+    ]])
+
+    command('$')
+    feed('?the')
+    wait()
+    feed('<c-t>')
+    wait()
+    feed('<cr>')
+    screen:expect([[
+        1 ^the first                           |
+        2 the second                          |
+        3 the third                           |
+      ?the                                    |
+    ]])
+
+    command('$')
+    feed('?the')
+    wait()
+    feed('<c-t>')
+    wait()
+    feed('<c-t>')
+    wait()
+    feed('<cr>')
+    screen:expect([[
+        1 the first                           |
+        2 the second                          |
+        3 ^the third                           |
+      ?the                                    |
+    ]])
+
+    command('$')
+    feed('?the')
+    wait()
+    feed('<c-t>')
+    wait()
+    feed('<c-t>')
+    wait()
+    feed('<c-t>')
+    wait()
+    feed('<cr>')
+    screen:expect([[
+        1 the first                           |
+        2 ^the second                          |
+        3 the third                           |
+      ?the                                    |
+    ]])
+  end)
 end)