From dd9554a8205c18ab4194d21445bb1fe6c960229f Mon Sep 17 00:00:00 2001
From: "Justin M. Keyes" <justinkz@gmail.com>
Date: Mon, 25 Mar 2019 03:27:24 +0100
Subject: [PATCH 1/2] inccommand: Ignore :redraw during preview

closes #9777
---
 src/nvim/ex_docmd.c                    | 14 +++++++------
 test/functional/ui/inccommand_spec.lua | 27 ++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index c452129719..4d958b201a 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -7807,11 +7807,12 @@ static void ex_redir(exarg_T *eap)
     redir_off = FALSE;
 }
 
-/*
- * ":redraw": force redraw
- */
+/// ":redraw": force redraw
 static void ex_redraw(exarg_T *eap)
 {
+  if (State & CMDPREVIEW) {
+    return;  // Ignore :redraw during 'inccommand' preview. #9777
+  }
   int r = RedrawingDisabled;
   int p = p_lz;
 
@@ -7840,11 +7841,12 @@ static void ex_redraw(exarg_T *eap)
   ui_flush();
 }
 
-/*
- * ":redrawstatus": force redraw of status line(s)
- */
+/// ":redrawstatus": force redraw of status line(s)
 static void ex_redrawstatus(exarg_T *eap)
 {
+  if (State & CMDPREVIEW) {
+    return;  // Ignore :redrawstatus during 'inccommand' preview. #9777
+  }
   int r = RedrawingDisabled;
   int p = p_lz;
 
diff --git a/test/functional/ui/inccommand_spec.lua b/test/functional/ui/inccommand_spec.lua
index c215ece2f2..4f243e6413 100644
--- a/test/functional/ui/inccommand_spec.lua
+++ b/test/functional/ui/inccommand_spec.lua
@@ -2607,3 +2607,30 @@ it(':substitute with inccommand during :terminal activity', function()
 
   end)
 end)
+
+it(':substitute with inccommand, timer-induced :redraw #9777', function()
+  local screen = Screen.new(30,12)
+  clear()
+  command('set cmdwinheight=3')
+  command('call timer_start(10, {-> execute("redraw")}, {"repeat":-1})')
+  command('call timer_start(10, {-> execute("redrawstatus")}, {"repeat":-1})')
+  common_setup(screen, 'split', 'foo bar baz\nbar baz fox\nbar foo baz')
+
+  feed('gg')
+  feed(':%s/foo/ZZZ')
+  sleep(20)  -- Allow some timer activity.
+  screen:expect([[
+    {12:ZZZ} bar baz                   |
+    bar baz fox                   |
+    bar {12:ZZZ} baz                   |
+    {15:~                             }|
+    {15:~                             }|
+    {15:~                             }|
+    {11:[No Name] [+]                 }|
+    |1| {12:ZZZ} bar baz               |
+    |3| bar {12:ZZZ} baz               |
+    {15:~                             }|
+    {10:[Preview]                     }|
+    :%s/foo/ZZZ^                   |
+  ]])
+end)

From 0b8fc2742b9b559c4607202f5e6a79166a2b60d0 Mon Sep 17 00:00:00 2001
From: "Justin M. Keyes" <justinkz@gmail.com>
Date: Mon, 25 Mar 2019 03:55:12 +0100
Subject: [PATCH 2/2] inccommand: Disable K_EVENT during preview calculation

'inccommand' invokes ex_substitute() to build its "preview". During the
brief (~millisecond) time it takes to execute that function, the buffer
is "dirty" (its contents are invalid). Events must not be handled during
this time, else they would see a temporary state which is not the true,
logical state of the buffer.

ref #9777
---
 src/nvim/ex_cmds.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index af92a9c846..150e13efd5 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -6392,6 +6392,7 @@ void ex_substitute(exarg_T *eap)
   }
 
   block_autocmds();           // Disable events during command preview.
+  input_disable_events();
 
   char_u *save_eap = eap->arg;
   garray_T save_view;
@@ -6434,6 +6435,7 @@ void ex_substitute(exarg_T *eap)
   restore_search_patterns();
   win_size_restore(&save_view);
   ga_clear(&save_view);
+  input_enable_events();
   unblock_autocmds();
 }