From 26d08dfd0d9d2f8e3685a4fe083588519bd5dac0 Mon Sep 17 00:00:00 2001
From: KillTheMule <KillTheMule@users.noreply.github.com>
Date: Mon, 28 Aug 2017 21:33:31 +0200
Subject: [PATCH] inccommand: fix optimization logic #7224

Before this change the preview changes in the buffer viewport were
limited to the size of the preview window ('cmdwinheight').

closes #7220
---
 src/nvim/ex_cmds.c                     |  6 ++++--
 test/functional/ui/inccommand_spec.lua | 25 +++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 32dbf4cc69..4b3e02e5fd 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -3332,10 +3332,12 @@ static buf_T *do_sub(exarg_T *eap, proftime_T timeout)
     sub = regtilde(sub, p_magic);
 
   // Check for a match on each line.
+  // If preview: limit to max('cmdwinheight', viewport).
   linenr_T line2 = eap->line2;
   for (linenr_T lnum = eap->line1;
-       lnum <= line2 && !(got_quit || aborting())
-       && (!preview || matched_lines.size <= (size_t)p_cwh);
+       lnum <= line2 && !got_quit && !aborting()
+       && (!preview || matched_lines.size < (size_t)p_cwh
+           || lnum <= curwin->w_botline);
        lnum++) {
     long nmatch = vim_regexec_multi(&regmatch, curwin, curbuf, lnum,
                                     (colnr_T)0, NULL);
diff --git a/test/functional/ui/inccommand_spec.lua b/test/functional/ui/inccommand_spec.lua
index 64965ccb94..e83bd72ad3 100644
--- a/test/functional/ui/inccommand_spec.lua
+++ b/test/functional/ui/inccommand_spec.lua
@@ -892,6 +892,31 @@ describe(":substitute, inccommand=split", function()
     ]])
   end)
 
+  it('previews correctly when previewhight is small', function()
+    feed_command('set cwh=3')
+    feed_command('set hls')
+    feed('ggdG')
+    insert(string.rep('abc abc abc\n', 20))
+    feed(':%s/abc/MMM/g')
+    screen:expect([[
+      MMM MMM MMM                   |
+      MMM MMM MMM                   |
+      MMM MMM MMM                   |
+      MMM MMM MMM                   |
+      MMM MMM MMM                   |
+      MMM MMM MMM                   |
+      MMM MMM MMM                   |
+      MMM MMM MMM                   |
+      MMM MMM MMM                   |
+      {11:[No Name] [+]                 }|
+      | 1| {12:MMM} {12:MMM} {12:MMM}              |
+      | 2| {12:MMM} {12:MMM} {12:MMM}              |
+      | 3| {12:MMM} {12:MMM} {12:MMM}              |
+      {10:[Preview]                     }|
+      :%s/abc/MMM/g^                 |
+    ]])
+  end)
+
   it('actually replaces text', function()
     feed(":%s/tw/XX/g<Enter>")