From 2ffe66a5a4e1297ee24fd3ab8cc4dda45b1381bd Mon Sep 17 00:00:00 2001
From: zeertzjq <zeertzjq@outlook.com>
Date: Thu, 17 Feb 2022 07:18:10 +0800
Subject: vim-patch:8.2.4338: an error from an expression mapping messes up the
 display

Problem:    An error from an expression mapping messes up the display.
Solution:   When the expression results in an empty string return K_IGNORE.
            In cmdline mode redraw the command line. (closes vim/vim#9726)
https://github.com/vim/vim/commit/74a0a5b26d0180f3ea89e9495dff6a26f0df23cb
---
 src/nvim/testdir/test_mapping.vim | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

(limited to 'src/nvim/testdir/test_mapping.vim')

diff --git a/src/nvim/testdir/test_mapping.vim b/src/nvim/testdir/test_mapping.vim
index 749c75106e..105f70e6bb 100644
--- a/src/nvim/testdir/test_mapping.vim
+++ b/src/nvim/testdir/test_mapping.vim
@@ -483,6 +483,38 @@ func Test_expr_map_restore_cursor()
   call delete('XtestExprMap')
 endfunc
 
+func Test_expr_map_error()
+  CheckScreendump
+
+  let lines =<< trim END
+      func Func()
+        throw 'test'
+        return ''
+      endfunc
+
+      nnoremap <expr> <F2> Func()
+      cnoremap <expr> <F2> Func()
+
+      call test_override('ui_delay', 10)
+  END
+  call writefile(lines, 'XtestExprMap')
+  let buf = RunVimInTerminal('-S XtestExprMap', #{rows: 10})
+  call TermWait(buf)
+  call term_sendkeys(buf, "\<F2>")
+  call TermWait(buf)
+  call term_sendkeys(buf, "\<CR>")
+  call VerifyScreenDump(buf, 'Test_map_expr_2', {})
+
+  call term_sendkeys(buf, ":abc\<F2>")
+  call VerifyScreenDump(buf, 'Test_map_expr_3', {})
+  call term_sendkeys(buf, "\<Esc>0")
+  call VerifyScreenDump(buf, 'Test_map_expr_4', {})
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('XtestExprMap')
+endfunc
+
 " Test for mapping errors
 func Test_map_error()
   call assert_fails('unmap', 'E474:')
-- 
cgit