patch 8.2.4660: cursorcolumn is sometimes not correct
Problem: Cursorcolumn is sometimes not correct.
Solution: Recompute the cursor column when entering Insert mode and the
cursor is on a character wider than a screen cell.
diff --git a/src/testdir/dumps/Test_cursorcolumn_insert_on_tab_1.dump b/src/testdir/dumps/Test_cursorcolumn_insert_on_tab_1.dump
new file mode 100644
index 0000000..7a691e8
--- /dev/null
+++ b/src/testdir/dumps/Test_cursorcolumn_insert_on_tab_1.dump
@@ -0,0 +1,8 @@
+|1+0&#ffffff0|2|3|4|5|6|7|8+0&#e0e0e08|9+0&#ffffff0| @65
+|a| @5> |b| @65
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+| +0#0000000&@56|2|,|2|-|8| @8|A|l@1|
diff --git a/src/testdir/dumps/Test_cursorcolumn_insert_on_tab_2.dump b/src/testdir/dumps/Test_cursorcolumn_insert_on_tab_2.dump
new file mode 100644
index 0000000..29d6b19
--- /dev/null
+++ b/src/testdir/dumps/Test_cursorcolumn_insert_on_tab_2.dump
@@ -0,0 +1,8 @@
+|1+0&#ffffff0|2+0&#e0e0e08|3+0&#ffffff0|4|5|6|7|8|9| @65
+|a> @6|b| @65
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|-+2#0000000&@1| |I|N|S|E|R|T| |-@1| +0&&@44|2|,|2| @10|A|l@1|
diff --git a/src/testdir/test_highlight.vim b/src/testdir/test_highlight.vim
index b07ba11..4b8cd86 100644
--- a/src/testdir/test_highlight.vim
+++ b/src/testdir/test_highlight.vim
@@ -592,6 +592,28 @@
call delete('Xtest_cursorline_with_visualmode')
endfunc
+func Test_cursorcolumn_insert_on_tab()
+ CheckScreendump
+
+ let lines =<< trim END
+ call setline(1, ['123456789', "a\tb"])
+ set cursorcolumn
+ call cursor(2, 2)
+ END
+ call writefile(lines, 'Xcuc_insert_on_tab')
+
+ let buf = RunVimInTerminal('-S Xcuc_insert_on_tab', #{rows: 8})
+ call TermWait(buf)
+ call VerifyScreenDump(buf, 'Test_cursorcolumn_insert_on_tab_1', {})
+
+ call term_sendkeys(buf, 'i')
+ call TermWait(buf)
+ call VerifyScreenDump(buf, 'Test_cursorcolumn_insert_on_tab_2', {})
+
+ call StopVimInTerminal(buf)
+ call delete('Xcuc_insert_on_tab')
+endfunc
+
func Test_cursorcolumn_callback()
CheckScreendump
CheckFeature timers