Bug#848336: less: bad redraw with double-width character after search

[Vincent Lefevre]

Control: severity -1 848336

On 2016-12-16 12:34:03 +0100, Vincent Lefevre wrote:
> When a long line contains a double-width character, it is redrawn
> incorrectly after a search. To reproduce this issue:

I get more and more display corruption with such characters, which
are more and more common.

For instance, with the attached file:

1. Unset any LESS* environment variable.
2. Open this file with "less" in a 80-column terminal.
3. Type "<" (→ the first line is not visible).
4. Search for an unmatched pattern (→ complete screen corruption).

-- 
Vincent Lefèvre <vinc...@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)

Line 1

Line 3
Line 4 abc
Line 5 def
Line 6 123456

Line 8
Line 9 789
Line 10 xyz

Line 12 foo bar
Line 13
Line 14 ...
Line 15 blah!

Line 16
Line 17 ..... 😂😂😂😂😂😂😂😂😂😂😂 1234567890 1234567890 1234567890 1234567890 1234567890

1. Unset any LESS* environment variable.
2. Open this file with "less" in a 80-column terminal.
3. Type "<" (→ the first line is not visible).
4. Search for an unmatched pattern (→ complete screen corruption).