Looking up the man page for `index` was failing on systems using
GNU/coreutils. The `:man` command matched whatever page it was given with
the `expr` utility. This tool behaves as expected when it follows strictly
the POSIX standard but the GNU implementation introduces additional commands
(including `index`), about which the standard states:
```
The use of string arguments length, substr, index, or match produces unspecified results.
```
As a result, parsing the man page number is now implemented with pure
shell expansions, to avoid triggering an undefined behavior when the topic
searched is one of the keywords above.
Certain cases, like diffing an empty buffer with a big buffer, were
very slow, now this should get better as we will directly detect the
matching eol at the end of both buffers, end then immediatly detect
we need to add the rest of the big buffer.
We still are too slow on some general diff when there is a lot of
differences.
We can index native arrays negatively, so just setup V1 and V2 to
point in the middle of the work arrays and remove the need for
creating MirroredArray.
Replacing with empty strings is essentially a deletion, which means
it can end up push some selections out of the buffer (imagine 3 a
2 empty line buffer, and deleting the second one). We are fixing
the selections in SelectionList::erase, but we were not doing that
in SelectionList::insert.
Fixes#1504
Due to the way Selection::min/max worked, we were creating backward
selections, with cursor < anchor, which was triggering an assert when
trying to move cursor back one char when it was already on the first
char of the buffer.
codepoint_width is locale dependent, and we could end up with it
returning a different value depending on the locale. It is better
to return a string of the wrong column length than fail on assert
in this case as we cannot fix it anyway.
Fixes#1489
This fix a bug when opening a file where a line has a lot of unprintable
chars (like a binary file) which was confusing Kakoune into considering
that the line length in column was negative.
