On 12 April 2016, Yegappan Lakshmanan <[email protected]> wrote:
> LCD 47 <[email protected]> wrote:
[...]
> > Can you please give an example when setting the cursor before an
> > autocmd would "break functionality that depends on these events"?
> >
>
> Consider for example, you have a BufReadPre autocommand that either
> uncompresses a file or performs a network operation to load the
> buffer. If these autocommands are delayed, then the buffer cannot be
> loaded and the location list cannot position the cursor.
>
> Note that selecting an entry from the location can trigger various
> autocommands depending on whether the buffer is already loaded in a
> window or hidden or not in memory.
>
> Also, depending on the 'switchbuf' setting, selecting an entry from
> the quickfix list can create a new window or a tab, jump to a tab or
> window. This will trigger additional autocommand events. You cannot
> delay autocommands in these cases (for example TabEnter/WinEnter).
Right, this actually makes the case that patch 1640 is the wrong
fix, and also that the problem I'm pointing to has nothing to do with
patch 1592.
Currently .ll when jumping to file "example.txt" line N goes roughly
like this:
(1) load "example.txt"
(2) trigger autocmds for "example.txt"
(3) go to line N.
If the loclist changes between (2) and (3) there's trouble because
you're reading from free()d memory. For this reason, your patch 1640
adds a safeguard between (2) and (3), making sure the loclist is still
the same.
This breaks autocmds for "example.txt" that override the current
loclist. It also breaks autocmds for "example.txt" that modify the
contents of "example.txt", because line N from .ll might no longer be
the same after the autocmds.
I suggest swapping (2) and (3), that is, delaying autocmds for
"example.txt" until the jump is finished:
(1') load "example.txt"
(2') go to line N
(3') trigger autocmds for "example.txt".
With this approach there is no need to care whether autocmds change
the current loclist or not, since the old loclist is no longer needed,
and can be safely discarded at that point.
The cursor also stand more chances to stay on the right line if the
autocmds change the contents of the buffer, since Vim can keep track of
it.
And finally, setting the cursor before running the autocmds is
highly unlikely to change the conditions that trigger said autocmds.
Reference: quickfix.c lines 1857-1969 in 1724.
Summary: 1640 was the wrong fix. It breaks existing plugins, such
as syntastic and vim-go, which now have to find workarounds.
/lcd
--
--
You received this message from the "vim_dev" maillist.
Do not top-post! Type your reply below the text you are replying to.
For more information, visit http://www.vim.org/maillist.php
---
You received this message because you are subscribed to the Google Groups
"vim_dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
