Add the buffer number as an argument to sy#stop()

sy#stop() is called by the BufDelete autocmd so b: variables may not
correspond to the buffer actually being deleted.  Instead, we must use
<abuf> to determine which buffer is being deleted and pass that into
sy#stop().

There are some ripple effects, causing sy#sign#remove_all_signs to also
gain a buffer number argument.

Signed-off-by: James McCoy <vega.james@gmail.com>

autoload/sy.vim

@@ -88,15 +88,16 @@ function! sy#start() abort
 endfunction
 
 " Function: #stop {{{1
-function! sy#stop() abort
-  if !exists('b:sy')
+function! sy#stop(bufnr) abort
+  let sy = getbufvar(a:bufnr, 'sy')
+  if empty(sy)
     return
   endif
 
-  call sy#sign#remove_all_signs()
+  call sy#sign#remove_all_signs(a:bufnr)
 
   augroup signify
-    execute printf('autocmd! * <buffer=%d>', b:sy.buffer)
+    execute printf('autocmd! * <buffer=%d>', sy.buffer)
   augroup END
 endfunction
 
@@ -108,7 +109,7 @@ function! sy#toggle() abort
   endif
 
   if b:sy.active
-    call sy#stop()
+    call sy#stop(b:sy.buffer)
     let b:sy.active = 0
     let b:sy.stats = [-1, -1, -1]
   else

autoload/sy/sign.vim

@@ -189,15 +189,17 @@ function! sy#sign#process_diff(diff) abort
 endfunction
 
 " Function: #remove_all_signs {{{1
-function! sy#sign#remove_all_signs() abort
-  for hunk in b:sy.hunks
+function! sy#sign#remove_all_signs(bufnr) abort
+  let sy = getbufvar(a:bufnr, 'sy')
+
+  for hunk in sy.hunks
     for id in hunk.ids
       execute 'sign unplace' id
     endfor
   endfor
 
-  let b:sy.hunks = []
-  let b:sy.stats = [0, 0, 0]
+  let sy.hunks = []
+  let sy.stats = [0, 0, 0]
 endfunction
 
 " Function: s:add_sign {{{1

plugin/signify.vim

@@ -17,7 +17,7 @@ augroup signify
   autocmd!
 
   autocmd BufRead,BufWritePost * call sy#start()
-  autocmd BufDelete            * call sy#stop()
+  autocmd BufDelete            * call sy#stop(expand('<abuf>'))
 
   autocmd QuickFixCmdPre  *vimgrep* let g:signify_locked = 1
   autocmd QuickFixCmdPost *vimgrep* let g:signify_locked = 0