#3319 - Try to modify buffers later for ALEFix

autoload/ale/fix.vim

@@ -15,6 +15,7 @@ function! ale#fix#ApplyQueuedFixes(buffer) abort
 
     call remove(g:ale_fix_buffer_data, a:buffer)
 
+    try
         if l:data.changes_made
             let l:new_lines = ale#util#SetBufferContents(a:buffer, l:data.output)
 
@@ -31,6 +32,12 @@ function! ale#fix#ApplyQueuedFixes(buffer) abort
                 endif
             endif
         endif
+    catch /E21/
+        " If we cannot modify the buffer now, try again later.
+        let g:ale_fix_buffer_data[a:buffer] = l:data
+
+        return
+    endtry
 
     if l:data.should_save
         let l:should_lint = ale#Var(a:buffer, 'fix_on_save')

autoload/ale/util.vim

@@ -505,13 +505,6 @@ function! ale#util#SetBufferContents(buffer, lines) abort
     \   : a:lines
     let l:first_line_to_remove = len(l:new_lines) + 1
 
-    " We'll temporarily make a buffer modifiable, to force edits.
-    let l:modifiable = getbufvar(a:buffer, '&modifiable')
-
-    if !l:modifiable
-        call setbufvar(a:buffer, '&modifiable', 1)
-    endif
-
     " Use a Vim API for setting lines in other buffers, if available.
     if l:has_bufline_api
         call setbufline(a:buffer, 1, l:new_lines)
@@ -530,9 +523,5 @@ function! ale#util#SetBufferContents(buffer, lines) abort
         call setline(1, l:new_lines)
     endif
 
-    if !l:modifiable
-        call setbufvar(a:buffer, '&modifiable', 0)
-    endif
-
     return l:new_lines
 endfunction

test/fix/test_ale_fix.vader

@@ -727,6 +727,19 @@ Expect(There should be only two lines):
   a
   b
 
+Execute(ALEFix should modify a buffer that is not modifiable, if it becomes modifable later):
+  let g:ale_fixers.testft = ['RemoveLastLineOneArg']
+
+  set nomodifiable
+  ALEFix
+  call ale#test#FlushJobs()
+  set modifiable
+  call ale#fix#ApplyQueuedFixes(bufnr(''))
+
+Expect(There should be only two lines):
+  a
+  b
+
 Execute(b:ale_fix_on_save = 1 should override g:ale_fix_on_save = 0):
   let g:ale_fix_on_save = 0
   let b:ale_fix_on_save = 1