From ecd7abecc08ead5d8f055b26498e1c4a2a2c3065 Mon Sep 17 00:00:00 2001
From: w0rp <devw0rp@gmail.com>
Date: Thu, 27 Aug 2020 21:29:13 +0100
Subject: [PATCH] Fix #3319 - Force modifications to buffers

---
 autoload/ale/util.vim | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/autoload/ale/util.vim b/autoload/ale/util.vim
index 1f396377..05f11993 100644
--- a/autoload/ale/util.vim
+++ b/autoload/ale/util.vim
@@ -505,6 +505,13 @@ 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)
@@ -523,5 +530,9 @@ 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