#505 - Do not lint files on enter if the option for linting when the filetype changed is on

autoload/ale/events.vim

@@ -33,7 +33,13 @@ endfunction
 function! ale#events#FileTypeEvent(buffer, new_filetype) abort
     let l:filetype = getbufvar(a:buffer, 'ale_original_filetype', '')
 
-    if a:new_filetype isnot# l:filetype
+    " If we're setting the filetype for the first time after it was blank,
+    " and the option for linting on enter is off, then we should set this
+    " filetype as the original filetype. Otherwise ALE will still appear to
+    " lint files because of the BufEnter event, etc.
+    if empty(l:filetype) && !ale#Var(a:buffer, 'lint_on_enter')
+        call setbufvar(a:buffer, 'ale_original_filetype', a:new_filetype)
+    elseif a:new_filetype isnot# l:filetype
         call ale#Queue(300, 'lint_file', a:buffer)
     endif
 endfunction

doc/ale.txt

@@ -683,6 +683,10 @@ g:ale_lint_on_filetype_changed                 *g:ale_lint_on_filetype_changed*
   changed quickly several times in a row, but resulting in only one lint
   cycle.
 
+  If |g:ale_lint_on_enter| is set to `0`, then ALE will not lint a file when
+  the filetype is initially set. Otherwise ALE would still lint files when
+  buffers are opened, and the option for doing so is turned off.
+
 
 g:ale_lint_on_save                                         *g:ale_lint_on_save*
 

test/sign/test_sign_placement.vader

@@ -3,6 +3,9 @@ Before:
 
   let g:ale_set_signs = 1
 
+  call ale#linter#Reset()
+  sign unplace *
+
   function! GenerateResults(buffer, output)
     return [
     \ {

test/test_lint_on_filetype_changed.vader

@@ -3,6 +3,8 @@ Before:
 
   let g:queue_calls = []
 
+  unlet! b:ale_lint_on_enter
+
   function! ale#Queue(...)
     call add(g:queue_calls, a:000)
   endfunction
@@ -10,6 +12,7 @@ Before:
 After:
   Restore
 
+  unlet! b:ale_lint_on_enter
   unlet! g:queue_calls
 
   " Reload the ALE code to load the real function again.
@@ -45,3 +48,27 @@ Execute(Linting should be queued when the filetype changes):
   call ale#events#FileTypeEvent(bufnr(''), 'bazboz')
 
   AssertEqual [[300, 'lint_file', bufnr('')]], g:queue_calls
+
+Execute(Linting shouldn't be done when the original filetype was blank and linting on enter is off):
+  let b:ale_lint_on_enter = 0
+  let b:ale_original_filetype = ''
+
+  call ale#events#FileTypeEvent(bufnr(''), 'bazboz')
+
+  AssertEqual [], g:queue_calls
+
+Execute(Linting should be done when the original filetype was blank and linting on enter is on):
+  let b:ale_lint_on_enter = 1
+  let b:ale_original_filetype = ''
+
+  call ale#events#FileTypeEvent(bufnr(''), 'bazboz')
+
+  AssertEqual [[300, 'lint_file', bufnr('')]], g:queue_calls
+
+Execute(The new filetype should become the "original" one if the original was blank and linting on enter is off):
+  let b:ale_lint_on_enter = 0
+  let b:ale_original_filetype = ''
+
+  call ale#events#FileTypeEvent(bufnr(''), 'bazboz')
+
+  AssertEqual 'bazboz', b:ale_original_filetype