Disable piping buffer data into commands for fixing files where needed

autoload/ale/fix.vim

@@ -185,6 +185,7 @@ function! s:RunJob(options) abort
     let l:output_stream = a:options.output_stream
     let l:read_temporary_file = a:options.read_temporary_file
     let l:chain_with = a:options.chain_with
+    let l:read_buffer = a:options.read_buffer
 
     if empty(l:command)
         " If there's nothing further to chain the command with, stop here.
@@ -205,7 +206,11 @@ function! s:RunJob(options) abort
         return 1
     endif
 
-    let [l:temporary_file, l:command] = ale#command#FormatCommand(l:buffer, l:command, 1)
+    let [l:temporary_file, l:command] = ale#command#FormatCommand(
+    \   l:buffer,
+    \   l:command,
+    \   l:read_buffer,
+    \)
     call s:CreateTemporaryFileForJob(l:buffer, l:temporary_file, l:input)
 
     let l:command = ale#job#PrepareCommand(l:command)
@@ -309,13 +314,19 @@ function! s:RunFixer(options) abort
             let l:input = l:result
             let l:index += 1
         else
+            " Capitals are required for funcrefs.
+            let l:Chain_with = get(l:result, 'chain_with', v:null)
+            " Default to piping the buffer for the last fixer in the chain.
+            let l:read_buffer = get(l:result, 'read_buffer', l:Chain_with is v:null)
+
             let l:job_ran = s:RunJob({
             \   'buffer': l:buffer,
             \   'command': l:result.command,
             \   'input': l:input,
             \   'output_stream': get(l:result, 'output_stream', 'stdout'),
             \   'read_temporary_file': get(l:result, 'read_temporary_file', 0),
-            \   'chain_with': get(l:result, 'chain_with', v:null),
+            \   'read_buffer': l:read_buffer,
+            \   'chain_with': l:Chain_with,
             \   'callback_list': a:options.callback_list,
             \   'callback_index': l:index,
             \})

doc/ale.txt

@@ -479,6 +479,18 @@ are supported for running the commands.
                       that are cached. An empty List will be passed to the
                       next callback in the chain for the `output`.
 
+  `read_buffer`         An optional key for disabling reading the buffer.
+
+                      When set to `0`, ALE will not pipe the buffer's data
+                      into the command via stdin. This option is ignored and
+                      the buffer is not read when `read_temporary_file` is
+                      `1`.
+
+                      This option defaults to `0` when `chain_with` is defined
+                      as anything other than `v:null`, and defaults to `1`
+                      otherwise. This is so earlier commands in a chain
+                      do not receive the buffer's data by default.
+
                                                         *ale-fix-configuration*
 
 Synchronous functions and asynchronous jobs will be run in a sequence for

test/test_ale_fix.vader

@@ -110,6 +110,10 @@ Before:
     return {'command': has('win32') ? 'echo(' : 'echo'}
   endfunction
 
+  function! EchoLineNoPipe(buffer, output)
+    return {'command': 'echo new line', 'read_buffer': 0}
+  endfunction
+
   function! SetUpLinters()
     call ale#linter#Define('testft', {
     \ 'name': 'testlinter',
@@ -155,6 +159,7 @@ After:
   delfunction SetUpLinters
   delfunction GetLastMessage
   delfunction IgnoredEmptyOutput
+  delfunction EchoLineNoPipe
 
   call ale#test#RestoreDirectory()
 
@@ -540,6 +545,14 @@ Execute(Test fixing with chained callbacks):
   let g:ale_fixers.testft = ['FirstChainCallback']
   ALEFix
 
+  " The buffer shouldn't be piped in for earlier commands in the chain.
+  AssertEqual
+  \ [
+  \   string(ale#job#PrepareCommand('echo echoline')),
+  \   string(ale#job#PrepareCommand('echo echoline')),
+  \ ],
+  \ map(ale#history#Get(bufnr(''))[-2:-1], 'string(v:val.command)')
+
 Expect(The echoed line should be added):
   a
   b
@@ -583,3 +596,14 @@ Expect(The lines should be the same):
   a
   b
   c
+
+Execute(A temporary file shouldn't be piped into the command when disabled):
+  let g:ale_fixers.testft = ['EchoLineNoPipe']
+  ALEFix
+
+  AssertEqual
+  \ string(ale#job#PrepareCommand('echo new line')),
+  \ string(ale#history#Get(bufnr(''))[-1].command)
+
+Expect(The new line should be used):
+  new line