Redirect stderr to log file by default (#174)

* Redirect stderr to log file by default, fixes #172

* Echom stderr output of formatter if verbose logging is set on

* Document new ‘stderr’ flag

* Remove stderr redirections from definitions, as they are added automatically now

README.md

@@ -82,6 +82,7 @@ Options:
 | `args`             | list of arguments                                                                                                 | \[]     | optional            |
 | `replace`          | overwrite the file, instead of updating the buffer                                                                | 0       | optional            |
 | `stdin`            | send data to the stdin of the formatter                                                                           | 0       | optional            |
+| `stderr`           | capture stderr output from formatter                                                                              | 0       | optional            |
 | `no_append`        | do not append the `path` of the file to the formatter command, used when the `path` is in the middle of a command | 0       | optional            |
 | `env`              | list of environment variable definitions to be prepended to the formatter command                                 | \[]     | optional            |
 | `valid_exit_codes` | list of valid exit codes for formatters who do not respect common unix practices                                  | \[0]    | optional            |

autoload/neoformat.vim

@@ -102,6 +102,11 @@ function! s:neoformat(bang, user_input, start_line, end_line) abort
         call neoformat#utils#log(v:shell_error)
 
         let process_ran_succesfully = index(cmd.valid_exit_codes, v:shell_error) != -1
+
+        if cmd.stderr_log != ''
+            call neoformat#utils#log('stderr output redirected to file' . cmd.stderr_log)
+            call neoformat#utils#log_file_content(cmd.stderr_log)
+        endif
         if process_ran_succesfully
             " 1. append the lines that are before and after the formatterd content
             let lines_after = getbufline(bufnr('%'), a:end_line + 1, '$')
@@ -229,6 +234,8 @@ function! s:generate_cmd(definition, filetype) abort
 
     let no_append = get(a:definition, 'no_append', 0)
     let using_stdin = get(a:definition, 'stdin', 0)
+    let using_stderr = get(a:definition, 'stderr', 0)
+    let stderr_log = ''
 
     let filename = expand('%:t')
 
@@ -250,10 +257,20 @@ function! s:generate_cmd(definition, filetype) abort
     let _fullcmd = join(inline_environment, ' ') . ' ' . executable . ' ' . join(args_expanded) . ' ' . (no_append ? '' : path)
     " make sure there aren't any double spaces in the cmd
     let fullcmd = join(split(_fullcmd))
+    if !using_stderr
+        if neoformat#utils#should_be_verbose()
+            let stderr_log = expand(tmp_dir . '/stderr.log')
+            let fullcmd = fullcmd . ' 2> ' . stderr_log
+        else
+            let stderr_log = ''
+            let fullcmd = fullcmd . ' 2> ' . '/dev/null'
+        endif
+    endif
 
     return {
         \ 'exe':       fullcmd,
         \ 'stdin':     using_stdin,
+        \ 'stderr_log': stderr_log,
         \ 'name':      a:definition.exe,
         \ 'replace':   get(a:definition, 'replace', 0),
         \ 'tmp_file_path': path,

autoload/neoformat/formatters/haskell.vim

@@ -13,7 +13,6 @@ endfunction
 function! neoformat#formatters#haskell#stylishhaskell() abort
     return {
         \ 'exe': 'stylish-haskell',
-        \ 'args': ['2>/dev/null'],
         \ 'stdin': 1,
         \ }
 endfunction

autoload/neoformat/formatters/python.vim

@@ -39,7 +39,7 @@ function! neoformat#formatters#python#black() abort
     return {
                 \ 'exe': 'black',
                 \ 'stdin': 1,
-                \ 'args': ['-', '2>/dev/null'],
+                \ 'args': ['-'],
                 \ }
 endfunction
 

autoload/neoformat/formatters/ruby.vim

@@ -22,5 +22,6 @@ function! neoformat#formatters#ruby#rubocop() abort
         \ 'exe': 'rubocop',
         \ 'args': ['--auto-correct', '--stdin', '%:p', '2>/dev/null', '|', 'sed "1,/^====================$/d"'],
         \ 'stdin': 1,
+        \ 'stderr': 1
         \ }
 endfunction

autoload/neoformat/utils.vim

@@ -1,12 +1,15 @@
 function! neoformat#utils#log(msg) abort
-    if !exists('g:neoformat_verbose')
-        let g:neoformat_verbose = 0
-    endif
-    if &verbose || g:neoformat_verbose
+    if neoformat#utils#should_be_verbose()
         return s:better_echo(a:msg)
     endif
 endfunction
 
+function! neoformat#utils#log_file_content(path) abort
+    if neoformat#utils#should_be_verbose()
+        return s:better_echo(readfile(a:path))
+    endif
+endfunction
+
 function! neoformat#utils#warn(msg) abort
     echohl WarningMsg | call s:better_echo(a:msg) | echohl NONE
 endfunction
@@ -18,6 +21,13 @@ function! neoformat#utils#msg(msg) abort
     return s:better_echo(a:msg)
 endfunction
 
+function! neoformat#utils#should_be_verbose() abort
+    if !exists('g:neoformat_verbose')
+        let g:neoformat_verbose = 0
+    endif
+    return &verbose || g:neoformat_verbose
+endfunction
+
 function! s:better_echo(msg) abort
     if type(a:msg) != type('')
         echom 'Neoformat: ' . string(a:msg)

doc/neoformat.txt

@@ -89,6 +89,9 @@ Options:
 | `args`      | list of arguments | default: [] | optional
 | `replace`   | overwrite the file, instead of updating the buffer | default: 0 | optional
 | `stdin`     | send data to the stdin of the formatter | default 0 | optional
+| `stderr`    | used to specify whether stderr output should be read along with
+	     the stdin, otherwise redirects stderr to `stderr.log` file in neoformat's
+	     temporary directory | default 0 | optional
 | `no_append` | do not append the `path` of the file to the formatter command,
 	     used when the `path` is in the middle of a command | default: 0 |
 	     optional