Add hdevtools linter for haskell

This adds support for the hdevtools haskell linter
https://github.com/hdevtools/hdevtools

The output for hdevtools is near identical to the ghc output so this
also extracts the ghc handler into the handle file and adds tests

* Add testing for previous major release of ghc

ale_linters/haskell/ghc.vim

@@ -1,10 +1,6 @@
 " Author: w0rp <devw0rp@gmail.com>
 " Description: ghc for Haskell files
 
-if exists('g:loaded_ale_linters_haskell_ghc')
-    finish
-endif
-
 call ale#linter#Define('haskell', {
 \   'name': 'ghc',
 \   'output_stream': 'stderr',

ale_linters/haskell/hdevtools.vim

@@ -1,4 +1,4 @@
-" Author: w0rp <devw0rp@gmail.com>
+" Author: rob-b
 " Description: hdevtools for Haskell files
 
 call ale#linter#Define('haskell', {

autoload/ale/handlers.vim

@@ -224,18 +224,15 @@ endfunction
 function! ale#handlers#HandleGhcFormat(buffer, lines) abort
     " Look for lines like the following.
     "
-    " /dev/stdin:28:26: Not in scope: `>>>>>'
-     "Appoint/Lib.hs:8:1: warning:
-    let l:pattern = '^[^:]\+:\(\d\+\):\(\d\+\):\s\{-}\(warning\|error\)\(.\+\)$'
+    "Appoint/Lib.hs:8:1: warning:
+    "Appoint/Lib.hs:8:1:
+    let l:pattern = '^[^:]\+:\(\d\+\):\(\d\+\):\(.*\)\?$'
     let l:output = []
 
     let l:corrected_lines = []
     for l:line in a:lines
         if len(matchlist(l:line, l:pattern)) > 0
             call add(l:corrected_lines, l:line)
-            if l:line !~# '\(: error\|warning\):$'
-                call add(l:corrected_lines, '')
-            endif
         elseif l:line ==# ''
             call add(l:corrected_lines, l:line)
         else
@@ -253,13 +250,24 @@ function! ale#handlers#HandleGhcFormat(buffer, lines) abort
             continue
         endif
 
+        let l:errors = matchlist(l:match[3], '\(warning:\|error:\)\(.*\)')
+
+        if len(l:errors) > 0
+          let l:type = l:errors[1]
+          let l:text = l:errors[2]
+        else
+          let l:type = ''
+          let l:text = l:match[3]
+        end
+        let l:type = l:type ==# '' ? 'E' : toupper(l:type[0])
+
         call add(l:output, {
         \   'bufnr': a:buffer,
         \   'lnum': l:match[1] + 0,
         \   'vcol': 0,
         \   'col': l:match[2] + 0,
-        \   'text': l:match[4],
-        \   'type': toupper(l:match[3][0]),
+        \   'text': l:text,
+        \   'type': l:type,
         \   'nr': -1,
         \})
     endfor

test/test_ghc_handler.vader

@@ -2,7 +2,7 @@ Execute(The ghc handler should handle hdevtools output):
 
   AssertEqual
   \ [
-  \   {'lnum': 147, 'bufnr': 12, 'vcol': 0, 'nr': -1, 'type': 'W', 'col': 62, 'text': ':• Couldnt match type ‘a -> T.Text’ with ‘T.Text’ Expected type: [T.Text]'},
+  \   {'lnum': 147, 'bufnr': 12, 'vcol': 0, 'nr': -1, 'type': 'W', 'col': 62, 'text': '• Couldnt match type ‘a -> T.Text’ with ‘T.Text’ Expected type: [T.Text]'},
   \ ],
   \ ale#handlers#HandleGhcFormat(12, [
   \ '/path/to/foo.hs:147:62: warning:',
@@ -11,12 +11,12 @@ Execute(The ghc handler should handle hdevtools output):
   \ ])
 
 
-Execute(The ghc handler should handle ghc output):
+Execute(The ghc handler should handle ghc 8 output):
 
   AssertEqual
   \ [
-  \   {'lnum': 6, 'bufnr': 47, 'vcol': 0, 'nr': -1, 'type': 'E', 'col': 1, 'text': ': Failed to load interface for ‘GitHub.Data’ Use -v to see a list of the files searched for.'},
-  \   {'lnum': 7, 'bufnr': 47, 'vcol': 0, 'nr': -1, 'type': 'E', 'col': 1, 'text': ': Failed to load interface for ‘GitHub.Endpoints.PullRequests’ Use -v to see a list of the files searched for.'},
+  \   {'lnum': 6, 'bufnr': 47, 'vcol': 0, 'nr': -1, 'type': 'E', 'col': 1, 'text': ' Failed to load interface for ‘GitHub.Data’ Use -v to see a list of the files searched for.'},
+  \   {'lnum': 7, 'bufnr': 47, 'vcol': 0, 'nr': -1, 'type': 'W', 'col': 1, 'text': ' Failed to load interface for ‘GitHub.Endpoints.PullRequests’ Use -v to see a list of the files searched for.'},
   \ ],
   \ ale#handlers#HandleGhcFormat(47, [
   \ '',
@@ -24,7 +24,19 @@ Execute(The ghc handler should handle ghc output):
   \ '    Failed to load interface for ‘GitHub.Data’',
   \ '    Use -v to see a list of the files searched for.',
   \ '',
-  \ 'src/Appoint/Lib.hs:7:1: error:',
+  \ 'src/Appoint/Lib.hs:7:1: warning:',
   \ '    Failed to load interface for ‘GitHub.Endpoints.PullRequests’',
   \ '    Use -v to see a list of the files searched for.',
   \ ])
+
+
+Execute(The ghc handler should handle ghc 7 output):
+
+  AssertEqual
+  \ [
+  \   {'lnum': 168, 'bufnr': 47, 'vcol': 0, 'nr': -1, 'type': 'E', 'col': 1, 'text': ' parse error (possibly incorrect indentation or mismatched brackets)'},
+  \ ],
+  \ ale#handlers#HandleGhcFormat(47, [
+  \ 'src/Main.hs:168:1:',
+  \ '    parse error (possibly incorrect indentation or mismatched brackets)',
+  \ ])