#894 - Replace ugly temporary filenames for Haskell problems with the buffer's basename

autoload/ale/handlers/haskell.vim

@@ -1,11 +1,24 @@
 " Author: w0rp <devw0rp@gmail.com>
 " Description: Error handling for the format GHC outputs.
 
+" Remember the directory used for temporary files for Vim.
+let s:temp_dir = fnamemodify(tempname(), ':h')
+" Build part of a regular expression for matching ALE temporary filenames.
+let s:temp_regex_prefix =
+\   '\M'
+\   . substitute(s:temp_dir, '\\', '\\\\', 'g')
+\   . '\.\{-}'
+
 function! ale#handlers#haskell#HandleGHCFormat(buffer, lines) abort
     " Look for lines like the following.
     "
     "Appoint/Lib.hs:8:1: warning:
     "Appoint/Lib.hs:8:1:
+    let l:basename = expand('#' . a:buffer . ':t')
+    " Build a complete regular expression for replacing temporary filenames
+    " in Haskell error messages with the basename for this file.
+    let l:temp_filename_regex = s:temp_regex_prefix . l:basename
+
     let l:pattern = '\v^([a-zA-Z]?:?[^:]+):(\d+):(\d+):(.*)?$'
     let l:output = []
 
@@ -51,6 +64,9 @@ function! ale#handlers#haskell#HandleGHCFormat(buffer, lines) abort
             let l:type = 'E'
         endif
 
+        " Replace temporary filenames in problem messages with the basename
+        let l:text = substitute(l:text, l:temp_filename_regex, l:basename, 'g')
+
         call add(l:output, {
         \   'lnum': l:match[2] + 0,
         \   'col': l:match[3] + 0,

test/handler/test_ghc_mod_handler.vader

@@ -21,10 +21,17 @@ Execute(HandleGhcFormat should handle ghc-mod problems):
   \     'type': 'W',
   \     'text': 'Eta reduceFound:  myFunc x = succ xWhy not:  myFunc = succ',
   \   },
+  \   {
+  \     'lnum': 28,
+  \     'col': 28,
+  \     'type': 'W',
+  \     'text': 'Defaulting the following constraints to type ‘Integer’ (Num a0) arising from the literal ‘3’ at check2.hs:28:28 (Eq a0) arising from a use of ‘lookup’ at check2.hs:28:21-28 • In the first argument of ‘lookup’, namely ‘3’ In the expression: lookup 3 In the second argument of ‘fmap’, namely ‘(lookup 3 $ zip [1, 2, 3] [4, 5, 6])''’'
+  \   },
   \ ],
   \ ale#handlers#haskell#HandleGHCFormat(bufnr(''), [
   \   'check2.hs:2:1:Failed to load interface for ‘Missing’Use -v to see a list of the files searched for.',
   \   'check2.hs:2:1: Suggestion: Use camelCaseFound:  my_variable = ...Why not:  myVariable = ...',
   \   'check2.hs:6:1: Warning: Eta reduceFound:  myFunc x = succ xWhy not:  myFunc = succ',
   \   'xxx.hs:6:1: Warning: Eta reduceFound:  myFunc x = succ xWhy not:  myFunc = succ',
+  \   printf("check2.hs:28:28: Warning: Defaulting the following constraints to type ‘Integer’ (Num a0) arising from the literal ‘3’ at %s/check2.hs:28:28 (Eq a0) arising from a use of ‘lookup’ at %s/check2.hs:28:21-28 • In the first argument of ‘lookup’, namely ‘3’ In the expression: lookup 3 In the second argument of ‘fmap’, namely ‘(lookup 3 $ zip [1, 2, 3] [4, 5, 6])'’", tempname(), tempname()),
   \ ])