elixir: Fix mix linter and support warnings

ale_linters/elixir/mix.vim

@@ -1,45 +1,84 @@
 " Author: evnu - https://github.com/evnu
 " Author: colbydehart - https://github.com/colbydehart
+" Author: toupeira - https://github.com/toupeira
 " Description: Mix compile checking for Elixir files
 
 function! ale_linters#elixir#mix#Handle(buffer, lines) abort
-    " Matches patterns like the following:
+    " Example output from Elixir 1.20.0:
     "
-    " Error format
-    " ** (CompileError) apps/sim/lib/sim/server.ex:87: undefined function update_in/4
+    "     warning: variable "a" is unused (if the variable is not meant to be used, prefix it with an underscore)
+    "     │
+    "  16 │     a = missing_var
+    "     │     ~
+    "     │
+    "     └─ lib/foo.ex:16:5: Foo.hello/0
     "
-    " TODO: Warning format
-    " warning: variable "foobar" does not exist and is being expanded to "foobar()", please use parentheses to remove the ambiguity or change the variable name
-    let l:pattern = '\v\(([^\)]+Error)\) ([^:]+):([^:]+): (.+)$'
+    "     warning: variable "b" is unused (if the variable is not meant to be used, prefix it with an underscore)
+    "     │
+    "  17 │     b = another_missing_var
+    "     │     ~
+    "     │
+    "     └─ lib/foo.ex:17:5: Foo.hello/0
+    "
+    "     error: undefined variable "another_missing_var"
+    "     │
+    "  17 │     b = another_missing_var
+    "     │         ^^^^^^^^^^^^^^^^^^^
+    "     │
+    "     └─ lib/foo.ex:17:9: Foo.hello/0
+    "
+    "     error: undefined variable "missing_var"
+    "     │
+    "  16 │     a = missing_var
+    "     │         ^^^^^^^^^^^
+    "     │
+    "     └─ lib/foo.ex:16:9: Foo.hello/0
+    "
+    "
+    " == Compilation error in file lib/foo.ex ==
+    " ** (CompileError) lib/foo.ex: cannot compile module Foo (errors have been logged)
+    "
+    " NOTE: The line with the error class is not captured because it always
+    " seems to be either a `CompileError` or a `SyntaxError`, with a generic
+    " message.
+    "
+    let l:pattern_text = '\v^    (warning|error): (.+)$'
+    let l:pattern_file = '\v^    └─ ([^ :]+):([0-9]+):([0-9]+)?'
+
+    let l:match_texts = ale#util#GetMatches(a:lines, l:pattern_text)
+    let l:match_files = ale#util#GetMatches(a:lines, l:pattern_file)
+
     let l:output = []
+    let l:index = 0
+
+    " Always add the full output as detail
+    let l:detail = join(a:lines, "\n")
 
-    for l:match in ale#util#GetMatches(a:lines, l:pattern)
-        let l:type = 'E'
-        let l:text = l:match[4]
+    for l:match_text in l:match_texts
+        let l:type = toupper(l:match_text[1][0])
+        let l:match_file = get(l:match_files, l:index, [])
 
         call add(l:output, {
         \   'bufnr': a:buffer,
-        \   'lnum': l:match[3] + 0,
-        \   'col': 0,
         \   'type': l:type,
-        \   'text': l:text,
+        \   'detail': l:detail,
+        \   'text': get(l:match_text, 2, v:null),
+        \   'lnum': get(l:match_file, 2, v:null),
+        \   'col': get(l:match_file, 3, v:null),
         \})
+
+        let l:index += 1
     endfor
 
     return l:output
 endfunction
 
-function! ale_linters#elixir#mix#GetCommand(buffer) abort
-    let l:temp_dir = ale#command#CreateDirectory(a:buffer)
-
-    return ale#Env('MIX_BUILD_PATH', l:temp_dir) . 'mix compile %s'
-endfunction
-
 call ale#linter#Define('elixir', {
 \   'name': 'mix',
 \   'executable': 'mix',
 \   'cwd': function('ale#handlers#elixir#FindMixProjectRoot'),
-\   'command': function('ale_linters#elixir#mix#GetCommand'),
+\   'command': '%e compile',
+\   'output_stream': 'stderr',
 \   'callback': 'ale_linters#elixir#mix#Handle',
 \   'lint_file': 1,
 \})

test/linter/test_elixir_mix.vader

@@ -1,19 +1,16 @@
 Before:
   call ale#assert#SetUpLinterTest('elixir', 'mix')
   call ale#test#SetFilename('../test-files/elixir/mix_project/lib/app.ex')
-  let g:env_prefix = ale#Env('MIX_BUILD_PATH', 'TEMP_DIR')
 
 After:
-  unlet! g:env_prefix
-
   call ale#assert#TearDownLinterTest()
 
 Execute(The default mix command should be correct):
   AssertLinterCwd ale#path#Simplify(g:dir . '/../test-files/elixir/mix_project')
-  AssertLinter 'mix', g:env_prefix . 'mix compile %s'
+  AssertLinter 'mix', 'mix compile'
 
 Execute(Build mix commands with an umbrella root):
   call ale#test#SetFilename('../test-files/elixir/umbrella_project/apps/mix_project/lib/app.ex')
 
   AssertLinterCwd ale#path#Simplify(g:dir . '/../test-files/elixir/umbrella_project')
-  AssertLinter 'mix', g:env_prefix . 'mix compile %s'
+  AssertLinter 'mix', 'mix compile'