#392 Handle clang header errors too

autoload/ale/handlers/gcc.vim

@@ -14,8 +14,12 @@ function! s:AddIncludedErrors(output, include_lnum, include_lines) abort
     endif
 endfunction
 
+function! s:IsHeaderFile(filename) abort
+    return a:filename =~? '\v\.(h|hpp)$'
+endfunction
+
 function! ale#handlers#gcc#HandleGCCFormat(buffer, lines) abort
-    let l:include_pattern = '\v^(In file included | *)from [^:]*:(\d+)'
+    let l:include_pattern = '\v^(In file included | *)from ([^:]*):(\d+)'
     let l:include_lnum = 0
     let l:include_lines = []
     let l:included_filename = ''
@@ -41,9 +45,15 @@ function! ale#handlers#gcc#HandleGCCFormat(buffer, lines) abort
                 " need to collect it.
                 call add(l:include_lines, l:line)
             else
-                " Get the line number out of the parsed include line,
-                " and reset the other variables.
-                let l:include_lnum = str2nr(l:include_match[2])
+                " GCC and clang return the lists of files in different orders,
+                " so we'll only grab the line number from lines which aren't
+                " header files.
+                if !s:IsHeaderFile(l:include_match[2])
+                    " Get the line number out of the parsed include line,
+                    " and reset the other variables.
+                    let l:include_lnum = str2nr(l:include_match[3])
+                endif
+
                 let l:include_lines = []
                 let l:included_filename = ''
             endif

test/handler/test_clang_handler.vader

@@ -0,0 +1,23 @@
+Execute(clang errors from included files should be parsed correctly):
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 3,
+  \     'type': 'E',
+  \     'text': 'Problems were found in the header (See :ALEDetail)',
+  \     'detail': join([
+  \       './b.h:1:1: error: expected identifier or ''(''',
+  \       '{{{',
+  \       '^',
+  \       '1 error generated.',
+  \     ], "\n"),
+  \   },
+  \ ],
+  \ ale#handlers#gcc#HandleGCCFormat(347, [
+  \   'In file included from test.c:3:',
+  \   'In file included from ./a.h:1:',
+  \   './b.h:1:1: error: expected identifier or ''(''',
+  \   '{{{',
+  \   '^',
+  \   '1 error generated.',
+  \ ])