Complain about incorrect uses of expand('%...')

ale_linters/go/gometalinter.vim

@@ -6,7 +6,9 @@ if !exists('g:ale_go_gometalinter_options')
 endif
 
 function! ale_linters#go#gometalinter#GetCommand(buffer) abort
-    return 'gometalinter --include=''^' . expand('%:p') . '.*$'' '
+    let l:filename = expand('#' . a:buffer . ':p')
+
+    return 'gometalinter --include=''^' . l:filename . '.*$'' '
     \   . ale#Var(a:buffer, 'go_gometalinter_options')
     \   . ' ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h'))
 endfunction

autoload/ale/pattern_options.vim

@@ -2,7 +2,7 @@
 " Description: Set options in files based on regex patterns.
 
 function! ale#pattern_options#SetOptions() abort
-    let l:filename = expand('%:p')
+    let l:filename = expand('%:p') " no-custom-checks
     let l:options = {}
 
     for l:pattern in keys(g:ale_pattern_options)

custom-checks

@@ -55,6 +55,7 @@ check_errors() {
             RETURN_CODE=1
             echo "$match $message"
         done < <(grep -n "$regex" "$directory"/**/*.vim \
+            | grep -v 'no-custom-checks' \
             | grep -o '^[^:]\+:[0-9]\+' \
             | sed 's:^\./::')
     done
@@ -77,5 +78,6 @@ check_errors $'\t' 'Use four spaces, not tabs'
 # This check should prevent people from using a particular inconsistent name.
 check_errors 'let g:ale_\w\+_\w\+_args =' 'Name your option g:ale_<filetype>_<lintername>_options instead'
 check_errors 'shellescape(' 'Use ale#Escape instead of shellescape'
+check_errors "expand(['\"]%" "Use expand('#' . a:buffer . '...') instead. You might get a filename for the wrong buffer."
 
 exit $RETURN_CODE