Fix --file-filter option on cppcheck command

autoload/ale/handlers/cppcheck.vim

@@ -46,13 +46,11 @@ function! ale#handlers#cppcheck#GetCompileCommandsOptions(buffer) abort
     " If we find it, we'll `cd` to where the compile_commands.json file is,
     " then use the file to set up import paths, etc.
     let [l:dir, l:json_path] = ale#c#FindCompileCommands(a:buffer)
-    let b:root_index = len(l:dir) + 1
-    let b:buffer_file= bufname(a:buffer)
 
     " By default, cppcheck processes every config in compile_commands.json.
     " Use --file-filter to limit to just the buffer file.
     return !empty(l:json_path)
-    \   ? '--project=' . ale#Escape(l:json_path[b:root_index: ]) . ' --file-filter=' . ale#Escape(b:buffer_file[b:root_index:])
+    \   ? '--project=' . ale#Escape(l:json_path[len(l:dir) + 1: ]) . ' --file-filter=' . ale#Escape(bufname(a:buffer))
     \   : ''
 endfunction
 

test/linter/test_c_cppcheck.vader

@@ -3,6 +3,7 @@ Before:
   let b:command_tail = ' -q --language=c --template=' . ale#Escape('{file}:{line}:{column}: {severity}:{inconclusive:inconclusive:} {message} [{id}]\\n{code}') . ' --enable=style -I' . ale#Escape(ale#path#Simplify(g:dir)) .' %t'
 
 After:
+  unlet! b:rel_file_path
   unlet! b:command_tail
   call ale#assert#TearDownLinterTest()
 
@@ -15,25 +16,27 @@ Execute(The executable should be configurable):
   AssertLinter 'foobar', ale#Escape('foobar') . b:command_tail
 
 Execute(cppcheck for C should detect compile_commands.json files):
-  call ale#test#SetFilename('../test-files/cppcheck/one/foo.c')
+  let b:rel_file_path = '../test-files/cppcheck/one/foo.c'
+  call ale#test#SetFilename(b:rel_file_path)
 
   AssertLinterCwd ale#path#Simplify(g:dir . '/../test-files/cppcheck/one')
   AssertLinter 'cppcheck', ale#Escape('cppcheck')
   \   . ' -q --language=c'
   \   . ' --template=' . ale#Escape('{file}:{line}:{column}: {severity}:{inconclusive:inconclusive:} {message} [{id}]\\n{code}')
   \   . ' --project=' . ale#Escape('compile_commands.json')
-  \   . ' --file-filter=' . ale#Escape('foo.c')
+  \   . ' --file-filter=' . ale#Escape(ale#test#GetFilename(b:rel_file_path))
   \   . ' --enable=style %t'
 
 Execute(cppcheck for C should detect compile_commands.json files in build directories):
-  call ale#test#SetFilename('../test-files/cppcheck/with_build_dir/foo.c')
+  let b:rel_file_path = '../test-files/cppcheck/with_build_dir/foo.c'
+  call ale#test#SetFilename(b:rel_file_path)
 
   AssertLinterCwd ale#path#Simplify(g:dir . '/../test-files/cppcheck/with_build_dir')
   AssertLinter 'cppcheck', ale#Escape('cppcheck')
   \   . ' -q --language=c'
   \   . ' --template=' . ale#Escape('{file}:{line}:{column}: {severity}:{inconclusive:inconclusive:} {message} [{id}]\\n{code}')
   \   . ' --project=' . ale#Escape(ale#path#Simplify('build/compile_commands.json'))
-  \   . ' --file-filter=' . ale#Escape('foo.c')
+  \   . ' --file-filter=' . ale#Escape(ale#test#GetFilename(b:rel_file_path))
   \   . ' --enable=style %t'
 
 Execute(cppcheck for C should include file dir if compile_commands.json file is not found):

test/linter/test_cpp_cppcheck.vader

@@ -9,6 +9,7 @@ After:
     set buftype=nofile
   endif
 
+  unlet! b:rel_file_path
   unlet! b:command_tail
   call ale#assert#TearDownLinterTest()
 
@@ -21,25 +22,27 @@ Execute(The executable should be configurable):
   AssertLinter 'foobar', ale#Escape('foobar') . b:command_tail
 
 Execute(cppcheck for C++ should detect compile_commands.json files):
-  call ale#test#SetFilename('../test-files/cppcheck/one/foo.cpp')
+  let b:rel_file_path = '../test-files/cppcheck/one/foo.cpp'
+  call ale#test#SetFilename(b:rel_file_path)
 
   AssertLinterCwd ale#path#Simplify(g:dir . '/../test-files/cppcheck/one')
   AssertLinter 'cppcheck', ale#Escape('cppcheck')
   \   . ' -q --language=c++'
   \   . ' --template=' . ale#Escape('{file}:{line}:{column}: {severity}:{inconclusive:inconclusive:} {message} [{id}]\\n{code}')
   \   . ' --project=' . ale#Escape('compile_commands.json')
-  \   . ' --file-filter=' . ale#Escape('foo.cpp')
+  \   . ' --file-filter=' . ale#Escape(ale#test#GetFilename(b:rel_file_path))
   \   . ' --enable=style %t'
 
 Execute(cppcheck for C++ should detect compile_commands.json files in build directories):
-  call ale#test#SetFilename('../test-files/cppcheck/with_build_dir/foo.cpp')
+  let b:rel_file_path = '../test-files/cppcheck/with_build_dir/foo.cpp'
+  call ale#test#SetFilename(b:rel_file_path)
 
   AssertLinterCwd ale#path#Simplify(g:dir . '/../test-files/cppcheck/with_build_dir')
   AssertLinter 'cppcheck', ale#Escape('cppcheck')
   \   . ' -q --language=c++'
   \   . ' --template=' . ale#Escape('{file}:{line}:{column}: {severity}:{inconclusive:inconclusive:} {message} [{id}]\\n{code}')
   \   . ' --project=' . ale#Escape(ale#path#Simplify('build/compile_commands.json'))
-  \   . ' --file-filter=' . ale#Escape('foo.cpp')
+  \   . ' --file-filter=' . ale#Escape(ale#test#GetFilename(b:rel_file_path))
   \   . ' --enable=style %t'
 
 Execute(cppcheck for C++ should include file dir if compile_commands.json file is not found):