Allow clangformat to use a local style file (#3587)

* Allow clangformat to use a local style file.

* Add tests.

* Fix Vint issue.

* Improve explanation of feature in documentation.

* Fix failing test.

The test was checking the wrong directory.

4 files changed, 88 insertions, 1 deletions

diff --git a/autoload/ale/fixers/clangformat.vim b/autoload/ale/fixers/clangformat.vim
index ea5743a5..ecff080a 100644
--- a/autoload/ale/fixers/clangformat.vim
+++ b/autoload/ale/fixers/clangformat.vim
@@ -5,6 +5,8 @@ scriptencoding utf-8
 call ale#Set('c_clangformat_executable', 'clang-format')
 call ale#Set('c_clangformat_use_global', get(g:, 'ale_use_global_executables', 0))
 call ale#Set('c_clangformat_options', '')
+call ale#Set('c_clangformat_style_option', '')
+call ale#Set('c_clangformat_use_local_file', 0)
 
 function! ale#fixers#clangformat#GetExecutable(buffer) abort
     return ale#node#FindExecutable(a:buffer, 'c_clangformat', [
@@ -16,6 +18,24 @@ function! ale#fixers#clangformat#Fix(buffer) abort
     let l:executable = ale#Escape(ale#fixers#clangformat#GetExecutable(a:buffer))
     let l:filename = ale#Escape(bufname(a:buffer))
     let l:options = ale#Var(a:buffer, 'c_clangformat_options')
+    let l:style_option = ale#Var(a:buffer, 'c_clangformat_style_option')
+    let l:use_local_file = ale#Var(a:buffer, 'c_clangformat_use_local_file')
+
+    if l:style_option isnot# ''
+        let l:style_option = '-style=' . "'" . l:style_option . "'"
+    endif
+
+    if l:use_local_file
+        let l:config = ale#path#FindNearestFile(a:buffer, '.clang-format')
+
+        if !empty(l:config)
+            let l:style_option = '-style=file'
+        endif
+    endif
+
+    if l:style_option isnot# ''
+        let l:options .= ' ' . l:style_option
+    endif
 
     let l:command = l:executable . ' --assume-filename=' . l:filename
 
diff --git a/doc/ale-c.txt b/doc/ale-c.txt
index b0d94b8e..3b9fbc44 100644
--- a/doc/ale-c.txt
+++ b/doc/ale-c.txt
@@ -202,7 +202,45 @@ g:ale_c_clangformat_options                       *g:ale_c_clangformat_options*
   Type: |String|
   Default: `''`
 
-  This variable can be change to modify flags given to clang-format.
+  This variable can be changed to modify flags given to clang-format.
+
+
+g:ale_c_clangformat_style_option             *g:ale_c_clangformat_style_option*
+                                             *b:ale_c_clangformat_style_option*
+  Type: |String|
+  Default: `''`
+
+  This variable can be changed to modify only the style flag given to
+  clang-format. The contents of the variable are passed directly to the -style
+  flag of clang-format.
+
+  Example: >
+      {
+    \ BasedOnStyle:                        Microsoft,
+    \ ColumnLimit:                         80,
+    \ AllowShortBlocksOnASingleLine:       Always,
+    \ AllowShortFunctionsOnASingleLine:    Inline,
+    \ }
+<
+  If you set this variable, ensure you don't modify -style in
+  |g:ale_c_clangformat_options|, as this will cause clang-format to error.
+
+
+g:ale_c_clangformat_use_local_file         *g:ale_c_clangformat_use_local_file*
+                                           *b:ale_c_clangformat_use_local_file*
+  Type: |Number|
+  Default: `0`
+
+  This variable can be changed to modify whether to use a local .clang-format
+  file. If the file is found, the flag '-style=file' is passed to clang-format
+  and any options configured via |g:ale_c_clangformat_style_option| are not
+  passed.
+
+  If this option is enabled but no .clang-format file is found, default back to
+  |g:ale_c_clangformat_style_option|, if it set.
+
+  If you set this variable, ensure you don't modify -style in
+  |g:ale_c_clangformat_options|, as this will cause clang-format to error.
 
 
 ===============================================================================
diff --git a/test/command_callback/clangformat_paths/with_clangformat/.clang-format b/test/command_callback/clangformat_paths/with_clangformat/.clang-format
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/command_callback/clangformat_paths/with_clangformat/.clang-format
diff --git a/test/fixers/test_clangformat_fixer_callback.vader b/test/fixers/test_clangformat_fixer_callback.vader
index ae7db4cf..b9b74ee8 100644
--- a/test/fixers/test_clangformat_fixer_callback.vader
+++ b/test/fixers/test_clangformat_fixer_callback.vader
@@ -1,5 +1,7 @@
 Before:
   Save g:ale_c_clangformat_executable
+  Save g:c_clangformat_style_option
+  Save g:c_clangformat_use_local_file
 
   " Use an invalid global executable, so we don't match it.
   let g:ale_c_clangformat_executable = 'xxxinvalid'
@@ -35,3 +37,30 @@ Execute(The clangformat callback should include any additional options):
   \     . ' --some-option',
   \ },
   \ ale#fixers#clangformat#Fix(bufnr(''))
+
+Execute(The clangformat callback should include style options as well):
+  call ale#test#SetFilename('c_paths/dummy.c')
+  let g:ale_c_clangformat_options = '--some-option'
+  let g:ale_c_clangformat_style_option = '{BasedOnStyle: Microsoft, ColumnLimit:80,}'
+
+  AssertEqual
+  \ {
+  \   'command': ale#Escape(g:ale_c_clangformat_executable)
+  \     . ' --assume-filename=' . ale#Escape(bufname(bufnr('')))
+  \     . ' --some-option' . " -style='{BasedOnStyle: Microsoft, ColumnLimit:80,}'",
+  \ },
+  \ ale#fixers#clangformat#Fix(bufnr(''))
+
+Execute(The clangformat callback should use local file instead of style options):
+  call ale#test#SetFilename('clangformat_paths/with_clangformat/dummy.c')
+  let g:ale_c_clangformat_options = '--some-option'
+  let g:ale_c_clangformat_style_option = '{BasedOnStyle: Microsoft, ColumnLimit:80,}'
+  let g:ale_c_clangformat_use_local_file = 1
+
+  AssertEqual
+  \ {
+  \   'command': ale#Escape(g:ale_c_clangformat_executable)
+  \     . ' --assume-filename=' . ale#Escape(bufname(bufnr('')))
+  \     . ' --some-option' . ' -style=file',
+  \ },
+  \ ale#fixers#clangformat#Fix(bufnr(''))