Add clang-format fixer for C/C++ (#873)

* Add clang-format fixer for C/C++

* Document clang-format options

* Refer ale-cpp-clangformat to ale-c-clangformat

8 files changed, 94 insertions, 4 deletions

diff --git a/README.md b/README.md
index 22866120..24024d3d 100644
--- a/README.md
+++ b/README.md
@@ -65,8 +65,8 @@ name. That seems to be the fairest way to arrange this table.
 | Awk | [gawk](https://www.gnu.org/software/gawk/)|
 | Bash | [-n flag](https://www.gnu.org/software/bash/manual/bash.html#index-set), [shellcheck](https://www.shellcheck.net/) |
 | Bourne Shell | [-n flag](http://linux.die.net/man/1/sh), [shellcheck](https://www.shellcheck.net/) |
-| C | [cppcheck](http://cppcheck.sourceforge.net), [gcc](https://gcc.gnu.org/), [clang](http://clang.llvm.org/)|
-| C++ (filetype cpp) | [clang](http://clang.llvm.org/), [clangcheck](http://clang.llvm.org/docs/ClangCheck.html), [clangtidy](http://clang.llvm.org/extra/clang-tidy/), [cppcheck](http://cppcheck.sourceforge.net), [cpplint](https://github.com/google/styleguide/tree/gh-pages/cpplint), [gcc](https://gcc.gnu.org/)|
+| C | [cppcheck](http://cppcheck.sourceforge.net), [gcc](https://gcc.gnu.org/), [clang](http://clang.llvm.org/), [clang-format](https://clang.llvm.org/docs/ClangFormat.html)|
+| C++ (filetype cpp) | [clang](http://clang.llvm.org/), [clangcheck](http://clang.llvm.org/docs/ClangCheck.html), [clangtidy](http://clang.llvm.org/extra/clang-tidy/), [cppcheck](http://cppcheck.sourceforge.net), [cpplint](https://github.com/google/styleguide/tree/gh-pages/cpplint), [gcc](https://gcc.gnu.org/), [clang-format](https://clang.llvm.org/docs/ClangFormat.html)|
 | C# | [mcs](http://www.mono-project.com/docs/about-mono/languages/csharp/) |
 | Chef | [foodcritic](http://www.foodcritic.io/) |
 | CMake | [cmakelint](https://github.com/richq/cmake-lint) |
diff --git a/autoload/ale/fix/registry.vim b/autoload/ale/fix/registry.vim
index 5c3b8d94..b77ac031 100644
--- a/autoload/ale/fix/registry.vim
+++ b/autoload/ale/fix/registry.vim
@@ -82,6 +82,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['php'],
 \       'description': 'Fix PHP files with phpcbf.',
 \   },
+\   'clang-format': {
+\       'function': 'ale#fixers#clangformat#Fix',
+\       'suggested_filetypes': ['c', 'cpp'],
+\       'description': 'Fix C/C++ files with clang-format.',
+\   },
 \}
 
 " Reset the function registry to the default entries.
diff --git a/autoload/ale/fixers/clangformat.vim b/autoload/ale/fixers/clangformat.vim
new file mode 100644
index 00000000..b2ed7daa
--- /dev/null
+++ b/autoload/ale/fixers/clangformat.vim
@@ -0,0 +1,21 @@
+" Author: Peter Renström <renstrom.peter@gmail.com>
+" Description: Fixing C/C++ files with clang-format.
+
+call ale#Set('c_clangformat_executable', 'clang-format')
+call ale#Set('c_clangformat_use_global', 0)
+call ale#Set('c_clangformat_options', '')
+
+function! ale#fixers#clangformat#GetExecutable(buffer) abort
+    return ale#node#FindExecutable(a:buffer, 'c_clangformat', [
+    \   'clang-format',
+    \])
+endfunction
+
+function! ale#fixers#clangformat#Fix(buffer) abort
+    let l:options = ale#Var(a:buffer, 'c_clangformat_options')
+
+    return {
+    \   'command': ale#Escape(ale#fixers#clangformat#GetExecutable(a:buffer))
+    \       . ' ' . l:options,
+    \}
+endfunction
diff --git a/doc/ale-c.txt b/doc/ale-c.txt
index 2572d885..1e1322bc 100644
--- a/doc/ale-c.txt
+++ b/doc/ale-c.txt
@@ -60,4 +60,23 @@ g:ale_c_gcc_options                                       *g:ale_c_gcc_options*
 
 
 ===============================================================================
+clang-format                                                *ale-c-clangformat*
+
+g:ale_c_clangformat_executable                 *g:ale_c_clangformat_executable*
+                                               *b:ale_c_clangformat_executable*
+  Type: |String|
+  Default: `'clang-format'`
+
+  This variable can be changed to use a different executable for clang-format.
+
+
+g:ale_c_clangformat_options                       *g:ale_c_clangformat_options*
+                                                  *b:ale_c_clangformat_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be change to modify flags given to clang-format.
+
+
+===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:
diff --git a/doc/ale-cpp.txt b/doc/ale-cpp.txt
index 854e9b4e..2ece6843 100644
--- a/doc/ale-cpp.txt
+++ b/doc/ale-cpp.txt
@@ -190,4 +190,11 @@ g:ale_cpp_gcc_options                                   *g:ale_cpp_gcc_options*
 
 
 ===============================================================================
+clang-format                                              *ale-cpp-clangformat*
+
+See |ale-c-clangformat| for information about the available options.
+Note that the C options are also used for C++.
+
+
+===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:
diff --git a/doc/ale.txt b/doc/ale.txt
index 18ea367c..56c5946e 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -19,6 +19,7 @@ CONTENTS                                                         *ale-contents*
       clang...............................|ale-c-clang|
       cppcheck............................|ale-c-cppcheck|
       gcc.................................|ale-c-gcc|
+      clang-format........................|ale-c-clangformat|
     chef..................................|ale-chef-options|
       foodcritic..........................|ale-chef-foodcritic|
     cpp...................................|ale-cpp-options|
@@ -28,6 +29,7 @@ CONTENTS                                                         *ale-contents*
       cppcheck............................|ale-cpp-cppcheck|
       cpplint.............................|ale-cpp-cpplint|
       gcc.................................|ale-cpp-gcc|
+      clang-format........................|ale-cpp-clangformat|
     css...................................|ale-css-options|
       stylelint...........................|ale-css-stylelint|
     cmake.................................|ale-cmake-options|
@@ -176,8 +178,8 @@ The following languages and tools are supported.
 * Asciidoc: 'proselint'
 * Bash: 'shell' (-n flag), 'shellcheck'
 * Bourne Shell: 'shell' (-n flag), 'shellcheck'
-* C: 'cppcheck', 'gcc', 'clang'
-* C++ (filetype cpp): 'clang', 'clangtidy', 'cppcheck', 'cpplint', 'gcc'
+* C: 'cppcheck', 'gcc', 'clang', 'clang-format'
+* C++ (filetype cpp): 'clang', 'clangtidy', 'cppcheck', 'cpplint', 'gcc', 'clang-format'
 * C#: 'mcs'
 * Chef: 'foodcritic'
 * CMake: 'cmakelint'
diff --git a/test/command_callback/c_paths/dummy.c b/test/command_callback/c_paths/dummy.c
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/command_callback/c_paths/dummy.c
diff --git a/test/fixers/test_clangformat_fixer_callback.vader b/test/fixers/test_clangformat_fixer_callback.vader
new file mode 100644
index 00000000..a55576bf
--- /dev/null
+++ b/test/fixers/test_clangformat_fixer_callback.vader
@@ -0,0 +1,36 @@
+Before:
+  Save g:ale_c_clangformat_executable
+
+  " Use an invalid global executable, so we don't match it.
+  let g:ale_c_clangformat_executable = 'xxxinvalid'
+
+  call ale#test#SetDirectory('/testplugin/test/fixers')
+  silent cd ..
+  silent cd command_callback
+  let g:dir = getcwd()
+
+After:
+  Restore
+
+  call ale#test#RestoreDirectory()
+
+Execute(The clang-format callback should return the correct default values):
+  call ale#test#SetFilename('c_paths/dummy.c')
+
+  AssertEqual
+  \ {
+  \   'command': ale#Escape(g:ale_c_clangformat_executable)
+  \       . ' '
+  \ },
+  \ ale#fixers#clangformat#Fix(bufnr(''))
+
+Execute(The clangformat callback should include any additional options):
+  call ale#test#SetFilename('c_paths/dummy.c')
+  let g:ale_c_clangformat_options = '--some-option'
+
+  AssertEqual
+  \ {
+  \   'command': ale#Escape(g:ale_c_clangformat_executable)
+  \     . ' --some-option',
+  \ },
+  \ ale#fixers#clangformat#Fix(bufnr(''))