Fix double undo

README.md

@@ -116,6 +116,12 @@ When the value is 0, `-fallback-style=none` option is added on executing clang-f
 It means that vim-clang-format does nothing when `.clang-format` is not found.
 The default value is 1.
 
+- `g:clang_format#praise`
+
+When the value is 1, you will be praised for already having well-formatted code.
+Some users might not want/need praise, thus providing this variable.
+The default value is 1.
+
 ## Vimrc Example
 
 ```vim

autoload/clang_format.vim

@@ -89,9 +89,9 @@ endfunction
 
 function! s:error_message(result) abort
     echoerr 'clang-format has failed to format.'
-    if a:result =~# '^YAML:\d\+:\d\+: error: unknown key '
+    if a:result =~# '^YAML:\d\+:\d\+: error: '
         echohl ErrorMsg
-        for l in split(a:result, "\n")[0:1]
+        for l in split(a:result, "\n")
             echomsg l
         endfor
         echohl None
@@ -147,7 +147,7 @@ function! s:verify_command() abort
     if invalidity == 1
         echoerr "clang-format is not found. check g:clang_format#command."
     elseif invalidity == 2
-        echoerr 'clang-format 3.3 or earlier is not supported for the lack of aruguments'
+        echoerr 'clang-format 3.3 or earlier is not supported for the lack of arguments'
     endif
 endfunction
 
@@ -191,6 +191,7 @@ let g:clang_format#filetype_style_options = s:getg('clang_format#filetype_style_
 
 let g:clang_format#detect_style_file = s:getg('clang_format#detect_style_file', 1)
 let g:clang_format#enable_fallback_style = s:getg('clang_format#enable_fallback_style', 1)
+let g:clang_format#praise = s:getg('clang_format#praise', 1)
 
 let g:clang_format#auto_format = s:getg('clang_format#auto_format', 0)
 let g:clang_format#auto_format_on_insert_leave = s:getg('clang_format#auto_format_on_insert_leave', 0)
@@ -236,10 +237,21 @@ function! clang_format#replace(line1, line2, ...) abort
         return
     endif
 
-    let winview = winsaveview()
     let splitted = split(formatted, '\n', 1)
+    if getline(a:line1, a:line2) ==# splitted[a:line1-1:a:line2-1]
+        if g:clang_format#praise
+            echo "No formatting needed, looking fabulous already!"
+        endif
+        " Early out, no need to introduce a change
+        return
+    endif
 
-    silent! undojoin
+    if g:clang_format#praise
+        " Reset any previous praise
+        echo ""
+    endif
+
+    let winview = winsaveview()
     if line('$') > len(splitted)
         execute len(splitted) .',$delete' '_'
     endif

doc/clang-format.txt

@@ -206,6 +206,13 @@ g:clang_format#enable_fallback_style	  *g:clang_format#enable_fallback_style*
     ".clang-format" is not found.
     The default value is 1.
 
+g:clang_format#praise                                    *g:clang_format#praise*
+
+    When the value is 1, |vim-clang-format| will praise you for already having
+    well-formatted code.  Some users might not want/need praise, thus
+    providing this variable.
+    The default value is 1.
+
 
 
 ==============================================================================

test/VimFlavor.lock

@@ -1,3 +1,3 @@
 kana/vim-operator-user (0.1.0)
-kana/vim-vspec (1.6.1)
+kana/vim-vspec (1.9.0)
 rhysd/vim-vspec-matchers (0.0.4)

test/t/clang_format_spec.vim

@@ -99,6 +99,7 @@ describe 'default settings'
         Expect exists('g:clang_format#filetype_style_options') to_be_true
         Expect exists('g:clang_format#command') to_be_true
         Expect exists('g:clang_format#detect_style_file') to_be_true
+        Expect exists('g:clang_format#praise') to_be_true
         Expect exists('g:clang_format#auto_format') to_be_true
         Expect exists('g:clang_format#auto_format_on_insert_leave') to_be_true
         Expect g:clang_format#extra_args to_be_empty
@@ -107,6 +108,7 @@ describe 'default settings'
         Expect g:clang_format#filetype_style_options to_be_empty
         Expect executable(g:clang_format#command) to_be_true
         Expect g:clang_format#detect_style_file to_be_true
+        Expect g:clang_format#praise to_be_true
     end
 
     it 'provide commands'
@@ -457,9 +459,28 @@ describe 'undo formatting text'
         bdelete!
     end
 
+    it 'can make a change, format (constitutes as a second change), then undo and keep the first change'
+        normal! ggOmega
+        ClangFormat
+        " When running :ClangFormat from a normal vim instance, setline() does add an entry in the undolist
+        " For some reason it does not do so when running in this test framework
+        " Also, seems like it is hard to even add another item to the change list too, always rendering:
+        " # number changes  when               saved
+        " #      9       1  0 seconds ago
+        normal! ggOadditional
+        :Debug GetBuffer()
+        " TODO: should enable this
+        " normal! u
+        Expect 0 != search('mega', 'cw')
+        undo
+        Expect 0 == search('mega', 'cw')
+    end
+
     it 'restores previous text as editing buffer normally'
         let prev = GetBuffer()
         ClangFormat
+        let buf = GetBuffer()
+        Expect prev != buf
         undo
         let buf = GetBuffer()
         Expect prev ==# buf