Only call clang-format if file is not empty

Signed-off-by: Wolfgang E. Sanyer <WolfgangSanyer@Google.com>

Author: ezzieyguywuf

autoload/codefmt/clangformat.vim

@@ -171,7 +171,7 @@ function! codefmt#clangformat#GetFormatter() abort
  let l:result = maktaba#syscall#Create(l:cmd).WithStdin(l:input).Call()
  let l:formatted = split(l:result.stdout, "\n")
 
- if l:supports_cursor
+ if l:supports_cursor && !(line('$') == 1 && getline(1) == '')
  " With -cursor, the first line is a JSON object.
  let l:header = remove(l:formatted, 0)
  call maktaba#buffer#Overwrite(1, line('$'), l:formatted)

vroom/clangformat.vroom

@@ -181,3 +181,12 @@ current buffer.
 
 The -assume-filename arg passed above is also related, used by the clang-format
 tool to detect any custom style rules particular to the current file.
+
+
+Bug #102. When the buffer is empty, clang-format does _not_ return a cursor
+position
+
+ @clear
+ :call maktaba#error#TryCommand('FormatCode clang-format')
+ ! clang-format -style file .*
+ $ echo -n