YcmDiags now doesn't hang when no flags available

Fixes #46

autoload/youcompleteme.vim

@@ -438,13 +438,27 @@ function! s:ForceCompile()
     if diagnostics_ready
       break
     endif
+
+    let getting_completions = pyeval(
+          \ 'ycm_state.GettingCompletions()' )
+
+    if !getting_completions
+      echom "Unable to retrieve diagnostics."
+      return 0
+    endif
+
     sleep 100m
   endwhile
+  return 1
 endfunction
 
 
 function! s:ForceCompileAndDiagnostics()
-  call s:ForceCompile()
+  let compilation_succeeded = s:ForceCompile()
+  if !compilation_succeeded
+    return
+  endif
+
   call s:UpdateDiagnosticNotifications()
   echom "Diagnostics refreshed."
 endfunction

python/completers/completer.py

@@ -81,6 +81,9 @@ class Completer( object ):
   def ShowDetailedDiagnostic( self ):
     pass
 
+  def GettingCompletions( self ):
+    return False
+
 
   @abc.abstractmethod
   def SupportedFiletypes( self ):

python/completers/cpp/clang_completer.py

@@ -146,6 +146,10 @@ class ClangCompleter( Completer ):
     return self.parse_future.ResultsReady()
 
 
+  def GettingCompletions( self ):
+    return self.completer.UpdatingTranslationUnit( vim.current.buffer.name )
+
+
   def GetDiagnosticsForCurrentFile( self ):
     if self.DiagnosticsForCurrentFileReady():
       diagnostics = self.completer.DiagnosticsForFile( vim.current.buffer.name )

python/ycm.py

@@ -141,6 +141,12 @@ class YouCompleteMe( object ):
       return self.GetFiletypeCompleterForCurrentFile().ShowDetailedDiagnostic()
 
 
+  def GettingCompletions( self ):
+    if self.FiletypeCompletionEnabledForCurrentFile():
+      return self.GetFiletypeCompleterForCurrentFile().GettingCompletions()
+    return False
+
+
   def OnCurrentIdentifierFinished( self ):
     self.identcomp.OnCurrentIdentifierFinished()