Echoing diag text on when cursor on diag line

autoload/youcompleteme.vim

@@ -365,6 +365,7 @@ function! s:OnCursorMovedInsertMode()
     return
   endif
 
+  py ycm_state.OnCursorMoved()
   call s:UpdateCursorMoved()
 
   " Basically, we need to only trigger the completion menu when the user has
@@ -402,6 +403,7 @@ function! s:OnCursorMovedNormalMode()
   endif
 
   call s:OnFileReadyToParse()
+  py ycm_state.OnCursorMoved()
 endfunction
 
 

python/ycm/diagnostic_interface.py

@@ -20,36 +20,66 @@
 from collections import defaultdict
 from operator import itemgetter
 from ycm import vimsupport
+import vim
 
 
 class DiagnosticInterface( object ):
   def __init__( self ):
-    self._buffer_number_to_diags = {}
+    # Line and column numbers are 1-based
+    self._buffer_number_to_line_to_diags = defaultdict(
+      lambda: defaultdict( list ) )
     self._next_sign_id = 1
+    self._previous_line_number = -1
+
+
+  def OnCursorMoved( self ):
+    line, _ = vimsupport.CurrentLineAndColumn()
+    line += 1  # Convert to 1-based
+    if line != self._previous_line_number:
+      self._previous_line_number = line
+      self._EchoDiagnosticForLine( line )
 
 
   def UpdateWithNewDiagnostics( self, diags ):
-    self._buffer_number_to_diags = ConvertDiagListToDict( diags )
-    for buffer_number, buffer_diags in self._buffer_number_to_diags.iteritems():
-      if not vimsupport.BufferIsVisible( buffer_number ):
-        continue
-
-      vimsupport.UnplaceAllSignsInBuffer( buffer_number )
-      for diag in buffer_diags:
-        vimsupport.PlaceSign( self._next_sign_id,
-                              diag[ 'lnum' ],
+    self._buffer_number_to_line_to_diags = _ConvertDiagListToDict( diags )
+    self._next_sign_id = _UpdateSigns( self._buffer_number_to_line_to_diags,
+                                       self._next_sign_id )
+
+
+  def _EchoDiagnosticForLine( self, line_num ):
+    buffer_num = vim.current.buffer.number
+    diags = self._buffer_number_to_line_to_diags[ buffer_num ][ line_num ]
+    if not diags:
+      # Clear any previous diag echo
+      vimsupport.EchoText( '', False )
+      return
+    vimsupport.EchoTextVimWidth( diags[ 0 ][ 'text' ] )
+
+
+def _UpdateSigns( buffer_number_to_line_to_diags, next_sign_id ):
+  for buffer_number, line_to_diags in buffer_number_to_line_to_diags.iteritems():
+    if not vimsupport.BufferIsVisible( buffer_number ):
+      continue
+
+    vimsupport.UnplaceAllSignsInBuffer( buffer_number )
+    for line, diags in line_to_diags.iteritems():
+      for diag in diags:
+        vimsupport.PlaceSign( next_sign_id,
+                              line,
                               buffer_number,
                               diag[ 'type' ] == 'E' )
-        self._next_sign_id += 1
-
-
-def ConvertDiagListToDict( diags ):
-  buffer_to_diags = defaultdict( list )
-  for diag in diags:
-    buffer_to_diags[ diag[ 'bufnr' ] ].append( diag )
-  for buffer_diags in buffer_to_diags.itervalues():
-    # We also want errors to be listed before warnings so that errors aren't
-    # hidden by the warnings; Vim won't place a sign oven an existing one.
-    buffer_diags.sort( key = lambda diag: itemgetter( 'lnum', 'col', 'type' ) )
-  return buffer_to_diags
+        next_sign_id += 1
+  return next_sign_id
+
+
+def _ConvertDiagListToDict( diag_list ):
+  buffer_to_line_to_diags = defaultdict( lambda: defaultdict( list ) )
+  for diag in diag_list:
+    buffer_to_line_to_diags[ diag[ 'bufnr' ] ][ diag[ 'lnum' ] ].append( diag )
+  for line_to_diags in buffer_to_line_to_diags.itervalues():
+    for diags in line_to_diags.itervalues():
+      # We also want errors to be listed before warnings so that errors aren't
+      # hidden by the warnings; Vim won't place a sign oven an existing one.
+      diags.sort( key = lambda diag: itemgetter( 'col', 'type' ) )
+  return buffer_to_line_to_diags
 

python/ycm/vimsupport.py

@@ -220,14 +220,23 @@ def Confirm( message ):
   return bool( PresentDialog( message, [ "Ok", "Cancel" ] ) == 0 )
 
 
-def EchoText( text ):
+def EchoText( text, log_as_message = True ):
   def EchoLine( text ):
-    vim.command( "echom '{0}'".format( EscapeForVim( text ) ) )
+    command = 'echom' if log_as_message else 'echo'
+    vim.command( "{0} '{1}'".format( command, EscapeForVim( text ) ) )
 
   for line in text.split( '\n' ):
     EchoLine( line )
 
 
+# Echos text but truncates the text so that it all fits on one line
+def EchoTextVimWidth( text ):
+  vim_width = GetIntValue( '&columns' )
+  truncated_text = text[ : int( vim_width * 0.9 ) ]
+  truncated_text.replace( '\n', ' ' )
+  EchoText( truncated_text, False )
+
+
 def EscapeForVim( text ):
   return text.replace( "'", "''" )
 

python/ycm/youcompleteme.py

@@ -246,6 +246,10 @@ class YouCompleteMe( object ):
     SendEventNotificationAsync( 'InsertLeave' )
 
 
+  def OnCursorMoved( self ):
+    self._diag_interface.OnCursorMoved()
+
+
   def OnVimLeave( self ):
     self._ServerCleanup()