Store multiline diags for each line they appear on

Diagnostic interface used to store multiline diags only on thte starting
line.
With this pull commit, _line_to_diags stores a multiline diagnostic for
each line in the range `diag['range']['start'/'end'].

python/ycm/diagnostic_interface.py

@@ -277,11 +277,13 @@ def _UpdateSigns( self ):
   def _ConvertDiagListToDict( self ):
     self._line_to_diags = defaultdict( list )
     for diag in self._diagnostics:
-      location = diag[ 'location' ]
-      bufnr = vimsupport.GetBufferNumberForFilename( location[ 'filepath' ] )
+      location_extent = diag[ 'location_extent' ]
+      start = location_extent[ 'start' ]
+      end = location_extent[ 'end' ]
+      bufnr = vimsupport.GetBufferNumberForFilename( start[ 'filepath' ] )
       if bufnr == self._bufnr:
-        line_number = location[ 'line_num' ]
-        self._line_to_diags[ line_number ].append( diag )
+        for line_number in range( start[ 'line_num' ], end[ 'line_num' ] + 1 ):
+          self._line_to_diags[ line_number ].append( diag )
 
     for diags in self._line_to_diags.values():
       # We also want errors to be listed before warnings so that errors aren't

python/ycm/tests/youcompleteme_test.py

@@ -78,15 +78,14 @@ def YouCompleteMe_UpdateDiagnosticInterface( ycm, post_vim_message, *args ):
       'line_num': 2,
       'column_num': 31
     },
-    # Looks strange but this is really what ycmd is returning.
     'location_extent': {
       'start': {
-        'filepath': '',
+        'filepath': 'buffer',
         'line_num': 2,
         'column_num': 31,
       },
       'end': {
-        'filepath': '',
+        'filepath': 'buffer',
         'line_num': 2,
         'column_num': 32,
       }
@@ -624,6 +623,18 @@ def test_YouCompleteMe_ShowDiagnostics_DiagnosticsFound_DoNotOpenLocationList(
         'filepath': 'buffer',
         'line_num': 19,
         'column_num': 2
+      },
+      'location_extent': {
+        'start': {
+          'filepath': 'buffer',
+          'line_num': 19,
+          'column_num': 2
+        },
+        'end': {
+          'filepath': 'buffer',
+          'line_num': 19,
+          'column_num': 3
+        }
       }
     }
 
@@ -673,6 +684,18 @@ def test_YouCompleteMe_ShowDiagnostics_DiagnosticsFound_OpenLocationList(
         'filepath': 'buffer',
         'line_num': 19,
         'column_num': 2
+      },
+      'location_extent': {
+        'start': {
+          'filepath': 'buffer',
+          'line_num': 19,
+          'column_num': 2
+        },
+        'end': {
+          'filepath': 'buffer',
+          'line_num': 19,
+          'column_num': 2
+        }
       }
     }