Make all parameters non-optional.

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller.Session.cs

@@ -101,7 +101,9 @@ private void OnPresenterSessionItemSelected(object sender, PresentationItemEvent
                 // Update the filter state for the model.  Note: if we end up filtering everything
                 // out we do *not* want to dismiss the completion list. 
                 this.FilterModel(CompletionFilterReason.ItemFiltersChanged,
-                    dismissIfEmptyAllowed: false, filterState: e.FilterState);
+                    recheckCaretPosition: false,
+                    dismissIfEmptyAllowed: false,
+                    filterState: e.FilterState);
             }
         }
     }

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller.Session_FilterModel.cs

@@ -19,9 +19,9 @@ internal partial class Session
         {
             public void FilterModel(
                 CompletionFilterReason filterReason,
-                bool recheckCaretPosition = false,
-                bool dismissIfEmptyAllowed = true,
-                ImmutableDictionary<CompletionItemFilter, bool> filterState = null)
+                bool recheckCaretPosition,
+                bool dismissIfEmptyAllowed,
+                ImmutableDictionary<CompletionItemFilter, bool> filterState)
             {
                 AssertIsForeground();
 
@@ -46,7 +46,10 @@ internal partial class Session
                     });
             }
 
-            public void IdentifyBestMatchAndFilterToAllItems(CompletionFilterReason filterReason, bool recheckCaretPosition = false, bool dismissIfEmptyAllowed = true)
+            public void IdentifyBestMatchAndFilterToAllItems(
+                CompletionFilterReason filterReason,
+                bool recheckCaretPosition,
+                bool dismissIfEmptyAllowed)
             {
                 AssertIsForeground();
 

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller.cs

@@ -143,7 +143,11 @@ private bool StartNewModelComputation(CompletionService completionService, bool
                 CompletionTrigger.Default, filterItems, dismissIfEmptyAllowed);
         }
 
-        private bool StartNewModelComputation(CompletionService completionService, CompletionTrigger trigger, bool filterItems, bool dismissIfEmptyAllowed = true)
+        private bool StartNewModelComputation(
+            CompletionService completionService,
+            CompletionTrigger trigger,
+            bool filterItems,
+            bool dismissIfEmptyAllowed = true)
         {
             AssertIsForeground();
             Contract.ThrowIfTrue(sessionOpt != null);
@@ -183,11 +187,18 @@ private bool StartNewModelComputation(CompletionService completionService, Compl
 
             if (filterItems)
             {
-                sessionOpt.FilterModel(filterReason, dismissIfEmptyAllowed: dismissIfEmptyAllowed);
+                sessionOpt.FilterModel(
+                    filterReason, 
+                    recheckCaretPosition: false,
+                    dismissIfEmptyAllowed: dismissIfEmptyAllowed,
+                    filterState: null);
             }
             else
             {
-                sessionOpt.IdentifyBestMatchAndFilterToAllItems(filterReason, dismissIfEmptyAllowed: dismissIfEmptyAllowed);
+                sessionOpt.IdentifyBestMatchAndFilterToAllItems(
+                    filterReason,
+                    recheckCaretPosition: false,
+                    dismissIfEmptyAllowed: dismissIfEmptyAllowed);
             }
 
             return true;

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller_Backspace.cs

@@ -100,7 +100,11 @@ private void ExecuteBackspaceOrDelete(ITextView textView, Action nextHandler, bo
                 else if (model != null && model.Trigger.Kind != CompletionTriggerKind.Deletion)
                 {
                     // Filter the model if it wasn't invoked on backspace.
-                    sessionOpt.FilterModel(CompletionFilterReason.BackspaceOrDelete);
+                    sessionOpt.FilterModel(
+                        CompletionFilterReason.BackspaceOrDelete,
+                        recheckCaretPosition: false,
+                        dismissIfEmptyAllowed: true,
+                        filterState: null);
                 }
             }
         }

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller_OnTextViewBufferPostChanged.cs

@@ -30,7 +30,11 @@ internal override void OnTextViewBufferPostChanged(object sender, EventArgs e)
             else
             {
                 // Filter the model, recheck the caret position if we haven't computed the initial model yet
-                sessionOpt.FilterModel(CompletionFilterReason.TypeChar, recheckCaretPosition: model == null);
+                sessionOpt.FilterModel(
+                    CompletionFilterReason.TypeChar, 
+                    recheckCaretPosition: model == null,
+                    dismissIfEmptyAllowed: true,
+                    filterState: null);
             }
         }
     }

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller_TabKey.cs

@@ -118,7 +118,8 @@ private bool TryInvokeSnippetCompletion(TabKeyCommandArgs args, CompletionServic
             // we delete the last <question> that was typed.
             var textChange = new TextChange(TextSpan.FromBounds(caretPoint - 1, caretPoint), string.Empty);
             workspace.ApplyTextChanges(documentId, textChange, CancellationToken.None);
-            this.StartNewModelComputation(completionService, new CompletionTrigger(CompletionTriggerKind.Snippets), filterItems: false);
+            this.StartNewModelComputation(
+                completionService, new CompletionTrigger(CompletionTriggerKind.Snippets), filterItems: false);
             return true;
         }
 

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller_TypeChar.cs

@@ -175,7 +175,11 @@ void ICommandHandler<TypeCharCommandArgs>.ExecuteCommand(TypeCharCommandArgs arg
                     }
 
                     // Now filter whatever result we have.
-                    sessionOpt.FilterModel(CompletionFilterReason.TypeChar);
+                    sessionOpt.FilterModel(
+                        CompletionFilterReason.TypeChar,
+                        recheckCaretPosition: false,
+                        dismissIfEmptyAllowed: true,
+                        filterState: null);
                 }
                 else
                 {
@@ -201,7 +205,10 @@ void ICommandHandler<TypeCharCommandArgs>.ExecuteCommand(TypeCharCommandArgs arg
 
                         // Known to be a filter character for the currently selected item.  So just 
                         // filter the session.
-                        sessionOpt.FilterModel(CompletionFilterReason.TypeChar);
+                        sessionOpt.FilterModel(CompletionFilterReason.TypeChar,
+                            recheckCaretPosition: false,
+                            dismissIfEmptyAllowed: true,
+                            filterState: null);
                         return;
                     }