Merge pull request #4305 from dpoeschl/FixTypeInferrerAfterInvocation

Fix VB TypeInferrer after ArgumentList

src/EditorFeatures/VisualBasicTest/Completion/CompletionProviders/CompletionListTagCompletionProviderTests.vb

@@ -368,6 +368,33 @@ End Class
             VerifyNoItemsExist(markup)
         End Sub
 
+        <WorkItem(3518, "https://github.com/dotnet/roslyn/issues/3518")>
+        <Fact, Trait(Traits.Feature, Traits.Features.Completion)>
+        Public Sub NotAfterInvocationWithCompletionListTagTypeAsFirstParameter()
+            Dim markup = <Text><![CDATA[
+Class C
+    Sub Test()
+        M(Type2.A)
+        $$
+    End Sub
+
+    Private Sub M(a As Type1)
+        Throw New NotImplementedException()
+    End Sub
+End Class
+''' <completionlist cref="Type2"/>
+Public Class Type1
+End Class
+
+Public Class Type2
+    Public Shared A As Type1
+    Public Shared B As Type1
+End Class
+]]></Text>.Value
+            VerifyNoItemsExist(markup)
+        End Sub
+
+
         Friend Overrides Function CreateCompletionProvider() As CompletionListProvider
             Return New CompletionListTagCompletionProvider()
         End Function

src/EditorFeatures/VisualBasicTest/TypeInferrer/TypeInferrerTests.vb

@@ -710,5 +710,20 @@ Module M
 End Module"
             Test(text, "Global.System.Threading.Tasks.Task(Of System.Boolean)", testPosition:=True)
         End Sub
+
+        <Fact, Trait(Traits.Feature, Traits.Features.TypeInferenceService)>
+        <WorkItem(3518, "https://github.com/dotnet/roslyn/issues/3518")>
+        Public Sub NoTypeAfterInvocationWithCompletionListTagTypeAsFirstParameter()
+            Dim text = "Class C
+    Sub Test()
+        M(5)
+        [|x|]
+    End Sub
+
+    Sub M(x As Integer)
+    End Sub
+End Class"
+            Test(text, "System.Object", testNode:=False, testPosition:=True)
+        End Sub
     End Class
 End Namespace

src/Workspaces/VisualBasic/Portable/LanguageServices/VisualBasicTypeInferenceService.TypeInferrer.vb

@@ -217,6 +217,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                             index = GetArgumentListIndex(argumentList, previousToken)
                         End If
 
+                        If index < 0 Then
+                            Return SpecializedCollections.EmptyEnumerable(Of ITypeSymbol)()
+                        End If
+
                         Dim info = _semanticModel.GetSymbolInfo(invocation)
                         ' Check all the methods that have at least enough arguments to support being
                         ' called with argument at this position.  Note: if they're calling an extension
@@ -259,6 +263,11 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                 Else
                                     index = GetArgumentListIndex(argumentList, previousToken)
                                 End If
+
+                                If index < 0 Then
+                                    Return SpecializedCollections.EmptyEnumerable(Of ITypeSymbol)()
+                                End If
+
                                 Dim constructors = namedType.InstanceConstructors.Where(Function(m) m.Parameters.Length > index)
                                 Return InferTypeInArgument(argumentOpt, index, constructors)
                             End If
@@ -279,6 +288,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                             index = GetArgumentListIndex(argumentList, previousToken)
                         End If
 
+                        If index < 0 Then
+                            Return SpecializedCollections.EmptyEnumerable(Of ITypeSymbol)()
+                        End If
+
                         Dim info = _semanticModel.GetSymbolInfo(attribute)
                         Dim symbols = info.GetBestOrAllSymbols()
                         If symbols.Any() Then
@@ -838,7 +851,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 End If
 
                 Dim index = argumentList.Arguments.GetWithSeparators().IndexOf(previousToken)
-                Return (index + 1) \ 2
+                Return If(index >= 0, (index + 1) \ 2, -1)
             End Function
 
             Private Function InferTypeInCollectionInitializerExpression(