Add Annotations and LINQ to IsCompleteSubmission

IsCompleteSubmission now returns false for a standalone annotation.
IsCompleteSubmission now returns false for a LINQ query that is not
followed by an empty new line.

src/Compilers/VisualBasic/Portable/Syntax/SyntaxFactory.vb

@@ -532,6 +532,28 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             Return SyntaxEquivalence.AreEquivalent(oldList.Node, newList.Node, ignoreChildNode, topLevel:=False)
         End Function
 
+        ''' <summary>
+        ''' Determines if a syntax node is a part of a LINQ query.
+        ''' If so then a query is not terminated the syntax tree ends with an empty line.
+        ''' </summary>
+        ''' <returns>True if the token is part of a LINQ query and syntax tree ends with an empty line.</returns>
+        Private Shared Function IsPartOfUnterminatedLinqQuery(token As SyntaxToken, statementNode As SyntaxNode, endOfFileToken As SyntaxToken) As Boolean
+            Dim node = token.Parent
+            Do
+                If node.IsKind(SyntaxKind.QueryExpression) Then
+                    Return Not endOfFileToken.LeadingTrivia.Contains(Function(trivia) trivia.IsKind(SyntaxKind.EndOfLineTrivia))
+                End If
+
+                If node Is statementNode Then
+                    Exit Do
+                End If
+
+                node = node.Parent
+            Loop
+
+            Return False
+        End Function
+
         ''' <summary>
         ''' Determines if a submission is complete.
         ''' Returns false if the syntax is valid but incomplete.
@@ -572,14 +594,15 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
             Dim lastToken = lastNode.GetLastToken(includeZeroWidth:=True, includeSkipped:=True)
 
-            If lastToken.HasTrailingTrivia AndAlso lastToken.TrailingTrivia.Last().IsKind(SyntaxKind.LineContinuationTrivia) Then
+            If IsPartOfUnterminatedLinqQuery(lastToken, lastNode, compilation.EndOfFileToken) OrElse
+                    (lastToken.HasTrailingTrivia AndAlso lastToken.TrailingTrivia.Last().IsKind(SyntaxKind.LineContinuationTrivia)) Then
                 ' Even if the compilation is correct but has a line continuation trivia return statement as incomplete.
                 ' For example `Dim x = 12 _` has no compilation errors but should be treated as an incomplete statement.
                 Return False
             ElseIf Not compilation.HasErrors Then
                 ' No errors returned. This is a valid and complete submission.
                 Return True
-            ElseIf lastToken.IsMissing Then
+            ElseIf lastNode.IsKind(SyntaxKind.IncompleteMember) OrElse lastToken.IsMissing Then
                 Return False
             End If
 

src/Compilers/VisualBasic/Test/Syntax/Syntax/SyntaxSubmissionsTests.vb

@@ -37,6 +37,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests
             AssertInvalidCompleteSubmission("Dim x = 1 Dim y = 2")
             AssertValidCompleteSubmission("Dim x = 1: Dim y = 2")
             AssertIncompleteSubmission("Dim x =")
+            AssertIncompleteSubmission("Dim x = ""str"" & ")
             AssertIncompleteSubmission("Dim x = 12 _")
             AssertValidCompleteSubmission(
 "Dim x =
@@ -48,6 +49,20 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests
 "Dim x = _
     & ""hello""")
 
+            ' Annotations
+            AssertIncompleteSubmission("<AttributeUsage(AttributeTargets.All)>")
+            AssertIncompleteSubmission(
+"<AttributeUsage(AttributeTargets.All)>
+<AttributeUsage(AttributeTargets.All)>")
+            AssertIncompleteSubmission(
+"<AttributeUsage(
+    AttributeTargets.All)>")
+            AssertValidCompleteSubmission(
+"<AttributeUsage(
+    AttributeTargets.All)>
+Class C
+End Class")
+
             ' Xml literals
             AssertValidCompleteSubmission("Dim xml = <xml></xml>")
             AssertIncompleteSubmission(
@@ -150,6 +165,27 @@ Next")
 "If holidays
     TakeABreak()
 End If")
+
+            ' LINQ queries
+            AssertIncompleteSubmission("Dim x = FROM x In {1, 2, 3}")
+            AssertIncompleteSubmission(
+"Dim x = FROM x In {1, 2, 3}
+         WHERE x > 1")
+            AssertIncompleteSubmission(
+"Dim x = FROM x In {1, 2, 3}
+         WHERE x > 1
+         SELECT x + 1")
+            AssertValidCompleteSubmission(
+"Dim x = FROM x In {1, 2, 3}
+         WHERE x > 1
+
+")
+            AssertValidCompleteSubmission(
+"Dim x = FROM x In {1, 2, 3}
+         WHERE x > 1
+         SELECT x + 1
+
+")
         End Sub
     End Class