Fixing (removing) suggestion mode after declaration pattern

src/EditorFeatures/CSharpTest/Extensions/ContextQuery/IsPossibleDeconstructionDesignationTests.cs

@@ -153,5 +153,26 @@ public void False1()
         {
             VerifyFalse(AddInsideMethod(@"var $$"));
         }
+
+        [WorkItem(25084, "https://github.com/dotnet/roslyn/issues/25084#issuecomment-369075537")]
+        [Fact, Trait(Traits.Feature, Traits.Features.Completion)]
+        public void FalseAfterPattern1()
+        {
+            VerifyFalse(AddInsideMethod(@"if (1 is int i $$"));
+        }
+
+        [WorkItem(25084, "https://github.com/dotnet/roslyn/issues/25084#issuecomment-369075537")]
+        [Fact, Trait(Traits.Feature, Traits.Features.Completion)]
+        public void FalseAfterPattern2()
+        {
+            VerifyFalse(AddInsideMethod(@"if (1 is int i $$);"));
+        }
+
+        [WorkItem(25084, "https://github.com/dotnet/roslyn/issues/25084#issuecomment-369075537")]
+        [Fact, Trait(Traits.Feature, Traits.Features.Completion)]
+        public void FalseAfterPattern3()
+        {
+            VerifyFalse(AddInsideMethod(@"switch (1) { case int i $$ }"));
+        }
     }
 }

src/Workspaces/CSharp/Portable/Extensions/ContextQuery/SyntaxTreeExtensions.cs

@@ -1322,7 +1322,8 @@ public static bool IsPossibleTupleOpenParenOrComma(SyntaxToken possibleCommaOrPa
             // The well-formed cases:
             // var ($$, y) = e;
             // (var $$, var y) = e;
-            if (leftToken.Parent.IsKind(SyntaxKind.SingleVariableDesignation, SyntaxKind.ParenthesizedVariableDesignation))
+            if (leftToken.Parent.IsKind(SyntaxKind.ParenthesizedVariableDesignation) ||
+                leftToken.Parent.IsParentKind(SyntaxKind.ParenthesizedVariableDesignation))
             {
                 return true;
             }