Merge pull request #21176 from CyrusNajmabadi/patternMatchingDynamic

No pattern matching with dynamic.

src/EditorFeatures/CSharpTest/UsePatternMatching/CSharpAsAndNullCheckTests.cs

@@ -726,6 +726,23 @@ void M()
         {
         }
     }
+}");
+        }
+
+        [WorkItem(21172, "https://github.com/dotnet/roslyn/issues/21172")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsInlineTypeCheck)]
+        public async Task TestMissingWithDynamic()
+        {
+            await TestMissingAsync(
+@"class C
+{
+    void M(object o)
+    {
+        [|var|] x = o as dynamic;
+        if (x != null)
+        {
+        }
+    }
 }");
         }
     }

src/EditorFeatures/CSharpTest/UsePatternMatching/CSharpIsAndCastCheckDiagnosticAnalyzerTests.cs

@@ -538,5 +538,25 @@ public object Convert(object value)
     }
 }");
         }
+
+        [WorkItem(21172, "https://github.com/dotnet/roslyn/issues/21172")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsInlineTypeCheck)]
+        public async Task TestMissingWithDynamic()
+        {
+            await TestMissingInRegularAndScriptAsync(
+@"
+class C
+{
+    public object Convert(object value)
+    {
+        if (value is dynamic)
+        {
+            [|dynamic|] tmp = (dynamic)value;
+        }
+
+        return null;
+    }
+}");
+        }
     }
 }

src/Features/CSharp/Portable/UsePatternMatching/CSharpAsAndNullCheckDiagnosticAnalyzer.cs

@@ -103,6 +103,12 @@ private void SyntaxNodeAction(SyntaxNodeAnalysisContext syntaxContext)
                 return;
             }
 
+            if (asType?.TypeKind == TypeKind.Dynamic)
+            {
+                // Not legal to use dynamic in a pattern.
+                return;
+            }
+
             var localSymbol = (ILocalSymbol)semanticModel.GetDeclaredSymbol(declarator);
             if (!localSymbol.Type.Equals(asType))
             {

src/Features/CSharp/Portable/UsePatternMatching/CSharpIsAndCastCheckDiagnosticAnalyzer.cs

@@ -112,6 +112,12 @@ private void SyntaxNodeAction(SyntaxNodeAnalysisContext syntaxContext)
                 return;
             }
 
+            if (isType?.TypeKind == TypeKind.Dynamic)
+            {
+                // Not legal to use dynamic in a pattern.
+                return;
+            }
+
             if (!localSymbol.Type.Equals(isType))
             {
                 // we have something like: