add workaround on extract method on https://github.com/dotnet/roslyn/issues/30548 (#30550)

src/Compilers/CSharp/Test/Semantic/FlowAnalysis/RegionAnalysisTests.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System;
-using System.Collections.Generic;
 using System.Linq;
 using Microsoft.CodeAnalysis.CSharp.Symbols;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Text;
 using Roslyn.Test.Utilities;
 using Xunit;
 
@@ -6314,6 +6312,54 @@ void M()
             Assert.Equal("this, x", GetSymbolNamesJoined(dataFlowAnalysisResults.WrittenOutside));
         }
 
+        [Fact(Skip = "https://github.com/dotnet/roslyn/issues/30548")]
+        [WorkItem(30548, "https://github.com/dotnet/roslyn/issues/30548")]
+        public void SymbolInDataFlowInButNotInReadInside()
+        {
+            var analysisResults = CompileAndAnalyzeControlAndDataFlowStatements(@"
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace ConsoleApp39
+{
+    class Program
+    {
+        void Method(out object test)
+        {
+            test = null;
+
+            var a = test != null;
+            /*<bind>*/if (a)
+            {
+                return;
+            }
+
+            if (A == a)
+            {
+                test = new object();
+            }/*</bind>*/
+        }
+    }
+}");
+
+            var dataFlowAnalysisResults = analysisResults.Item2;
+
+            Assert.Equal(null, GetSymbolNamesJoined(dataFlowAnalysisResults.VariablesDeclared));
+            Assert.Equal(null, GetSymbolNamesJoined(dataFlowAnalysisResults.AlwaysAssigned));
+            Assert.Equal(null, GetSymbolNamesJoined(dataFlowAnalysisResults.Captured));
+            Assert.Equal(null, GetSymbolNamesJoined(dataFlowAnalysisResults.CapturedInside));
+            Assert.Equal(null, GetSymbolNamesJoined(dataFlowAnalysisResults.CapturedOutside));
+            Assert.Equal("test, a", GetSymbolNamesJoined(dataFlowAnalysisResults.DataFlowsIn));
+            Assert.Equal("test", GetSymbolNamesJoined(dataFlowAnalysisResults.DataFlowsOut));
+            Assert.Equal("a", GetSymbolNamesJoined(dataFlowAnalysisResults.ReadInside));
+            Assert.Equal("test", GetSymbolNamesJoined(dataFlowAnalysisResults.ReadOutside));
+            Assert.Equal("test", GetSymbolNamesJoined(dataFlowAnalysisResults.WrittenInside));
+            Assert.Equal("this, test, a", GetSymbolNamesJoined(dataFlowAnalysisResults.WrittenOutside));
+        }
+
         #endregion
     }
 }

src/EditorFeatures/CSharpTest/ExtractMethod/ExtractMethodTests.cs

@@ -10939,5 +10939,72 @@ private void NewMethod(int value, int value2)
 
             await TestExtractMethodAsync(code, expected);
         }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.ExtractMethod)]
+        public async Task TestDataFlowInButNoReadInside()
+        {
+            var code = @"using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace ConsoleApp39
+{
+    class Program
+    {
+        void Method(out object test)
+        {
+            test = null;
+
+            var a = test != null;
+            [|if (a)
+            {
+                return;
+            }
+
+            if (A == a)
+            {
+                test = new object();
+            }|]
+        }
+    }
+}";
+
+            var expected = @"using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace ConsoleApp39
+{
+    class Program
+    {
+        void Method(out object test)
+        {
+            test = null;
+
+            var a = test != null;
+            NewMethod(ref test, a);
+        }
+
+        private static void NewMethod(ref object test, bool a)
+        {
+            if (a)
+            {
+                return;
+            }
+
+            if (A == a)
+            {
+                test = new object();
+            }
+        }
+    }
+}";
+
+            await TestExtractMethodAsync(code, expected);
+        }
     }
 }

src/Features/Core/Portable/ExtractMethod/ExtractMethodMatrix.cs

@@ -158,6 +158,10 @@ private static void BuildMatrix()
             s_matrix.Add(new Key(dataFlowIn: true, dataFlowOut: false, alwaysAssigned: true, variableDeclared: false, readInside: true, writtenInside: true, readOutside: false, writtenOutside: true), VariableStyle.InputOnly);
             s_matrix.Add(new Key(dataFlowIn: true, dataFlowOut: false, alwaysAssigned: true, variableDeclared: false, readInside: true, writtenInside: true, readOutside: true, writtenOutside: false), VariableStyle.InputOnly);
             s_matrix.Add(new Key(dataFlowIn: true, dataFlowOut: false, alwaysAssigned: true, variableDeclared: false, readInside: true, writtenInside: true, readOutside: true, writtenOutside: true), VariableStyle.InputOnly);
+
+            // workaround for the bug(https://github.com/dotnet/roslyn/issues/30548)
+            s_matrix.Add(new Key(dataFlowIn: true, dataFlowOut: true, alwaysAssigned: false, variableDeclared: false, readInside: false, writtenInside: true, readOutside: true, writtenOutside: true), VariableStyle.Ref);
+
             s_matrix.Add(new Key(dataFlowIn: true, dataFlowOut: true, alwaysAssigned: false, variableDeclared: false, readInside: true, writtenInside: true, readOutside: true, writtenOutside: false), VariableStyle.OutWithErrorInput);
             s_matrix.Add(new Key(dataFlowIn: true, dataFlowOut: true, alwaysAssigned: false, variableDeclared: false, readInside: true, writtenInside: true, readOutside: true, writtenOutside: true), VariableStyle.Ref);
             s_matrix.Add(new Key(dataFlowIn: true, dataFlowOut: true, alwaysAssigned: true, variableDeclared: false, readInside: true, writtenInside: true, readOutside: true, writtenOutside: false), VariableStyle.OutWithErrorInput);