Reproduce and fix 'Use expression body' indenting new expression body oddly

src/Analyzers/CSharp/Tests/UseExpressionBody/UseExpressionBodyForPropertiesAnalyzerTests.cs

@@ -580,4 +580,48 @@ public long Length                   //N
             """;
         await TestWithUseExpressionBody(code, fixedCode);
     }
+
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38057")]
+    public async Task TestUseExpressionBodyPreserveComments2()
+    {
+        var code = """
+            public class C
+            {
+                {|IDE0025:public long Length // cool prop
+                {
+                    get { return 1 + 2; }
+                }|}
+            }
+            """;
+        var fixedCode = """
+            public class C
+            {
+                public long Length // cool prop
+                    => 1 + 2;
+            }
+            """;
+        await TestWithUseExpressionBody(code, fixedCode);
+    }
+
+    [Fact]
+    public async Task TestUseExpressionBodyPreserveComments3()
+    {
+        var code = """
+            public class C
+            {
+                {|IDE0025:public long Length // cool prop
+                {
+                /*a*/ get { return 1 + 2; }
+                }|}
+            }
+            """;
+        var fixedCode = """
+            public class C
+            {
+                public long Length // cool prop
+                /*a*/ => 1 + 2;
+            }
+            """;
+        await TestWithUseExpressionBody(code, fixedCode);
+    }
 }

src/Workspaces/SharedUtilitiesAndExtensions/Compiler/CSharp/Extensions/BlockSyntaxExtensions.cs

@@ -137,8 +137,13 @@ public static bool TryConvertToArrowExpressionBody(
                 var comments = parent.GetLeadingTrivia().Where(t => !t.IsWhitespaceOrEndOfLine());
                 if (!comments.IsEmpty())
                 {
-                    arrowExpression = arrowExpression.WithLeadingTrivia(
-                        parent.GetLeadingTrivia());
+                    arrowExpression = arrowExpression.WithLeadingTrivia(parent.GetLeadingTrivia());
+                }
+                else if (parent.GetLeadingTrivia().All(t => t.IsWhitespace()))
+                {
+                    // Manually copy indentation, but keep the elastic to erase the newline trivia after the property
+                    // identifier token if there is no comment following it.
+                    arrowExpression = arrowExpression.WithPrependedLeadingTrivia(parent.GetLeadingTrivia());
                 }
             }