Update to check entire block for directives instead of just close brace

This is more conservative and handles cases where directives appear anywhere in the block, not just at the end.

Co-authored-by: CyrusNajmabadi <4564579+CyrusNajmabadi@users.noreply.github.com>

Author: Copilot

src/Analyzers/CSharp/Analyzers/UseNullPropagation/CSharpUseNullPropagationDiagnosticAnalyzer.cs

@@ -72,12 +72,13 @@ protected override bool TryAnalyzePatternCondition(
         IfStatementSyntax ifStatement,
         CancellationToken cancellationToken)
     {
-        // Check if the if-statement has a block statement with directives on the close brace.
+        // Check if the if-statement has a block statement with preprocessor directives.
         // If so, we can't convert to null propagation because the directives (like #if DEBUG)
-        // would be lost or cause compilation issues.
+        // would be lost or cause compilation issues. We check the entire block rather than
+        // just the close brace to handle cases where directives appear anywhere in the block.
         if (ifStatement.Statement is BlockSyntax block)
         {
-            if (block.CloseBraceToken.ContainsDirectives)
+            if (block.ContainsDirectives)
                 return null;
         }
 

src/Analyzers/CSharp/Tests/UseNullPropagation/UseNullPropagationTests.cs

@@ -2830,6 +2830,29 @@ public void Dispose()
             }
             """);
 
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/77777")]
+    public Task TestIfStatement_WithPreprocessorDirective_BeforeStatement()
+        => TestMissingInRegularAndScriptAsync(
+            """
+            using System.Diagnostics;
+
+            class C
+            {
+                private object? _controlToLayout;
+
+                public void Dispose()
+                {
+                    if (_controlToLayout != null)
+                    {
+            #if DEBUG
+                        Debug.WriteLine("Debug mode");
+            #endif
+                        _controlToLayout.ToString();
+                    }
+                }
+            }
+            """);
+
     [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/77777")]
     public Task TestIfStatement_WithoutPreprocessorDirective_StillWorks()
         => TestInRegularAndScriptAsync(