Update CS0193 error message documentation for function pointers (#46423)

* Initial plan for issue

* Update CS0193 error message documentation for function pointers

Co-authored-by: yufeih <[email protected]>

* Refine CS0193 documentation with additional unsafe context and links

Co-authored-by: yufeih <[email protected]>

* Update ms.date to 05/27/2025 as requested

Co-authored-by: BillWagner <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: yufeih <[email protected]>
Co-authored-by: BillWagner <[email protected]>
Co-authored-by: Bill Wagner <[email protected]>

Author: 3 people

docs/csharp/misc/cs0193.md

@@ -1,7 +1,7 @@
 ---
 description: "Compiler Error CS0193"
 title: "Compiler Error CS0193"
-ms.date: 07/20/2015
+ms.date: 05/27/2025
 f1_keywords: 
   - "CS0193"
 helpviewer_keywords: 
@@ -10,9 +10,9 @@ ms.assetid: 7b60fd99-9eee-4d61-ad75-585a16e22e96
 ---
 # Compiler Error CS0193
 
-The \* or -> operator must be applied to a pointer  
+The \* or -> operator must be applied to a data pointer  
 
-The \* or -> operator was used with a nonpointer type. For more information, see [Pointer types](../language-reference/unsafe-code.md#pointer-types).  
+The \* or -> operator was used with a nonpointer type or with a function pointer. Function pointers cannot be dereferenced in C#. For more information, see [Pointer types](../language-reference/unsafe-code.md#pointer-types) and [Function pointers](../language-reference/unsafe-code.md#function-pointers).  
 
  The following sample generates CS0193:  
 
@@ -45,3 +45,19 @@ public class MyClass
    }  
 }  
 ```
+
+The following example shows that function pointers cannot be dereferenced in C#, unlike in C/C++:
+
+```csharp
+unsafe class FunctionPointerExample
+{
+    public static void Log() { /* ... */ }
+    
+    public static unsafe void Example()
+    {
+        delegate*<void> fp = &Log;   // pointer to managed function Log()
+        fp();                        // OK; call Log() via function pointer
+        (*fp)();                     // Error; CS0193, function pointers cannot be dereferenced
+    }
+}
+```