Fix "Introduce local" generating invalid code for function pointer types

src/Features/CSharpTest/IntroduceVariable/IntroduceVariableTests.cs

@@ -8497,4 +8497,62 @@ void M(object[] p)
             }
             """,
             new(parseOptions: TestOptions.Regular));
+
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/80982")]
+    public Task TestFunctionPointerType()
+        => TestInRegularAndScriptAsync(
+            """
+            unsafe class C
+            {
+                public delegate* managed<void> D
+                {
+                    get
+                    {
+                        return [|field|];
+                    }
+                }
+            }
+            """,
+            """
+            unsafe class C
+            {
+                public delegate* managed<void> D
+                {
+                    get
+                    {
+                        delegate*<void> {|Rename:value|} = field;
+                        return value;
+                    }
+                }
+            }
+            """);
+
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/80982")]
+    public Task TestPointerType()
+        => TestInRegularAndScriptAsync(
+            """
+            unsafe class C
+            {
+                public void* D
+                {
+                    get
+                    {
+                        return [|field|];
+                    }
+                }
+            }
+            """,
+            """
+            unsafe class C
+            {
+                public void* D
+                {
+                    get
+                    {
+                        void* {|Rename:value|} = field;
+                        return value;
+                    }
+                }
+            }
+            """);
 }

src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Extensions/Symbols/ITypeSymbolExtensions.cs

@@ -340,9 +340,11 @@ public static string CreateParameterName(this ITypeSymbol type, bool capitalize
                 case IArrayTypeSymbol arrayType:
                     type = arrayType.ElementType;
                     continue;
-                case IPointerTypeSymbol pointerType:
-                    type = pointerType.PointedAtType;
-                    continue;
+                case IPointerTypeSymbol:
+                case IFunctionPointerTypeSymbol:
+                    // Pointer types like "void*" and function pointer types like "delegate*<void>" 
+                    // don't have meaningful names, so use the default parameter name
+                    return capitalize ? DefaultParameterName.ToPascalCase() : DefaultParameterName;
             }
 
             break;