Merge pull request #5794 from Rageking8/add-example-in-c2154-error-reference

Add example in C2154 error reference

Author: ttorble

docs/error-messages/compiler-errors-1/compiler-error-c2154.md

@@ -1,16 +1,36 @@
 ---
 title: "Compiler Error C2154"
 description: "Learn more about: Compiler Error C2154"
-ms.date: 11/04/2016
+ms.date: 09/21/2025
 f1_keywords: ["C2154"]
 helpviewer_keywords: ["C2154"]
 ---
 # Compiler Error C2154
 
-> 'type' : only enumeration type is allowed as an argument to compiler intrinsic type trait '__underlying_type'
+> '*type*': only enumeration type is allowed as an argument to compiler intrinsic type trait '__underlying_type'
 
 ## Remarks
 
-You can only get the underlying type of an enumeration type.
+You can only get the underlying type of an [enumeration](../../cpp/enumerations-cpp.md) type.
 
-For more information, see [Compiler Support for Type Traits](../../extensions/compiler-support-for-type-traits-cpp-component-extensions.md).
+## Example
+
+The following example generates C2154:
+
+```cpp
+// C2154.cpp
+// compile with: /c
+
+struct S {};
+enum E {};
+enum class EC {};
+
+__underlying_type(S) s;     // C2154
+__underlying_type(int) i;   // C2154
+__underlying_type(E) e;     // OK
+__underlying_type(EC) ec;   // OK
+```
+
+## See also
+
+[`underlying_type` class](../../standard-library/underlying-type-class.md)

docs/error-messages/compiler-errors-1/compiler-errors-c2100-through-c2199.md

@@ -69,7 +69,7 @@ The articles in this section of the documentation explain a subset of the error
 |[Compiler error C2151](compiler-error-c2151.md)|more than one language attribute|
 |[Compiler error C2152](compiler-error-c2152.md)|'*identifier*': pointers to functions with different attributes|
 |[Compiler error C2153](compiler-error-c2153.md)|integer literals must have at least one digit|
-|[Compiler error C2154](compiler-error-c2154.md)|'*type*': only enumeration type is allowed as an argument to compiler intrinsic type trait '*trait*'|
+|[Compiler error C2154](compiler-error-c2154.md)|'*type*': only enumeration type is allowed as an argument to compiler intrinsic type trait '__underlying_type'|
 |[Compiler error C2155](compiler-error-c2155.md)|'?': invalid left operand, expected arithmetic or pointer type|
 |[Compiler error C2156](compiler-error-c2156.md)|pragma must be outside function|
 |[Compiler error C2157](compiler-error-c2157.md)|'*identifier*': must be declared before use in pragma list|