Merge pull request #5992 from TylerMSFT/c7742

new article

Author: denrea

docs/error-messages/compiler-errors-1/compiler-error-c2462.md

@@ -4,19 +4,19 @@ title: "Compiler Error C2462"
 ms.date: "11/04/2016"
 f1_keywords: ["C2462"]
 helpviewer_keywords: ["C2462"]
-ms.assetid: a8601bf8-f5ce-41de-9117-e2632bd4996b
 ---
 # Compiler Error C2462
 
-'identifier' : cannot define a type in a 'new-expression'
+> 'identifier' : cannot define a type in a 'new-expression'
 
 You cannot define a type in the operand field of the **`new`** operator. Put the type definition in a separate statement.
 
 The following sample generates C2462:
 
 ```cpp
 // C2462.cpp
-int main() {
+int main()
+{
    new struct S { int i; };   // C2462
 }
 ```

docs/error-messages/compiler-errors-2/compiler-error-c7742.md

@@ -0,0 +1,43 @@
+---
+description: "Learn more about: Compiler Error C7742"
+title: "Compiler Error C7742"
+ms.date: "07/02/2025"
+ai-usage: ai-assisted
+f1_keywords: ["C7742"]
+helpviewer_keywords: ["C7742"]
+---
+# Compiler Error C7742
+
+> *Identifier*: a forward declaration of an enum can only use a simple identifier
+
+The C++ Standard doesn't allow declaring an opaque enumeration using a qualified-id. An opaque enum declaration specifies the name and the underlying type, but doesn't list the enumerators or their values.
+
+The following example generates C7742:
+
+```cpp
+// C7742.cpp
+class MyClass
+{ 
+public: 
+    enum MyEnum
+    { 
+        e1, 
+        e2 
+    }; 
+}; 
+  
+enum MyClass::MyEnum;   // C7742
+```
+
+To fix this error, remove the opaque enumeration declaration because it doesn't add anything to the program.
+
+However, you can define an enumeration with a qualified-id. For example:
+
+```cpp
+struct S
+{
+   enum E : int;
+};
+
+enum S::E : int { e1, e2, e3 };
+```

docs/error-messages/compiler-errors-2/compiler-errors-c7500-through-c7999.md

@@ -240,6 +240,7 @@ The articles in this section of the documentation explain a subset of the error
 | Compiler error C7739 | cannot jump from this `goto` statement to its label |
 | Compiler error C7740 | cannot jump to case label |
 | Compiler error C7741 | ABI inconsistency: '*function*' was originally assumed to use '`C`' return semantics but now it requires '`C++`' return semantics |
+| [Compiler error C7742](compiler-error-c7742.md) | '*identifier*': a forward declaration of an enum can only use a simple identifier |
 | Compiler error C7800 | duplicate explicit instantiation definition of '*name*' |
 | Compiler error C7801 | '*function*': if one declaration of '*identifier*' has the '`[[msvc::disptach]]`' attribute then all functions must have the attribute |
 | Compiler error C7802 | '*identifier*': a capability must resolve to an enumerator |

docs/error-messages/toc.yml

@@ -3169,6 +3169,8 @@ items:
           href: compiler-warnings/c5208.md
         - name: Compiler error C7688
           href: compiler-errors-2/compiler-error-c7688.md
+        - name: Compiler error C7742
+          href: compiler-errors-2/compiler-error-c7742.md
 - name: Compiler warnings C4000 through C5999
   expanded: false
   items: