Skip to content

Commit ed2d4ed

Browse files
TylerMSFTTylerMSFT
committed
new article
1 parent 72d7d3d commit ed2d4ed

File tree

3 files changed

+47
-2
lines changed

3 files changed

+47
-2
lines changed

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

Lines changed: 42 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,42 @@
1+
---
2+
description: "Learn more about: Compiler Error C7742"
3+
title: "Compiler Error C7742"
4+
ms.date: "07/02/2025"
5+
f1_keywords: ["C7742"]
6+
helpviewer_keywords: ["C7742"]
7+
---
8+
# Compiler Error C7742
9+
10+
*identifier*': a forward declaration of an enum can only use a simple identifier
11+
12+
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.
13+
14+
The following example generates C7742:
15+
16+
```cpp
17+
// C7742.cpp
18+
class MyClass
19+
{
20+
public:
21+
enum MyEnum
22+
{
23+
e1,
24+
e2
25+
};
26+
};
27+
28+
enum MyClass::MyEnum; // C7742
29+
```
30+
31+
To fix this, remove the opaque enumeration declaration because it doesn't add anything to the program.
32+
33+
However, you can define an enumeration with a qualified-id. For example:
34+
35+
```cpp
36+
struct S
37+
{
38+
enum E : int;
39+
};
40+
41+
enum S::E : int { e1, e2, e3 };
42+
```

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

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2,8 +2,8 @@
22
description: "Learn more about: Compiler errors C7500 through C7999"
33
title: "Compiler errors C7500 through C7999"
44
ms.date: 10/13/2023
5-
f1_keywords: ["C7500", "C7501", "C7502", "C7503", "C7504", "C7505", "C7506", "C7507", "C7508", "C7509", "C7511", "C7512", "C7513", "C7514", "C7515", "C7516", "C7517", "C7518", "C7519", "C7520", "C7521", "C7522", "C7523", "C7524", "C7525", "C7526", "C7527", "C7528", "C7529", "C7530", "C7531", "C7532", "C7533", "C7534", "C7535", "C7537", "C7538", "C7539", "C7540", "C7541", "C7542", "C7543", "C7544", "C7545", "C7546", "C7547", "C7548", "C7549", "C7550", "C7551", "C7552", "C7554", "C7555", "C7556", "C7557", "C7558", "C7559", "C7560", "C7561", "C7562", "C7563", "C7564", "C7565", "C7566", "C7567", "C7568", "C7569", "C7570", "C7571", "C7572", "C7573", "C7574", "C7575", "C7576", "C7577", "C7578", "C7579", "C7580", "C7581", "C7582", "C7583", "C7584", "C7585", "C7586", "C7587", "C7588", "C7589", "C7590", "C7591", "C7592", "C7593", "C7594", "C7595", "C7596", "C7597", "C7599", "C7600", "C7601", "C7602", "C7603", "C7604", "C7605", "C7606", "C7607", "C7608", "C7609", "C7610", "C7611", "C7612", "C7613", "C7614", "C7615", "C7616", "C7617", "C7618", "C7619", "C7620", "C7621", "C7622", "C7623", "C7624", "C7625", "C7627", "C7628", "C7629", "C7630", "C7631", "C7632", "C7633", "C7634", "C7635", "C7636", "C7637", "C7638", "C7639", "C7640", "C7641", "C7642", "C7643", "C7644", "C7645", "C7646", "C7647", "C7648", "C7649", "C7650", "C7651", "C7652", "C7653", "C7654", "C7655", "C7656", "C7657", "C7658", "C7659", "C7660", "C7661", "C7662", "C7686", "C7700", "C7701", "C7702", "C7703", "C7704"]
6-
helpviewer_keywords: ["C7500", "C7501", "C7502", "C7503", "C7504", "C7505", "C7506", "C7507", "C7508", "C7509", "C7511", "C7512", "C7513", "C7514", "C7515", "C7516", "C7517", "C7518", "C7519", "C7520", "C7521", "C7522", "C7523", "C7524", "C7525", "C7526", "C7527", "C7528", "C7529", "C7530", "C7531", "C7532", "C7533", "C7534", "C7535", "C7537", "C7538", "C7539", "C7540", "C7541", "C7542", "C7543", "C7544", "C7545", "C7546", "C7547", "C7548", "C7549", "C7550", "C7551", "C7552", "C7554", "C7555", "C7556", "C7557", "C7558", "C7559", "C7560", "C7561", "C7562", "C7563", "C7564", "C7565", "C7566", "C7567", "C7568", "C7569", "C7570", "C7571", "C7572", "C7573", "C7574", "C7575", "C7576", "C7577", "C7578", "C7579", "C7580", "C7581", "C7582", "C7583", "C7584", "C7585", "C7586", "C7587", "C7588", "C7589", "C7590", "C7591", "C7592", "C7593", "C7594", "C7595", "C7596", "C7597", "C7599", "C7600", "C7601", "C7602", "C7603", "C7604", "C7605", "C7606", "C7607", "C7608", "C7609", "C7610", "C7611", "C7612", "C7613", "C7614", "C7615", "C7616", "C7617", "C7618", "C7619", "C7620", "C7621", "C7622", "C7623", "C7624", "C7625", "C7627", "C7628", "C7629", "C7630", "C7631", "C7632", "C7633", "C7634", "C7635", "C7636", "C7637", "C7638", "C7639", "C7640", "C7641", "C7642", "C7643", "C7644", "C7645", "C7646", "C7647", "C7648", "C7649", "C7650", "C7651", "C7652", "C7653", "C7654", "C7655", "C7656", "C7657", "C7658", "C7659", "C7660", "C7661", "C7662", "C7686", "C7700", "C7701", "C7702", "C7703", "C7704"]
5+
f1_keywords: ["C7500", "C7501", "C7502", "C7503", "C7504", "C7505", "C7506", "C7507", "C7508", "C7509", "C7511", "C7512", "C7513", "C7514", "C7515", "C7516", "C7517", "C7518", "C7519", "C7520", "C7521", "C7522", "C7523", "C7524", "C7525", "C7526", "C7527", "C7528", "C7529", "C7530", "C7531", "C7532", "C7533", "C7534", "C7535", "C7537", "C7538", "C7539", "C7540", "C7541", "C7542", "C7543", "C7544", "C7545", "C7546", "C7547", "C7548", "C7549", "C7550", "C7551", "C7552", "C7554", "C7555", "C7556", "C7557", "C7558", "C7559", "C7560", "C7561", "C7562", "C7563", "C7564", "C7565", "C7566", "C7567", "C7568", "C7569", "C7570", "C7571", "C7572", "C7573", "C7574", "C7575", "C7576", "C7577", "C7578", "C7579", "C7580", "C7581", "C7582", "C7583", "C7584", "C7585", "C7586", "C7587", "C7588", "C7589", "C7590", "C7591", "C7592", "C7593", "C7594", "C7595", "C7596", "C7597", "C7599", "C7600", "C7601", "C7602", "C7603", "C7604", "C7605", "C7606", "C7607", "C7608", "C7609", "C7610", "C7611", "C7612", "C7613", "C7614", "C7615", "C7616", "C7617", "C7618", "C7619", "C7620", "C7621", "C7622", "C7623", "C7624", "C7625", "C7627", "C7628", "C7629", "C7630", "C7631", "C7632", "C7633", "C7634", "C7635", "C7636", "C7637", "C7638", "C7639", "C7640", "C7641", "C7642", "C7643", "C7644", "C7645", "C7646", "C7647", "C7648", "C7649", "C7650", "C7651", "C7652", "C7653", "C7654", "C7655", "C7656", "C7657", "C7658", "C7659", "C7660", "C7661", "C7662", "C7686", "C7700", "C7701", "C7702", "C7703", "C7704", "C7742"]
6+
helpviewer_keywords: ["C7500", "C7501", "C7502", "C7503", "C7504", "C7505", "C7506", "C7507", "C7508", "C7509", "C7511", "C7512", "C7513", "C7514", "C7515", "C7516", "C7517", "C7518", "C7519", "C7520", "C7521", "C7522", "C7523", "C7524", "C7525", "C7526", "C7527", "C7528", "C7529", "C7530", "C7531", "C7532", "C7533", "C7534", "C7535", "C7537", "C7538", "C7539", "C7540", "C7541", "C7542", "C7543", "C7544", "C7545", "C7546", "C7547", "C7548", "C7549", "C7550", "C7551", "C7552", "C7554", "C7555", "C7556", "C7557", "C7558", "C7559", "C7560", "C7561", "C7562", "C7563", "C7564", "C7565", "C7566", "C7567", "C7568", "C7569", "C7570", "C7571", "C7572", "C7573", "C7574", "C7575", "C7576", "C7577", "C7578", "C7579", "C7580", "C7581", "C7582", "C7583", "C7584", "C7585", "C7586", "C7587", "C7588", "C7589", "C7590", "C7591", "C7592", "C7593", "C7594", "C7595", "C7596", "C7597", "C7599", "C7600", "C7601", "C7602", "C7603", "C7604", "C7605", "C7606", "C7607", "C7608", "C7609", "C7610", "C7611", "C7612", "C7613", "C7614", "C7615", "C7616", "C7617", "C7618", "C7619", "C7620", "C7621", "C7622", "C7623", "C7624", "C7625", "C7627", "C7628", "C7629", "C7630", "C7631", "C7632", "C7633", "C7634", "C7635", "C7636", "C7637", "C7638", "C7639", "C7640", "C7641", "C7642", "C7643", "C7644", "C7645", "C7646", "C7647", "C7648", "C7649", "C7650", "C7651", "C7652", "C7653", "C7654", "C7655", "C7656", "C7657", "C7658", "C7659", "C7660", "C7661", "C7662", "C7686", "C7700", "C7701", "C7702", "C7703", "C7704", "C7742"]
77
---
88
# Compiler errors C7500 through C7999
99

@@ -240,6 +240,7 @@ The articles in this section of the documentation explain a subset of the error
240240
| Compiler error C7739 | cannot jump from this `goto` statement to its label |
241241
| Compiler error C7740 | cannot jump to case label |
242242
| Compiler error C7741 | ABI inconsistency: '*function*' was originally assumed to use '`C`' return semantics but now it requires '`C++`' return semantics |
243+
| [Compiler error C7742](compiler-error-c7742.md) | '*identifier*': a forward declaration of an enum can only use a simple identifier |
243244
| Compiler error C7800 | duplicate explicit instantiation definition of '*name*' |
244245
| Compiler error C7801 | '*function*': if one declaration of '*identifier*' has the '`[[msvc::disptach]]`' attribute then all functions must have the attribute |
245246
| Compiler error C7802 | '*identifier*': a capability must resolve to an enumerator |

‎docs/error-messages/toc.yml‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3169,6 +3169,8 @@ items:
31693169
href: compiler-warnings/c5208.md
31703170
- name: Compiler error C7688
31713171
href: compiler-errors-2/compiler-error-c7688.md
3172+
- name: Compiler error C7742
3173+
href: compiler-errors-2/compiler-error-c7742.md
31723174
- name: Compiler warnings C4000 through C5999
31733175
expanded: false
31743176
items:

0 commit comments

Comments
 (0)