| Issue |
131503
|
| Summary |
[clang++] template nested class declaration works unexpectedly
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
AnonymousPC
|
(clang++, version=19.1.7, platform=MacOS)
See this code below
```cpp
template < class T >
concept my_concept = true;
template < class T >
struct my_class
{
template < my_concept U >
struct my_nested_class;
};
template < class T >
template < my_concept U >
#if defined(__GNUC__) and not defined(__clang__)
struct my_class<T>::my_nested_class // *** Expected way, which works on gcc ***
#elifdef __clang__
struct my_class<T>::my_nested_class<U> // *** In clang++ we must write in this way ***
#endif
{
};
```
When we declare as the first way in clang++, we get a compile-error like this:
```text
main.cpp:12:12: error: type constraint differs in template redeclaration
12 | template < my_concept type2 >
| ^
main.cpp:7:16: note: previous template declaration is here
7 | template < my_concept type2 >
|
```
while declare as the second way is accepted in clang++.
However ***the first way is expected***, because when we declare a ***non-concept*** template nested class, it should be written like this:
```cpp
template < class T >
struct your_class
{
template < class U >
struct your_nested_class;
};
template < class T >
template < class U >
struct your_class<T>::your_nested_class /* clang++ requires no <U> here. Same do g++ */;
```
and it should be along with the one with ***concept*** -constrained nested class.
![]()
_______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
