| Issue |
141732
|
| Summary |
[clang] Failed to compile simple and legal code while gcc is ok
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
yaoxinliu
|
See: [https://godbolt.org/z/GqbzYfa78](https://godbolt.org/z/GqbzYfa78)
```
template<typename T>
concept IsOK =
[]<typename U> consteval -> bool { return requires { requires sizeof(U) > 1; }; }.template operator()<T>();
static_assert(IsOK<int>);
int main() {
}
```
**gcc is ok, but clang gives errors as follows:**
> <source>:3:67: error: substitution into constraint _expression_ resulted in a non-constant _expression_
> 3 | []<typename U> consteval -> bool { return requires { requires sizeof(U) > 1; }; }.template operator()<T>();
> | ^~~~~~~~~~~~~
> <source>:3:67: note: while checking the satisfaction of nested requirement requested here
> 3 | []<typename U> consteval -> bool { return requires { requires sizeof(U) > 1; }; }.template operator()<T>();
> | ^~~~~~~~~~~~~
> <source>:3:67: note: in instantiation of requirement here
> 3 | []<typename U> consteval -> bool { return requires { requires sizeof(U) > 1; }; }.template operator()<T>();
> | ^~~~~~~~~~~~~
> <source>:3:67: note: while checking the satisfaction of nested requirement requested here
> 3 | []<typename U> consteval -> bool { return requires { requires sizeof(U) > 1; }; }.template operator()<T>();
> | ^~~~~~~~~~~~~
> <source>:3:38: note: while substituting into a lambda _expression_ here
> 3 | []<typename U> consteval -> bool { return requires { requires sizeof(U) > 1; }; }.template operator()<T>();
> | ^
> <source>:3:5: note: while substituting template arguments into constraint _expression_ here
> 3 | []<typename U> consteval -> bool { return requires { requires sizeof(U) > 1; }; }.template operator()<T>();
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> <source>:5:15: note: while checking the satisfaction of concept 'IsOK<int>' requested here
> 5 | static_assert(IsOK<int>);
> | ^~~~~~~~~
> <source>:3:67: note: subexpression not valid in a constant _expression_
> 3 | []<typename U> consteval -> bool { return requires { requires sizeof(U) > 1; }; }.template operator()<T>();
> | ^
> <source>:5:15: error: static assertion failed
> 5 | static_assert(IsOK<int>);
> | ^~~~~~~~~
> <source>:5:15: note: because 'int' does not satisfy 'IsOK'
> <source>:3:5: note: because '[]<typename U>() -> bool {
> return requires { requires <<error-_expression_>>; };
> }.template operator()<int>()' evaluated to false
> 3 | []<typename U> consteval -> bool { return requires { requires sizeof(U) > 1; }; }.template operator()<T>();
> | ^
> 2 errors generated.
> Compiler returned: 1
>
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