| Issue |
115118
|
| Summary |
Error when explicitly specifying return type of generic lambda in constraint?
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
Eczbek
|
https://godbolt.org/z/Yfsdrnn4E
```cpp
struct foo {
foo(const foo&) = default;
foo(auto) requires([]<int = 0> -> bool { return true; }()) {}
};
struct bar { foo x; };
int main() {}
```
```
<source>:4:21: error: substitution into constraint _expression_ resulted in a non-constant _expression_
4 | foo(auto) requires([]<int = 0> -> bool { return true; }()) {}
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:1:8: note: while checking constraint satisfaction for template 'foo<foo>' required here
1 | struct foo {
| ^~~
<source>:1:8: note: in instantiation of function template specialization 'foo::foo<foo>' requested here
<source>:7:8: note: while declaring the implicit copy constructor for 'bar'
7 | struct bar { foo x; };
| ^
<source>:4:21: note: undefined function 'operator()<0>' cannot be used in a constant _expression_
4 | foo(auto) requires([]<int = 0> -> bool { return true; }()) {}
| ^
<source>:4:21: note: declared here
<source>:4:21: error: substitution into constraint _expression_ resulted in a non-constant _expression_
4 | foo(auto) requires([]<int = 0> -> bool { return true; }()) {}
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:1:8: note: while checking constraint satisfaction for template 'foo<foo>' required here
1 | struct foo {
| ^~~
<source>:1:8: note: while substituting deduced template arguments into function template 'foo' [with auto:1 = foo]
<source>:7:8: note: while declaring the implicit move constructor for 'bar'
7 | struct bar { foo x; };
| ^
<source>:4:21: note: undefined function 'operator()<0>' cannot be used in a constant _expression_
4 | foo(auto) requires([]<int = 0> -> bool { return true; }()) {}
| ^
<source>:4:21: note: declared here
2 errors generated.
Compiler returned: 1
```
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