| Issue |
75891
|
| Summary |
`cppcoreguidelines-missing-std-forward` should consider expressions in lambda captures.
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
DXPower
|
The following code triggers a false positive in Clang-Tidy 17 and many versions prior:
```cpp
#include <utility>
template<typename F>
auto MakeFunc(F&& func) {
return [func2 = std::forward<F>(func)]() {
func2();
};
}
```
```
[warning: forwarding reference parameter 'func' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
```
However, this is a false positive because the `func` variable is captured by an _expression_ in which `std::forward` is indeed called on it. It's pretty easy to test that `std::forward` is being called too:
```cpp
#include<utility>
template<typename F>auto MakeFunc(F&&func){
return[func=std::forward<F>(func)]{
func();
};
}
#include<iostream>
struct foo{
foo(){std::cout<<"default construction\n";}
foo(const foo&){std::cout<<"copy construction\n";}
foo(foo&&){std::cout<<"move construction\n";}
foo&operator=(const foo&){std::cout<<"copy assignment\n";return*this;}
foo&operator=(foo&&){std::cout<<"move assignment\n";return*this;}
void operator()()const&{std::cout<<"lvalue\n";}
void operator()()const&&{std::cout<<"rvalue\n";}
};
int main(){
MakeFunc(foo())();
foo f;
MakeFunc(f)();
}
```
Prints:
```
default construction
move construction
lvalue
default construction
copy construction
lvalue
```
`cppcoreguidelines-missing-std-forward` should consider expressions in lambda captures.
Godbolt's for the above snippets:
https://godbolt.org/z/9sh3szr7c
https://godbolt.org/z/sYxhsss14
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