| Issue |
137907
|
| Summary |
inherited constructor causes `source_locationI::current()` to point at wrong line
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
snarkmaster
|
In this code (https://godbolt.org/z/dPhq718e5), `Foo foo{}` ends up with an incorrect `source_location`, while `Foo foo{Potato{}` is fine.
It looks like `using Bar::Bar` generates a default ctor for `Foo`, which becomes the evaluation site for `source_location::current()`.
I'm not a standards lawyer, but I didn't find any suggestion that what we're seeing here is the specified behavior. And for default arguments, the the clear intent of the C++ standard is for default arguments to be evaluated at the **call site**. The current behavior violates at least the spirit of that rule. It also breaks the typical `source_location`-stamping technique.
```
#include <iostream>
#include <source_location>
struct Potato {};
struct Bar {
std::source_location sl_;
explicit Bar(Potato = {}, std::source_location sl = std::source_location::current())
: sl_(sl) {}
};
struct Foo : Bar { // `foo.sl_` points here on GCC & clang
using Bar::Bar;
}; // `foo.sl_` points here on MSVC
int main() {
Foo foo{}; // Why isn't `sl_` pointing here?
std::cout << "foo @ line " << foo.sl_.line() << std::endl;
Foo foo2{Potato{}}; // But this is fine!
std::cout << "foo2 @ line " << foo2.sl_.line() << std::endl;
return 0;
}
```
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