| Issue |
177747
|
| Summary |
-Wnrvo has annoying false positives with lifetimes and inside templates
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
higher-performance
|
```
template<class T>
auto foo(T v) {
if constexpr (sizeof(v) > 0) {
struct {} a;
return a;
} else {
return 0;
}
}
int main() {
foo(0);
}
```
[produces](https://godbolt.org/z/vEModM9Pq):
```
<source>:5:10: warning: not eliding copy on return [-Wnrvo]
5 | return a;
| ^
<source>:12:2: note: in instantiation of function template specialization 'foo<int>' requested here
12 | foo(0);
| ^
```
It appears as if the check naively looks for multiple `return` statements inside the template, completely missing two key facts:
1. The different parts of the template are not instantiated simultaneously.
1. The lifetimes of the possible return values do not overlap.
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