https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125644
Bug ID: 125644
Summary: narrowing warnings emitted twice
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ivan.lazaric.gcc at gmail dot com
Target Milestone: ---
```cpp
#include <vector>
void fn(auto... args) {
std::vector<std::size_t>{args...};
}
int main() {
fn(3, 3);
}
```
Compiler flags: "-std=c++26" (-Wnarrowing is defaulted)
Compiler diagnostics:
```
<source>: In instantiation of 'void fn(auto:6 ...) [with auto:6 = {int, int}]':
<source>:8:7: required from here
8 | fn(3, 3);
| ~~^~~~~~
<source>:4:30: warning: narrowing conversion of 'args#0' from 'int' to 'long
unsigned int' [-Wnarrowing]
4 | std::vector<std::size_t>{args...};
| ^~~~
<source>:4:30: warning: narrowing conversion of 'args#0' from 'int' to 'long
unsigned int' [-Wnarrowing]
<source>:4:30: warning: narrowing conversion of 'args#1' from 'int' to 'long
unsigned int' [-Wnarrowing]
<source>:4:30: warning: narrowing conversion of 'args#1' from 'int' to 'long
unsigned int' [-Wnarrowing]
Compiler returned: 0
```
Compiler emitted two warnings for each member of the parameter pack,
a single warning per suffices.
In this specific case no warning would also be fine IMO since `3`
is representable in both `int` and `long unsigned int` exactly.
Godbolt: https://godbolt.org/z/7bTGvjGfz
