https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69864
Bug ID: 69864
Summary: Narrowing conversion
Product: gcc
Version: 5.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mgsergio at yandex dot ru
Target Milestone: ---
#include <iostream>
#include <type_traits>
using namespace std;
template <typename T, typename U>
inline T narrowing_check(U const u)
{
// Also gives only warning
// T t{u};
// return t;
return {u};
}
int main() {
auto a = narrowing_check<int>(3.5);
cout << a;
// int b{2.3};
return 0;
}
gcc emits a waring on narrowing_check although it should be generated instead.
On int b{2.3} gcc correctly rejects the code.
g++-5 -Wall -Wextra -std=c++11 1.cc
1.cc: In instantiation of 'T narrowing_check(U) [with T = int; U = double]':
1.cc:15:36: required from here
1.cc:11:12: warning: narrowing conversion of '(double)u' from 'double' to 'int'
inside { } [-Wnarrowing]
return {u};
clang rejects this code.
1.cc:11:11: error: type 'double' cannot be narrowed to 'int' in initializer
list [-Wc++11-narrowing]
return {u};
^
1.cc:15:12: note: in instantiation of function template specialization
'narrowing_check<int, double>' requested here
auto a = narrowing_check<int>(3.5);
^
1.cc:11:11: note: insert an explicit cast to silence this issue
return {u};
^
static_cast<int>( )
1 error generated.
