https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71985
Bug ID: 71985
Summary: narrowing in initializer lists is not ill-formed where
required
Product: gcc
Version: 5.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: nico at josuttis dot de
Target Milestone: ---
double d;
std::vector<int> v1 { d };
only gives a warning instead of an error.
Unlike https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783,
here IMO there is a clear requoirement to result in an error because:
5.4.1 List-initialization [dcl.init.list] says:
> Otherwise, if T is a class type, constructors are considered. The applicable
> constructors are enumerated
> and the best one is chosen through overload resolution (13.3, 13.3.1.7). If a
> narrowing conversion (see
> below) is required to convert any of the arguments, the program is ill-formed.
and later:
> struct B {
> B(std::initializer_list<int>);
> };
> B b1 { 1, 2 }; // creates initializer_list<int> and calls constructor
> B b2 { 1, 2.0 }; // error: narrowing
This looks to me like my example, except that d is no constant.
But I see no difference between constants and avriables applied here
because according to 5.4.1 List-initialization [dcl.init.list]:
> A narrowing conversion is an implicit conversion
> — from a floating-point type to an integer type
Applies to all versions since C++11.
It tried 5.4.0 and other versions.
