https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92856
Bug ID: 92856
Summary: incorrectly accepts invalid C++11 braced
initialisation of double from long double
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: marc at kdab dot com
Target Milestone: ---
The following code:
// https://godbolt.org/z/tWa2dr
int main() {
extern long double ld;
double d{ld};
}
is invalid according to [dcl.list.init]3.9
(http://eel.is/c++draft/dcl.init.list#3.9): regardless of a target's actual
size for these types, long double -> double is considered a narrowing
conversion [dcl.list.init]/7 (http://eel.is/c++draft/dcl.init.list#7.2), and
the compiler cannot use the constant expression loophole here.
Clang and MSVC correctly error on this.
Actual behaviour: GCC only warns (-Wnarrowing), even with -pedantic.
Expected behaviour: GCC does not accept this code.
This bug exists in all compiler versions, afaict (4.7.4, 4.8.3, 9.1, trunk).
