https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89548
Bug ID: 89548
Summary: reinterpret_cast treats xvalue as prvalue
Product: gcc
Version: 8.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ndkrempel at gmail dot com
Target Milestone: ---
The following program fails to compile (with -std= any of c++11, c++14, c++17,
c++2a):
int main() {
reinterpret_cast<int&&>(static_cast<int&&>(0));
}
The error reported is:
gcc-xvalue-bug.cc: In function ‘int main()’:
gcc-xvalue-bug.cc:8:48: error: invalid cast of an rvalue expression of type
‘int’ to type ‘int&&’
reinterpret_cast<int&&>(static_cast<int&&>(0));
I.e. reinterpret_cast is treating its argument as a prvalue of type "int"
rather than an xvalue of type "int&&". Testing indicates that the return value
from the static_cast is of the correct type and value category, so the problem
lies with the reinterpret_cast.
The static_cast expression could also be replaced with a function returning
"int&&" and the same problem occurs.
The same problem also occurs when less trivial conversions are requested, for
example "reinterpret_cast<unsigned int&&>(static_cast<int&&>(0))".
For comparison, clang does not give an error, and that is consistent with my
reading of the standards.
