https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81911
Bug ID: 81911
Summary: Constant expression from permitted result of a
constant expression is not constexpr
Product: gcc
Version: 7.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: antoshkka at gmail dot com
Target Milestone: ---
The following code fails to compile:
int main() {
static const char someVar[] = "str";
constexpr auto c0 = someVar[0];
}
error: the value of 'someVar' is not usable in a constant expression
constexpr auto c0 = someVar[0];
^
This seems to be an error:
"In any constexpr variable declaration, the full-expression of the
initialization shall be a constant expression [expr.const]"
Where [expr.const] has the paragraphs:
"A constant expression is either a glvalue core constant expression that refers
to an entity that is a permitted result of a constant expression <skip>
An entity is a permitted result of a constant expression if it is an object
with static storage duration that is either not a temporary object <skip>"
