https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79398
Bug ID: 79398
Summary: misleading error static constexpr member function
called in a constant expression before its definition
is complete
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
The error below is a bit confusing: the definition of B::bar() is complete when
it's called.
I think I understand that the reason for the error below is actually that the
function is called before the definition of the class of which it's a member is
complete. The error should make that clear, although it seems that accepting
it (e.g., as an extension) would make static constexpr member functions quite a
bit more useful.
$ cat y.C && gcc -S -Wall -Wextra -Wpedantic y.C
struct A {
static constexpr int foo () { return 1; }
};
struct B: A {
static constexpr int bar () { return 2; }
enum E { e = B::foo () };
enum F { f = B::bar () };
};
y.C:8:23: error: ‘static constexpr int B::bar()’ called in a constant
expression before its definition is complete
enum F { f = B::bar () };
~~~~~~~^~
y.C:8:24: error: enumerator value for ‘f’ is not an integer constant
enum F { f = B::bar () };
^
