https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69127
Bug ID: 69127
Summary: inconsistent handling of initializers of zero-length
array members
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
G++ accepts zero-length array members as an extension, however as the test case
below shows, it doesn't handle their initialization consistently. In the test
case, since they are all equivalent, the constructors of all of B1, B2, and B3
should either all be rejected or all accepted.
As a data point, Clang rejects all three. I would suggest to follow suit.
$ cat u.c && ~/bin/gcc-5.1.0/bin/g++ -Wall -Wextra -std=c++11 u.c
struct A { A (int); };
struct B1 {
A a[0];
} b1;
struct B2 {
B2 (): a () { } // accepted
A a[0];
} b2;
struct B3 {
B3 () = default;
A a[0];
} b3;
u.c:5:3: error: use of deleted function ‘B1::B1()’
} b1;
^
u.c:3:8: note: ‘B1::B1()’ is implicitly deleted because the default definition
would be ill-formed:
struct B1 {
^
u.c:3:8: error: no matching function for call to ‘A::A()’
u.c:1:12: note: candidate: A::A(int)
struct A { A (int); };
^
u.c:1:12: note: candidate expects 1 argument, 0 provided
u.c:1:8: note: candidate: constexpr A::A(const A&)
struct A { A (int); };
^
u.c:1:8: note: candidate expects 1 argument, 0 provided
u.c:1:8: note: candidate: constexpr A::A(A&&)
u.c:1:8: note: candidate expects 1 argument, 0 provided
u.c:15:3: error: use of deleted function ‘B3::B3()’
} b3;
^
u.c:13:3: note: ‘B3::B3()’ is implicitly deleted because the default definition
would be ill-formed:
B3 () = default;
^
u.c:13:3: error: no matching function for call to ‘A::A()’
u.c:1:12: note: candidate: A::A(int)
struct A { A (int); };
^
u.c:1:12: note: candidate expects 1 argument, 0 provided
u.c:1:8: note: candidate: constexpr A::A(const A&)
struct A { A (int); };
^
u.c:1:8: note: candidate expects 1 argument, 0 provided
u.c:1:8: note: candidate: constexpr A::A(A&&)
u.c:1:8: note: candidate expects 1 argument, 0 provided
