http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52915
Bug #: 52915
Summary: [C++11] Deleted default-constructor of anonymous
unions not honored
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: [email protected]
ReportedBy: [email protected]
gcc 4.8.0 20120318 (experimental) in C++11 mode accepts the following code:
//---
struct S {
int val;
S(int v) : val(v) {}
};
void f() {
union { S a; };
}
//---
This seems to violate to what the standard says. According to 9.5 p5:
"A union of the form
union { member-specification } ;
is called an anonymous union; it defines an unnamed object of unnamed type."
combined with 12.1 p5 b6:
"A defaulted default constructor for class X is defined as deleted if:
[..]
— any [..] non-static data member with no brace-or-equal-initializer, has class
type M [..] and [..] M has no default constructor [..]"
The last item has the effect that the anonymous union defined in f() is a
union-like class that has a deleted default constructor, but the definition in
f() also defines an unnamed object of that type which is default-initialized.
It seems that gcc does not respect the last part of the semantics of this
declaration.
