https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120053
Bug ID: 120053
Summary: __is_trivially_constructible() requiring default
member initializer unnecessarily
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: thiago at kde dot org
Target Milestone: ---
Testcase:
#include <type_traits>
template <bool ShouldWarn> struct QThreadStorageTraits { };
template <class T> struct QThreadStorage
{
using Trait =
QThreadStorageTraits<std::is_trivially_default_constructible_v<T>>;
};
struct QQuick3DProfilerSceneGraphData
{
struct Timings {
unsigned nesting = 0;
};
template<unsigned size>
struct TimingData
{
Timings timings[size];
};
QThreadStorage<TimingData<1>> eventTimings;
};
With GCC 14, 15 and trunk (in Godbolt), this produces:
type_traits:3584:7: error: default member initializer for
'QQuick3DProfilerSceneGraphData::Timings::nesting' required before the end of
its enclosing class
3584 | = __is_trivially_constructible(_Tp);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This doesn't make sense. It looks like an internal state bug.
Godbolt run: https://gcc.godbolt.org/z/6nf7sGMP7
Fortunately, this identified a type that ought to have been trivial and wasn't.
